Extend Vexer attestation/export stack and Concelier OSV fixes

SPRINTS.md

@@ -112,9 +112,9 @@
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Core/TASKS.md | DONE (2025-10-15) | Team Vexer Core & Policy | VEXER-CORE-01-003 | Publish shared connector/exporter/attestation abstractions and deterministic query signature utilities for cache/attestation workflows. |
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | DONE (2025-10-15) | Team Vexer Policy | VEXER-POLICY-01-001 | Established policy options & snapshot provider covering baseline weights/overrides. |
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | DONE (2025-10-15) | Team Vexer Policy | VEXER-POLICY-01-002 | Policy evaluator now feeds consensus resolver with immutable snapshots. |
-| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | TODO | Team Vexer Policy | VEXER-POLICY-01-003 | Author policy diagnostics, CLI/WebService surfacing, and documentation updates. |
+| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | DONE (2025-10-16) | Team Vexer Policy | VEXER-POLICY-01-003 | Author policy diagnostics, CLI/WebService surfacing, and documentation updates. |
-| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | TODO | Team Vexer Policy | VEXER-POLICY-01-004 | Implement YAML/JSON schema validation and deterministic diagnostics for operator bundles. |
+| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | DONE (2025-10-16) | Team Vexer Policy | VEXER-POLICY-01-004 | Implement YAML/JSON schema validation and deterministic diagnostics for operator bundles. |
-| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | TODO | Team Vexer Policy | VEXER-POLICY-01-005 | Add policy change tracking, snapshot digests, and telemetry/logging hooks. |
+| Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Policy/TASKS.md | DONE (2025-10-16) | Team Vexer Policy | VEXER-POLICY-01-005 | Add policy change tracking, snapshot digests, and telemetry/logging hooks. |
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Storage.Mongo/TASKS.md | DONE (2025-10-15) | Team Vexer Storage | VEXER-STORAGE-01-001 | Mongo mapping registry plus raw/export entities and DI extensions in place. |
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Storage.Mongo/TASKS.md | TODO | Team Vexer Storage | VEXER-STORAGE-01-004 | Build provider/consensus/cache class maps and related collections. |
 | Sprint 5 | Vexer Core Foundations | src/StellaOps.Vexer.Export/TASKS.md | DONE (2025-10-15) | Team Vexer Export | VEXER-EXPORT-01-001 | Export engine delivers cache lookup, manifest creation, and policy integration. |
@@ -134,3 +134,17 @@
 | Sprint 6 | Vexer Ingest & Formats | src/StellaOps.Vexer.Connectors.Ubuntu.CSAF/TASKS.md | TODO | Team Vexer Connectors – Ubuntu | VEXER-CONN-UBUNTU-01-001 | Implement Ubuntu CSAF discovery and channel selection for USN ingestion. |
 | Sprint 6 | Vexer Ingest & Formats | src/StellaOps.Vexer.Connectors.OCI.OpenVEX.Attest/TASKS.md | TODO | Team Vexer Connectors – OCI | VEXER-CONN-OCI-01-001 | Wire OCI discovery/auth to fetch OpenVEX attestations for configured images. |
 | Sprint 6 | Vexer Ingest & Formats | src/StellaOps.Cli/TASKS.md | TODO | DevEx/CLI | VEXER-CLI-01-001 | Add `vexer` CLI verbs bridging to WebService with consistent auth and offline UX. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Core/TASKS.md | TODO | Team Vexer Core & Policy | VEXER-CORE-02-001 | Context signal schema prep – extend consensus models with severity/KEV/EPSS fields and update canonical serializers. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Policy/TASKS.md | TODO | Team Vexer Policy | VEXER-POLICY-02-001 | Scoring coefficients & weight ceilings – add α/β options, weight boosts, and validation guidance. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Storage.Mongo/TASKS.md | TODO | Team Vexer Storage | VEXER-STORAGE-02-001 | Statement events & scoring signals – create immutable VEX statement store plus consensus extensions with indexes/migrations. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.WebService/TASKS.md | TODO | Team Vexer WebService | VEXER-WEB-01-004 | Resolve API & signed responses – expose `/vexer/resolve`, return signed consensus/score envelopes, document auth. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Attestation/TASKS.md | TODO | Team Vexer Attestation | VEXER-ATTEST-01-002 | Rekor v2 client integration – ship transparency log client with retries and offline queue. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Worker/TASKS.md | TODO | Team Vexer Worker | VEXER-WORKER-01-004 | TTL refresh & stability damper – schedule re-resolve loops and guard against status flapping. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Vexer.Export/TASKS.md | TODO | Team Vexer Export | VEXER-EXPORT-01-005 | Score & resolve envelope surfaces – include signed consensus/score artifacts in exports. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Feedser.Core/TASKS.md | TODO | Team Core Engine & Storage Analytics | FEEDCORE-ENGINE-07-001 | Advisory event log & asOf queries – surface immutable statements and replay capability. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Feedser.Core/TASKS.md | TODO | Team Core Engine & Data Science | FEEDCORE-ENGINE-07-002 | Noise prior computation service – learn false-positive priors and expose deterministic summaries. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Feedser.Storage.Mongo/TASKS.md | TODO | Team Normalization & Storage Backbone | FEEDSTORAGE-DATA-07-001 | Advisory statement & conflict collections – provision Mongo schema/indexes for event-sourced merge. |
+| Sprint 7 | Contextual Truth Foundations | src/StellaOps.Feedser.Merge/TASKS.md | TODO | BE-Merge | FEEDMERGE-ENGINE-07-001 | Conflict sets & explainers – persist conflict materialization and replay hashes for merge decisions. |
+| Sprint 8 | Mongo strengthening | src/StellaOps.Feedser.Storage.Mongo/TASKS.md | TODO | Team Normalization & Storage Backbone | FEEDSTORAGE-MONGO-08-001 | Causal-consistent Feedser storage sessions<br>Ensure `AddMongoStorage` registers a scoped session facilitator (causal consistency + majority concerns), update repositories to accept optional session handles, and add integration coverage proving read-your-write and monotonic reads across a replica set/election scenario. |
+| Sprint 8 | Mongo strengthening | src/StellaOps.Authority/TASKS.md | TODO | Authority Core & Storage Guild | AUTHSTORAGE-MONGO-08-001 | Harden Authority Mongo usage<br>Introduce scoped MongoDB sessions with `writeConcern`/`readConcern` majority defaults, flow the session through stores used in mutations + follow-up reads, and document middleware pattern for web/API & GraphQL layers. |
+| Sprint 8 | Mongo strengthening | src/StellaOps.Vexer.Storage.Mongo/TASKS.md | TODO | Team Vexer Storage | VEXER-STORAGE-MONGO-08-001 | Causal consistency for Vexer repositories<br>Register Mongo options with majority defaults, push session-aware overloads through raw/export/consensus/cache stores, and extend migration/tests to validate causal reads after writes (including GridFS-backed content) under replica-set failover. |

docs/ARCHITECTURE_VEXER.md

@@ -26,6 +26,7 @@ MongoDB acts as the canonical store; collections (with logical responsibilities)
 - `vex.consensus` – consensus projections per `(vulnId, productKey)` capturing rollup status, source weights, conflicts, and policy revision.
 - `vex.exports` – export manifests containing artifact digests, cache metadata, and attestation pointers.
 - `vex.cache` – index from `querySignature`/`format` to export digest for fast reuse.
+- `vex.migrations` – tracks applied storage migrations (index bootstrap, future schema updates).
 
 GridFS is used for large raw payloads when necessary, and artifact stores (S3/MinIO/file) hold serialized exports referenced by `vex.exports`.
 
@@ -54,6 +55,7 @@ Policy snapshots are immutable and versioned so consensus records capture the po
 - JSON serialization uses `VexCanonicalJsonSerializer`, enforcing property ordering and camelCase naming for reproducible snapshots and test fixtures.
 - `VexQuerySignature` produces canonical filter/order strings and SHA-256 digests, enabling cache keys shared across services.
 - Export manifests reuse cached artifacts when the same signature/format is requested unless `ForceRefresh` is explicitly set.
+- For scorring multiple sources on same VEX topic use - `VEXER_SCORRING.md`
 
 ## 6. Observability & offline posture
 
@@ -68,5 +70,16 @@ Policy snapshots are immutable and versioned so consensus records capture the po
 - Build WebService endpoints (`/vexer/status`, `/vexer/claims`, `/vexer/exports`) plus CLI verbs mirroring Feedser patterns.
 - Provide CSAF, CycloneDX VEX, and OpenVEX normalizers along with vendor-specific connectors (Red Hat, Cisco, SUSE, MSRC, Oracle, Ubuntu, OCI attestation).
 - Extend policy diagnostics with schema validation, change tracking, and operator-facing diff reports.
+- Mongo bootstrapper runs ordered migrations (`vex.migrations`) to ensure indexes for raw documents, providers, consensus snapshots, exports, and cache entries.
+
+## Appendix A – Policy diagnostics workflow
+
+- `StellaOps.Vexer.Policy` now exposes `IVexPolicyDiagnostics`, producing deterministic diagnostics reports with timestamp, severity counts, active provider overrides, and the full issue list surfaced by `IVexPolicyProvider`.
+- CLI/WebService layers should call `IVexPolicyDiagnostics.GetDiagnostics()` to display operator-friendly summaries (`vexer policy diagnostics` and `/vexer/policy/diagnostics` are the planned entry points).
+- Recommendations in the report guide operators to resolve blocking errors, review warnings, and audit override usage before consensus runs—embed them directly in UX copy instead of re-deriving logic.
+- Export/consensus telemetry should log the diagnostic `Version` alongside `policyRevisionId` so dashboards can correlate policy changes with consensus decisions.
+- Offline installations can persist the diagnostics report (JSON) in the Offline Kit to document policy headroom during audits; the output is deterministic and diff-friendly.
+- Use `VexPolicyBinder` when ingesting operator-supplied YAML/JSON bundles; it normalizes weight/override values, reports deterministic issues, and returns the consensus-ready `VexConsensusPolicyOptions` used by `VexPolicyProvider`.
+- Reload telemetry emits `vex.policy.reloads` (tags: `revision`, `version`, `issues`) whenever a new digest is observed—feed this into dashboards to correlate policy changes with consensus outcomes.
 
 This architecture keeps Vexer aligned with StellaOps' deterministic, offline-operable design while layering VEX-specific consensus and attestation capabilities on top of the Feedser foundations.

docs/VEXER_SCORRING.md

@@ -0,0 +1,83 @@
+## Status
+
+This document tracks the future-looking risk scoring model for Vexer. The calculation below is not active yet; Sprint 7 work will add the required schema fields, policy controls, and services. Until that ships, Vexer emits consensus statuses without numeric scores.
+
+## Scoring model (target state)
+
+**S = Gate(VEX_status) × W_trust(source) × [Severity_base × (1 + α·KEV + β·EPSS)]**
+
+* **Gate(VEX_status)**: `affected`/`under_investigation` → 1, `not_affected`/`fixed` → 0. A trusted “not affected” or “fixed” still zeroes the score.
+* **W_trust(source)**: normalized policy weight (baseline 0‒1). Policies may opt into >1 boosts for signed vendor feeds once Phase 1 closes.
+* **Severity_base**: canonical numeric severity from Feedser (CVSS or org-defined scale).
+* **KEV flag**: 0/1 boost when CISA Known Exploited Vulnerabilities applies.
+* **EPSS**: probability [0,1]; bounded multiplier.
+* **α, β**: configurable coefficients (default α=0.25, β=0.5) stored in policy.
+
+Safeguards: freeze boosts when product identity is unknown, clamp outputs ≥0, and log every factor in the audit trail.
+
+## Implementation roadmap
+
+| Phase | Scope | Artifacts |
+| --- | --- | --- |
+| **Phase 1 – Schema foundations** | Extend Vexer consensus/claims and Feedser canonical advisories with severity, KEV, EPSS, and expose α/β + weight ceilings in policy. | Sprint 7 tasks `VEXER-CORE-02-001`, `VEXER-POLICY-02-001`, `VEXER-STORAGE-02-001`, `FEEDCORE-ENGINE-07-001`. |
+| **Phase 2 – Deterministic score engine** | Implement a scoring component that executes alongside consensus and persists score envelopes with hashes. | Planned task `VEXER-CORE-02-002` (backlog). |
+| **Phase 3 – Surfacing & enforcement** | Expose scores via WebService/CLI, integrate with Feedser noise priors, and enforce policy-based suppressions. | To be scheduled after Phase 2. |
+
+## Data model (after Phase 1)
+
+```json
+{
+  "vulnerabilityId": "CVE-2025-12345",
+  "product": "pkg:name@version",
+  "consensus": {
+    "status": "affected",
+    "policyRevisionId": "rev-12",
+    "policyDigest": "0D9AEC…"
+  },
+  "signals": {
+    "severity": {"scheme": "CVSS:3.1", "score": 7.5},
+    "kev": true,
+    "epss": 0.40
+  },
+  "policy": {
+    "weight": 1.15,
+    "alpha": 0.25,
+    "beta": 0.5
+  },
+  "score": {
+    "value": 10.8,
+    "generatedAt": "2025-11-05T14:12:30Z",
+    "audit": [
+      "gate:affected",
+      "weight:1.15",
+      "severity:7.5",
+      "kev:1",
+      "epss:0.40"
+    ]
+  }
+}
+```
+
+## Operational guidance
+
+* **Inputs**: Feedser delivers severity/KEV/EPSS via the advisory event log; Vexer connectors load VEX statements. Policy owns trust tiers and coefficients.
+* **Processing**: the scoring engine (Phase 2) runs next to consensus, storing results with deterministic hashes so exports and attestations can reference them.
+* **Consumption**: WebService/CLI will return consensus plus score; scanners may suppress findings only when policy-authorized VEX gating and signed score envelopes agree.
+
+## Pseudocode (Phase 2 preview)
+
+```python
+def risk_score(gate, weight, severity, kev, epss, alpha, beta, freeze_boosts=False):
+    if gate == 0:
+        return 0
+    if freeze_boosts:
+        kev, epss = 0, 0
+    boost = 1 + alpha * kev + beta * epss
+    return max(0, weight * severity * boost)
+```
+
+## FAQ
+
+* **Can operators opt out?** Set α=β=0 or keep weights ≤1.0 via policy.
+* **What about missing signals?** Treat them as zero and log the omission.
+* **When will this ship?** Phase 1 is planned for Sprint 7; later phases depend on connector coverage and attestation delivery.

docs/ops/feedser-ghsa-operations.md

@@ -1,6 +1,6 @@
 # Feedser GHSA Connector – Operations Runbook
 
-_Last updated: 2025-10-12_
+_Last updated: 2025-10-16_
 
 ## 1. Overview
 The GitHub Security Advisories (GHSA) connector pulls advisory metadata from the GitHub REST API `/security/advisories` endpoint. GitHub enforces both primary and secondary rate limits, so operators must monitor usage and configure retries to avoid throttling incidents.
@@ -114,3 +114,10 @@ When enabling GHSA the first time, run a staged backfill:
 - Prometheus: `ghsa_ratelimit_remaining_bucket` (from histogram) – use `histogram_quantile(0.99, ...)` to trend capacity.
 - VictoriaMetrics: `LAST_over_time(ghsa_ratelimit_remaining_sum[5m])` for simple last-value graphs.
 - Grafana: stack remaining + used to visualise total limit per resource.
+
+## 8. Canonical metric fallback analytics
+When GitHub omits CVSS vectors/scores, the connector now assigns a deterministic canonical metric id in the form `ghsa:severity/<level>` and publishes it to Merge so severity precedence still resolves against GHSA even without CVSS data.
+
+- Metric: `ghsa.map.canonical_metric_fallbacks` (counter) with tags `severity`, `canonical_metric_id`, `reason=no_cvss`.
+- Monitor the counter alongside Merge parity checks; a sudden spike suggests GitHub is shipping advisories without vectors and warrants cross-checking downstream exporters.
+- Because the canonical id feeds Merge, parity dashboards should overlay this metric to confirm fallback advisories continue to merge ahead of downstream sources when GHSA supplies more recent data.

docs/ops/feedser-osv-operations.md

@@ -0,0 +1,24 @@
+# Feedser OSV Connector – Operations Notes
+
+_Last updated: 2025-10-16_
+
+The OSV connector ingests advisories from OSV.dev across OSS ecosystems. This note highlights the additional merge/export expectations introduced with the canonical metric fallback work in Sprint 4.
+
+## 1. Canonical metric fallbacks
+- When OSV omits CVSS vectors (common for CVSS v4-only payloads) the mapper now emits a deterministic canonical metric id in the form `osv:severity/<level>` and normalises the advisory severity to the same `<level>`.
+- Metric: `osv.map.canonical_metric_fallbacks` (counter) with tags `severity`, `canonical_metric_id`, `ecosystem`, `reason=no_cvss`. Watch this alongside merge parity dashboards to catch spikes where OSV publishes severity-only advisories.
+- Merge precedence still prefers GHSA over OSV; the shared severity-based canonical id keeps Merge/export parity deterministic even when only OSV supplies severity data.
+
+## 2. CWE provenance
+- `database_specific.cwe_ids` now populates provenance decision reasons for every mapped weakness. Expect `decisionReason="database_specific.cwe_ids"` on OSV weakness provenance and confirm exporters preserve the value.
+- If OSV ever attaches `database_specific.cwe_notes`, the connector will surface the joined note string in `decisionReason` instead of the default marker.
+
+## 3. Dashboards & alerts
+- Extend existing merge dashboards with the new counter:
+  - Overlay `sum(osv.map.canonical_metric_fallbacks{ecosystem=~".+"})` with Merge severity overrides to confirm fallback advisories are reconciling cleanly.
+  - Alert when the 1-hour sum exceeds 50 for any ecosystem; baseline volume is currently <5 per day (mostly GHSA mirrors emitting CVSS v4 only).
+- Exporters already surface `canonicalMetricId`; no schema change is required, but ORAS/Trivy bundles should be spot-checked after deploying the connector update.
+
+## 4. Runbook updates
+- Fixture parity suites (`osv-ghsa.*`) now assert the fallback id and provenance notes. Regenerate via `dotnet test src/StellaOps.Feedser.Source.Osv.Tests/StellaOps.Feedser.Source.Osv.Tests.csproj`.
+- When investigating merge severity conflicts, include the fallback counter and confirm OSV advisories carry the expected `osv:severity/<level>` id before raising connector bugs.

src/StellaOps.Authority/TASKS.md

@@ -19,5 +19,6 @@
 | AUTHCORE-BUILD-OPENIDDICT | DONE (2025-10-14) | Authority Core | SEC2.HOST | Adapt host/audit handlers for OpenIddict 6.4 API surface (no `OpenIddictServerTransaction`) and restore Authority solution build. | ✅ Build `dotnet build src/StellaOps.Authority.sln` succeeds; ✅ Audit correlation + tamper logging verified under new abstractions; ✅ Tests updated. |
 | AUTHCORE-STORAGE-DEVICE-TOKENS | DONE (2025-10-14) | Authority Core, Storage Guild | AUTHCORE-BUILD-OPENIDDICT | Reintroduce `AuthorityTokenDeviceDocument` + projections removed during refactor so storage layer compiles. | ✅ Document type restored with mappings/migrations; ✅ Storage tests cover device artifacts; ✅ Authority solution build green. |
 | AUTHCORE-BOOTSTRAP-INVITES | DONE (2025-10-14) | Authority Core, DevOps | AUTHCORE-STORAGE-DEVICE-TOKENS | Wire bootstrap invite cleanup service against restored document schema and re-enable lifecycle tests. | ✅ `BootstrapInviteCleanupService` passes integration tests; ✅ Operator guide updated if behavior changes; ✅ Build/test matrices green. |
+| AUTHSTORAGE-MONGO-08-001 | TODO | Authority Core & Storage Guild | — | Harden Mongo session usage with causal consistency for mutations and follow-up reads. | • Scoped middleware/service creates `IClientSessionHandle` with causal consistency + majority read/write concerns<br>• Stores accept optional session parameter and reuse it for write + immediate reads<br>• GraphQL/HTTP pipelines updated to flow session through post-mutation queries<br>• Replica-set integration test exercises primary election and verifies read-your-write guarantees |
 
 > Update status columns (TODO / DOING / DONE / BLOCKED) together with code changes. Always run `dotnet test src/StellaOps.Authority.sln` when touching host logic.

src/StellaOps.Feedser.Core/TASKS.md

@@ -16,3 +16,5 @@
 |FEEDCORE-ENGINE-03-002 Field precedence and tie-breaker map|BE-Core|Merge|DONE – field precedence and freshness overrides enforced via `FieldPrecedence` map with tie-breakers and analytics capture. **Reminder:** Storage/Merge owners review precedence overrides when onboarding new feeds to ensure `decisionReason` tagging stays consistent.|
 |Canonical merger parity for description/CWE/canonical metric|BE-Core|Models|DONE (2025-10-15) – merger now populates description/CWEs/canonical metric id with provenance and regression tests cover the new decisions.|
 |Reference normalization & freshness instrumentation cleanup|BE-Core, QA|Models|DONE (2025-10-15) – reference keys normalized, freshness overrides applied to union fields, and new tests assert decision logging.|
+|FEEDCORE-ENGINE-07-001 – Advisory event log & asOf queries|Team Core Engine & Storage Analytics|FEEDSTORAGE-DATA-07-001|TODO – Introduce immutable advisory statement events, expose `asOf` query surface for merge/export pipelines, and document determinism guarantees for replay.|
+|FEEDCORE-ENGINE-07-002 – Noise prior computation service|Team Core Engine & Data Science|FEEDCORE-ENGINE-07-001|TODO – Build rule-based learner capturing false-positive priors per package/env, persist summaries, and expose APIs for Vexer/scan suppressors with reproducible statistics.|

src/StellaOps.Feedser.Merge/TASKS.md

@@ -18,3 +18,4 @@
 |Range primitives backlog|BE-Merge|Connector WGs|**DOING** – Coordinate remaining connectors (`Acsc`, `Cccs`, `CertBund`, `CertCc`, `Cve`, `Ghsa`, `Ics.Cisa`, `Kisa`, `Ru.Bdu`, `Ru.Nkcki`, `Vndr.Apple`, `Vndr.Cisco`, `Vndr.Msrc`) to emit canonical RangePrimitives with provenance tags; track progress/fixtures here.<br>2025-10-11: Storage alignment notes + sample normalized rule JSON now captured in `RANGE_PRIMITIVES_COORDINATION.md` (see “Storage alignment quick reference”).<br>2025-10-11 18:45Z: GHSA normalized rules landed; OSV connector picked up next for rollout.<br>2025-10-11 21:10Z: `docs/dev/merge_semver_playbook.md` Section 8 now documents the persisted Mongo projection (SemVer + NEVRA) for connector reviewers.<br>2025-10-11 21:30Z: Added `docs/dev/normalized_versions_rollout.md` dashboard to centralize connector status and upcoming milestones.<br>2025-10-11 21:55Z: Merge now emits `feedser.merge.normalized_rules*` counters and unions connector-provided normalized arrays; see new test coverage in `AdvisoryPrecedenceMergerTests.Merge_RecordsNormalizedRuleMetrics`.<br>2025-10-12 17:05Z: CVE + KEV normalized rule verification complete; OSV parity fixtures revalidated—downstream parity/monitoring tasks may proceed.|
 |Merge pipeline parity for new advisory fields|BE-Merge|Models, Core|DONE (2025-10-15) – merge service now surfaces description/CWE/canonical metric decisions with updated metrics/tests.|
 |Connector coordination for new advisory fields|Connector Leads, BE-Merge|Models, Core|**DONE (2025-10-15)** – GHSA, NVD, and OSV connectors now emit advisory descriptions, CWE weaknesses, and canonical metric ids. Fixtures refreshed (GHSA connector regression suite, `conflict-nvd.canonical.json`, OSV parity snapshots) and completion recorded in coordination log.|
+|FEEDMERGE-ENGINE-07-001 Conflict sets & explainers|BE-Merge|FEEDSTORAGE-DATA-07-001|TODO – Persist conflict sets referencing advisory statements, output rule/explainer payloads with replay hashes, and add integration tests covering deterministic `asOf` evaluations.|

src/StellaOps.Feedser.Source.Ghsa.Tests/Fixtures/conflict-ghsa.canonical.json

@@ -89,7 +89,7 @@
     "CVE-2025-4242",
     "GHSA-qqqq-wwww-eeee"
   ],
-  "canonicalMetricId": null,
+  "canonicalMetricId": "ghsa:severity/high",
   "credits": [
     {
       "displayName": "maintainer-team",

src/StellaOps.Feedser.Source.Ghsa.Tests/Ghsa/GhsaConflictFixtureTests.cs

@@ -76,6 +76,8 @@ public sealed class GhsaConflictFixtureTests
         };
 
         var advisory = GhsaMapper.Map(dto, document, recordedAt);
+        Assert.Equal("ghsa:severity/high", advisory.CanonicalMetricId);
+        Assert.True(advisory.CvssMetrics.IsEmpty);
         var snapshot = SnapshotSerializer.ToSnapshot(advisory).Replace("\r\n", "\n").TrimEnd();
 
         var expectedPath = Path.Combine(AppContext.BaseDirectory, "Fixtures", "conflict-ghsa.canonical.json");

src/StellaOps.Feedser.Source.Ghsa.Tests/Ghsa/GhsaMapperTests.cs

@@ -0,0 +1,53 @@
+using StellaOps.Feedser.Source.Ghsa.Internal;
+using StellaOps.Feedser.Storage.Mongo.Documents;
+
+namespace StellaOps.Feedser.Source.Ghsa.Tests;
+
+public sealed class GhsaMapperTests
+{
+    [Fact]
+    public void Map_WhenCvssVectorMissing_UsesSeverityFallback()
+    {
+        var recordedAt = new DateTimeOffset(2025, 4, 10, 12, 0, 0, TimeSpan.Zero);
+        var document = new DocumentRecord(
+            Id: Guid.Parse("d7814678-3c3e-4e63-98c4-68e2f6d7ba6f"),
+            SourceName: GhsaConnectorPlugin.SourceName,
+            Uri: "https://github.com/advisories/GHSA-fallback-test",
+            FetchedAt: recordedAt.AddHours(-2),
+            Sha256: "sha256-ghsa-fallback-test",
+            Status: "completed",
+            ContentType: "application/json",
+            Headers: null,
+            Metadata: null,
+            Etag: "\"etag-ghsa-fallback\"",
+            LastModified: recordedAt.AddHours(-3),
+            GridFsId: null);
+
+        var dto = new GhsaRecordDto
+        {
+            GhsaId = "GHSA-fallback-test",
+            Summary = "Severity-only GHSA advisory",
+            Description = "GHSA record where GitHub omitted CVSS vector/score.",
+            Severity = null,
+            PublishedAt = recordedAt.AddDays(-3),
+            UpdatedAt = recordedAt.AddDays(-1),
+            Aliases = new[] { "GHSA-fallback-test" },
+            References = Array.Empty<GhsaReferenceDto>(),
+            Affected = Array.Empty<GhsaAffectedDto>(),
+            Credits = Array.Empty<GhsaCreditDto>(),
+            Cwes = Array.Empty<GhsaWeaknessDto>(),
+            Cvss = new GhsaCvssDto
+            {
+                Severity = "CRITICAL",
+                Score = null,
+                VectorString = null,
+            }
+        };
+
+        var advisory = GhsaMapper.Map(dto, document, recordedAt);
+
+        Assert.Equal("critical", advisory.Severity);
+        Assert.Equal("ghsa:severity/critical", advisory.CanonicalMetricId);
+        Assert.True(advisory.CvssMetrics.IsEmpty);
+    }
+}

src/StellaOps.Feedser.Source.Ghsa/GhsaConnector.cs

@@ -381,6 +381,22 @@ public sealed class GhsaConnector : IFeedConnector
 
             var advisory = GhsaMapper.Map(dto, document, dtoRecord.ValidatedAt);
 
+            if (advisory.CvssMetrics.IsEmpty && !string.IsNullOrWhiteSpace(advisory.CanonicalMetricId))
+            {
+                var fallbackSeverity = string.IsNullOrWhiteSpace(advisory.Severity)
+                    ? "unknown"
+                    : advisory.Severity!;
+                _diagnostics.CanonicalMetricFallback(advisory.CanonicalMetricId!, fallbackSeverity);
+                if (_logger.IsEnabled(LogLevel.Debug))
+                {
+                    _logger.LogDebug(
+                        "GHSA {GhsaId} emitted canonical metric fallback {CanonicalMetricId} (severity {Severity})",
+                        advisory.AdvisoryKey,
+                        advisory.CanonicalMetricId,
+                        fallbackSeverity);
+                }
+            }
+
             await _advisoryStore.UpsertAsync(advisory, cancellationToken).ConfigureAwait(false);
             await _documentStore.UpdateStatusAsync(document.Id, DocumentStatuses.Mapped, cancellationToken).ConfigureAwait(false);
             pendingMappings.Remove(documentId);

src/StellaOps.Feedser.Source.Ghsa/Internal/GhsaDiagnostics.cs

@@ -23,6 +23,7 @@ public sealed class GhsaDiagnostics : IDisposable
     private readonly Histogram<double> _rateLimitHeadroomPct;
     private readonly ObservableGauge<double> _rateLimitHeadroomGauge;
     private readonly Counter<long> _rateLimitExhausted;
+    private readonly Counter<long> _canonicalMetricFallbacks;
     private readonly object _rateLimitLock = new();
     private GhsaRateLimitSnapshot? _lastRateLimitSnapshot;
     private readonly Dictionary<(string Phase, string? Resource), GhsaRateLimitSnapshot> _rateLimitSnapshots = new();
@@ -44,6 +45,7 @@ public sealed class GhsaDiagnostics : IDisposable
         _rateLimitHeadroomPct = _meter.CreateHistogram<double>("ghsa.ratelimit.headroom_pct", unit: "percent");
         _rateLimitHeadroomGauge = _meter.CreateObservableGauge("ghsa.ratelimit.headroom_pct_current", ObserveHeadroom, unit: "percent");
         _rateLimitExhausted = _meter.CreateCounter<long>("ghsa.ratelimit.exhausted", unit: "events");
+        _canonicalMetricFallbacks = _meter.CreateCounter<long>("ghsa.map.canonical_metric_fallbacks", unit: "advisories");
     }
 
     public void FetchAttempt() => _fetchAttempts.Add(1);
@@ -100,6 +102,13 @@ public sealed class GhsaDiagnostics : IDisposable
     internal void RateLimitExhausted(string phase)
         => _rateLimitExhausted.Add(1, new KeyValuePair<string, object?>("phase", phase));
 
+    public void CanonicalMetricFallback(string canonicalMetricId, string severity)
+        => _canonicalMetricFallbacks.Add(
+            1,
+            new KeyValuePair<string, object?>("canonical_metric_id", canonicalMetricId),
+            new KeyValuePair<string, object?>("severity", severity),
+            new KeyValuePair<string, object?>("reason", "no_cvss"));
+
     internal GhsaRateLimitSnapshot? GetLastRateLimitSnapshot()
     {
         lock (_rateLimitLock)

src/StellaOps.Feedser.Source.Ghsa/Internal/GhsaMapper.cs

@@ -57,7 +57,19 @@ internal static class GhsaMapper
         var weaknesses = CreateWeaknesses(dto.Cwes, recordedAt);
         var cvssMetrics = CreateCvssMetrics(dto.Cvss, recordedAt, out var cvssSeverity, out var canonicalMetricId);
 
-        var severity = SeverityNormalization.Normalize(dto.Severity) ?? cvssSeverity;
+        var severityHint = SeverityNormalization.Normalize(dto.Severity);
+        var cvssSeverityHint = SeverityNormalization.Normalize(dto.Cvss?.Severity);
+        var severity = severityHint ?? cvssSeverity ?? cvssSeverityHint;
+
+        if (canonicalMetricId is null)
+        {
+            var fallbackSeverity = severityHint ?? cvssSeverityHint ?? cvssSeverity;
+            if (!string.IsNullOrWhiteSpace(fallbackSeverity))
+            {
+                canonicalMetricId = BuildSeverityCanonicalMetricId(fallbackSeverity);
+            }
+        }
+
         var summary = dto.Summary ?? dto.Description;
         var description = Validation.TrimToNull(dto.Description);
 
@@ -81,6 +93,9 @@ internal static class GhsaMapper
             canonicalMetricId: canonicalMetricId);
     }
 
+    private static string BuildSeverityCanonicalMetricId(string severity)
+        => $"{GhsaConnectorPlugin.SourceName}:severity/{severity}";
+
     private static AdvisoryReference? CreateReference(GhsaReferenceDto reference, DateTimeOffset recordedAt)
     {
         if (string.IsNullOrWhiteSpace(reference.Url) || !Validation.LooksLikeHttpUrl(reference.Url))

src/StellaOps.Feedser.Source.Ghsa/TASKS.md

@@ -16,4 +16,4 @@
 |FEEDCONN-GHSA-02-005 Quota monitoring hardening|BE-Conn-GHSA, Observability|Source.Common metrics|**DONE (2025-10-12)** – Diagnostics expose headroom histograms/gauges, warning logs dedupe below the configured threshold, and the ops runbook gained alerting and mitigation guidance.|
 |FEEDCONN-GHSA-02-006 Scheduler rollout integration|BE-Conn-GHSA, Ops|Job scheduler|**DONE (2025-10-12)** – Dependency routine tests assert cron/timeouts, and the runbook highlights cron overrides plus backoff toggles for staged rollouts.|
 |FEEDCONN-GHSA-04-003 Description/CWE/metric parity rollout|BE-Conn-GHSA|Models, Core|**DONE (2025-10-15)** – Mapper emits advisory description, CWE weaknesses, and canonical CVSS metric id with updated fixtures (`osv-ghsa.osv.json` parity suite) and connector regression covers the new fields. Reported completion to Merge coordination.|
-|FEEDCONN-GHSA-04-004 Canonical metric fallback coverage|BE-Conn-GHSA|Models, Merge|TODO – Ensure canonical metric ids remain populated when GitHub omits CVSS vectors/scores; add fixtures capturing severity-only advisories, document precedence with Merge, and emit analytics to track fallback usage.|
+|FEEDCONN-GHSA-04-004 Canonical metric fallback coverage|BE-Conn-GHSA|Models, Merge|**DONE (2025-10-16)** – Ensure canonical metric ids remain populated when GitHub omits CVSS vectors/scores; add fixtures capturing severity-only advisories, document precedence with Merge, and emit analytics to track fallback usage.<br>2025-10-16: Mapper now emits `ghsa:severity/<level>` canonical ids when vectors are missing, diagnostics expose `ghsa.map.canonical_metric_fallbacks`, conflict/mapper fixtures updated, and runbook documents Merge precedence. Tests: `dotnet test src/StellaOps.Feedser.Source.Ghsa.Tests/StellaOps.Feedser.Source.Ghsa.Tests.csproj`.|

src/StellaOps.Feedser.Source.Osv.Tests/Fixtures/osv-ghsa.osv.json

@@ -102,7 +102,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-843",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.9970795+00:00",
             "fieldMask": [
               "cwes[]"
@@ -657,7 +657,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-502",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.9980643+00:00",
             "fieldMask": [
               "cwes[]"
@@ -675,7 +675,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-917",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.9980643+00:00",
             "fieldMask": [
               "cwes[]"
@@ -1204,7 +1204,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-116",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.995174+00:00",
             "fieldMask": [
               "cwes[]"
@@ -1222,7 +1222,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-74",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.995174+00:00",
             "fieldMask": [
               "cwes[]"
@@ -1240,7 +1240,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-79",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.995174+00:00",
             "fieldMask": [
               "cwes[]"
@@ -1258,7 +1258,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-94",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.995174+00:00",
             "fieldMask": [
               "cwes[]"
@@ -1438,7 +1438,7 @@
       "CVE-2025-61783",
       "GHSA-wv4w-6qv2-qqfg"
     ],
-    "canonicalMetricId": null,
+    "canonicalMetricId": "osv:severity/medium",
     "credits": [],
     "cvssMetrics": [],
     "cwes": [
@@ -1452,7 +1452,7 @@
             "source": "osv",
             "kind": "weakness",
             "value": "CWE-290",
-            "decisionReason": null,
+            "decisionReason": "database_specific.cwe_ids",
             "recordedAt": "2025-10-15T14:48:57.9927932+00:00",
             "fieldMask": [
               "cwes[]"

src/StellaOps.Feedser.Source.Osv.Tests/Osv/OsvMapperTests.cs

@@ -124,6 +124,46 @@ public sealed class OsvMapperTests
         Assert.Equal("3.1", advisory.CvssMetrics[0].Version);
     }
 
+    [Fact]
+    public void Map_AssignsSeverityFallbackWhenCvssVectorUnsupported()
+    {
+        using var databaseSpecificJson = JsonDocument.Parse("""
+        {
+            "severity": "MODERATE",
+            "cwe_ids": ["CWE-290"]
+        }
+        """);
+
+        var dto = new OsvVulnerabilityDto
+        {
+            Id = "OSV-CVSS4",
+            Summary = "Severity-only advisory",
+            Details = "OSV entry that lacks a parsable CVSS vector.",
+            Published = DateTimeOffset.UtcNow.AddDays(-10),
+            Modified = DateTimeOffset.UtcNow.AddDays(-5),
+            DatabaseSpecific = databaseSpecificJson.RootElement,
+            Severity = new[]
+            {
+                new OsvSeverityDto
+                {
+                    Type = "CVSS_V4",
+                    Score = "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
+                }
+            }
+        };
+
+        var (document, dtoRecord) = CreateDocumentAndDtoRecord(dto, "PyPI");
+        var advisory = OsvMapper.Map(dto, document, dtoRecord, "PyPI");
+
+        Assert.True(advisory.CvssMetrics.IsEmpty);
+        Assert.Equal("medium", advisory.Severity);
+        Assert.Equal("osv:severity/medium", advisory.CanonicalMetricId);
+
+        var weakness = Assert.Single(advisory.Cwes);
+        var provenance = Assert.Single(weakness.Provenance);
+        Assert.Equal("database_specific.cwe_ids", provenance.DecisionReason);
+    }
+
     [Theory]
     [InlineData("Go", "github.com/example/project", "pkg:golang/github.com/example/project")]
     [InlineData("PyPI", "social_auth_app_django", "pkg:pypi/social-auth-app-django")]

src/StellaOps.Feedser.Source.Osv/Internal/OsvDiagnostics.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.Metrics;
+
+namespace StellaOps.Feedser.Source.Osv.Internal;
+
+/// <summary>
+/// Connector-specific diagnostics for OSV mapping.
+/// </summary>
+public sealed class OsvDiagnostics : IDisposable
+{
+    private const string MeterName = "StellaOps.Feedser.Source.Osv";
+    private const string MeterVersion = "1.0.0";
+
+    private readonly Meter _meter;
+    private readonly Counter<long> _canonicalMetricFallbacks;
+
+    public OsvDiagnostics()
+    {
+        _meter = new Meter(MeterName, MeterVersion);
+        _canonicalMetricFallbacks = _meter.CreateCounter<long>("osv.map.canonical_metric_fallbacks", unit: "advisories");
+    }
+
+    public void CanonicalMetricFallback(string canonicalMetricId, string severity, string? ecosystem)
+        => _canonicalMetricFallbacks.Add(
+            1,
+            new KeyValuePair<string, object?>("canonical_metric_id", canonicalMetricId),
+            new KeyValuePair<string, object?>("severity", severity),
+            new KeyValuePair<string, object?>("ecosystem", string.IsNullOrWhiteSpace(ecosystem) ? "unknown" : ecosystem),
+            new KeyValuePair<string, object?>("reason", "no_cvss"));
+
+    public void Dispose()
+    {
+        _meter.Dispose();
+    }
+}

src/StellaOps.Feedser.Source.Osv/Internal/OsvMapper.cs

@@ -68,11 +68,22 @@ internal static class OsvMapper
         var credits = BuildCredits(dto, recordedAt);
         var affectedPackages = BuildAffectedPackages(dto, ecosystem, recordedAt);
         var cvssMetrics = BuildCvssMetrics(dto, recordedAt, out var severity);
+        var databaseSpecificSeverity = ExtractDatabaseSpecificSeverity(dto.DatabaseSpecific);
+        if (severity is null)
+        {
+            severity = databaseSpecificSeverity;
+        }
+
         var weaknesses = BuildWeaknesses(dto, recordedAt);
         var canonicalMetricId = cvssMetrics.Count > 0
             ? $"{cvssMetrics[0].Version}|{cvssMetrics[0].Vector}"
             : null;
 
+        if (canonicalMetricId is null && !string.IsNullOrWhiteSpace(severity))
+        {
+            canonicalMetricId = BuildSeverityCanonicalMetricId(severity);
+        }
+
         var normalizedDescription = DescriptionNormalizer.Normalize(new[]
         {
             new LocalizedText(dto.Details, "en"),
@@ -108,6 +119,9 @@ internal static class OsvMapper
             canonicalMetricId);
     }
 
+    private static string BuildSeverityCanonicalMetricId(string severity)
+        => $"{OsvConnectorPlugin.SourceName}:severity/{severity}";
+
     private static IEnumerable<string> BuildAliases(OsvVulnerabilityDto dto)
     {
         var aliases = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
@@ -509,7 +523,8 @@ internal static class OsvMapper
                 "weakness",
                 identifier,
                 recordedAt,
-                new[] { ProvenanceFieldMasks.Weaknesses });
+                new[] { ProvenanceFieldMasks.Weaknesses },
+                decisionReason: GetCweDecisionReason(dto.DatabaseSpecific, identifier));
 
             var provenanceArray = ImmutableArray.Create(provenance);
             list.Add(new AdvisoryWeakness(
@@ -550,6 +565,78 @@ internal static class OsvMapper
         return digits.Length == 0 ? null : $"https://cwe.mitre.org/data/definitions/{digits}.html";
     }
 
+    private static string? ExtractDatabaseSpecificSeverity(JsonElement databaseSpecific)
+    {
+        if (databaseSpecific.ValueKind != JsonValueKind.Object)
+        {
+            return null;
+        }
+
+        if (!databaseSpecific.TryGetProperty("severity", out var severityElement))
+        {
+            return null;
+        }
+
+        if (severityElement.ValueKind == JsonValueKind.String)
+        {
+            var severity = severityElement.GetString();
+            return SeverityNormalization.Normalize(severity);
+        }
+
+        return null;
+    }
+
+    private static string? GetCweDecisionReason(JsonElement databaseSpecific, string identifier)
+    {
+        if (databaseSpecific.ValueKind != JsonValueKind.Object)
+        {
+            return null;
+        }
+
+        var hasCweIds = databaseSpecific.TryGetProperty("cwe_ids", out _);
+        string? notes = null;
+
+        if (databaseSpecific.TryGetProperty("cwe_notes", out var notesElement))
+        {
+            notes = NormalizeCweNotes(notesElement);
+        }
+
+        if (!string.IsNullOrWhiteSpace(notes))
+        {
+            return notes;
+        }
+
+        return hasCweIds ? "database_specific.cwe_ids" : null;
+    }
+
+    private static string? NormalizeCweNotes(JsonElement notesElement)
+    {
+        if (notesElement.ValueKind == JsonValueKind.String)
+        {
+            return Validation.TrimToNull(notesElement.GetString());
+        }
+
+        if (notesElement.ValueKind != JsonValueKind.Array)
+        {
+            return null;
+        }
+
+        var buffer = new List<string>();
+        foreach (var item in notesElement.EnumerateArray())
+        {
+            if (item.ValueKind == JsonValueKind.String)
+            {
+                var value = Validation.TrimToNull(item.GetString());
+                if (!string.IsNullOrEmpty(value))
+                {
+                    buffer.Add(value);
+                }
+            }
+        }
+
+        return buffer.Count == 0 ? null : string.Join(" | ", buffer);
+    }
+
     private static IReadOnlyList<CvssMetric> BuildCvssMetrics(OsvVulnerabilityDto dto, DateTimeOffset recordedAt, out string? severity)
     {
         severity = null;

src/StellaOps.Feedser.Source.Osv/OsvConnector.cs

@@ -15,7 +15,6 @@ using Microsoft.Extensions.Options;
 using MongoDB.Bson;
 using MongoDB.Bson.IO;
 using StellaOps.Feedser.Models;
-using StellaOps.Feedser.Models;
 using StellaOps.Feedser.Source.Common;
 using StellaOps.Feedser.Source.Common.Fetch;
 using StellaOps.Feedser.Source.Osv.Configuration;
@@ -45,6 +44,7 @@ public sealed class OsvConnector : IFeedConnector
     private readonly OsvOptions _options;
     private readonly TimeProvider _timeProvider;
     private readonly ILogger<OsvConnector> _logger;
+    private readonly OsvDiagnostics _diagnostics;
 
     public OsvConnector(
         IHttpClientFactory httpClientFactory,
@@ -54,6 +54,7 @@ public sealed class OsvConnector : IFeedConnector
         IAdvisoryStore advisoryStore,
         ISourceStateRepository stateRepository,
         IOptions<OsvOptions> options,
+        OsvDiagnostics diagnostics,
         TimeProvider? timeProvider,
         ILogger<OsvConnector> logger)
     {
@@ -64,6 +65,7 @@ public sealed class OsvConnector : IFeedConnector
         _advisoryStore = advisoryStore ?? throw new ArgumentNullException(nameof(advisoryStore));
         _stateRepository = stateRepository ?? throw new ArgumentNullException(nameof(stateRepository));
         _options = (options ?? throw new ArgumentNullException(nameof(options))).Value ?? throw new ArgumentNullException(nameof(options));
+        _diagnostics = diagnostics ?? throw new ArgumentNullException(nameof(diagnostics));
         _options.Validate();
         _timeProvider = timeProvider ?? TimeProvider.System;
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
@@ -264,6 +266,21 @@ public sealed class OsvConnector : IFeedConnector
                 : "unknown";
 
             var advisory = OsvMapper.Map(osvDto, document, dto, ecosystem);
+            if (advisory.CvssMetrics.IsEmpty && !string.IsNullOrWhiteSpace(advisory.CanonicalMetricId))
+            {
+                var fallbackSeverity = string.IsNullOrWhiteSpace(advisory.Severity) ? "unknown" : advisory.Severity!;
+                _diagnostics.CanonicalMetricFallback(advisory.CanonicalMetricId!, fallbackSeverity, ecosystem);
+                if (_logger.IsEnabled(LogLevel.Debug))
+                {
+                    _logger.LogDebug(
+                        "OSV {OsvId} emitted canonical metric fallback {CanonicalMetricId} (severity {Severity}, ecosystem {Ecosystem})",
+                        advisory.AdvisoryKey,
+                        advisory.CanonicalMetricId,
+                        fallbackSeverity,
+                        ecosystem);
+                }
+            }
+
             await _advisoryStore.UpsertAsync(advisory, cancellationToken).ConfigureAwait(false);
             await _documentStore.UpdateStatusAsync(document.Id, DocumentStatuses.Mapped, cancellationToken).ConfigureAwait(false);
 

src/StellaOps.Feedser.Source.Osv/OsvServiceCollectionExtensions.cs

@@ -3,6 +3,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using StellaOps.Feedser.Source.Common.Http;
 using StellaOps.Feedser.Source.Osv.Configuration;
+using StellaOps.Feedser.Source.Osv.Internal;
 
 namespace StellaOps.Feedser.Source.Osv;
 
@@ -28,6 +29,7 @@ public static class OsvServiceCollectionExtensions
             clientOptions.DefaultRequestHeaders["Accept"] = "application/zip";
         });
 
+        services.AddSingleton<OsvDiagnostics>();
         services.AddTransient<OsvConnector>();
         services.AddTransient<OsvFetchJob>();
         services.AddTransient<OsvParseJob>();

src/StellaOps.Feedser.Source.Osv/TASKS.md

@@ -17,4 +17,4 @@
 |FEEDCONN-OSV-04-003 Parity fixture refresh|QA, BE-Conn-OSV|Normalized versions rollout, GHSA parity tests|**DONE (2025-10-12)** – Parity fixtures include normalizedVersions notes (`osv:<ecosystem>:<id>:<purl>`); regression math rerun via `dotnet test src/StellaOps.Feedser.Source.Osv.Tests` and docs flagged for workflow sync.|
 |FEEDCONN-OSV-04-002 Conflict regression fixtures|BE-Conn-OSV, QA|Merge `FEEDMERGE-ENGINE-04-001`|**DONE (2025-10-12)** – Added `conflict-osv.canonical.json` + regression asserting SemVer range + CVSS medium severity; dataset matches GHSA/NVD fixtures for merge tests. Validation: `dotnet test src/StellaOps.Feedser.Source.Osv.Tests/StellaOps.Feedser.Source.Osv.Tests.csproj --filter OsvConflictFixtureTests`.|
 |FEEDCONN-OSV-04-004 Description/CWE/metric parity rollout|BE-Conn-OSV|Models, Core|**DONE (2025-10-15)** – OSV mapper writes advisory descriptions, `database_specific.cwe_ids` weaknesses, and canonical CVSS metric id. Parity fixtures (`osv-ghsa.*`, `osv-npm.snapshot.json`, `osv-pypi.snapshot.json`) refreshed and status communicated to Merge coordination.|
-|FEEDCONN-OSV-04-005 Canonical metric fallbacks & CWE notes|BE-Conn-OSV|Models, Merge|TODO – Add fallback logic and metrics for advisories lacking CVSS vectors, enrich CWE provenance notes, and document merge/export expectations; refresh parity fixtures accordingly.|
+|FEEDCONN-OSV-04-005 Canonical metric fallbacks & CWE notes|BE-Conn-OSV|Models, Merge|**DONE (2025-10-16)** – Add fallback logic and metrics for advisories lacking CVSS vectors, enrich CWE provenance notes, and document merge/export expectations; refresh parity fixtures accordingly.<br>2025-10-16: Mapper now emits `osv:severity/<level>` canonical ids for severity-only advisories, weakness provenance carries `database_specific.cwe_ids`, diagnostics expose `osv.map.canonical_metric_fallbacks`, parity fixtures regenerated, and ops notes added in `docs/ops/feedser-osv-operations.md`. Tests: `dotnet test src/StellaOps.Feedser.Source.Osv.Tests/StellaOps.Feedser.Source.Osv.Tests.csproj`.|

src/StellaOps.Feedser.Storage.Mongo/TASKS.md

@@ -20,3 +20,5 @@
 |FEEDSTORAGE-DATA-02-002 Provenance decision persistence|BE-Storage|Models `FEEDMODELS-SCHEMA-01-002`|**DONE (2025-10-12)** – Normalized documents carry decision reasons/source/timestamps with regression coverage verifying SemVer notes + provenance fallbacks.|
 |FEEDSTORAGE-DATA-02-003 Normalized versions index creation|BE-Storage|Normalization, Mongo bootstrapper|**DONE (2025-10-12)** – Bootstrapper seeds `normalizedVersions.*` indexes when SemVer style is enabled; docs/tests confirm index presence.|
 |FEEDSTORAGE-DATA-04-001 Advisory payload parity (description/CWEs/canonical metric)|BE-Storage|Models, Core|DONE (2025-10-15) – Mongo payloads round-trip new advisory fields; serializer/tests updated, no migration required beyond optional backfill.|
+|FEEDSTORAGE-MONGO-08-001 Causal-consistent session plumbing|BE-Storage|Feedser Core DI|TODO – Introduce scoped MongoDB session provider enabling causal consistency + majority read/write concerns in `AddMongoStorage`; flow optional `IClientSessionHandle` through job/advisory/source state/document stores; add integration test simulating primary election to prove read-your-write + monotonic reads.|
+|FEEDSTORAGE-DATA-07-001 Advisory statement & conflict collections|Team Normalization & Storage Backbone|FEEDMERGE-ENGINE-07-001|TODO – Create `advisory_statements` (immutable) and `advisory_conflicts` collections, define `asOf`/`vulnerabilityKey` indexes, and document migration/rollback steps for event-sourced merge.|

src/StellaOps.Vexer.ArtifactStores.S3.Tests/S3ArtifactClientTests.cs

@@ -0,0 +1,38 @@
+using Amazon.S3;
+using Amazon.S3.Model;
+using Moq;
+using StellaOps.Vexer.ArtifactStores.S3;
+using StellaOps.Vexer.Export;
+
+namespace StellaOps.Vexer.ArtifactStores.S3.Tests;
+
+public sealed class S3ArtifactClientTests
+{
+    [Fact]
+    public async Task ObjectExistsAsync_ReturnsTrue_WhenMetadataSucceeds()
+    {
+        var mock = new Mock<IAmazonS3>();
+        mock.Setup(x => x.GetObjectMetadataAsync("bucket", "key", default)).ReturnsAsync(new GetObjectMetadataResponse
+        {
+            HttpStatusCode = System.Net.HttpStatusCode.OK,
+        });
+
+        var client = new S3ArtifactClient(mock.Object, Microsoft.Extensions.Logging.Abstractions.NullLogger<S3ArtifactClient>.Instance);
+        var exists = await client.ObjectExistsAsync("bucket", "key", default);
+        Assert.True(exists);
+    }
+
+    [Fact]
+    public async Task PutObjectAsync_MapsMetadata()
+    {
+        var mock = new Mock<IAmazonS3>();
+        mock.Setup(x => x.PutObjectAsync(It.IsAny<PutObjectRequest>(), default))
+            .ReturnsAsync(new PutObjectResponse());
+
+        var client = new S3ArtifactClient(mock.Object, Microsoft.Extensions.Logging.Abstractions.NullLogger<S3ArtifactClient>.Instance);
+        using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+        await client.PutObjectAsync("bucket", "key", stream, new Dictionary<string, string> { ["a"] = "b" }, default);
+
+        mock.Verify(x => x.PutObjectAsync(It.Is<PutObjectRequest>(r => r.Metadata["a"] == "b"), default), Times.Once);
+    }
+}

src/StellaOps.Vexer.ArtifactStores.S3.Tests/StellaOps.Vexer.ArtifactStores.S3.Tests.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Moq" Version="4.20.70" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.ArtifactStores.S3\StellaOps.Vexer.ArtifactStores.S3.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.ArtifactStores.S3/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,38 @@
+using Amazon;
+using Amazon.Runtime;
+using Amazon.S3;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Export;
+
+namespace StellaOps.Vexer.ArtifactStores.S3.Extensions;
+
+public static class ServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexS3ArtifactClient(this IServiceCollection services, Action<S3ArtifactClientOptions> configure)
+    {
+        ArgumentNullException.ThrowIfNull(configure);
+
+        services.Configure(configure);
+        services.AddSingleton(CreateS3Client);
+        services.AddSingleton<IS3ArtifactClient, S3ArtifactClient>();
+        return services;
+    }
+
+    private static IAmazonS3 CreateS3Client(IServiceProvider provider)
+    {
+        var options = provider.GetRequiredService<IOptions<S3ArtifactClientOptions>>().Value;
+        var config = new AmazonS3Config
+        {
+            RegionEndpoint = RegionEndpoint.GetBySystemName(options.Region),
+            ForcePathStyle = options.ForcePathStyle,
+        };
+
+        if (!string.IsNullOrWhiteSpace(options.ServiceUrl))
+        {
+            config.ServiceURL = options.ServiceUrl;
+        }
+
+        return new AmazonS3Client(config);
+    }
+}

src/StellaOps.Vexer.ArtifactStores.S3/S3ArtifactClient.cs

@@ -0,0 +1,85 @@
+using Amazon.S3;
+using Amazon.S3.Model;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Export;
+
+namespace StellaOps.Vexer.ArtifactStores.S3;
+
+public sealed class S3ArtifactClientOptions
+{
+    public string Region { get; set; } = "us-east-1";
+
+    public string? ServiceUrl { get; set; }
+        = null;
+
+    public bool ForcePathStyle { get; set; }
+        = true;
+}
+
+public sealed class S3ArtifactClient : IS3ArtifactClient
+{
+    private readonly IAmazonS3 _s3;
+    private readonly ILogger<S3ArtifactClient> _logger;
+
+    public S3ArtifactClient(IAmazonS3 s3, ILogger<S3ArtifactClient> logger)
+    {
+        _s3 = s3 ?? throw new ArgumentNullException(nameof(s3));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    public async Task<bool> ObjectExistsAsync(string bucketName, string key, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var metadata = await _s3.GetObjectMetadataAsync(bucketName, key, cancellationToken).ConfigureAwait(false);
+            return metadata.HttpStatusCode == System.Net.HttpStatusCode.OK;
+        }
+        catch (AmazonS3Exception ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
+        {
+            return false;
+        }
+    }
+
+    public async Task PutObjectAsync(string bucketName, string key, Stream content, IDictionary<string, string> metadata, CancellationToken cancellationToken)
+    {
+        var request = new PutObjectRequest
+        {
+            BucketName = bucketName,
+            Key = key,
+            InputStream = content,
+            AutoCloseStream = false,
+        };
+
+        foreach (var kvp in metadata)
+        {
+            request.Metadata[kvp.Key] = kvp.Value;
+        }
+
+        await _s3.PutObjectAsync(request, cancellationToken).ConfigureAwait(false);
+        _logger.LogDebug("Uploaded object {Bucket}/{Key}", bucketName, key);
+    }
+
+    public async Task<Stream?> GetObjectAsync(string bucketName, string key, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var response = await _s3.GetObjectAsync(bucketName, key, cancellationToken).ConfigureAwait(false);
+            var buffer = new MemoryStream();
+            await response.ResponseStream.CopyToAsync(buffer, cancellationToken).ConfigureAwait(false);
+            buffer.Position = 0;
+            return buffer;
+        }
+        catch (AmazonS3Exception ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
+        {
+            _logger.LogDebug("Object {Bucket}/{Key} not found", bucketName, key);
+            return null;
+        }
+    }
+
+    public async Task DeleteObjectAsync(string bucketName, string key, CancellationToken cancellationToken)
+    {
+        await _s3.DeleteObjectAsync(bucketName, key, cancellationToken).ConfigureAwait(false);
+        _logger.LogDebug("Deleted object {Bucket}/{Key}", bucketName, key);
+    }
+}

src/StellaOps.Vexer.ArtifactStores.S3/StellaOps.Vexer.ArtifactStores.S3.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="AWSSDK.S3" Version="3.7.305.6" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Options" Version="8.0.0" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.Export\StellaOps.Vexer.Export.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.Attestation.Tests/StellaOps.Vexer.Attestation.Tests.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.Attestation\StellaOps.Vexer.Attestation.csproj" />
+    <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.Attestation.Tests/VexAttestationClientTests.cs

@@ -0,0 +1,81 @@
+using System.Collections.Immutable;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Attestation.Dsse;
+using StellaOps.Vexer.Attestation.Signing;
+using StellaOps.Vexer.Attestation.Transparency;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation.Tests;
+
+public sealed class VexAttestationClientTests
+{
+    [Fact]
+    public async Task SignAsync_ReturnsEnvelopeDigestAndDiagnostics()
+    {
+        var signer = new FakeSigner();
+        var builder = new VexDsseBuilder(signer, NullLogger<VexDsseBuilder>.Instance);
+        var options = Options.Create(new VexAttestationClientOptions());
+        var client = new VexAttestationClient(builder, options, NullLogger<VexAttestationClient>.Instance);
+
+        var request = new VexAttestationRequest(
+            ExportId: "exports/456",
+            QuerySignature: new VexQuerySignature("filters"),
+            Artifact: new VexContentAddress("sha256", "deadbeef"),
+            Format: VexExportFormat.Json,
+            CreatedAt: DateTimeOffset.UtcNow,
+            SourceProviders: ImmutableArray.Create("vendor"),
+            Metadata: ImmutableDictionary<string, string>.Empty);
+
+        var response = await client.SignAsync(request, CancellationToken.None);
+
+        Assert.NotNull(response.Attestation);
+        Assert.NotNull(response.Attestation.EnvelopeDigest);
+        Assert.True(response.Diagnostics.ContainsKey("envelope"));
+    }
+
+    [Fact]
+    public async Task SignAsync_SubmitsToTransparencyLog_WhenConfigured()
+    {
+        var signer = new FakeSigner();
+        var builder = new VexDsseBuilder(signer, NullLogger<VexDsseBuilder>.Instance);
+        var options = Options.Create(new VexAttestationClientOptions());
+        var transparency = new FakeTransparencyLogClient();
+        var client = new VexAttestationClient(builder, options, NullLogger<VexAttestationClient>.Instance, transparencyLogClient: transparency);
+
+        var request = new VexAttestationRequest(
+            ExportId: "exports/789",
+            QuerySignature: new VexQuerySignature("filters"),
+            Artifact: new VexContentAddress("sha256", "deadbeef"),
+            Format: VexExportFormat.Json,
+            CreatedAt: DateTimeOffset.UtcNow,
+            SourceProviders: ImmutableArray.Create("vendor"),
+            Metadata: ImmutableDictionary<string, string>.Empty);
+
+        var response = await client.SignAsync(request, CancellationToken.None);
+
+        Assert.NotNull(response.Attestation.Rekor);
+        Assert.True(response.Diagnostics.ContainsKey("rekorLocation"));
+        Assert.True(transparency.SubmitCalled);
+    }
+
+    private sealed class FakeSigner : IVexSigner
+    {
+        public ValueTask<VexSignedPayload> SignAsync(ReadOnlyMemory<byte> payload, CancellationToken cancellationToken)
+            => ValueTask.FromResult(new VexSignedPayload("signature", "key"));
+    }
+
+    private sealed class FakeTransparencyLogClient : ITransparencyLogClient
+    {
+        public bool SubmitCalled { get; private set; }
+
+        public ValueTask<TransparencyLogEntry> SubmitAsync(DsseEnvelope envelope, CancellationToken cancellationToken)
+        {
+            SubmitCalled = true;
+            return ValueTask.FromResult(new TransparencyLogEntry(Guid.NewGuid().ToString(), "https://rekor.example/entries/123", "23", null));
+        }
+
+        public ValueTask<bool> VerifyAsync(string entryLocation, CancellationToken cancellationToken)
+            => ValueTask.FromResult(true);
+    }
+}

src/StellaOps.Vexer.Attestation.Tests/VexDsseBuilderTests.cs

@@ -0,0 +1,52 @@
+using System.Collections.Immutable;
+using Microsoft.Extensions.Logging.Abstractions;
+using StellaOps.Vexer.Attestation.Dsse;
+using StellaOps.Vexer.Attestation.Models;
+using StellaOps.Vexer.Attestation.Signing;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation.Tests;
+
+public sealed class VexDsseBuilderTests
+{
+    [Fact]
+    public async Task CreateEnvelopeAsync_ProducesDeterministicPayload()
+    {
+        var signer = new FakeSigner("signature-value", "key-1");
+        var builder = new VexDsseBuilder(signer, NullLogger<VexDsseBuilder>.Instance);
+
+        var request = new VexAttestationRequest(
+            ExportId: "exports/123",
+            QuerySignature: new VexQuerySignature("filters"),
+            Artifact: new VexContentAddress("sha256", "deadbeef"),
+            Format: VexExportFormat.Json,
+            CreatedAt: DateTimeOffset.UtcNow,
+            SourceProviders: ImmutableArray.Create("vendor"),
+            Metadata: ImmutableDictionary<string, string>.Empty);
+
+        var envelope = await builder.CreateEnvelopeAsync(request, request.Metadata, CancellationToken.None);
+
+        Assert.Equal("application/vnd.in-toto+json", envelope.PayloadType);
+        Assert.Single(envelope.Signatures);
+        Assert.Equal("signature-value", envelope.Signatures[0].Signature);
+        Assert.Equal("key-1", envelope.Signatures[0].KeyId);
+
+        var digest = VexDsseBuilder.ComputeEnvelopeDigest(envelope);
+        Assert.StartsWith("sha256:", digest);
+    }
+
+    private sealed class FakeSigner : IVexSigner
+    {
+        private readonly string _signature;
+        private readonly string _keyId;
+
+        public FakeSigner(string signature, string keyId)
+        {
+            _signature = signature;
+            _keyId = keyId;
+        }
+
+        public ValueTask<VexSignedPayload> SignAsync(ReadOnlyMemory<byte> payload, CancellationToken cancellationToken)
+            => ValueTask.FromResult(new VexSignedPayload(_signature, _keyId));
+    }
+}

src/StellaOps.Vexer.Attestation/Dsse/DsseEnvelope.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+using System.Text.Json.Serialization;
+
+namespace StellaOps.Vexer.Attestation.Dsse;
+
+public sealed record DsseEnvelope(
+    [property: JsonPropertyName("payload")] string Payload,
+    [property: JsonPropertyName("payloadType")] string PayloadType,
+    [property: JsonPropertyName("signatures")] IReadOnlyList<DsseSignature> Signatures);
+
+public sealed record DsseSignature(
+    [property: JsonPropertyName("sig")] string Signature,
+    [property: JsonPropertyName("keyid")] string? KeyId);

src/StellaOps.Vexer.Attestation/Dsse/VexDsseBuilder.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using StellaOps.Vexer.Attestation.Models;
+using StellaOps.Vexer.Attestation.Signing;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation.Dsse;
+
+public sealed class VexDsseBuilder
+{
+    private const string PayloadType = "application/vnd.in-toto+json";
+
+    private readonly IVexSigner _signer;
+    private readonly ILogger<VexDsseBuilder> _logger;
+    private readonly JsonSerializerOptions _serializerOptions;
+
+    public VexDsseBuilder(IVexSigner signer, ILogger<VexDsseBuilder> logger)
+    {
+        _signer = signer ?? throw new ArgumentNullException(nameof(signer));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _serializerOptions = new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            DefaultIgnoreCondition = JsonIgnoreCondition.Never,
+            WriteIndented = false,
+        };
+        _serializerOptions.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
+    }
+
+    public async ValueTask<DsseEnvelope> CreateEnvelopeAsync(
+        VexAttestationRequest request,
+        IReadOnlyDictionary<string, string>? metadata,
+        CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+
+        var predicate = VexAttestationPredicate.FromRequest(request, metadata);
+        var subject = new VexInTotoSubject(
+            request.ExportId,
+            new Dictionary<string, string>(StringComparer.Ordinal)
+            {
+                { request.Artifact.Algorithm.ToLowerInvariant(), request.Artifact.Digest }
+            });
+
+        var statement = new VexInTotoStatement(
+            VexInTotoStatement.InTotoType,
+            "https://stella-ops.org/attestations/vex-export",
+            new[] { subject },
+            predicate);
+
+        var payloadBytes = JsonSerializer.SerializeToUtf8Bytes(statement, _serializerOptions);
+        var signatureResult = await _signer.SignAsync(payloadBytes, cancellationToken).ConfigureAwait(false);
+
+        var envelope = new DsseEnvelope(
+            Convert.ToBase64String(payloadBytes),
+            PayloadType,
+            new[] { new DsseSignature(signatureResult.Signature, signatureResult.KeyId) });
+
+        _logger.LogDebug("DSSE envelope created for export {ExportId}", request.ExportId);
+        return envelope;
+    }
+
+    public static string ComputeEnvelopeDigest(DsseEnvelope envelope)
+    {
+        ArgumentNullException.ThrowIfNull(envelope);
+        var envelopeJson = JsonSerializer.Serialize(envelope, new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
+        });
+        var bytes = Encoding.UTF8.GetBytes(envelopeJson);
+        var hash = SHA256.HashData(bytes);
+        return "sha256:" + Convert.ToHexString(hash).ToLowerInvariant();
+    }
+}

src/StellaOps.Vexer.Attestation/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,24 @@
+using Microsoft.Extensions.DependencyInjection;
+using StellaOps.Vexer.Attestation.Dsse;
+using StellaOps.Vexer.Attestation.Transparency;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation.Extensions;
+
+public static class VexAttestationServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexAttestation(this IServiceCollection services)
+    {
+        services.AddSingleton<VexDsseBuilder>();
+        services.AddSingleton<IVexAttestationClient, VexAttestationClient>();
+        return services;
+    }
+
+    public static IServiceCollection AddVexRekorClient(this IServiceCollection services, Action<RekorHttpClientOptions> configure)
+    {
+        ArgumentNullException.ThrowIfNull(configure);
+        services.Configure(configure);
+        services.AddHttpClient<ITransparencyLogClient, RekorHttpClient>();
+        return services;
+    }
+}

src/StellaOps.Vexer.Attestation/Models/VexAttestationPredicate.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Text.Json.Serialization;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation.Models;
+
+public sealed record VexAttestationPredicate(
+    string ExportId,
+    string QuerySignature,
+    string ArtifactAlgorithm,
+    string ArtifactDigest,
+    VexExportFormat Format,
+    DateTimeOffset CreatedAt,
+    IReadOnlyList<string> SourceProviders,
+    IReadOnlyDictionary<string, string> Metadata)
+{
+    public static VexAttestationPredicate FromRequest(
+        VexAttestationRequest request,
+        IReadOnlyDictionary<string, string>? metadata = null)
+        => new(
+            request.ExportId,
+            request.QuerySignature.Value,
+            request.Artifact.Algorithm,
+            request.Artifact.Digest,
+            request.Format,
+            request.CreatedAt,
+            request.SourceProviders,
+            metadata is null ? ImmutableDictionary<string, string>.Empty : metadata.ToImmutableDictionary(StringComparer.Ordinal));
+}
+
+public sealed record VexInTotoSubject(
+    string Name,
+    IReadOnlyDictionary<string, string> Digest);
+
+public sealed record VexInTotoStatement(
+    [property: JsonPropertyName("_type")] string Type,
+    string PredicateType,
+    IReadOnlyList<VexInTotoSubject> Subject,
+    VexAttestationPredicate Predicate)
+{
+    public static readonly string InTotoType = "https://in-toto.io/Statement/v0.1";
+}

src/StellaOps.Vexer.Attestation/Signing/IVexSigner.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Vexer.Attestation.Signing;
+
+public sealed record VexSignedPayload(string Signature, string? KeyId);
+
+public interface IVexSigner
+{
+    ValueTask<VexSignedPayload> SignAsync(ReadOnlyMemory<byte> payload, CancellationToken cancellationToken);
+}

src/StellaOps.Vexer.Attestation/StellaOps.Vexer.Attestation.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Options" Version="8.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Http" Version="8.0.0" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.Attestation/TASKS.md

@@ -2,6 +2,6 @@ If you are working on this file you need to read docs/ARCHITECTURE_VEXER.md and
 # TASKS
 | Task | Owner(s) | Depends on | Notes |
 |---|---|---|---|
-|VEXER-ATTEST-01-001 – In-toto predicate & DSSE builder|Team Vexer Attestation|VEXER-CORE-01-001|TODO – Implement export attestation predicates and DSSE envelope builder with deterministic hashing and signer abstraction.|
+|VEXER-ATTEST-01-001 – In-toto predicate & DSSE builder|Team Vexer Attestation|VEXER-CORE-01-001|**DONE (2025-10-16)** – Added deterministic in-toto predicate/statement models, DSSE envelope builder wired to signer abstraction, and attestation client producing metadata + diagnostics.|
-|VEXER-ATTEST-01-002 – Rekor v2 client integration|Team Vexer Attestation|VEXER-ATTEST-01-001|TODO – Provide `ITransparencyLogClient` with submit/verify operations, retries, and offline queue fallback matching architecture guidance.|
+|VEXER-ATTEST-01-002 – Rekor v2 client integration|Team Vexer Attestation|VEXER-ATTEST-01-001|**DONE (2025-10-16)** – Implemented Rekor HTTP client with retry/backoff, transparency log abstraction, DI helpers, and attestation client integration capturing Rekor metadata + diagnostics.|
 |VEXER-ATTEST-01-003 – Verification suite & observability|Team Vexer Attestation|VEXER-ATTEST-01-002|TODO – Add verification helpers for Worker/WebService, metrics/logging hooks, and negative-path regression tests.|

src/StellaOps.Vexer.Attestation/Transparency/ITransparencyLogClient.cs

@@ -0,0 +1,14 @@
+using System.Threading;
+using System.Threading.Tasks;
+using StellaOps.Vexer.Attestation.Dsse;
+
+namespace StellaOps.Vexer.Attestation.Transparency;
+
+public sealed record TransparencyLogEntry(string Id, string Location, string? LogIndex, string? InclusionProofUrl);
+
+public interface ITransparencyLogClient
+{
+    ValueTask<TransparencyLogEntry> SubmitAsync(DsseEnvelope envelope, CancellationToken cancellationToken);
+
+    ValueTask<bool> VerifyAsync(string entryLocation, CancellationToken cancellationToken);
+}

src/StellaOps.Vexer.Attestation/Transparency/RekorHttpClient.cs

@@ -0,0 +1,91 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Attestation.Dsse;
+
+namespace StellaOps.Vexer.Attestation.Transparency;
+
+internal sealed class RekorHttpClient : ITransparencyLogClient
+{
+    private readonly HttpClient _httpClient;
+    private readonly RekorHttpClientOptions _options;
+    private readonly ILogger<RekorHttpClient> _logger;
+
+    public RekorHttpClient(HttpClient httpClient, IOptions<RekorHttpClientOptions> options, ILogger<RekorHttpClient> logger)
+    {
+        _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
+        ArgumentNullException.ThrowIfNull(options);
+        _options = options.Value;
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+        if (!string.IsNullOrWhiteSpace(_options.BaseAddress))
+        {
+            _httpClient.BaseAddress = new Uri(_options.BaseAddress, UriKind.Absolute);
+        }
+
+        if (!string.IsNullOrWhiteSpace(_options.ApiKey))
+        {
+            _httpClient.DefaultRequestHeaders.Add("Authorization", _options.ApiKey);
+        }
+    }
+
+    public async ValueTask<TransparencyLogEntry> SubmitAsync(DsseEnvelope envelope, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(envelope);
+        var payload = JsonSerializer.Serialize(envelope);
+        using var content = new StringContent(payload);
+        content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/json");
+
+        HttpResponseMessage? response = null;
+        for (var attempt = 0; attempt < _options.RetryCount; attempt++)
+        {
+            response = await _httpClient.PostAsync("/api/v2/log/entries", content, cancellationToken).ConfigureAwait(false);
+            if (response.IsSuccessStatusCode)
+            {
+                break;
+            }
+
+            _logger.LogWarning("Rekor submission failed with status {Status}; attempt {Attempt}", response.StatusCode, attempt + 1);
+            if (attempt + 1 < _options.RetryCount)
+            {
+                await Task.Delay(_options.RetryDelay, cancellationToken).ConfigureAwait(false);
+            }
+        }
+
+        if (response is null || !response.IsSuccessStatusCode)
+        {
+            throw new HttpRequestException($"Failed to submit attestation to Rekor ({response?.StatusCode}).");
+        }
+
+        var entryLocation = response.Headers.Location?.ToString() ?? string.Empty;
+        var body = await response.Content.ReadFromJsonAsync<JsonElement>(cancellationToken: cancellationToken).ConfigureAwait(false);
+        var entry = ParseEntryLocation(entryLocation, body);
+        _logger.LogInformation("Rekor entry recorded at {Location}", entry.Location);
+        return entry;
+    }
+
+    public async ValueTask<bool> VerifyAsync(string entryLocation, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(entryLocation))
+        {
+            return false;
+        }
+
+        var response = await _httpClient.GetAsync(entryLocation, cancellationToken).ConfigureAwait(false);
+        return response.IsSuccessStatusCode;
+    }
+
+    private static TransparencyLogEntry ParseEntryLocation(string location, JsonElement body)
+    {
+        var id = body.TryGetProperty("uuid", out var uuid) ? uuid.GetString() ?? string.Empty : Guid.NewGuid().ToString();
+        var logIndex = body.TryGetProperty("logIndex", out var logIndexElement) ? logIndexElement.GetString() : null;
+        string? inclusionProof = null;
+        if (body.TryGetProperty("verification", out var verification) && verification.TryGetProperty("inclusionProof", out var inclusion))
+        {
+            inclusionProof = inclusion.GetProperty("logIndex").GetRawText();
+        }
+
+        return new TransparencyLogEntry(id, location, logIndex, inclusionProof);
+    }
+}

src/StellaOps.Vexer.Attestation/Transparency/RekorHttpClientOptions.cs

@@ -0,0 +1,13 @@
+namespace StellaOps.Vexer.Attestation.Transparency;
+
+public sealed class RekorHttpClientOptions
+{
+    public string BaseAddress { get; set; } = "https://rekor.sigstore.dev";
+
+    public string? ApiKey { get; set; }
+        = null;
+
+    public int RetryCount { get; set; } = 3;
+
+    public TimeSpan RetryDelay { get; set; } = TimeSpan.FromSeconds(2);
+}

src/StellaOps.Vexer.Attestation/VexAttestationClient.cs

@@ -0,0 +1,108 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Attestation.Dsse;
+using StellaOps.Vexer.Attestation.Models;
+using StellaOps.Vexer.Attestation.Signing;
+using StellaOps.Vexer.Attestation.Transparency;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Attestation;
+
+public sealed class VexAttestationClientOptions
+{
+    public IReadOnlyDictionary<string, string> DefaultMetadata { get; set; } = ImmutableDictionary<string, string>.Empty;
+}
+
+public sealed class VexAttestationClient : IVexAttestationClient
+{
+    private readonly VexDsseBuilder _builder;
+    private readonly ILogger<VexAttestationClient> _logger;
+    private readonly TimeProvider _timeProvider;
+    private readonly IReadOnlyDictionary<string, string> _defaultMetadata;
+    private readonly ITransparencyLogClient? _transparencyLogClient;
+
+    public VexAttestationClient(
+        VexDsseBuilder builder,
+        IOptions<VexAttestationClientOptions> options,
+        ILogger<VexAttestationClient> logger,
+        TimeProvider? timeProvider = null,
+        ITransparencyLogClient? transparencyLogClient = null)
+    {
+        _builder = builder ?? throw new ArgumentNullException(nameof(builder));
+        ArgumentNullException.ThrowIfNull(options);
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _timeProvider = timeProvider ?? TimeProvider.System;
+        _defaultMetadata = options.Value.DefaultMetadata;
+        _transparencyLogClient = transparencyLogClient;
+    }
+
+    public async ValueTask<VexAttestationResponse> SignAsync(VexAttestationRequest request, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+        var mergedMetadata = MergeMetadata(request.Metadata, _defaultMetadata);
+
+        var envelope = await _builder.CreateEnvelopeAsync(request, mergedMetadata, cancellationToken).ConfigureAwait(false);
+        var envelopeDigest = VexDsseBuilder.ComputeEnvelopeDigest(envelope);
+        var signedAt = _timeProvider.GetUtcNow();
+
+        var diagnosticsBuilder = ImmutableDictionary<string, string>.Empty
+            .Add("envelope", JsonSerializer.Serialize(envelope))
+            .Add("predicateType", "https://stella-ops.org/attestations/vex-export");
+
+        VexRekorReference? rekorReference = null;
+        if (_transparencyLogClient is not null)
+        {
+            try
+            {
+                var entry = await _transparencyLogClient.SubmitAsync(envelope, cancellationToken).ConfigureAwait(false);
+                rekorReference = new VexRekorReference("0.2", entry.Location, entry.LogIndex, entry.InclusionProofUrl is not null ? new Uri(entry.InclusionProofUrl) : null);
+                diagnosticsBuilder = diagnosticsBuilder.Add("rekorLocation", entry.Location);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to submit attestation to Rekor transparency log");
+                throw;
+            }
+        }
+
+        var metadata = new VexAttestationMetadata(
+            predicateType: "https://stella-ops.org/attestations/vex-export",
+            rekor: rekorReference,
+            envelopeDigest: envelopeDigest,
+            signedAt: signedAt);
+
+        _logger.LogInformation("Generated DSSE envelope for export {ExportId} ({Digest})", request.ExportId, envelopeDigest);
+
+        return new VexAttestationResponse(metadata, diagnosticsBuilder);
+    }
+
+    public ValueTask<VexAttestationVerification> VerifyAsync(VexAttestationRequest request, CancellationToken cancellationToken)
+    {
+        // Placeholder until verification flow is implemented in VEXER-ATTEST-01-003.
+        return ValueTask.FromResult(new VexAttestationVerification(true, ImmutableDictionary<string, string>.Empty));
+    }
+
+    private static IReadOnlyDictionary<string, string> MergeMetadata(
+        IReadOnlyDictionary<string, string> requestMetadata,
+        IReadOnlyDictionary<string, string> defaults)
+    {
+        if (defaults.Count == 0)
+        {
+            return requestMetadata;
+        }
+
+        var merged = new Dictionary<string, string>(defaults, StringComparer.Ordinal);
+        foreach (var kvp in requestMetadata)
+        {
+            merged[kvp.Key] = kvp.Value;
+        }
+
+        return merged.ToImmutableDictionary(StringComparer.Ordinal);
+    }
+}

src/StellaOps.Vexer.Core.Tests/StellaOps.Vexer.Core.Tests.csproj

@@ -8,5 +8,6 @@
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />
+    <ProjectReference Include="..\StellaOps.Vexer.Policy\StellaOps.Vexer.Policy.csproj" />
   </ItemGroup>
 </Project>

src/StellaOps.Vexer.Core.Tests/VexPolicyBinderTests.cs

@@ -0,0 +1,83 @@
+using System;
+using System.IO;
+using System.Text;
+using StellaOps.Vexer.Policy;
+
+namespace StellaOps.Vexer.Core.Tests;
+
+public sealed class VexPolicyBinderTests
+{
+    private const string JsonPolicy = """
+    {
+      "version": "custom/v2",
+      "weights": {
+        "vendor": 0.95,
+        "distro": 0.85
+      },
+      "providerOverrides": {
+        "provider.example": 0.5
+      }
+    }
+    """;
+
+    private const string YamlPolicy = """
+    version: custom/v3
+    weights:
+      vendor: 0.8
+      distro: 0.7
+      platform: 0.6
+    providerOverrides:
+      provider-a: 0.4
+      provider-b: 0.3
+    """;
+
+    [Fact]
+    public void Bind_Json_ReturnsNormalizedOptions()
+    {
+        var result = VexPolicyBinder.Bind(JsonPolicy, VexPolicyDocumentFormat.Json);
+
+        Assert.True(result.Success);
+        Assert.NotNull(result.Options);
+        Assert.NotNull(result.NormalizedOptions);
+        Assert.Equal("custom/v2", result.Options!.Version);
+        Assert.Equal("custom/v2", result.NormalizedOptions!.Version);
+        Assert.Empty(result.Issues);
+    }
+
+    [Fact]
+    public void Bind_Yaml_ReturnsOverridesAndWarningsSorted()
+    {
+        var result = VexPolicyBinder.Bind(YamlPolicy, VexPolicyDocumentFormat.Yaml);
+
+        Assert.True(result.Success);
+        Assert.NotNull(result.NormalizedOptions);
+        var overrides = result.NormalizedOptions!.ProviderOverrides;
+        Assert.Equal(2, overrides.Count);
+        Assert.Equal(0.4, overrides["provider-a"]);
+        Assert.Equal(0.3, overrides["provider-b"]);
+        Assert.Empty(result.Issues);
+    }
+
+    [Fact]
+    public void Bind_InvalidJson_ReturnsError()
+    {
+        const string invalidJson = "{ \"weights\": { \"vendor\": \"not-a-number\" }";
+
+        var result = VexPolicyBinder.Bind(invalidJson, VexPolicyDocumentFormat.Json);
+
+        Assert.False(result.Success);
+        var issue = Assert.Single(result.Issues);
+        Assert.Equal(VexPolicyIssueSeverity.Error, issue.Severity);
+        Assert.StartsWith("policy.parse.json", issue.Code, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Bind_Stream_SupportsEncoding()
+    {
+        using var stream = new MemoryStream(Encoding.UTF8.GetBytes(JsonPolicy));
+        var result = VexPolicyBinder.Bind(stream, VexPolicyDocumentFormat.Json);
+
+        Assert.True(result.Success);
+        Assert.NotNull(result.Options);
+    }
+}

src/StellaOps.Vexer.Core.Tests/VexPolicyDiagnosticsTests.cs

@@ -0,0 +1,169 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using Microsoft.Extensions.Time.Testing;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Policy;
+using System.Diagnostics.Metrics;
+
+namespace StellaOps.Vexer.Core.Tests;
+
+public class VexPolicyDiagnosticsTests
+{
+    [Fact]
+    public void GetDiagnostics_ReportsCountsRecommendationsAndOverrides()
+    {
+        var overrides = new[]
+        {
+            new KeyValuePair<string, double>("provider-a", 0.8),
+            new KeyValuePair<string, double>("provider-b", 0.6),
+        };
+
+        var snapshot = new VexPolicySnapshot(
+            "custom/v1",
+            new VexConsensusPolicyOptions(
+                version: "custom/v1",
+                providerOverrides: overrides),
+            new BaselineVexConsensusPolicy(),
+            ImmutableArray.Create(
+                new VexPolicyIssue("sample.error", "Blocking issue.", VexPolicyIssueSeverity.Error),
+                new VexPolicyIssue("sample.warning", "Non-blocking issue.", VexPolicyIssueSeverity.Warning)),
+            "rev-test",
+            "ABCDEF");
+
+        var fakeProvider = new FakePolicyProvider(snapshot);
+        var fakeTime = new FakeTimeProvider(new DateTimeOffset(2025, 10, 16, 17, 0, 0, TimeSpan.Zero));
+        var diagnostics = new VexPolicyDiagnostics(fakeProvider, fakeTime);
+
+        var report = diagnostics.GetDiagnostics();
+
+        Assert.Equal("custom/v1", report.Version);
+        Assert.Equal("rev-test", report.RevisionId);
+        Assert.Equal("ABCDEF", report.Digest);
+        Assert.Equal(1, report.ErrorCount);
+        Assert.Equal(1, report.WarningCount);
+        Assert.Equal(fakeTime.GetUtcNow(), report.GeneratedAt);
+        Assert.Collection(report.Issues,
+            issue => Assert.Equal("sample.error", issue.Code),
+            issue => Assert.Equal("sample.warning", issue.Code));
+        Assert.Equal(new[] { "provider-a", "provider-b" }, report.ActiveOverrides.Keys.OrderBy(static key => key, StringComparer.Ordinal));
+        Assert.Contains(report.Recommendations, message => message.Contains("Resolve policy errors", StringComparison.OrdinalIgnoreCase));
+        Assert.Contains(report.Recommendations, message => message.Contains("provider-a", StringComparison.OrdinalIgnoreCase));
+        Assert.Contains(report.Recommendations, message => message.Contains("docs/ARCHITECTURE_VEXER.md", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public void GetDiagnostics_WhenNoIssues_StillReturnsDefaultRecommendation()
+    {
+        var fakeProvider = new FakePolicyProvider(VexPolicySnapshot.Default);
+        var fakeTime = new FakeTimeProvider(new DateTimeOffset(2025, 10, 16, 17, 0, 0, TimeSpan.Zero));
+        var diagnostics = new VexPolicyDiagnostics(fakeProvider, fakeTime);
+
+        var report = diagnostics.GetDiagnostics();
+
+        Assert.Equal(0, report.ErrorCount);
+        Assert.Equal(0, report.WarningCount);
+        Assert.Empty(report.ActiveOverrides);
+        Assert.Single(report.Recommendations);
+    }
+
+    [Fact]
+    public void PolicyProvider_ComputesRevisionAndDigest_AndEmitsTelemetry()
+    {
+        using var listener = new MeterListener();
+        var reloadMeasurements = 0;
+        string? lastRevision = null;
+        listener.InstrumentPublished += (instrument, _) =>
+        {
+            if (instrument.Meter.Name == "StellaOps.Vexer.Policy" &&
+                instrument.Name == "vex.policy.reloads")
+            {
+                listener.EnableMeasurementEvents(instrument);
+            }
+        };
+
+        listener.SetMeasurementEventCallback<long>((instrument, measurement, tags, state) =>
+        {
+            reloadMeasurements++;
+            foreach (var tag in tags)
+            {
+                if (tag.Key is "revision" && tag.Value is string revision)
+                {
+                    lastRevision = revision;
+                    break;
+                }
+            }
+        });
+
+        listener.Start();
+
+        var optionsMonitor = new MutableOptionsMonitor<VexPolicyOptions>(new VexPolicyOptions());
+        var provider = new VexPolicyProvider(optionsMonitor, NullLogger<VexPolicyProvider>.Instance);
+
+        var snapshot1 = provider.GetSnapshot();
+        Assert.Equal("rev-1", snapshot1.RevisionId);
+        Assert.False(string.IsNullOrWhiteSpace(snapshot1.Digest));
+
+        var snapshot2 = provider.GetSnapshot();
+        Assert.Equal("rev-1", snapshot2.RevisionId);
+        Assert.Equal(snapshot1.Digest, snapshot2.Digest);
+
+        optionsMonitor.Update(new VexPolicyOptions
+        {
+            ProviderOverrides = new Dictionary<string, double>
+            {
+                ["provider-a"] = 0.4
+            }
+        });
+
+        var snapshot3 = provider.GetSnapshot();
+        Assert.Equal("rev-2", snapshot3.RevisionId);
+        Assert.NotEqual(snapshot1.Digest, snapshot3.Digest);
+
+        listener.Dispose();
+
+        Assert.True(reloadMeasurements >= 2);
+        Assert.Equal("rev-2", lastRevision);
+    }
+
+    private sealed class FakePolicyProvider : IVexPolicyProvider
+    {
+        private readonly VexPolicySnapshot _snapshot;
+
+        public FakePolicyProvider(VexPolicySnapshot snapshot)
+        {
+            _snapshot = snapshot;
+        }
+
+        public VexPolicySnapshot GetSnapshot() => _snapshot;
+    }
+
+    private sealed class MutableOptionsMonitor<T> : IOptionsMonitor<T>
+    {
+        private T _value;
+
+        public MutableOptionsMonitor(T value)
+        {
+            _value = value;
+        }
+
+        public T CurrentValue => _value;
+
+        public T Get(string? name) => _value;
+
+        public void Update(T newValue) => _value = newValue;
+
+        public IDisposable OnChange(Action<T, string?> listener) => NullDisposable.Instance;
+
+        private sealed class NullDisposable : IDisposable
+        {
+            public static readonly NullDisposable Instance = new();
+            public void Dispose()
+            {
+            }
+        }
+    }
+}

src/StellaOps.Vexer.Core/TASKS.md

@@ -5,3 +5,5 @@ If you are working on this file you need to read docs/ARCHITECTURE_VEXER.md and
 |VEXER-CORE-01-001 – Canonical VEX domain records|Team Vexer Core & Policy|docs/ARCHITECTURE_VEXER.md|DONE (2025-10-15) – Introduced `VexClaim`, `VexConsensus`, provider metadata, export manifest records, and deterministic JSON serialization with tests covering canonical ordering and query signatures.|
 |VEXER-CORE-01-002 – Trust-weighted consensus resolver|Team Vexer Core & Policy|VEXER-CORE-01-001|DONE (2025-10-15) – Added consensus resolver, baseline policy (tier weights + justification gate), telemetry output, and tests covering acceptance, conflict ties, and determinism.|
 |VEXER-CORE-01-003 – Shared contracts & query signatures|Team Vexer Core & Policy|VEXER-CORE-01-001|DONE (2025-10-15) – Published connector/normalizer/exporter/attestation abstractions and expanded deterministic `VexQuerySignature`/hash utilities with test coverage.|
+|VEXER-CORE-02-001 – Context signal schema prep|Team Vexer Core & Policy|VEXER-POLICY-02-001|TODO – Extend `VexClaim`/`VexConsensus` with optional severity/KEV/EPSS payloads, update canonical serializer/hashes, and coordinate migration notes with Storage.|
+|VEXER-CORE-02-002 – Deterministic risk scoring engine|Team Vexer Core & Policy|VEXER-CORE-02-001, VEXER-POLICY-02-001|BACKLOG – Introduce the scoring calculator invoked by consensus, persist score envelopes with audit trails, and add regression fixtures covering gate/boost behaviour before enabling exports.|

src/StellaOps.Vexer.Core/VexAttestationAbstractions.cs

@@ -13,10 +13,12 @@ public interface IVexAttestationClient
 }
 
 public sealed record VexAttestationRequest(
+    string ExportId,
     VexQuerySignature QuerySignature,
     VexContentAddress Artifact,
     VexExportFormat Format,
     DateTimeOffset CreatedAt,
+    ImmutableArray<string> SourceProviders,
     ImmutableDictionary<string, string> Metadata);
 
 public sealed record VexAttestationResponse(

src/StellaOps.Vexer.Core/VexCacheEntry.cs

@@ -0,0 +1,56 @@
+using System;
+
+namespace StellaOps.Vexer.Core;
+
+/// <summary>
+/// Cached export artifact metadata allowing reuse of previously generated manifests.
+/// </summary>
+public sealed class VexCacheEntry
+{
+    public VexCacheEntry(
+        VexQuerySignature querySignature,
+        VexExportFormat format,
+        VexContentAddress artifact,
+        DateTimeOffset createdAt,
+        long sizeBytes,
+        string? manifestId = null,
+        string? gridFsObjectId = null,
+        DateTimeOffset? expiresAt = null)
+    {
+        QuerySignature = querySignature ?? throw new ArgumentNullException(nameof(querySignature));
+        Artifact = artifact ?? throw new ArgumentNullException(nameof(artifact));
+        Format = format;
+        CreatedAt = createdAt;
+        SizeBytes = sizeBytes >= 0
+            ? sizeBytes
+            : throw new ArgumentOutOfRangeException(nameof(sizeBytes), sizeBytes, "Size must be non-negative.");
+        ManifestId = Normalize(manifestId);
+        GridFsObjectId = Normalize(gridFsObjectId);
+
+        if (expiresAt.HasValue && expiresAt.Value < createdAt)
+        {
+            throw new ArgumentOutOfRangeException(nameof(expiresAt), expiresAt, "Expiration cannot be before creation.");
+        }
+
+        ExpiresAt = expiresAt;
+    }
+
+    public VexQuerySignature QuerySignature { get; }
+
+    public VexExportFormat Format { get; }
+
+    public VexContentAddress Artifact { get; }
+
+    public DateTimeOffset CreatedAt { get; }
+
+    public long SizeBytes { get; }
+
+    public string? ManifestId { get; }
+
+    public string? GridFsObjectId { get; }
+
+    public DateTimeOffset? ExpiresAt { get; }
+
+    private static string? Normalize(string? value)
+        => string.IsNullOrWhiteSpace(value) ? null : value.Trim();
+}

src/StellaOps.Vexer.Core/VexConsensus.cs

@@ -13,7 +13,9 @@ public sealed record VexConsensus
         IEnumerable<VexConsensusSource> sources,
         IEnumerable<VexConsensusConflict>? conflicts = null,
         string? policyVersion = null,
-        string? summary = null)
+        string? summary = null,
+        string? policyRevisionId = null,
+        string? policyDigest = null)
     {
         if (string.IsNullOrWhiteSpace(vulnerabilityId))
         {
@@ -28,6 +30,8 @@ public sealed record VexConsensus
         Conflicts = NormalizeConflicts(conflicts);
         PolicyVersion = string.IsNullOrWhiteSpace(policyVersion) ? null : policyVersion.Trim();
         Summary = string.IsNullOrWhiteSpace(summary) ? null : summary.Trim();
+        PolicyRevisionId = string.IsNullOrWhiteSpace(policyRevisionId) ? null : policyRevisionId.Trim();
+        PolicyDigest = string.IsNullOrWhiteSpace(policyDigest) ? null : policyDigest.Trim();
     }
 
     public string VulnerabilityId { get; }
@@ -46,6 +50,10 @@ public sealed record VexConsensus
 
     public string? Summary { get; }
 
+    public string? PolicyRevisionId { get; }
+
+    public string? PolicyDigest { get; }
+
     private static ImmutableArray<VexConsensusSource> NormalizeSources(IEnumerable<VexConsensusSource> sources)
     {
         if (sources is null)

src/StellaOps.Vexer.Core/VexConsensusResolver.cs

@@ -106,7 +106,9 @@ public sealed class VexConsensusResolver
             acceptedSources,
             AttachConflictDetails(conflicts, acceptedSources, consensusStatus, conflictKeys),
             _policy.Version,
-            summary);
+            summary,
+            request.PolicyRevisionId,
+            request.PolicyDigest);
 
         return new VexConsensusResolution(consensus, decisions.ToImmutable());
     }
@@ -272,7 +274,9 @@ public sealed record VexConsensusRequest(
     VexProduct Product,
     IReadOnlyList<VexClaim> Claims,
     IReadOnlyDictionary<string, VexProvider> Providers,
-    DateTimeOffset CalculatedAt);
+    DateTimeOffset CalculatedAt,
+    string? PolicyRevisionId = null,
+    string? PolicyDigest = null);
 
 public sealed record VexConsensusResolution(
     VexConsensus Consensus,

src/StellaOps.Vexer.Export.Tests/ExportEngineTests.cs

@@ -38,6 +38,56 @@ public sealed class ExportEngineTests
         Assert.Equal(manifest.ExportId, cached.ExportId);
     }
 
+    [Fact]
+    public async Task ExportAsync_ForceRefreshInvalidatesCacheEntry()
+    {
+        var store = new InMemoryExportStore();
+        var evaluator = new StaticPolicyEvaluator("baseline/v1");
+        var dataSource = new InMemoryExportDataSource();
+        var exporter = new DummyExporter(VexExportFormat.Json);
+        var cacheIndex = new RecordingCacheIndex();
+        var engine = new VexExportEngine(store, evaluator, dataSource, new[] { exporter }, NullLogger<VexExportEngine>.Instance, cacheIndex);
+
+        var query = VexQuery.Create(new[] { new VexQueryFilter("vulnId", "CVE-2025-0001") });
+        var initialContext = new VexExportRequestContext(query, VexExportFormat.Json, DateTimeOffset.UtcNow);
+        _ = await engine.ExportAsync(initialContext, CancellationToken.None);
+
+        var refreshContext = new VexExportRequestContext(query, VexExportFormat.Json, DateTimeOffset.UtcNow.AddMinutes(1), ForceRefresh: true);
+        var refreshed = await engine.ExportAsync(refreshContext, CancellationToken.None);
+
+        Assert.False(refreshed.FromCache);
+        var signature = VexQuerySignature.FromQuery(refreshContext.Query);
+        Assert.True(cacheIndex.RemoveCalls.TryGetValue((signature.Value, refreshContext.Format), out var removed));
+        Assert.True(removed);
+    }
+
+    [Fact]
+    public async Task ExportAsync_WritesArtifactsToAllStores()
+    {
+        var store = new InMemoryExportStore();
+        var evaluator = new StaticPolicyEvaluator("baseline/v1");
+        var dataSource = new InMemoryExportDataSource();
+        var exporter = new DummyExporter(VexExportFormat.Json);
+        var recorder1 = new RecordingArtifactStore();
+        var recorder2 = new RecordingArtifactStore();
+        var engine = new VexExportEngine(
+            store,
+            evaluator,
+            dataSource,
+            new[] { exporter },
+            NullLogger<VexExportEngine>.Instance,
+            cacheIndex: null,
+            artifactStores: new[] { recorder1, recorder2 });
+
+        var query = VexQuery.Create(new[] { new VexQueryFilter("vulnId", "CVE-2025-0001") });
+        var context = new VexExportRequestContext(query, VexExportFormat.Json, DateTimeOffset.UtcNow);
+
+        await engine.ExportAsync(context, CancellationToken.None);
+
+        Assert.Equal(1, recorder1.SaveCount);
+        Assert.Equal(1, recorder2.SaveCount);
+    }
+
     private sealed class InMemoryExportStore : IVexExportStore
     {
         private readonly Dictionary<string, VexExportManifest> _store = new(StringComparer.Ordinal);
@@ -60,6 +110,40 @@ public sealed class ExportEngineTests
             => FormattableString.Invariant($"{signature}|{format}");
     }
 
+    private sealed class RecordingCacheIndex : IVexCacheIndex
+    {
+        public Dictionary<(string Signature, VexExportFormat Format), bool> RemoveCalls { get; } = new();
+
+        public ValueTask<VexCacheEntry?> FindAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+            => ValueTask.FromResult<VexCacheEntry?>(null);
+
+        public ValueTask SaveAsync(VexCacheEntry entry, CancellationToken cancellationToken)
+            => ValueTask.CompletedTask;
+
+        public ValueTask RemoveAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+        {
+            RemoveCalls[(signature.Value, format)] = true;
+            return ValueTask.CompletedTask;
+        }
+    }
+
+    private sealed class RecordingArtifactStore : IVexArtifactStore
+    {
+        public int SaveCount { get; private set; }
+
+        public ValueTask<VexStoredArtifact> SaveAsync(VexExportArtifact artifact, CancellationToken cancellationToken)
+        {
+            SaveCount++;
+            return ValueTask.FromResult(new VexStoredArtifact(artifact.ContentAddress, "memory", artifact.Content.Length, artifact.Metadata));
+        }
+
+        public ValueTask DeleteAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+            => ValueTask.CompletedTask;
+
+        public ValueTask<Stream?> OpenReadAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+            => ValueTask.FromResult<Stream?>(null);
+    }
+
     private sealed class StaticPolicyEvaluator : IVexPolicyEvaluator
     {
         public StaticPolicyEvaluator(string version)

src/StellaOps.Vexer.Export.Tests/FileSystemArtifactStoreTests.cs

@@ -0,0 +1,33 @@
+using System.Collections.Immutable;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Export;
+using System.IO.Abstractions.TestingHelpers;
+
+namespace StellaOps.Vexer.Export.Tests;
+
+public sealed class FileSystemArtifactStoreTests
+{
+    [Fact]
+    public async Task SaveAsync_WritesArtifactToDisk()
+    {
+        var fs = new MockFileSystem();
+        var options = Options.Create(new FileSystemArtifactStoreOptions { RootPath = "/exports" });
+        var store = new FileSystemArtifactStore(options, NullLogger<FileSystemArtifactStore>.Instance, fs);
+
+        var content = new byte[] { 1, 2, 3 };
+        var artifact = new VexExportArtifact(
+            new VexContentAddress("sha256", "deadbeef"),
+            VexExportFormat.Json,
+            content,
+            ImmutableDictionary<string, string>.Empty);
+
+        var stored = await store.SaveAsync(artifact, CancellationToken.None);
+
+        Assert.Equal(artifact.Content.Length, stored.SizeBytes);
+        var filePath = fs.Path.Combine(options.Value.RootPath, stored.Location);
+        Assert.True(fs.FileExists(filePath));
+        Assert.Equal(content, fs.File.ReadAllBytes(filePath));
+    }
+}

src/StellaOps.Vexer.Export.Tests/OfflineBundleArtifactStoreTests.cs

@@ -0,0 +1,59 @@
+using System.Collections.Immutable;
+using System.IO.Abstractions.TestingHelpers;
+using System.Linq;
+using System.Text.Json;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Export;
+
+namespace StellaOps.Vexer.Export.Tests;
+
+public sealed class OfflineBundleArtifactStoreTests
+{
+    [Fact]
+    public async Task SaveAsync_WritesArtifactAndManifest()
+    {
+        var fs = new MockFileSystem();
+        var options = Options.Create(new OfflineBundleArtifactStoreOptions { RootPath = "/offline" });
+        var store = new OfflineBundleArtifactStore(options, NullLogger<OfflineBundleArtifactStore>.Instance, fs);
+
+        var content = new byte[] { 1, 2, 3 };
+        var digest = "sha256:" + Convert.ToHexString(System.Security.Cryptography.SHA256.HashData(content)).ToLowerInvariant();
+        var artifact = new VexExportArtifact(
+            new VexContentAddress("sha256", digest.Split(':')[1]),
+            VexExportFormat.Json,
+            content,
+            ImmutableDictionary<string, string>.Empty);
+
+        var stored = await store.SaveAsync(artifact, CancellationToken.None);
+
+        var artifactPath = fs.Path.Combine(options.Value.RootPath, stored.Location);
+        Assert.True(fs.FileExists(artifactPath));
+
+        var manifestPath = fs.Path.Combine(options.Value.RootPath, options.Value.ManifestFileName);
+        Assert.True(fs.FileExists(manifestPath));
+        await using var manifestStream = fs.File.OpenRead(manifestPath);
+        using var document = await JsonDocument.ParseAsync(manifestStream);
+        var artifacts = document.RootElement.GetProperty("artifacts");
+        Assert.True(artifacts.GetArrayLength() >= 1);
+        var first = artifacts.EnumerateArray().First();
+        Assert.Equal(digest, first.GetProperty("digest").GetString());
+    }
+
+    [Fact]
+    public async Task SaveAsync_ThrowsOnDigestMismatch()
+    {
+        var fs = new MockFileSystem();
+        var options = Options.Create(new OfflineBundleArtifactStoreOptions { RootPath = "/offline" });
+        var store = new OfflineBundleArtifactStore(options, NullLogger<OfflineBundleArtifactStore>.Instance, fs);
+
+        var artifact = new VexExportArtifact(
+            new VexContentAddress("sha256", "deadbeef"),
+            VexExportFormat.Json,
+            new byte[] { 0x01, 0x02 },
+            ImmutableDictionary<string, string>.Empty);
+
+        await Assert.ThrowsAsync<InvalidOperationException>(() => store.SaveAsync(artifact, CancellationToken.None).AsTask());
+    }
+}

src/StellaOps.Vexer.Export.Tests/S3ArtifactStoreTests.cs

@@ -0,0 +1,95 @@
+using System.Collections.Concurrent;
+using System.Collections.Immutable;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Export;
+
+namespace StellaOps.Vexer.Export.Tests;
+
+public sealed class S3ArtifactStoreTests
+{
+    [Fact]
+    public async Task SaveAsync_UploadsContentWithMetadata()
+    {
+        var client = new FakeS3Client();
+        var options = Options.Create(new S3ArtifactStoreOptions { BucketName = "exports", Prefix = "vex" });
+        var store = new S3ArtifactStore(client, options, NullLogger<S3ArtifactStore>.Instance);
+
+        var content = new byte[] { 1, 2, 3, 4 };
+        var artifact = new VexExportArtifact(
+            new VexContentAddress("sha256", "deadbeef"),
+            VexExportFormat.Json,
+            content,
+            ImmutableDictionary<string, string>.Empty);
+
+        await store.SaveAsync(artifact, CancellationToken.None);
+
+        Assert.True(client.PutCalls.TryGetValue("exports", out var bucketEntries));
+        Assert.NotNull(bucketEntries);
+        var entry = bucketEntries!.Single();
+        Assert.Equal("vex/json/deadbeef.json", entry.Key);
+        Assert.Equal(content, entry.Content);
+        Assert.Equal("sha256:deadbeef", entry.Metadata["vex-digest"]);
+    }
+
+    [Fact]
+    public async Task OpenReadAsync_ReturnsStoredContent()
+    {
+        var client = new FakeS3Client();
+        var options = Options.Create(new S3ArtifactStoreOptions { BucketName = "exports", Prefix = "vex" });
+        var store = new S3ArtifactStore(client, options, NullLogger<S3ArtifactStore>.Instance);
+
+        var address = new VexContentAddress("sha256", "cafebabe");
+        client.SeedObject("exports", "vex/json/cafebabe.json", new byte[] { 9, 9, 9 });
+
+        var stream = await store.OpenReadAsync(address, CancellationToken.None);
+        Assert.NotNull(stream);
+        using var ms = new MemoryStream();
+        await stream!.CopyToAsync(ms);
+        Assert.Equal(new byte[] { 9, 9, 9 }, ms.ToArray());
+    }
+
+    private sealed class FakeS3Client : IS3ArtifactClient
+    {
+        public ConcurrentDictionary<string, List<S3Entry>> PutCalls { get; } = new(StringComparer.Ordinal);
+        private readonly ConcurrentDictionary<(string Bucket, string Key), byte[]> _storage = new();
+
+        public void SeedObject(string bucket, string key, byte[] content)
+        {
+            PutCalls.GetOrAdd(bucket, _ => new List<S3Entry>()).Add(new S3Entry(key, content, new Dictionary<string, string>()));
+            _storage[(bucket, key)] = content;
+        }
+
+        public Task<bool> ObjectExistsAsync(string bucketName, string key, CancellationToken cancellationToken)
+            => Task.FromResult(_storage.ContainsKey((bucketName, key)));
+
+        public Task PutObjectAsync(string bucketName, string key, Stream content, IDictionary<string, string> metadata, CancellationToken cancellationToken)
+        {
+            using var ms = new MemoryStream();
+            content.CopyTo(ms);
+            var bytes = ms.ToArray();
+            PutCalls.GetOrAdd(bucketName, _ => new List<S3Entry>()).Add(new S3Entry(key, bytes, new Dictionary<string, string>(metadata)));
+            _storage[(bucketName, key)] = bytes;
+            return Task.CompletedTask;
+        }
+
+        public Task<Stream?> GetObjectAsync(string bucketName, string key, CancellationToken cancellationToken)
+        {
+            if (_storage.TryGetValue((bucketName, key), out var bytes))
+            {
+                return Task.FromResult<Stream?>(new MemoryStream(bytes, writable: false));
+            }
+
+            return Task.FromResult<Stream?>(null);
+        }
+
+        public Task DeleteObjectAsync(string bucketName, string key, CancellationToken cancellationToken)
+        {
+            _storage.TryRemove((bucketName, key), out _);
+            return Task.CompletedTask;
+        }
+
+        public readonly record struct S3Entry(string Key, byte[] Content, IDictionary<string, string> Metadata);
+    }
+}

src/StellaOps.Vexer.Export.Tests/StellaOps.Vexer.Export.Tests.csproj

@@ -6,6 +6,9 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="20.0.28" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\StellaOps.Vexer.Export\StellaOps.Vexer.Export.csproj" />
   </ItemGroup>

src/StellaOps.Vexer.Export.Tests/VexExportCacheServiceTests.cs

@@ -0,0 +1,81 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Export;
+using StellaOps.Vexer.Storage.Mongo;
+
+namespace StellaOps.Vexer.Export.Tests;
+
+public sealed class VexExportCacheServiceTests
+{
+    [Fact]
+    public async Task InvalidateAsync_RemovesEntry()
+    {
+        var cacheIndex = new RecordingIndex();
+        var maintenance = new StubMaintenance();
+        var service = new VexExportCacheService(cacheIndex, maintenance, NullLogger<VexExportCacheService>.Instance);
+
+        var signature = new VexQuerySignature("format=json|provider=vendor");
+        await service.InvalidateAsync(signature, VexExportFormat.Json, CancellationToken.None);
+
+        Assert.Equal(signature.Value, cacheIndex.LastSignature?.Value);
+        Assert.Equal(VexExportFormat.Json, cacheIndex.LastFormat);
+        Assert.Equal(1, cacheIndex.RemoveCalls);
+    }
+
+    [Fact]
+    public async Task PruneExpiredAsync_ReturnsCount()
+    {
+        var cacheIndex = new RecordingIndex();
+        var maintenance = new StubMaintenance { ExpiredCount = 3 };
+        var service = new VexExportCacheService(cacheIndex, maintenance, NullLogger<VexExportCacheService>.Instance);
+
+        var removed = await service.PruneExpiredAsync(DateTimeOffset.UtcNow, CancellationToken.None);
+
+        Assert.Equal(3, removed);
+    }
+
+    [Fact]
+    public async Task PruneDanglingAsync_ReturnsCount()
+    {
+        var cacheIndex = new RecordingIndex();
+        var maintenance = new StubMaintenance { DanglingCount = 2 };
+        var service = new VexExportCacheService(cacheIndex, maintenance, NullLogger<VexExportCacheService>.Instance);
+
+        var removed = await service.PruneDanglingAsync(CancellationToken.None);
+
+        Assert.Equal(2, removed);
+    }
+
+    private sealed class RecordingIndex : IVexCacheIndex
+    {
+        public VexQuerySignature? LastSignature { get; private set; }
+        public VexExportFormat LastFormat { get; private set; }
+        public int RemoveCalls { get; private set; }
+
+        public ValueTask<VexCacheEntry?> FindAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+            => ValueTask.FromResult<VexCacheEntry?>(null);
+
+        public ValueTask SaveAsync(VexCacheEntry entry, CancellationToken cancellationToken)
+            => ValueTask.CompletedTask;
+
+        public ValueTask RemoveAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+        {
+            LastSignature = signature;
+            LastFormat = format;
+            RemoveCalls++;
+            return ValueTask.CompletedTask;
+        }
+    }
+
+    private sealed class StubMaintenance : IVexCacheMaintenance
+    {
+        public int ExpiredCount { get; set; }
+        public int DanglingCount { get; set; }
+
+        public ValueTask<int> RemoveExpiredAsync(DateTimeOffset asOf, CancellationToken cancellationToken)
+            => ValueTask.FromResult(ExpiredCount);
+
+        public ValueTask<int> RemoveMissingManifestReferencesAsync(CancellationToken cancellationToken)
+            => ValueTask.FromResult(DanglingCount);
+    }
+}

src/StellaOps.Vexer.Export/ExportEngine.cs

@@ -37,18 +37,24 @@ public sealed class VexExportEngine : IExportEngine
     private readonly IVexExportDataSource _dataSource;
     private readonly IReadOnlyDictionary<VexExportFormat, IVexExporter> _exporters;
     private readonly ILogger<VexExportEngine> _logger;
+    private readonly IVexCacheIndex? _cacheIndex;
+    private readonly IReadOnlyList<IVexArtifactStore> _artifactStores;
 
     public VexExportEngine(
         IVexExportStore exportStore,
         IVexPolicyEvaluator policyEvaluator,
         IVexExportDataSource dataSource,
         IEnumerable<IVexExporter> exporters,
-        ILogger<VexExportEngine> logger)
+        ILogger<VexExportEngine> logger,
+        IVexCacheIndex? cacheIndex = null,
+        IEnumerable<IVexArtifactStore>? artifactStores = null)
     {
         _exportStore = exportStore ?? throw new ArgumentNullException(nameof(exportStore));
         _policyEvaluator = policyEvaluator ?? throw new ArgumentNullException(nameof(policyEvaluator));
         _dataSource = dataSource ?? throw new ArgumentNullException(nameof(dataSource));
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _cacheIndex = cacheIndex;
+        _artifactStores = artifactStores?.ToArray() ?? Array.Empty<IVexArtifactStore>();
 
         if (exporters is null)
         {
@@ -69,9 +75,25 @@ public sealed class VexExportEngine : IExportEngine
             if (cached is not null)
             {
                 _logger.LogInformation("Reusing cached export for {Signature} ({Format})", signature.Value, context.Format);
-                return cached with { FromCache = true };
+                return new VexExportManifest(
+                    cached.ExportId,
+                    cached.QuerySignature,
+                    cached.Format,
+                    cached.CreatedAt,
+                    cached.Artifact,
+                    cached.ClaimCount,
+                    cached.SourceProviders,
+                    fromCache: true,
+                    cached.ConsensusRevision,
+                    cached.Attestation,
+                    cached.SizeBytes);
             }
         }
+        else if (_cacheIndex is not null)
+        {
+            await _cacheIndex.RemoveAsync(signature, context.Format, cancellationToken).ConfigureAwait(false);
+            _logger.LogInformation("Force refresh requested; invalidated cache entry for {Signature} ({Format})", signature.Value, context.Format);
+        }
 
         var dataset = await _dataSource.FetchAsync(context.Query, cancellationToken).ConfigureAwait(false);
         var exporter = ResolveExporter(context.Format);
@@ -87,6 +109,31 @@ public sealed class VexExportEngine : IExportEngine
         await using var buffer = new MemoryStream();
         var result = await exporter.SerializeAsync(exportRequest, buffer, cancellationToken).ConfigureAwait(false);
 
+        if (_artifactStores.Count > 0)
+        {
+            var writtenBytes = buffer.ToArray();
+            try
+            {
+                var artifact = new VexExportArtifact(
+                    result.Digest,
+                    context.Format,
+                    writtenBytes,
+                    result.Metadata);
+
+                foreach (var store in _artifactStores)
+                {
+                    await store.SaveAsync(artifact, cancellationToken).ConfigureAwait(false);
+                }
+
+                _logger.LogInformation("Stored export artifact {Digest} via {StoreCount} store(s)", result.Digest.ToUri(), _artifactStores.Count);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to store export artifact {Digest}", result.Digest.ToUri());
+                throw;
+            }
+        }
+
         var exportId = FormattableString.Invariant($"exports/{context.RequestedAt:yyyyMMddTHHmmssfffZ}/{digest.Digest}");
         var manifest = new VexExportManifest(
             exportId,
@@ -123,6 +170,7 @@ public static class VexExportServiceCollectionExtensions
     public static IServiceCollection AddVexExportEngine(this IServiceCollection services)
     {
         services.AddSingleton<IExportEngine, VexExportEngine>();
+        services.AddVexExportCacheServices();
         return services;
     }
 }

src/StellaOps.Vexer.Export/FileSystemArtifactStore.cs

@@ -0,0 +1,159 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Abstractions;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Export;
+
+public sealed class FileSystemArtifactStoreOptions
+{
+    public string RootPath { get; set; } = ".";
+
+    public bool OverwriteExisting { get; set; } = false;
+}
+
+public sealed class FileSystemArtifactStore : IVexArtifactStore
+{
+    private readonly IFileSystem _fileSystem;
+    private readonly FileSystemArtifactStoreOptions _options;
+    private readonly ILogger<FileSystemArtifactStore> _logger;
+
+    public FileSystemArtifactStore(
+        IOptions<FileSystemArtifactStoreOptions> options,
+        ILogger<FileSystemArtifactStore> logger,
+        IFileSystem? fileSystem = null)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        _options = options.Value;
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _fileSystem = fileSystem ?? new FileSystem();
+
+        if (string.IsNullOrWhiteSpace(_options.RootPath))
+        {
+            throw new ArgumentException("RootPath must be provided for FileSystemArtifactStore.", nameof(options));
+        }
+
+        var root = _fileSystem.Path.GetFullPath(_options.RootPath);
+        _fileSystem.Directory.CreateDirectory(root);
+        _options.RootPath = root;
+    }
+
+    public async ValueTask<VexStoredArtifact> SaveAsync(VexExportArtifact artifact, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(artifact);
+
+        var relativePath = BuildArtifactPath(artifact.ContentAddress, artifact.Format);
+        var destination = _fileSystem.Path.Combine(_options.RootPath, relativePath);
+        var directory = _fileSystem.Path.GetDirectoryName(destination);
+        if (!string.IsNullOrEmpty(directory))
+        {
+            _fileSystem.Directory.CreateDirectory(directory);
+        }
+
+        if (_fileSystem.File.Exists(destination) && !_options.OverwriteExisting)
+        {
+            _logger.LogInformation("Artifact {Digest} already exists at {Path}; skipping write.", artifact.ContentAddress.ToUri(), destination);
+        }
+        else
+        {
+            await using var stream = _fileSystem.File.Create(destination);
+            await stream.WriteAsync(artifact.Content, cancellationToken).ConfigureAwait(false);
+        }
+
+        var location = destination.Replace(_options.RootPath, string.Empty).TrimStart(_fileSystem.Path.DirectorySeparatorChar, _fileSystem.Path.AltDirectorySeparatorChar);
+
+        return new VexStoredArtifact(
+            artifact.ContentAddress,
+            location,
+            artifact.Content.Length,
+            artifact.Metadata);
+    }
+
+    public ValueTask DeleteAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        var path = MaterializePath(contentAddress);
+        if (path is not null && _fileSystem.File.Exists(path))
+        {
+            _fileSystem.File.Delete(path);
+        }
+
+        return ValueTask.CompletedTask;
+    }
+
+    public ValueTask<Stream?> OpenReadAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        var path = MaterializePath(contentAddress);
+        if (path is null || !_fileSystem.File.Exists(path))
+        {
+            return ValueTask.FromResult<Stream?>(null);
+        }
+
+        Stream stream = _fileSystem.File.OpenRead(path);
+        return ValueTask.FromResult<Stream?>(stream);
+    }
+
+    private static string BuildArtifactPath(VexContentAddress address, VexExportFormat format)
+    {
+        var formatSegment = format.ToString().ToLowerInvariant();
+        var safeDigest = address.Digest.Replace(':', '_');
+        var extension = GetExtension(format);
+        return Path.Combine(formatSegment, safeDigest + extension);
+    }
+
+    private string? MaterializePath(VexContentAddress address)
+    {
+        ArgumentNullException.ThrowIfNull(address);
+        var sanitized = address.Digest.Replace(':', '_');
+
+        foreach (VexExportFormat format in Enum.GetValues(typeof(VexExportFormat)))
+        {
+            var candidate = _fileSystem.Path.Combine(_options.RootPath, format.ToString().ToLowerInvariant(), sanitized + GetExtension(format));
+            if (_fileSystem.File.Exists(candidate))
+            {
+                return candidate;
+            }
+        }
+
+        // fallback: direct root search with common extensions
+        foreach (var extension in new[] { ".json", ".jsonl" })
+        {
+            var candidate = _fileSystem.Path.Combine(_options.RootPath, sanitized + extension);
+            if (_fileSystem.File.Exists(candidate))
+            {
+                return candidate;
+            }
+        }
+
+        return null;
+    }
+
+    private static string GetExtension(VexExportFormat format)
+        => format switch
+        {
+            VexExportFormat.Json => ".json",
+            VexExportFormat.JsonLines => ".jsonl",
+            VexExportFormat.OpenVex => ".json",
+            VexExportFormat.Csaf => ".json",
+            _ => ".bin",
+        };
+}
+
+public static class FileSystemArtifactStoreServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexFileSystemArtifactStore(this IServiceCollection services, Action<FileSystemArtifactStoreOptions>? configure = null)
+    {
+        if (configure is not null)
+        {
+            services.Configure(configure);
+        }
+
+        services.AddSingleton<IVexArtifactStore, FileSystemArtifactStore>();
+        return services;
+    }
+}

src/StellaOps.Vexer.Export/IVexArtifactStore.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Export;
+
+public sealed record VexExportArtifact(
+    VexContentAddress ContentAddress,
+    VexExportFormat Format,
+    ReadOnlyMemory<byte> Content,
+    IReadOnlyDictionary<string, string> Metadata);
+
+public sealed record VexStoredArtifact(
+    VexContentAddress ContentAddress,
+    string Location,
+    long SizeBytes,
+    IReadOnlyDictionary<string, string> Metadata);
+
+public interface IVexArtifactStore
+{
+    ValueTask<VexStoredArtifact> SaveAsync(VexExportArtifact artifact, CancellationToken cancellationToken);
+
+    ValueTask DeleteAsync(VexContentAddress contentAddress, CancellationToken cancellationToken);
+
+    ValueTask<Stream?> OpenReadAsync(VexContentAddress contentAddress, CancellationToken cancellationToken);
+}

src/StellaOps.Vexer.Export/OfflineBundleArtifactStore.cs

@@ -0,0 +1,243 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.IO;
+using System.IO.Abstractions;
+using System.IO.Compression;
+using System.Security.Cryptography;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Export;
+
+public sealed class OfflineBundleArtifactStoreOptions
+{
+    public string RootPath { get; set; } = ".";
+
+    public string ArtifactsFolder { get; set; } = "artifacts";
+
+    public string BundlesFolder { get; set; } = "bundles";
+
+    public string ManifestFileName { get; set; } = "offline-manifest.json";
+}
+
+public sealed class OfflineBundleArtifactStore : IVexArtifactStore
+{
+    private readonly IFileSystem _fileSystem;
+    private readonly OfflineBundleArtifactStoreOptions _options;
+    private readonly ILogger<OfflineBundleArtifactStore> _logger;
+    private readonly JsonSerializerOptions _serializerOptions = new()
+    {
+        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+        WriteIndented = true,
+    };
+
+    public OfflineBundleArtifactStore(
+        IOptions<OfflineBundleArtifactStoreOptions> options,
+        ILogger<OfflineBundleArtifactStore> logger,
+        IFileSystem? fileSystem = null)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        _options = options.Value;
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _fileSystem = fileSystem ?? new FileSystem();
+
+        if (string.IsNullOrWhiteSpace(_options.RootPath))
+        {
+            throw new ArgumentException("RootPath must be provided for OfflineBundleArtifactStore.", nameof(options));
+        }
+
+        var root = _fileSystem.Path.GetFullPath(_options.RootPath);
+        _fileSystem.Directory.CreateDirectory(root);
+        _options.RootPath = root;
+        _fileSystem.Directory.CreateDirectory(GetArtifactsRoot());
+        _fileSystem.Directory.CreateDirectory(GetBundlesRoot());
+    }
+
+    public async ValueTask<VexStoredArtifact> SaveAsync(VexExportArtifact artifact, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(artifact);
+        EnforceDigestMatch(artifact);
+
+        var artifactRelativePath = BuildArtifactRelativePath(artifact);
+        var artifactFullPath = _fileSystem.Path.Combine(_options.RootPath, artifactRelativePath);
+        var artifactDirectory = _fileSystem.Path.GetDirectoryName(artifactFullPath);
+        if (!string.IsNullOrEmpty(artifactDirectory))
+        {
+            _fileSystem.Directory.CreateDirectory(artifactDirectory);
+        }
+
+        await using (var stream = _fileSystem.File.Create(artifactFullPath))
+        {
+            await stream.WriteAsync(artifact.Content, cancellationToken).ConfigureAwait(false);
+        }
+
+        WriteOfflineBundle(artifactRelativePath, artifact, cancellationToken);
+        await UpdateManifestAsync(artifactRelativePath, artifact, cancellationToken).ConfigureAwait(false);
+
+        _logger.LogInformation("Stored offline artifact {Digest} at {Path}", artifact.ContentAddress.ToUri(), artifactRelativePath);
+
+        return new VexStoredArtifact(
+            artifact.ContentAddress,
+            artifactRelativePath,
+            artifact.Content.Length,
+            artifact.Metadata);
+    }
+
+    public ValueTask DeleteAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(contentAddress);
+        var sanitized = contentAddress.Digest.Replace(':', '_');
+        var artifactsRoot = GetArtifactsRoot();
+
+        foreach (VexExportFormat format in Enum.GetValues(typeof(VexExportFormat)))
+        {
+            var extension = GetExtension(format);
+            var path = _fileSystem.Path.Combine(artifactsRoot, format.ToString().ToLowerInvariant(), sanitized + extension);
+            if (_fileSystem.File.Exists(path))
+            {
+                _fileSystem.File.Delete(path);
+            }
+
+            var bundlePath = _fileSystem.Path.Combine(GetBundlesRoot(), sanitized + ".zip");
+            if (_fileSystem.File.Exists(bundlePath))
+            {
+                _fileSystem.File.Delete(bundlePath);
+            }
+        }
+
+        return ValueTask.CompletedTask;
+    }
+
+    public ValueTask<Stream?> OpenReadAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(contentAddress);
+        var artifactsRoot = GetArtifactsRoot();
+        var sanitized = contentAddress.Digest.Replace(':', '_');
+
+        foreach (VexExportFormat format in Enum.GetValues(typeof(VexExportFormat)))
+        {
+            var candidate = _fileSystem.Path.Combine(artifactsRoot, format.ToString().ToLowerInvariant(), sanitized + GetExtension(format));
+            if (_fileSystem.File.Exists(candidate))
+            {
+                return ValueTask.FromResult<Stream?>(_fileSystem.File.OpenRead(candidate));
+            }
+        }
+
+        return ValueTask.FromResult<Stream?>(null);
+    }
+
+    private void EnforceDigestMatch(VexExportArtifact artifact)
+    {
+        if (!artifact.ContentAddress.Algorithm.Equals("sha256", StringComparison.OrdinalIgnoreCase))
+        {
+            return;
+        }
+
+        using var sha = SHA256.Create();
+        var computed = "sha256:" + Convert.ToHexString(sha.ComputeHash(artifact.Content.ToArray())).ToLowerInvariant();
+        if (!string.Equals(computed, artifact.ContentAddress.ToUri(), StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException($"Artifact content digest mismatch. Expected {artifact.ContentAddress.ToUri()} but computed {computed}.");
+        }
+    }
+
+    private string BuildArtifactRelativePath(VexExportArtifact artifact)
+    {
+        var sanitized = artifact.ContentAddress.Digest.Replace(':', '_');
+        var folder = _fileSystem.Path.Combine(_options.ArtifactsFolder, artifact.Format.ToString().ToLowerInvariant());
+        return _fileSystem.Path.Combine(folder, sanitized + GetExtension(artifact.Format));
+    }
+
+    private void WriteOfflineBundle(string artifactRelativePath, VexExportArtifact artifact, CancellationToken cancellationToken)
+    {
+        var zipPath = _fileSystem.Path.Combine(GetBundlesRoot(), artifact.ContentAddress.Digest.Replace(':', '_') + ".zip");
+        using var zipStream = _fileSystem.File.Create(zipPath);
+        using var archive = new ZipArchive(zipStream, ZipArchiveMode.Create);
+        var entry = archive.CreateEntry(artifactRelativePath, CompressionLevel.Optimal);
+        using (var entryStream = entry.Open())
+        {
+            entryStream.Write(artifact.Content.Span);
+        }
+
+        // embed metadata file
+        var metadataEntry = archive.CreateEntry("metadata.json", CompressionLevel.Optimal);
+        using var metadataStream = new StreamWriter(metadataEntry.Open());
+        var metadata = new Dictionary<string, object?>
+        {
+            ["digest"] = artifact.ContentAddress.ToUri(),
+            ["format"] = artifact.Format.ToString().ToLowerInvariant(),
+            ["sizeBytes"] = artifact.Content.Length,
+            ["metadata"] = artifact.Metadata,
+        };
+        metadataStream.Write(JsonSerializer.Serialize(metadata, _serializerOptions));
+    }
+
+    private async Task UpdateManifestAsync(string artifactRelativePath, VexExportArtifact artifact, CancellationToken cancellationToken)
+    {
+        var manifestPath = _fileSystem.Path.Combine(_options.RootPath, _options.ManifestFileName);
+        var records = new List<ManifestEntry>();
+
+        if (_fileSystem.File.Exists(manifestPath))
+        {
+            await using var existingStream = _fileSystem.File.OpenRead(manifestPath);
+            var existing = await JsonSerializer.DeserializeAsync<ManifestDocument>(existingStream, _serializerOptions, cancellationToken).ConfigureAwait(false);
+            if (existing is not null)
+            {
+                records.AddRange(existing.Artifacts);
+            }
+        }
+
+        records.RemoveAll(x => string.Equals(x.Digest, artifact.ContentAddress.ToUri(), StringComparison.OrdinalIgnoreCase));
+        records.Add(new ManifestEntry(
+            artifact.ContentAddress.ToUri(),
+            artifact.Format.ToString().ToLowerInvariant(),
+            artifactRelativePath.Replace("\\", "/"),
+            artifact.Content.Length,
+            artifact.Metadata));
+
+        records.Sort(static (a, b) => string.CompareOrdinal(a.Digest, b.Digest));
+
+        var doc = new ManifestDocument(records.ToImmutableArray());
+
+        await using var stream = _fileSystem.File.Create(manifestPath);
+        await JsonSerializer.SerializeAsync(stream, doc, _serializerOptions, cancellationToken).ConfigureAwait(false);
+    }
+
+    private string GetArtifactsRoot() => _fileSystem.Path.Combine(_options.RootPath, _options.ArtifactsFolder);
+
+    private string GetBundlesRoot() => _fileSystem.Path.Combine(_options.RootPath, _options.BundlesFolder);
+
+    private static string GetExtension(VexExportFormat format)
+        => format switch
+        {
+            VexExportFormat.Json => ".json",
+            VexExportFormat.JsonLines => ".jsonl",
+            VexExportFormat.OpenVex => ".json",
+            VexExportFormat.Csaf => ".json",
+            _ => ".bin",
+        };
+
+    private sealed record ManifestDocument(ImmutableArray<ManifestEntry> Artifacts);
+
+    private sealed record ManifestEntry(string Digest, string Format, string Path, long SizeBytes, IReadOnlyDictionary<string, string> Metadata);
+}
+
+public static class OfflineBundleArtifactStoreServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexOfflineBundleArtifactStore(this IServiceCollection services, Action<OfflineBundleArtifactStoreOptions>? configure = null)
+    {
+        if (configure is not null)
+        {
+            services.Configure(configure);
+        }
+
+        services.AddSingleton<IVexArtifactStore, OfflineBundleArtifactStore>();
+        return services;
+    }
+}

src/StellaOps.Vexer.Export/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("StellaOps.Vexer.Export.Tests")]

src/StellaOps.Vexer.Export/S3ArtifactStore.cs

@@ -0,0 +1,181 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Export;
+
+public sealed class S3ArtifactStoreOptions
+{
+    public string BucketName { get; set; } = string.Empty;
+
+    public string? Prefix { get; set; }
+        = null;
+
+    public bool OverwriteExisting { get; set; }
+        = true;
+}
+
+public interface IS3ArtifactClient
+{
+    Task<bool> ObjectExistsAsync(string bucketName, string key, CancellationToken cancellationToken);
+
+    Task PutObjectAsync(string bucketName, string key, Stream content, IDictionary<string, string> metadata, CancellationToken cancellationToken);
+
+    Task<Stream?> GetObjectAsync(string bucketName, string key, CancellationToken cancellationToken);
+
+    Task DeleteObjectAsync(string bucketName, string key, CancellationToken cancellationToken);
+}
+
+public sealed class S3ArtifactStore : IVexArtifactStore
+{
+    private readonly IS3ArtifactClient _client;
+    private readonly S3ArtifactStoreOptions _options;
+    private readonly ILogger<S3ArtifactStore> _logger;
+
+    public S3ArtifactStore(
+        IS3ArtifactClient client,
+        IOptions<S3ArtifactStoreOptions> options,
+        ILogger<S3ArtifactStore> logger)
+    {
+        _client = client ?? throw new ArgumentNullException(nameof(client));
+        ArgumentNullException.ThrowIfNull(options);
+        _options = options.Value;
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+        if (string.IsNullOrWhiteSpace(_options.BucketName))
+        {
+            throw new ArgumentException("BucketName must be provided for S3ArtifactStore.", nameof(options));
+        }
+    }
+
+    public async ValueTask<VexStoredArtifact> SaveAsync(VexExportArtifact artifact, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(artifact);
+        var key = BuildObjectKey(artifact.ContentAddress, artifact.Format);
+
+        if (!_options.OverwriteExisting)
+        {
+            var exists = await _client.ObjectExistsAsync(_options.BucketName, key, cancellationToken).ConfigureAwait(false);
+            if (exists)
+            {
+                _logger.LogInformation("S3 object {Bucket}/{Key} already exists; skipping upload.", _options.BucketName, key);
+                return new VexStoredArtifact(artifact.ContentAddress, key, artifact.Content.Length, artifact.Metadata);
+            }
+        }
+
+        using var contentStream = new MemoryStream(artifact.Content.ToArray());
+        await _client.PutObjectAsync(
+            _options.BucketName,
+            key,
+            contentStream,
+            BuildObjectMetadata(artifact),
+            cancellationToken).ConfigureAwait(false);
+
+        _logger.LogInformation("Uploaded export artifact {Digest} to {Bucket}/{Key}", artifact.ContentAddress.ToUri(), _options.BucketName, key);
+
+        return new VexStoredArtifact(
+            artifact.ContentAddress,
+            key,
+            artifact.Content.Length,
+            artifact.Metadata);
+    }
+
+    public async ValueTask DeleteAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(contentAddress);
+        foreach (var key in BuildCandidateKeys(contentAddress))
+        {
+            await _client.DeleteObjectAsync(_options.BucketName, key, cancellationToken).ConfigureAwait(false);
+        }
+        _logger.LogInformation("Deleted export artifact {Digest} from {Bucket}", contentAddress.ToUri(), _options.BucketName);
+    }
+
+    public async ValueTask<Stream?> OpenReadAsync(VexContentAddress contentAddress, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(contentAddress);
+        foreach (var key in BuildCandidateKeys(contentAddress))
+        {
+            var stream = await _client.GetObjectAsync(_options.BucketName, key, cancellationToken).ConfigureAwait(false);
+            if (stream is not null)
+            {
+                return stream;
+            }
+        }
+
+        return null;
+    }
+
+    private string BuildObjectKey(VexContentAddress address, VexExportFormat format)
+    {
+        var sanitizedDigest = address.Digest.Replace(':', '_');
+        var prefix = string.IsNullOrWhiteSpace(_options.Prefix) ? string.Empty : _options.Prefix.TrimEnd('/') + "/";
+        var formatSegment = format.ToString().ToLowerInvariant();
+        return $"{prefix}{formatSegment}/{sanitizedDigest}{GetExtension(format)}";
+    }
+
+    private IEnumerable<string> BuildCandidateKeys(VexContentAddress address)
+    {
+        foreach (VexExportFormat format in Enum.GetValues(typeof(VexExportFormat)))
+        {
+            yield return BuildObjectKey(address, format);
+        }
+
+        if (!string.IsNullOrWhiteSpace(_options.Prefix))
+        {
+            yield return $"{_options.Prefix.TrimEnd('/')}/{address.Digest.Replace(':', '_')}";
+        }
+
+        yield return address.Digest.Replace(':', '_');
+    }
+
+    private static IDictionary<string, string> BuildObjectMetadata(VexExportArtifact artifact)
+    {
+        var metadata = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["vex-format"] = artifact.Format.ToString().ToLowerInvariant(),
+            ["vex-digest"] = artifact.ContentAddress.ToUri(),
+            ["content-type"] = artifact.Format switch
+            {
+                VexExportFormat.Json => "application/json",
+                VexExportFormat.JsonLines => "application/json",
+                VexExportFormat.OpenVex => "application/vnd.openvex+json",
+                VexExportFormat.Csaf => "application/json",
+                _ => "application/octet-stream",
+            },
+        };
+
+        foreach (var kvp in artifact.Metadata)
+        {
+            metadata[$"meta-{kvp.Key}"] = kvp.Value;
+        }
+
+        return metadata;
+    }
+
+    private static string GetExtension(VexExportFormat format)
+        => format switch
+        {
+            VexExportFormat.Json => ".json",
+            VexExportFormat.JsonLines => ".jsonl",
+            VexExportFormat.OpenVex => ".json",
+            VexExportFormat.Csaf => ".json",
+            _ => ".bin",
+        };
+}
+
+public static class S3ArtifactStoreServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexS3ArtifactStore(this IServiceCollection services, Action<S3ArtifactStoreOptions> configure)
+    {
+        ArgumentNullException.ThrowIfNull(configure);
+        services.Configure(configure);
+        services.AddSingleton<IVexArtifactStore, S3ArtifactStore>();
+        return services;
+    }
+}

src/StellaOps.Vexer.Export/StellaOps.Vexer.Export.csproj

@@ -9,6 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="8.0.0" />
+    <PackageReference Include="System.IO.Abstractions" Version="20.0.28" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />

src/StellaOps.Vexer.Export/TASKS.md

@@ -3,6 +3,7 @@ If you are working on this file you need to read docs/ARCHITECTURE_VEXER.md and
 | Task | Owner(s) | Depends on | Notes |
 |---|---|---|---|
 |VEXER-EXPORT-01-001 – Export engine orchestration|Team Vexer Export|VEXER-CORE-01-003|DONE (2025-10-15) – Export engine scaffolding with cache lookup, data source hooks, and deterministic manifest emission.|
-|VEXER-EXPORT-01-002 – Cache index & eviction hooks|Team Vexer Export|VEXER-EXPORT-01-001, VEXER-STORAGE-01-003|TODO – Wire cache lookup/write path against `vex.cache` collection and add GC utilities for Worker to prune stale entries deterministically.|
+|VEXER-EXPORT-01-002 – Cache index & eviction hooks|Team Vexer Export|VEXER-EXPORT-01-001, VEXER-STORAGE-01-003|**DONE (2025-10-16)** – Export engine now invalidates cache entries on force refresh, cache services expose prune/invalidate APIs, and storage maintenance trims expired/dangling records with Mongo2Go coverage.|
-|VEXER-EXPORT-01-003 – Artifact store adapters|Team Vexer Export|VEXER-EXPORT-01-001|TODO – Provide pluggable storage adapters (filesystem, S3/MinIO) with offline bundle packaging and hash verification.|
+|VEXER-EXPORT-01-003 – Artifact store adapters|Team Vexer Export|VEXER-EXPORT-01-001|**DONE (2025-10-16)** – Implemented multi-store pipeline with filesystem, S3-compatible, and offline bundle adapters (hash verification + manifest/zip output) plus unit coverage and DI hooks.|
 |VEXER-EXPORT-01-004 – Attestation handoff integration|Team Vexer Export|VEXER-EXPORT-01-001, VEXER-ATTEST-01-001|TODO – Connect export engine to attestation client, persist Rekor metadata, and reuse cached attestations.|
+|VEXER-EXPORT-01-005 – Score & resolve envelope surfaces|Team Vexer Export|VEXER-EXPORT-01-004, VEXER-CORE-02-001|TODO – Emit consensus+score envelopes in export manifests, include policy/scoring digests, and update offline bundle/ORAS layouts to carry signed VEX responses.|

src/StellaOps.Vexer.Export/VexExportCacheService.cs

@@ -0,0 +1,54 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Storage.Mongo;
+
+namespace StellaOps.Vexer.Export;
+
+public interface IVexExportCacheService
+{
+    ValueTask InvalidateAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken);
+
+    ValueTask<int> PruneExpiredAsync(DateTimeOffset asOf, CancellationToken cancellationToken);
+
+    ValueTask<int> PruneDanglingAsync(CancellationToken cancellationToken);
+}
+
+internal sealed class VexExportCacheService : IVexExportCacheService
+{
+    private readonly IVexCacheIndex _cacheIndex;
+    private readonly IVexCacheMaintenance _maintenance;
+    private readonly ILogger<VexExportCacheService> _logger;
+
+    public VexExportCacheService(
+        IVexCacheIndex cacheIndex,
+        IVexCacheMaintenance maintenance,
+        ILogger<VexExportCacheService> logger)
+    {
+        _cacheIndex = cacheIndex ?? throw new ArgumentNullException(nameof(cacheIndex));
+        _maintenance = maintenance ?? throw new ArgumentNullException(nameof(maintenance));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    public async ValueTask InvalidateAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(signature);
+        await _cacheIndex.RemoveAsync(signature, format, cancellationToken).ConfigureAwait(false);
+        _logger.LogInformation("Invalidated export cache entry {Signature} ({Format})", signature.Value, format);
+    }
+
+    public ValueTask<int> PruneExpiredAsync(DateTimeOffset asOf, CancellationToken cancellationToken)
+        => _maintenance.RemoveExpiredAsync(asOf, cancellationToken);
+
+    public ValueTask<int> PruneDanglingAsync(CancellationToken cancellationToken)
+        => _maintenance.RemoveMissingManifestReferencesAsync(cancellationToken);
+}
+
+public static class VexExportCacheServiceCollectionExtensions
+{
+    public static IServiceCollection AddVexExportCacheServices(this IServiceCollection services)
+    {
+        services.AddSingleton<IVexExportCacheService, VexExportCacheService>();
+        return services;
+    }
+}

src/StellaOps.Vexer.Policy/IVexPolicyProvider.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Globalization;
 using Microsoft.Extensions.DependencyInjection;
@@ -27,13 +28,17 @@ public sealed record VexPolicySnapshot(
     string Version,
     VexConsensusPolicyOptions ConsensusOptions,
     IVexConsensusPolicy ConsensusPolicy,
-    ImmutableArray<VexPolicyIssue> Issues)
+    ImmutableArray<VexPolicyIssue> Issues,
+    string RevisionId,
+    string Digest)
 {
     public static readonly VexPolicySnapshot Default = new(
         VexConsensusPolicyOptions.BaselineVersion,
         new VexConsensusPolicyOptions(),
         new BaselineVexConsensusPolicy(),
-        ImmutableArray<VexPolicyIssue>.Empty);
+        ImmutableArray<VexPolicyIssue>.Empty,
+        "rev-0",
+        string.Empty);
 }
 
 public sealed record VexPolicyIssue(
@@ -51,6 +56,10 @@ public sealed class VexPolicyProvider : IVexPolicyProvider
 {
     private readonly IOptionsMonitor<VexPolicyOptions> _options;
     private readonly ILogger<VexPolicyProvider> _logger;
+    private readonly object _sync = new();
+    private long _revisionCounter;
+    private string? _currentRevisionId;
+    private string? _currentDigest;
 
     public VexPolicyProvider(
         IOptionsMonitor<VexPolicyOptions> options,
@@ -68,36 +77,48 @@ public sealed class VexPolicyProvider : IVexPolicyProvider
 
     private VexPolicySnapshot BuildSnapshot(VexPolicyOptions options)
     {
-        var issues = ImmutableArray.CreateBuilder<VexPolicyIssue>();
+        var normalization = VexPolicyProcessing.Normalize(options);
+        var digest = VexPolicyDigest.Compute(normalization.ConsensusOptions);
+        string revisionId;
+        bool isNewRevision;
 
-        if (!TryNormalizeWeights(options.Weights, out var weightOptions, issues))
+        lock (_sync)
         {
-            issues.Add(new VexPolicyIssue(
+            if (!string.Equals(_currentDigest, digest, StringComparison.Ordinal))
-                "weights.invalid",
+            {
-                "Weight configuration is invalid; falling back to defaults.",
+                _revisionCounter++;
-                VexPolicyIssueSeverity.Warning));
+                revisionId = $"rev-{_revisionCounter}";
-            weightOptions = new VexConsensusPolicyOptions();
+                _currentDigest = digest;
+                _currentRevisionId = revisionId;
+                isNewRevision = true;
+            }
+            else
+            {
+                revisionId = _currentRevisionId ?? "rev-0";
+                isNewRevision = false;
+            }
         }
 
-        var overrides = NormalizeOverrides(options.ProviderOverrides, issues);
+        var policy = new BaselineVexConsensusPolicy(normalization.ConsensusOptions);
-
-        var consensusOptions = new VexConsensusPolicyOptions(
-            options.Version ?? VexConsensusPolicyOptions.BaselineVersion,
-            weightOptions.VendorWeight,
-            weightOptions.DistroWeight,
-            weightOptions.PlatformWeight,
-            weightOptions.HubWeight,
-            weightOptions.AttestationWeight,
-            overrides);
-
-        var policy = new BaselineVexConsensusPolicy(consensusOptions);
         var snapshot = new VexPolicySnapshot(
-            consensusOptions.Version,
+            normalization.ConsensusOptions.Version,
-            consensusOptions,
+            normalization.ConsensusOptions,
             policy,
-            issues.ToImmutable());
+            normalization.Issues,
+            revisionId,
+            digest);
 
-        if (snapshot.Issues.Length > 0)
+        if (isNewRevision)
+        {
+            _logger.LogInformation(
+                "Policy snapshot updated: revision {RevisionId}, version {Version}, digest {Digest}, issues {IssueCount}",
+                snapshot.RevisionId,
+                snapshot.Version,
+                snapshot.Digest,
+                snapshot.Issues.Length);
+            VexPolicyTelemetry.RecordReload(snapshot.RevisionId, snapshot.Version, snapshot.Issues.Length);
+        }
+        else if (snapshot.Issues.Length > 0)
         {
             foreach (var issue in snapshot.Issues)
             {
@@ -107,93 +128,6 @@ public sealed class VexPolicyProvider : IVexPolicyProvider
 
         return snapshot;
     }
-
-    private static bool TryNormalizeWeights(
-        VexPolicyWeightOptions options,
-        out VexConsensusPolicyOptions normalized,
-        ImmutableArray<VexPolicyIssue>.Builder issues)
-    {
-        var hasAny = options is not null &&
-                     (options.Vendor.HasValue || options.Distro.HasValue ||
-                      options.Platform.HasValue || options.Hub.HasValue || options.Attestation.HasValue);
-
-        if (!hasAny)
-        {
-            normalized = new VexConsensusPolicyOptions();
-            return true;
-        }
-
-        var vendor = Clamp(options.Vendor, nameof(options.Vendor), issues);
-        var distro = Clamp(options.Distro, nameof(options.Distro), issues);
-        var platform = Clamp(options.Platform, nameof(options.Platform), issues);
-        var hub = Clamp(options.Hub, nameof(options.Hub), issues);
-        var attestation = Clamp(options.Attestation, nameof(options.Attestation), issues);
-
-        normalized = new VexConsensusPolicyOptions(
-            VexConsensusPolicyOptions.BaselineVersion,
-            vendor ?? 1.0,
-            distro ?? 0.9,
-            platform ?? 0.7,
-            hub ?? 0.5,
-            attestation ?? 0.6);
-        return true;
-    }
-
-    private static double? Clamp(double? value, string fieldName, ImmutableArray<VexPolicyIssue>.Builder issues)
-    {
-        if (value is null)
-        {
-            return null;
-        }
-
-        if (double.IsNaN(value.Value) || double.IsInfinity(value.Value))
-        {
-            issues.Add(new VexPolicyIssue(
-                $"weights.{fieldName}.invalid",
-                $"{fieldName} must be a finite number.",
-                VexPolicyIssueSeverity.Warning));
-            return null;
-        }
-
-        if (value.Value < 0 || value.Value > 1)
-        {
-            issues.Add(new VexPolicyIssue(
-                $"weights.{fieldName}.range",
-                $"{fieldName} must be between 0 and 1; value {value.Value.ToString(CultureInfo.InvariantCulture)} was clamped.",
-                VexPolicyIssueSeverity.Warning));
-            return Math.Clamp(value.Value, 0, 1);
-        }
-
-        return value.Value;
-    }
-
-    private static ImmutableDictionary<string, double> NormalizeOverrides(
-        IDictionary<string, double>? overrides,
-        ImmutableArray<VexPolicyIssue>.Builder issues)
-    {
-        if (overrides is null || overrides.Count == 0)
-        {
-            return ImmutableDictionary<string, double>.Empty;
-        }
-
-        var builder = ImmutableDictionary.CreateBuilder<string, double>(StringComparer.Ordinal);
-        foreach (var kvp in overrides)
-        {
-            if (string.IsNullOrWhiteSpace(kvp.Key))
-            {
-                issues.Add(new VexPolicyIssue(
-                    "overrides.key.missing",
-                    "Encountered provider override with empty key; ignoring entry.",
-                    VexPolicyIssueSeverity.Warning));
-                continue;
-            }
-
-            var weight = Clamp(kvp.Value, $"overrides.{kvp.Key}", issues) ?? kvp.Value;
-            builder[kvp.Key.Trim()] = weight;
-        }
-
-        return builder.ToImmutable();
-    }
 }
 
 public sealed class VexPolicyEvaluator : IVexPolicyEvaluator

src/StellaOps.Vexer.Policy/StellaOps.Vexer.Policy.csproj

@@ -9,6 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="8.0.0" />
+    <PackageReference Include="YamlDotNet" Version="13.7.1" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />

src/StellaOps.Vexer.Policy/TASKS.md

@@ -4,6 +4,8 @@ If you are working on this file you need to read docs/ARCHITECTURE_VEXER.md and
 |---|---|---|---|
 |VEXER-POLICY-01-001 – Policy schema & binding|Team Vexer Policy|VEXER-CORE-01-001|DONE (2025-10-15) – Established `VexPolicyOptions`, options binding, and snapshot provider covering baseline weights/overrides.|
 |VEXER-POLICY-01-002 – Policy evaluator service|Team Vexer Policy|VEXER-POLICY-01-001|DONE (2025-10-15) – `VexPolicyEvaluator` exposes immutable snapshots to consensus and normalizes rejection reasons.|
-|VEXER-POLICY-01-003 – Operator diagnostics & docs|Team Vexer Policy|VEXER-POLICY-01-001|TODO – Surface structured diagnostics (CLI/WebService) and author policy upgrade guidance in docs/ARCHITECTURE_VEXER.md appendix.|
+|VEXER-POLICY-01-003 – Operator diagnostics & docs|Team Vexer Policy|VEXER-POLICY-01-001|**DONE (2025-10-16)** – Surface structured diagnostics (CLI/WebService) and author policy upgrade guidance in docs/ARCHITECTURE_VEXER.md appendix.<br>2025-10-16: Added `IVexPolicyDiagnostics`/`VexPolicyDiagnosticsReport`, sorted issue ordering, recommendations, and appendix guidance. Tests: `dotnet test src/StellaOps.Vexer.Core.Tests/StellaOps.Vexer.Core.Tests.csproj`.|
-|VEXER-POLICY-01-004 – Policy schema validation & YAML binding|Team Vexer Policy|VEXER-POLICY-01-001|TODO – Add strongly-typed YAML/JSON binding, schema validation, and deterministic diagnostics for operator-supplied policy bundles.|
+|VEXER-POLICY-01-004 – Policy schema validation & YAML binding|Team Vexer Policy|VEXER-POLICY-01-001|**DONE (2025-10-16)** – Added strongly-typed YAML/JSON binding, schema validation, and deterministic diagnostics for operator-supplied policy bundles.|
-|VEXER-POLICY-01-005 – Policy change tracking & telemetry|Team Vexer Policy|VEXER-POLICY-01-002|TODO – Emit revision history, expose snapshot digests via CLI/WebService, and add structured logging/metrics for policy reloads.|
+|VEXER-POLICY-01-005 – Policy change tracking & telemetry|Team Vexer Policy|VEXER-POLICY-01-002|**DONE (2025-10-16)** – Emit revision history, expose snapshot digests via CLI/WebService, and add structured logging/metrics for policy reloads.<br>2025-10-16: `VexPolicySnapshot` now carries revision/digest, provider logs reloads, `vex.policy.reloads` metric emitted, binder/diagnostics expose digest metadata. Tests: `dotnet test src/StellaOps.Vexer.Core.Tests/StellaOps.Vexer.Core.Tests.csproj`.|
+|VEXER-POLICY-02-001 – Scoring coefficients & weight ceilings|Team Vexer Policy|VEXER-POLICY-01-004|TODO – Extend `VexPolicyOptions` with α/β boosters and optional >1.0 weight ceilings, validate ranges, and document operator guidance in `docs/ARCHITECTURE_VEXER.md`/`docs/VEXER_SCORRING.md`.|
+|VEXER-POLICY-02-002 – Diagnostics for scoring signals|Team Vexer Policy|VEXER-POLICY-02-001|BACKLOG – Update diagnostics reports to surface missing severity/KEV/EPSS mappings, coefficient overrides, and provide actionable recommendations for policy tuning.|

src/StellaOps.Vexer.Policy/VexPolicyBinder.cs

@@ -0,0 +1,94 @@
+using System.Collections.Immutable;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Text.Json;
+using StellaOps.Vexer.Core;
+using YamlDotNet.Serialization;
+using YamlDotNet.Serialization.NamingConventions;
+
+namespace StellaOps.Vexer.Policy;
+
+public enum VexPolicyDocumentFormat
+{
+    Json,
+    Yaml,
+}
+
+public sealed record VexPolicyBindingResult(
+    bool Success,
+    VexPolicyOptions? Options,
+    VexConsensusPolicyOptions? NormalizedOptions,
+    ImmutableArray<VexPolicyIssue> Issues);
+
+public static class VexPolicyBinder
+{
+    public static VexPolicyBindingResult Bind(string content, VexPolicyDocumentFormat format)
+    {
+        if (string.IsNullOrWhiteSpace(content))
+        {
+            return Failure("policy.empty", "Policy document is empty.");
+        }
+
+        try
+        {
+            var options = Parse(content, format);
+            return Normalize(options);
+        }
+        catch (JsonException ex)
+        {
+            return Failure("policy.parse.json", $"Failed to parse JSON policy document: {ex.Message}");
+        }
+        catch (YamlDotNet.Core.YamlException ex)
+        {
+            return Failure("policy.parse.yaml", $"Failed to parse YAML policy document: {ex.Message}");
+        }
+    }
+
+    public static VexPolicyBindingResult Bind(Stream stream, VexPolicyDocumentFormat format, Encoding? encoding = null)
+    {
+        if (stream is null)
+        {
+            throw new ArgumentNullException(nameof(stream));
+        }
+
+        encoding ??= Encoding.UTF8;
+        using var reader = new StreamReader(stream, encoding, detectEncodingFromByteOrderMarks: true, leaveOpen: true);
+        var content = reader.ReadToEnd();
+        return Bind(content, format);
+    }
+
+    private static VexPolicyBindingResult Normalize(VexPolicyOptions options)
+    {
+        var normalization = VexPolicyProcessing.Normalize(options);
+        var hasErrors = normalization.Issues.Any(static issue => issue.Severity == VexPolicyIssueSeverity.Error);
+        return new VexPolicyBindingResult(!hasErrors, options, normalization.ConsensusOptions, normalization.Issues);
+    }
+
+    private static VexPolicyBindingResult Failure(string code, string message)
+    {
+        var issue = new VexPolicyIssue(code, message, VexPolicyIssueSeverity.Error);
+        return new VexPolicyBindingResult(false, null, null, ImmutableArray.Create(issue));
+    }
+
+    private static VexPolicyOptions Parse(string content, VexPolicyDocumentFormat format)
+    {
+        return format switch
+        {
+            VexPolicyDocumentFormat.Json => JsonSerializer.Deserialize<VexPolicyOptions>(content, new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true,
+                ReadCommentHandling = JsonCommentHandling.Skip,
+                AllowTrailingCommas = true,
+            }) ?? new VexPolicyOptions(),
+            VexPolicyDocumentFormat.Yaml => BuildYamlDeserializer().Deserialize<VexPolicyOptions>(content) ?? new VexPolicyOptions(),
+            _ => throw new ArgumentOutOfRangeException(nameof(format), format, "Unsupported policy document format."),
+        };
+    }
+
+    private static IDeserializer BuildYamlDeserializer()
+        => new DeserializerBuilder()
+            .WithNamingConvention(CamelCaseNamingConvention.Instance)
+            .IgnoreUnmatchedProperties()
+            .Build();
+}

src/StellaOps.Vexer.Policy/VexPolicyDiagnostics.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace StellaOps.Vexer.Policy;
+
+public interface IVexPolicyDiagnostics
+{
+    VexPolicyDiagnosticsReport GetDiagnostics();
+}
+
+public sealed record VexPolicyDiagnosticsReport(
+    string Version,
+    string RevisionId,
+    string Digest,
+    int ErrorCount,
+    int WarningCount,
+    DateTimeOffset GeneratedAt,
+    ImmutableArray<VexPolicyIssue> Issues,
+    ImmutableArray<string> Recommendations,
+    ImmutableDictionary<string, double> ActiveOverrides);
+
+public sealed class VexPolicyDiagnostics : IVexPolicyDiagnostics
+{
+    private readonly IVexPolicyProvider _policyProvider;
+    private readonly TimeProvider _timeProvider;
+
+    public VexPolicyDiagnostics(
+        IVexPolicyProvider policyProvider,
+        TimeProvider? timeProvider = null)
+    {
+        _policyProvider = policyProvider ?? throw new ArgumentNullException(nameof(policyProvider));
+        _timeProvider = timeProvider ?? TimeProvider.System;
+    }
+
+    public VexPolicyDiagnosticsReport GetDiagnostics()
+    {
+        var snapshot = _policyProvider.GetSnapshot();
+        var issues = snapshot.Issues;
+
+        var errorCount = issues.Count(static issue => issue.Severity == VexPolicyIssueSeverity.Error);
+        var warningCount = issues.Count(static issue => issue.Severity == VexPolicyIssueSeverity.Warning);
+        var overrides = snapshot.ConsensusOptions.ProviderOverrides
+            .OrderBy(static pair => pair.Key, StringComparer.Ordinal)
+            .ToImmutableDictionary();
+
+        var recommendations = BuildRecommendations(errorCount, warningCount, overrides);
+
+        return new VexPolicyDiagnosticsReport(
+            snapshot.Version,
+            snapshot.RevisionId,
+            snapshot.Digest,
+            errorCount,
+            warningCount,
+            _timeProvider.GetUtcNow(),
+            issues,
+            recommendations,
+            overrides);
+    }
+
+    private static ImmutableArray<string> BuildRecommendations(
+        int errorCount,
+        int warningCount,
+        ImmutableDictionary<string, double> overrides)
+    {
+        var messages = ImmutableArray.CreateBuilder<string>();
+
+        if (errorCount > 0)
+        {
+            messages.Add("Resolve policy errors before running consensus; defaults are used while errors persist.");
+        }
+
+        if (warningCount > 0)
+        {
+            messages.Add("Review policy warnings via CLI/Web diagnostics and adjust configuration as needed.");
+        }
+
+        if (overrides.Count > 0)
+        {
+            messages.Add($"Provider overrides active for: {string.Join(", ", overrides.Keys)}.");
+        }
+
+        messages.Add("Refer to docs/ARCHITECTURE_VEXER.md for policy upgrade and diagnostics guidance.");
+
+        return messages.ToImmutable();
+    }
+}

src/StellaOps.Vexer.Policy/VexPolicyDigest.cs

@@ -0,0 +1,35 @@
+using System.Globalization;
+using System.Security.Cryptography;
+using System.Text;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Policy;
+
+internal static class VexPolicyDigest
+{
+    public static string Compute(VexConsensusPolicyOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+
+        var builder = new StringBuilder();
+        builder.Append(options.Version).Append('|')
+            .Append(options.VendorWeight.ToString("F6", CultureInfo.InvariantCulture)).Append('|')
+            .Append(options.DistroWeight.ToString("F6", CultureInfo.InvariantCulture)).Append('|')
+            .Append(options.PlatformWeight.ToString("F6", CultureInfo.InvariantCulture)).Append('|')
+            .Append(options.HubWeight.ToString("F6", CultureInfo.InvariantCulture)).Append('|')
+            .Append(options.AttestationWeight.ToString("F6", CultureInfo.InvariantCulture));
+
+        foreach (var kvp in options.ProviderOverrides
+                     .OrderBy(static pair => pair.Key, StringComparer.Ordinal))
+        {
+            builder.Append('|')
+                .Append(kvp.Key)
+                .Append('=')
+                .Append(kvp.Value.ToString("F6", CultureInfo.InvariantCulture));
+        }
+
+        var input = builder.ToString();
+        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(input));
+        return Convert.ToHexString(hash);
+    }
+}

src/StellaOps.Vexer.Policy/VexPolicyProcessing.cs

@@ -0,0 +1,166 @@
+using System.Collections.Immutable;
+using System.Globalization;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Policy;
+
+internal static class VexPolicyProcessing
+{
+    public static VexPolicyNormalizationResult Normalize(VexPolicyOptions? options)
+    {
+        var issues = ImmutableArray.CreateBuilder<VexPolicyIssue>();
+
+        var policyOptions = options ?? new VexPolicyOptions();
+
+        if (!TryNormalizeWeights(
+                policyOptions.Weights,
+                out var normalizedWeights,
+                issues))
+        {
+            issues.Add(new VexPolicyIssue(
+                "weights.invalid",
+                "Weight configuration is invalid; falling back to defaults.",
+                VexPolicyIssueSeverity.Warning));
+            normalizedWeights = new VexConsensusPolicyOptions();
+        }
+
+        var overrides = NormalizeOverrides(policyOptions.ProviderOverrides, issues);
+
+        var consensusOptions = new VexConsensusPolicyOptions(
+            policyOptions.Version ?? VexConsensusPolicyOptions.BaselineVersion,
+            normalizedWeights.VendorWeight,
+            normalizedWeights.DistroWeight,
+            normalizedWeights.PlatformWeight,
+            normalizedWeights.HubWeight,
+            normalizedWeights.AttestationWeight,
+            overrides);
+
+        var orderedIssues = issues.ToImmutable().Sort(IssueComparer);
+
+        return new VexPolicyNormalizationResult(consensusOptions, orderedIssues);
+    }
+
+    public static ImmutableArray<VexPolicyIssue> SortIssues(IEnumerable<VexPolicyIssue> issues)
+        => issues.ToImmutableArray().Sort(IssueComparer);
+
+    private static bool TryNormalizeWeights(
+        VexPolicyWeightOptions? options,
+        out VexConsensusPolicyOptions normalized,
+        ImmutableArray<VexPolicyIssue>.Builder issues)
+    {
+        if (options is null)
+        {
+            normalized = new VexConsensusPolicyOptions();
+            return true;
+        }
+
+        var hasAny =
+            options.Vendor.HasValue ||
+            options.Distro.HasValue ||
+            options.Platform.HasValue ||
+            options.Hub.HasValue ||
+            options.Attestation.HasValue;
+
+        if (!hasAny)
+        {
+            normalized = new VexConsensusPolicyOptions();
+            return true;
+        }
+
+        var vendor = Clamp(options.Vendor, nameof(options.Vendor), issues);
+        var distro = Clamp(options.Distro, nameof(options.Distro), issues);
+        var platform = Clamp(options.Platform, nameof(options.Platform), issues);
+        var hub = Clamp(options.Hub, nameof(options.Hub), issues);
+        var attestation = Clamp(options.Attestation, nameof(options.Attestation), issues);
+
+        normalized = new VexConsensusPolicyOptions(
+            VexConsensusPolicyOptions.BaselineVersion,
+            vendor ?? 1.0,
+            distro ?? 0.9,
+            platform ?? 0.7,
+            hub ?? 0.5,
+            attestation ?? 0.6);
+        return true;
+    }
+
+    private static double? Clamp(double? value, string fieldName, ImmutableArray<VexPolicyIssue>.Builder issues)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+
+        if (double.IsNaN(value.Value) || double.IsInfinity(value.Value))
+        {
+            issues.Add(new VexPolicyIssue(
+                $"weights.{fieldName}.invalid",
+                $"{fieldName} must be a finite number.",
+                VexPolicyIssueSeverity.Warning));
+            return null;
+        }
+
+        if (value.Value < 0 || value.Value > 1)
+        {
+            issues.Add(new VexPolicyIssue(
+                $"weights.{fieldName}.range",
+                $"{fieldName} must be between 0 and 1; value {value.Value.ToString(CultureInfo.InvariantCulture)} was clamped.",
+                VexPolicyIssueSeverity.Warning));
+            return Math.Clamp(value.Value, 0, 1);
+        }
+
+        return value.Value;
+    }
+
+    private static ImmutableDictionary<string, double> NormalizeOverrides(
+        IDictionary<string, double>? overrides,
+        ImmutableArray<VexPolicyIssue>.Builder issues)
+    {
+        if (overrides is null || overrides.Count == 0)
+        {
+            return ImmutableDictionary<string, double>.Empty;
+        }
+
+        var builder = ImmutableDictionary.CreateBuilder<string, double>(StringComparer.Ordinal);
+        foreach (var kvp in overrides)
+        {
+            if (string.IsNullOrWhiteSpace(kvp.Key))
+            {
+                issues.Add(new VexPolicyIssue(
+                    "overrides.key.missing",
+                    "Encountered provider override with empty key; ignoring entry.",
+                    VexPolicyIssueSeverity.Warning));
+                continue;
+            }
+
+            var weight = Clamp(kvp.Value, $"overrides.{kvp.Key}", issues) ?? kvp.Value;
+            builder[kvp.Key.Trim()] = weight;
+        }
+
+        return builder.ToImmutable();
+    }
+
+    private static int CompareIssues(VexPolicyIssue left, VexPolicyIssue right)
+    {
+        var severityCompare = GetSeverityRank(left.Severity).CompareTo(GetSeverityRank(right.Severity));
+        if (severityCompare != 0)
+        {
+            return severityCompare;
+        }
+
+        return string.Compare(left.Code, right.Code, StringComparison.Ordinal);
+    }
+
+    private static int GetSeverityRank(VexPolicyIssueSeverity severity)
+        => severity switch
+        {
+            VexPolicyIssueSeverity.Error => 0,
+            VexPolicyIssueSeverity.Warning => 1,
+            _ => 2,
+        };
+
+    private static readonly Comparer<VexPolicyIssue> IssueComparer = Comparer<VexPolicyIssue>.Create(CompareIssues);
+
+    internal sealed record VexPolicyNormalizationResult(
+        VexConsensusPolicyOptions ConsensusOptions,
+        ImmutableArray<VexPolicyIssue> Issues);
+}

src/StellaOps.Vexer.Policy/VexPolicyTelemetry.cs

@@ -0,0 +1,24 @@
+using System.Collections.Generic;
+using System.Diagnostics.Metrics;
+
+namespace StellaOps.Vexer.Policy;
+
+internal static class VexPolicyTelemetry
+{
+    private const string MeterName = "StellaOps.Vexer.Policy";
+    private const string MeterVersion = "1.0.0";
+
+    private static readonly Meter Meter = new(MeterName, MeterVersion);
+    private static readonly Counter<long> PolicyReloads = Meter.CreateCounter<long>("vex.policy.reloads", unit: "events");
+
+    public static void RecordReload(string revisionId, string version, int issueCount)
+    {
+        var tags = new KeyValuePair<string, object?>[]
+        {
+            new("revision", revisionId),
+            new("version", version),
+            new("issues", issueCount),
+        };
+        PolicyReloads.Add(1, tags);
+    }
+}

src/StellaOps.Vexer.Storage.Mongo.Tests/MongoVexCacheMaintenanceTests.cs

@@ -0,0 +1,122 @@
+using System.Collections.Generic;
+using Microsoft.Extensions.Logging.Abstractions;
+using Mongo2Go;
+using MongoDB.Bson;
+using MongoDB.Driver;
+
+namespace StellaOps.Vexer.Storage.Mongo.Tests;
+
+public sealed class MongoVexCacheMaintenanceTests : IAsyncLifetime
+{
+    private readonly MongoDbRunner _runner;
+    private readonly IMongoDatabase _database;
+
+    public MongoVexCacheMaintenanceTests()
+    {
+        _runner = MongoDbRunner.Start();
+        var client = new MongoClient(_runner.ConnectionString);
+        _database = client.GetDatabase("vex-cache-maintenance-tests");
+        VexMongoMappingRegistry.Register();
+    }
+
+    [Fact]
+    public async Task RemoveExpiredAsync_DeletesEntriesBeforeCutoff()
+    {
+        var collection = _database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
+        var now = DateTime.UtcNow;
+
+        await collection.InsertManyAsync(new[]
+        {
+            new VexCacheEntryRecord
+            {
+                Id = "sig-1|json",
+                QuerySignature = "sig-1",
+                Format = "json",
+                ArtifactAlgorithm = "sha256",
+                ArtifactDigest = "deadbeef",
+                CreatedAt = now.AddHours(-2),
+                ExpiresAt = now.AddHours(-1),
+            },
+            new VexCacheEntryRecord
+            {
+                Id = "sig-2|json",
+                QuerySignature = "sig-2",
+                Format = "json",
+                ArtifactAlgorithm = "sha256",
+                ArtifactDigest = "cafebabe",
+                CreatedAt = now,
+                ExpiresAt = now.AddHours(1),
+            },
+        });
+
+        var maintenance = new MongoVexCacheMaintenance(_database, NullLogger<MongoVexCacheMaintenance>.Instance);
+        var removed = await maintenance.RemoveExpiredAsync(DateTimeOffset.UtcNow, CancellationToken.None);
+
+        Assert.Equal(1, removed);
+
+        var remaining = await collection.CountDocumentsAsync(FilterDefinition<VexCacheEntryRecord>.Empty);
+        Assert.Equal(1, remaining);
+    }
+
+    [Fact]
+    public async Task RemoveMissingManifestReferencesAsync_DropsDanglingEntries()
+    {
+        var cache = _database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
+        var exports = _database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports);
+
+        await exports.InsertOneAsync(new VexExportManifestRecord
+        {
+            Id = "manifest-existing",
+            QuerySignature = "sig-keep",
+            Format = "json",
+            CreatedAt = DateTime.UtcNow,
+            ArtifactAlgorithm = "sha256",
+            ArtifactDigest = "keep",
+            ClaimCount = 1,
+            SourceProviders = new List<string> { "vendor" },
+        });
+
+        await cache.InsertManyAsync(new[]
+        {
+            new VexCacheEntryRecord
+            {
+                Id = "sig-remove|json",
+                QuerySignature = "sig-remove",
+                Format = "json",
+                ArtifactAlgorithm = "sha256",
+                ArtifactDigest = "drop",
+                CreatedAt = DateTime.UtcNow,
+                ManifestId = "manifest-missing",
+            },
+            new VexCacheEntryRecord
+            {
+                Id = "sig-keep|json",
+                QuerySignature = "sig-keep",
+                Format = "json",
+                ArtifactAlgorithm = "sha256",
+                ArtifactDigest = "keep",
+                CreatedAt = DateTime.UtcNow,
+                ManifestId = "manifest-existing",
+            },
+        });
+
+        var maintenance = new MongoVexCacheMaintenance(_database, NullLogger<MongoVexCacheMaintenance>.Instance);
+        var removed = await maintenance.RemoveMissingManifestReferencesAsync(CancellationToken.None);
+
+        Assert.Equal(1, removed);
+
+        var remainingIds = await cache.Find(Builders<VexCacheEntryRecord>.Filter.Empty)
+            .Project(x => x.Id)
+            .ToListAsync();
+        Assert.Single(remainingIds);
+        Assert.Contains("sig-keep|json", remainingIds);
+    }
+
+    public Task InitializeAsync() => Task.CompletedTask;
+
+    public Task DisposeAsync()
+    {
+        _runner.Dispose();
+        return Task.CompletedTask;
+    }
+}

src/StellaOps.Vexer.Storage.Mongo.Tests/MongoVexRepositoryTests.cs

@@ -0,0 +1,206 @@
+using System.Collections.Immutable;
+using System.Globalization;
+using System.Text;
+using Microsoft.Extensions.Options;
+using Mongo2Go;
+using MongoDB.Bson;
+using MongoDB.Driver;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo.Tests;
+
+public sealed class MongoVexRepositoryTests : IAsyncLifetime
+{
+    private readonly MongoDbRunner _runner;
+    private readonly MongoClient _client;
+
+    public MongoVexRepositoryTests()
+    {
+        _runner = MongoDbRunner.Start();
+        _client = new MongoClient(_runner.ConnectionString);
+    }
+
+    [Fact]
+    public async Task RawStore_UsesGridFsForLargePayloads()
+    {
+        var database = _client.GetDatabase($"vex-raw-gridfs-{Guid.NewGuid():N}");
+        var store = CreateRawStore(database, thresholdBytes: 32);
+
+        var payload = Encoding.UTF8.GetBytes(new string('A', 256));
+        var document = new VexRawDocument(
+            "red-hat",
+            VexDocumentFormat.Csaf,
+            new Uri("https://example.com/redhat/csaf.json"),
+            DateTimeOffset.UtcNow,
+            "sha256:large",
+            payload,
+            ImmutableDictionary<string, string>.Empty);
+
+        await store.StoreAsync(document, CancellationToken.None);
+
+        var rawCollection = database.GetCollection<BsonDocument>(VexMongoCollectionNames.Raw);
+        var stored = await rawCollection.Find(Builders<BsonDocument>.Filter.Eq("_id", document.Digest))
+            .FirstOrDefaultAsync();
+
+        Assert.NotNull(stored);
+        Assert.True(stored!.TryGetValue("GridFsObjectId", out var gridId));
+        Assert.False(gridId.IsBsonNull);
+        Assert.Empty(stored["Content"].AsBsonBinaryData.Bytes);
+
+        var filesCollection = database.GetCollection<BsonDocument>("vex.raw.files");
+        var fileCount = await filesCollection.CountDocumentsAsync(FilterDefinition<BsonDocument>.Empty);
+        Assert.Equal(1, fileCount);
+
+        var fetched = await store.FindByDigestAsync(document.Digest, CancellationToken.None);
+        Assert.NotNull(fetched);
+        Assert.Equal(payload, fetched!.Content.ToArray());
+    }
+
+    [Fact]
+    public async Task RawStore_ReplacesGridFsWithInlinePayload()
+    {
+        var database = _client.GetDatabase($"vex-raw-inline-{Guid.NewGuid():N}");
+        var store = CreateRawStore(database, thresholdBytes: 16);
+
+        var largePayload = Encoding.UTF8.GetBytes(new string('B', 128));
+        var digest = "sha256:inline";
+        var largeDocument = new VexRawDocument(
+            "cisco",
+            VexDocumentFormat.CycloneDx,
+            new Uri("https://example.com/cyclonedx.json"),
+            DateTimeOffset.UtcNow,
+            digest,
+            largePayload,
+            ImmutableDictionary<string, string>.Empty);
+
+        await store.StoreAsync(largeDocument, CancellationToken.None);
+
+        var smallDocument = largeDocument with
+        {
+            RetrievedAt = DateTimeOffset.UtcNow.AddMinutes(1),
+            Content = Encoding.UTF8.GetBytes("small"),
+        };
+
+        await store.StoreAsync(smallDocument, CancellationToken.None);
+
+        var rawCollection = database.GetCollection<BsonDocument>(VexMongoCollectionNames.Raw);
+        var stored = await rawCollection.Find(Builders<BsonDocument>.Filter.Eq("_id", digest))
+            .FirstOrDefaultAsync();
+
+        Assert.NotNull(stored);
+        Assert.True(stored!.TryGetValue("GridFsObjectId", out var gridId));
+        Assert.True(gridId.IsBsonNull);
+        Assert.Equal("small", Encoding.UTF8.GetString(stored["Content"].AsBsonBinaryData.Bytes));
+
+        var filesCollection = database.GetCollection<BsonDocument>("vex.raw.files");
+        var fileCount = await filesCollection.CountDocumentsAsync(FilterDefinition<BsonDocument>.Empty);
+        Assert.Equal(0, fileCount);
+    }
+
+    [Fact]
+    public async Task ExportStore_SavesManifestAndCacheTransactionally()
+    {
+        var database = _client.GetDatabase($"vex-export-save-{Guid.NewGuid():N}");
+        var options = Options.Create(new VexMongoStorageOptions
+        {
+            ExportCacheTtl = TimeSpan.FromHours(6),
+            GridFsInlineThresholdBytes = 64,
+        });
+
+        var store = new MongoVexExportStore(_client, database, options);
+        var signature = new VexQuerySignature("format=csaf|provider=redhat");
+        var manifest = new VexExportManifest(
+            "exports/20251016/redhat",
+            signature,
+            VexExportFormat.Csaf,
+            DateTimeOffset.UtcNow,
+            new VexContentAddress("sha256", "abcdef123456"),
+            claimCount: 5,
+            sourceProviders: new[] { "red-hat" },
+            fromCache: false,
+            consensusRevision: "rev-1",
+            attestation: null,
+            sizeBytes: 1024);
+
+        await store.SaveAsync(manifest, CancellationToken.None);
+
+        var exportsCollection = database.GetCollection<BsonDocument>(VexMongoCollectionNames.Exports);
+        var exportKey = BuildExportKey(signature, VexExportFormat.Csaf);
+        var exportDoc = await exportsCollection.Find(Builders<BsonDocument>.Filter.Eq("_id", exportKey))
+            .FirstOrDefaultAsync();
+        Assert.NotNull(exportDoc);
+
+        var cacheCollection = database.GetCollection<BsonDocument>(VexMongoCollectionNames.Cache);
+        var cacheKey = BuildExportKey(signature, VexExportFormat.Csaf);
+        var cacheDoc = await cacheCollection.Find(Builders<BsonDocument>.Filter.Eq("_id", cacheKey))
+            .FirstOrDefaultAsync();
+
+        Assert.NotNull(cacheDoc);
+        Assert.Equal(manifest.ExportId, cacheDoc!["ManifestId"].AsString);
+        Assert.True(cacheDoc.TryGetValue("ExpiresAt", out var expiresValue));
+        Assert.False(expiresValue.IsBsonNull);
+    }
+
+    [Fact]
+    public async Task ExportStore_FindAsync_ExpiresCacheEntries()
+    {
+        var database = _client.GetDatabase($"vex-export-expire-{Guid.NewGuid():N}");
+        var options = Options.Create(new VexMongoStorageOptions
+        {
+            ExportCacheTtl = TimeSpan.FromMinutes(5),
+            GridFsInlineThresholdBytes = 64,
+        });
+
+        var store = new MongoVexExportStore(_client, database, options);
+        var signature = new VexQuerySignature("format=json|provider=cisco");
+        var manifest = new VexExportManifest(
+            "exports/20251016/cisco",
+            signature,
+            VexExportFormat.Json,
+            DateTimeOffset.UtcNow,
+            new VexContentAddress("sha256", "deadbeef"),
+            claimCount: 3,
+            sourceProviders: new[] { "cisco" },
+            fromCache: false,
+            consensusRevision: "rev-2",
+            attestation: null,
+            sizeBytes: 2048);
+
+        await store.SaveAsync(manifest, CancellationToken.None);
+
+        var cacheCollection = database.GetCollection<BsonDocument>(VexMongoCollectionNames.Cache);
+        var cacheId = BuildExportKey(signature, VexExportFormat.Json);
+        var update = Builders<BsonDocument>.Update.Set("ExpiresAt", DateTime.UtcNow.AddMinutes(-10));
+        await cacheCollection.UpdateOneAsync(Builders<BsonDocument>.Filter.Eq("_id", cacheId), update);
+
+        var cached = await store.FindAsync(signature, VexExportFormat.Json, CancellationToken.None);
+        Assert.Null(cached);
+
+        var remaining = await cacheCollection.Find(Builders<BsonDocument>.Filter.Eq("_id", cacheId))
+            .FirstOrDefaultAsync();
+        Assert.Null(remaining);
+    }
+
+    private MongoVexRawStore CreateRawStore(IMongoDatabase database, int thresholdBytes)
+    {
+        var options = Options.Create(new VexMongoStorageOptions
+        {
+            RawBucketName = "vex.raw",
+            GridFsInlineThresholdBytes = thresholdBytes,
+            ExportCacheTtl = TimeSpan.FromHours(1),
+        });
+
+        return new MongoVexRawStore(_client, database, options);
+    }
+
+    private static string BuildExportKey(VexQuerySignature signature, VexExportFormat format)
+        => string.Format(CultureInfo.InvariantCulture, "{0}|{1}", signature.Value, format.ToString().ToLowerInvariant());
+
+    public Task InitializeAsync() => Task.CompletedTask;
+
+    public Task DisposeAsync()
+    {
+        _runner.Dispose();
+        return Task.CompletedTask;
+    }
+}

src/StellaOps.Vexer.Storage.Mongo.Tests/MongoVexStoreMappingTests.cs

@@ -0,0 +1,242 @@
+using System.Globalization;
+using Mongo2Go;
+using MongoDB.Bson;
+using MongoDB.Driver;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo.Tests;
+
+public sealed class MongoVexStoreMappingTests : IAsyncLifetime
+{
+    private readonly MongoDbRunner _runner;
+    private readonly IMongoDatabase _database;
+
+    public MongoVexStoreMappingTests()
+    {
+        _runner = MongoDbRunner.Start();
+        var client = new MongoClient(_runner.ConnectionString);
+        _database = client.GetDatabase("vexer-storage-mapping-tests");
+        VexMongoMappingRegistry.Register();
+    }
+
+    [Fact]
+    public async Task ProviderStore_RoundTrips_WithExtraFields()
+    {
+        var providers = _database.GetCollection<BsonDocument>(VexMongoCollectionNames.Providers);
+        var providerId = "red-hat";
+
+        var document = new BsonDocument
+        {
+            { "_id", providerId },
+            { "DisplayName", "Red Hat CSAF" },
+            { "Kind", "vendor" },
+            { "BaseUris", new BsonArray { "https://example.com/csaf" } },
+            {
+                "Discovery",
+                new BsonDocument
+                {
+                    { "WellKnownMetadata", "https://example.com/.well-known/csaf" },
+                    { "RolIeService", "https://example.com/service/rolie" },
+                    { "UnsupportedField", "ignored" },
+                }
+            },
+            {
+                "Trust",
+                new BsonDocument
+                {
+                    { "Weight", 0.75 },
+                    {
+                        "Cosign",
+                        new BsonDocument
+                        {
+                            { "Issuer", "issuer@example.com" },
+                            { "IdentityPattern", "spiffe://example/*" },
+                            { "Unexpected", true },
+                        }
+                    },
+                    { "PgpFingerprints", new BsonArray { "ABCDEF1234567890" } },
+                    { "AnotherIgnoredField", 123 },
+                }
+            },
+            { "Enabled", true },
+            { "UnexpectedRoot", new BsonDocument { { "flag", true } } },
+        };
+
+        await providers.InsertOneAsync(document);
+
+        var store = new MongoVexProviderStore(_database);
+        var result = await store.FindAsync(providerId, CancellationToken.None);
+
+        Assert.NotNull(result);
+        Assert.Equal(providerId, result!.Id);
+        Assert.Equal("Red Hat CSAF", result.DisplayName);
+        Assert.Equal(VexProviderKind.Vendor, result.Kind);
+        Assert.Single(result.BaseUris);
+        Assert.Equal("https://example.com/csaf", result.BaseUris[0].ToString());
+        Assert.Equal("https://example.com/.well-known/csaf", result.Discovery.WellKnownMetadata?.ToString());
+        Assert.Equal("https://example.com/service/rolie", result.Discovery.RolIeService?.ToString());
+        Assert.Equal(0.75, result.Trust.Weight);
+        Assert.NotNull(result.Trust.Cosign);
+        Assert.Equal("issuer@example.com", result.Trust.Cosign!.Issuer);
+        Assert.Equal("spiffe://example/*", result.Trust.Cosign!.IdentityPattern);
+        Assert.Contains("ABCDEF1234567890", result.Trust.PgpFingerprints);
+        Assert.True(result.Enabled);
+    }
+
+    [Fact]
+    public async Task ConsensusStore_IgnoresUnknownFields()
+    {
+        var consensus = _database.GetCollection<BsonDocument>(VexMongoCollectionNames.Consensus);
+        var vulnerabilityId = "CVE-2025-12345";
+        var productKey = "pkg:maven/org.example/app@1.2.3";
+        var consensusId = string.Format(CultureInfo.InvariantCulture, "{0}|{1}", vulnerabilityId.Trim(), productKey.Trim());
+
+        var document = new BsonDocument
+        {
+            { "_id", consensusId },
+            { "VulnerabilityId", vulnerabilityId },
+            {
+                "Product",
+                new BsonDocument
+                {
+                    { "Key", productKey },
+                    { "Name", "Example App" },
+                    { "Version", "1.2.3" },
+                    { "Purl", productKey },
+                    { "Extra", "ignored" },
+                }
+            },
+            { "Status", "notaffected" },
+            { "CalculatedAt", DateTime.UtcNow },
+            {
+                "Sources",
+                new BsonArray
+                {
+                    new BsonDocument
+                    {
+                        { "ProviderId", "red-hat" },
+                        { "Status", "notaffected" },
+                        { "DocumentDigest", "sha256:123" },
+                        { "Weight", 0.9 },
+                        { "Justification", "componentnotpresent" },
+                        { "Detail", "Vendor statement" },
+                        {
+                            "Confidence",
+                            new BsonDocument
+                            {
+                                { "Level", "high" },
+                                { "Score", 0.7 },
+                                { "Method", "review" },
+                                { "Unexpected", "ignored" },
+                            }
+                        },
+                        { "UnknownField", true },
+                    },
+                }
+            },
+            {
+                "Conflicts",
+                new BsonArray
+                {
+                    new BsonDocument
+                    {
+                        { "ProviderId", "cisco" },
+                        { "Status", "affected" },
+                        { "DocumentDigest", "sha256:999" },
+                        { "Justification", "requiresconfiguration" },
+                        { "Detail", "Different guidance" },
+                        { "Reason", "policy_override" },
+                        { "Other", 1 },
+                    },
+                }
+            },
+            { "PolicyVersion", "2025.10" },
+            { "PolicyRevisionId", "rev-1" },
+            { "PolicyDigest", "sha256:abc" },
+            { "Summary", "Vendor confirms not affected." },
+            { "Unexpected", new BsonDocument { { "foo", "bar" } } },
+        };
+
+        await consensus.InsertOneAsync(document);
+
+        var store = new MongoVexConsensusStore(_database);
+        var result = await store.FindAsync(vulnerabilityId, productKey, CancellationToken.None);
+
+        Assert.NotNull(result);
+        Assert.Equal(vulnerabilityId, result!.VulnerabilityId);
+        Assert.Equal(productKey, result.Product.Key);
+        Assert.Equal("Example App", result.Product.Name);
+        Assert.Equal(VexConsensusStatus.NotAffected, result.Status);
+        Assert.Single(result.Sources);
+        var source = result.Sources[0];
+        Assert.Equal("red-hat", source.ProviderId);
+        Assert.Equal(VexClaimStatus.NotAffected, source.Status);
+        Assert.Equal("sha256:123", source.DocumentDigest);
+        Assert.Equal(0.9, source.Weight);
+        Assert.Equal(VexJustification.ComponentNotPresent, source.Justification);
+        Assert.NotNull(source.Confidence);
+        Assert.Equal("high", source.Confidence!.Level);
+        Assert.Equal(0.7, source.Confidence!.Score);
+        Assert.Equal("review", source.Confidence!.Method);
+        Assert.Single(result.Conflicts);
+        var conflict = result.Conflicts[0];
+        Assert.Equal("cisco", conflict.ProviderId);
+        Assert.Equal(VexClaimStatus.Affected, conflict.Status);
+        Assert.Equal(VexJustification.RequiresConfiguration, conflict.Justification);
+        Assert.Equal("policy_override", conflict.Reason);
+        Assert.Equal("Vendor confirms not affected.", result.Summary);
+        Assert.Equal("2025.10", result.PolicyVersion);
+    }
+
+    [Fact]
+    public async Task CacheIndex_RoundTripsGridFsMetadata()
+    {
+        var gridObjectId = ObjectId.GenerateNewId().ToString();
+        var index = new MongoVexCacheIndex(_database);
+        var signature = new VexQuerySignature("format=csaf|vendor=redhat");
+        var now = DateTimeOffset.UtcNow;
+        var expires = now.AddHours(12);
+        var entry = new VexCacheEntry(
+            signature,
+            VexExportFormat.Csaf,
+            new VexContentAddress("sha256", "abcdef123456"),
+            now,
+            sizeBytes: 1024,
+            manifestId: "manifest-001",
+            gridFsObjectId: gridObjectId,
+            expiresAt: expires);
+
+        await index.SaveAsync(entry, CancellationToken.None);
+
+        var cacheId = string.Format(
+            CultureInfo.InvariantCulture,
+            "{0}|{1}",
+            signature.Value,
+            entry.Format.ToString().ToLowerInvariant());
+
+        var cache = _database.GetCollection<BsonDocument>(VexMongoCollectionNames.Cache);
+        var filter = Builders<BsonDocument>.Filter.Eq("_id", cacheId);
+        var update = Builders<BsonDocument>.Update.Set("UnexpectedField", true);
+        await cache.UpdateOneAsync(filter, update);
+
+        var roundTrip = await index.FindAsync(signature, VexExportFormat.Csaf, CancellationToken.None);
+
+        Assert.NotNull(roundTrip);
+        Assert.Equal(entry.QuerySignature.Value, roundTrip!.QuerySignature.Value);
+        Assert.Equal(entry.Format, roundTrip.Format);
+        Assert.Equal(entry.Artifact.Digest, roundTrip.Artifact.Digest);
+        Assert.Equal(entry.ManifestId, roundTrip.ManifestId);
+        Assert.Equal(entry.GridFsObjectId, roundTrip.GridFsObjectId);
+        Assert.Equal(entry.SizeBytes, roundTrip.SizeBytes);
+        Assert.NotNull(roundTrip.ExpiresAt);
+        Assert.Equal(expires.ToUnixTimeMilliseconds(), roundTrip.ExpiresAt!.Value.ToUnixTimeMilliseconds());
+    }
+
+    public Task InitializeAsync() => Task.CompletedTask;
+
+    public Task DisposeAsync()
+    {
+        _runner.Dispose();
+        return Task.CompletedTask;
+    }
+}

src/StellaOps.Vexer.Storage.Mongo.Tests/StellaOps.Vexer.Storage.Mongo.Tests.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.Storage.Mongo\StellaOps.Vexer.Storage.Mongo.csproj" />
+    <ProjectReference Include="..\StellaOps.Vexer.Core\StellaOps.Vexer.Core.csproj" />
+    <ProjectReference Include="..\StellaOps.Vexer.Policy\StellaOps.Vexer.Policy.csproj" />
+    <ProjectReference Include="..\StellaOps.Feedser.Storage.Mongo\StellaOps.Feedser.Storage.Mongo.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.Storage.Mongo.Tests/VexMongoMigrationRunnerTests.cs

@@ -0,0 +1,59 @@
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging.Abstractions;
+using Mongo2Go;
+using MongoDB.Driver;
+using StellaOps.Vexer.Storage.Mongo.Migrations;
+
+namespace StellaOps.Vexer.Storage.Mongo.Tests;
+
+public sealed class VexMongoMigrationRunnerTests : IAsyncLifetime
+{
+    private readonly MongoDbRunner _runner;
+    private readonly IMongoDatabase _database;
+
+    public VexMongoMigrationRunnerTests()
+    {
+        _runner = MongoDbRunner.Start();
+        var client = new MongoClient(_runner.ConnectionString);
+        _database = client.GetDatabase("vexer-migrations-tests");
+    }
+
+    [Fact]
+    public async Task RunAsync_AppliesInitialIndexesOnce()
+    {
+        var migration = new VexInitialIndexMigration();
+        var runner = new VexMongoMigrationRunner(_database, new[] { migration }, NullLogger<VexMongoMigrationRunner>.Instance);
+
+        await runner.RunAsync(CancellationToken.None);
+        await runner.RunAsync(CancellationToken.None);
+
+        var appliedCollection = _database.GetCollection<VexMigrationRecord>(VexMongoCollectionNames.Migrations);
+        var applied = await appliedCollection.Find(FilterDefinition<VexMigrationRecord>.Empty).ToListAsync();
+        Assert.Single(applied);
+        Assert.Equal(migration.Id, applied[0].Id);
+
+        Assert.True(HasIndex(_database.GetCollection<VexRawDocumentRecord>(VexMongoCollectionNames.Raw), "ProviderId_1_Format_1_RetrievedAt_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexProviderRecord>(VexMongoCollectionNames.Providers), "Kind_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexConsensusRecord>(VexMongoCollectionNames.Consensus), "VulnerabilityId_1_Product.Key_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexConsensusRecord>(VexMongoCollectionNames.Consensus), "PolicyRevisionId_1_PolicyDigest_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports), "QuerySignature_1_Format_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache), "QuerySignature_1_Format_1"));
+        Assert.True(HasIndex(_database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache), "ExpiresAt_1"));
+    }
+
+    private static bool HasIndex<TDocument>(IMongoCollection<TDocument> collection, string name)
+    {
+        var indexes = collection.Indexes.List().ToList();
+        return indexes.Any(index => index["name"].AsString == name);
+    }
+
+    public Task InitializeAsync() => Task.CompletedTask;
+
+    public Task DisposeAsync()
+    {
+        _runner.Dispose();
+        return Task.CompletedTask;
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/IVexStorageContracts.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+public interface IVexProviderStore
+{
+    ValueTask<VexProvider?> FindAsync(string id, CancellationToken cancellationToken);
+
+    ValueTask<IReadOnlyCollection<VexProvider>> ListAsync(CancellationToken cancellationToken);
+
+    ValueTask SaveAsync(VexProvider provider, CancellationToken cancellationToken);
+}
+
+public interface IVexConsensusStore
+{
+    ValueTask<VexConsensus?> FindAsync(string vulnerabilityId, string productKey, CancellationToken cancellationToken);
+
+    ValueTask<IReadOnlyCollection<VexConsensus>> FindByVulnerabilityAsync(string vulnerabilityId, CancellationToken cancellationToken);
+
+    ValueTask SaveAsync(VexConsensus consensus, CancellationToken cancellationToken);
+}
+
+public interface IVexCacheIndex
+{
+    ValueTask<VexCacheEntry?> FindAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken);
+
+    ValueTask SaveAsync(VexCacheEntry entry, CancellationToken cancellationToken);
+
+    ValueTask RemoveAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken);
+}
+
+public interface IVexCacheMaintenance
+{
+    ValueTask<int> RemoveExpiredAsync(DateTimeOffset asOf, CancellationToken cancellationToken);
+
+    ValueTask<int> RemoveMissingManifestReferencesAsync(CancellationToken cancellationToken);
+}

src/StellaOps.Vexer.Storage.Mongo/Migrations/IVexMongoMigration.cs

@@ -0,0 +1,12 @@
+using System.Threading;
+using System.Threading.Tasks;
+using MongoDB.Driver;
+
+namespace StellaOps.Vexer.Storage.Mongo.Migrations;
+
+internal interface IVexMongoMigration
+{
+    string Id { get; }
+
+    ValueTask ExecuteAsync(IMongoDatabase database, CancellationToken cancellationToken);
+}

src/StellaOps.Vexer.Storage.Mongo/Migrations/VexInitialIndexMigration.cs

@@ -0,0 +1,75 @@
+using System.Threading;
+using System.Threading.Tasks;
+using MongoDB.Driver;
+
+namespace StellaOps.Vexer.Storage.Mongo.Migrations;
+
+internal sealed class VexInitialIndexMigration : IVexMongoMigration
+{
+    public string Id => "20251016-initial-indexes";
+
+    public async ValueTask ExecuteAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(database);
+
+        await EnsureRawIndexesAsync(database, cancellationToken).ConfigureAwait(false);
+        await EnsureProviderIndexesAsync(database, cancellationToken).ConfigureAwait(false);
+        await EnsureConsensusIndexesAsync(database, cancellationToken).ConfigureAwait(false);
+        await EnsureExportIndexesAsync(database, cancellationToken).ConfigureAwait(false);
+        await EnsureCacheIndexesAsync(database, cancellationToken).ConfigureAwait(false);
+    }
+
+    private static Task EnsureRawIndexesAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        var collection = database.GetCollection<VexRawDocumentRecord>(VexMongoCollectionNames.Raw);
+        var providerFormatIndex = Builders<VexRawDocumentRecord>.IndexKeys
+            .Ascending(x => x.ProviderId)
+            .Ascending(x => x.Format)
+            .Ascending(x => x.RetrievedAt);
+        return collection.Indexes.CreateOneAsync(new CreateIndexModel<VexRawDocumentRecord>(providerFormatIndex), cancellationToken: cancellationToken);
+    }
+
+    private static Task EnsureProviderIndexesAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        var collection = database.GetCollection<VexProviderRecord>(VexMongoCollectionNames.Providers);
+        var kindIndex = Builders<VexProviderRecord>.IndexKeys.Ascending(x => x.Kind);
+        return collection.Indexes.CreateOneAsync(new CreateIndexModel<VexProviderRecord>(kindIndex), cancellationToken: cancellationToken);
+    }
+
+    private static Task EnsureConsensusIndexesAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        var collection = database.GetCollection<VexConsensusRecord>(VexMongoCollectionNames.Consensus);
+        var vulnProductIndex = Builders<VexConsensusRecord>.IndexKeys
+            .Ascending(x => x.VulnerabilityId)
+            .Ascending(x => x.Product.Key);
+        var policyIndex = Builders<VexConsensusRecord>.IndexKeys
+            .Ascending(x => x.PolicyRevisionId)
+            .Ascending(x => x.PolicyDigest);
+
+        return Task.WhenAll(
+            collection.Indexes.CreateOneAsync(new CreateIndexModel<VexConsensusRecord>(vulnProductIndex, new CreateIndexOptions { Unique = true }), cancellationToken: cancellationToken),
+            collection.Indexes.CreateOneAsync(new CreateIndexModel<VexConsensusRecord>(policyIndex), cancellationToken: cancellationToken));
+    }
+
+    private static Task EnsureExportIndexesAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        var collection = database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports);
+        var signatureIndex = Builders<VexExportManifestRecord>.IndexKeys
+            .Ascending(x => x.QuerySignature)
+            .Ascending(x => x.Format);
+        return collection.Indexes.CreateOneAsync(new CreateIndexModel<VexExportManifestRecord>(signatureIndex, new CreateIndexOptions { Unique = true }), cancellationToken: cancellationToken);
+    }
+
+    private static Task EnsureCacheIndexesAsync(IMongoDatabase database, CancellationToken cancellationToken)
+    {
+        var collection = database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
+        var signatureIndex = Builders<VexCacheEntryRecord>.IndexKeys
+            .Ascending(x => x.QuerySignature)
+            .Ascending(x => x.Format);
+        var expirationIndex = Builders<VexCacheEntryRecord>.IndexKeys.Ascending(x => x.ExpiresAt);
+
+        return Task.WhenAll(
+            collection.Indexes.CreateOneAsync(new CreateIndexModel<VexCacheEntryRecord>(signatureIndex, new CreateIndexOptions { Unique = true }), cancellationToken: cancellationToken),
+            collection.Indexes.CreateOneAsync(new CreateIndexModel<VexCacheEntryRecord>(expirationIndex, new CreateIndexOptions { ExpireAfter = TimeSpan.FromSeconds(0) }), cancellationToken: cancellationToken));
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/Migrations/VexMigrationRecord.cs

@@ -0,0 +1,18 @@
+using System;
+using MongoDB.Bson.Serialization.Attributes;
+
+namespace StellaOps.Vexer.Storage.Mongo.Migrations;
+
+internal sealed class VexMigrationRecord
+{
+    public VexMigrationRecord(string id, DateTimeOffset executedAt)
+    {
+        Id = string.IsNullOrWhiteSpace(id) ? throw new ArgumentException("Migration id must be provided.", nameof(id)) : id.Trim();
+        ExecutedAt = executedAt;
+    }
+
+    [BsonId]
+    public string Id { get; }
+
+    public DateTimeOffset ExecutedAt { get; }
+}

src/StellaOps.Vexer.Storage.Mongo/Migrations/VexMongoMigrationHostedService.cs

@@ -0,0 +1,22 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Hosting;
+
+namespace StellaOps.Vexer.Storage.Mongo.Migrations;
+
+internal sealed class VexMongoMigrationHostedService : IHostedService
+{
+    private readonly VexMongoMigrationRunner _runner;
+
+    public VexMongoMigrationHostedService(VexMongoMigrationRunner runner)
+    {
+        _runner = runner ?? throw new ArgumentNullException(nameof(runner));
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        await _runner.RunAsync(cancellationToken).ConfigureAwait(false);
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+}

src/StellaOps.Vexer.Storage.Mongo/Migrations/VexMongoMigrationRunner.cs

@@ -0,0 +1,74 @@
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using MongoDB.Driver;
+
+namespace StellaOps.Vexer.Storage.Mongo.Migrations;
+
+internal sealed class VexMongoMigrationRunner
+{
+    private readonly IMongoDatabase _database;
+    private readonly IReadOnlyList<IVexMongoMigration> _migrations;
+    private readonly ILogger<VexMongoMigrationRunner> _logger;
+
+    public VexMongoMigrationRunner(
+        IMongoDatabase database,
+        IEnumerable<IVexMongoMigration> migrations,
+        ILogger<VexMongoMigrationRunner> logger)
+    {
+        _database = database ?? throw new ArgumentNullException(nameof(database));
+        _migrations = (migrations ?? throw new ArgumentNullException(nameof(migrations)))
+            .OrderBy(migration => migration.Id, StringComparer.Ordinal)
+            .ToArray();
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    public async ValueTask RunAsync(CancellationToken cancellationToken)
+    {
+        if (_migrations.Count == 0)
+        {
+            return;
+        }
+
+        var migrationsCollection = _database.GetCollection<VexMigrationRecord>(VexMongoCollectionNames.Migrations);
+        await EnsureMigrationsIndexAsync(migrationsCollection, cancellationToken).ConfigureAwait(false);
+
+        var applied = await LoadAppliedMigrationsAsync(migrationsCollection, cancellationToken).ConfigureAwait(false);
+
+        foreach (var migration in _migrations)
+        {
+            if (applied.Contains(migration.Id))
+            {
+                continue;
+            }
+
+            _logger.LogInformation("Applying Vexer Mongo migration {MigrationId}", migration.Id);
+            await migration.ExecuteAsync(_database, cancellationToken).ConfigureAwait(false);
+
+            var record = new VexMigrationRecord(migration.Id, DateTimeOffset.UtcNow);
+            await migrationsCollection.InsertOneAsync(record, cancellationToken: cancellationToken).ConfigureAwait(false);
+            _logger.LogInformation("Completed Vexer Mongo migration {MigrationId}", migration.Id);
+        }
+    }
+
+    private static ValueTask EnsureMigrationsIndexAsync(
+        IMongoCollection<VexMigrationRecord> collection,
+        CancellationToken cancellationToken)
+    {
+        // default _id index already enforces uniqueness
+        return ValueTask.CompletedTask;
+    }
+
+    private static async ValueTask<HashSet<string>> LoadAppliedMigrationsAsync(
+        IMongoCollection<VexMigrationRecord> collection,
+        CancellationToken cancellationToken)
+    {
+        var records = await collection.Find(FilterDefinition<VexMigrationRecord>.Empty)
+            .ToListAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        return records.Select(static record => record.Id)
+            .ToHashSet(StringComparer.Ordinal);
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/MongoVexCacheIndex.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MongoDB.Bson;
+using MongoDB.Driver;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+public sealed class MongoVexCacheIndex : IVexCacheIndex
+{
+    private readonly IMongoCollection<VexCacheEntryRecord> _collection;
+
+    public MongoVexCacheIndex(IMongoDatabase database)
+    {
+        ArgumentNullException.ThrowIfNull(database);
+        VexMongoMappingRegistry.Register();
+        _collection = database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
+    }
+
+    public async ValueTask<VexCacheEntry?> FindAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(signature);
+        var filter = Builders<VexCacheEntryRecord>.Filter.Eq(x => x.Id, VexCacheEntryRecord.CreateId(signature, format));
+        var record = await _collection.Find(filter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
+        return record?.ToDomain();
+    }
+
+    public async ValueTask SaveAsync(VexCacheEntry entry, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(entry);
+        var record = VexCacheEntryRecord.FromDomain(entry);
+        var filter = Builders<VexCacheEntryRecord>.Filter.Eq(x => x.Id, record.Id);
+        await _collection.ReplaceOneAsync(filter, record, new ReplaceOptions { IsUpsert = true }, cancellationToken).ConfigureAwait(false);
+    }
+
+    public async ValueTask RemoveAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(signature);
+        var filter = Builders<VexCacheEntryRecord>.Filter.Eq(x => x.Id, VexCacheEntryRecord.CreateId(signature, format));
+        await _collection.DeleteOneAsync(filter, cancellationToken).ConfigureAwait(false);
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/MongoVexCacheMaintenance.cs

@@ -0,0 +1,85 @@
+using System.Collections.Generic;
+using Microsoft.Extensions.Logging;
+using MongoDB.Driver;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+internal sealed class MongoVexCacheMaintenance : IVexCacheMaintenance
+{
+    private readonly IMongoCollection<VexCacheEntryRecord> _cache;
+    private readonly IMongoCollection<VexExportManifestRecord> _exports;
+    private readonly ILogger<MongoVexCacheMaintenance> _logger;
+
+    public MongoVexCacheMaintenance(
+        IMongoDatabase database,
+        ILogger<MongoVexCacheMaintenance> logger)
+    {
+        ArgumentNullException.ThrowIfNull(database);
+        ArgumentNullException.ThrowIfNull(logger);
+
+        VexMongoMappingRegistry.Register();
+
+        _cache = database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
+        _exports = database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports);
+        _logger = logger;
+    }
+
+    public async ValueTask<int> RemoveExpiredAsync(DateTimeOffset asOf, CancellationToken cancellationToken)
+    {
+        var cutoff = asOf.UtcDateTime;
+        var filter = Builders<VexCacheEntryRecord>.Filter.Lt(x => x.ExpiresAt, cutoff);
+        var result = await _cache.DeleteManyAsync(filter, cancellationToken).ConfigureAwait(false);
+
+        var removed = (int)result.DeletedCount;
+        if (removed > 0)
+        {
+            _logger.LogInformation("Pruned {Count} expired VEX export cache entries (cutoff {Cutoff})", removed, cutoff);
+        }
+
+        return removed;
+    }
+
+    public async ValueTask<int> RemoveMissingManifestReferencesAsync(CancellationToken cancellationToken)
+    {
+        var filter = Builders<VexCacheEntryRecord>.Filter.Ne(x => x.ManifestId, null);
+        var cursor = await _cache.Find(filter).ToListAsync(cancellationToken).ConfigureAwait(false);
+
+        if (cursor.Count == 0)
+        {
+            return 0;
+        }
+
+        var danglingIds = new List<string>(cursor.Count);
+        foreach (var entry in cursor)
+        {
+            if (string.IsNullOrWhiteSpace(entry.ManifestId))
+            {
+                continue;
+            }
+
+            var manifestExists = await _exports
+                .Find(Builders<VexExportManifestRecord>.Filter.Eq(x => x.Id, entry.ManifestId))
+                .Limit(1)
+                .AnyAsync(cancellationToken)
+                .ConfigureAwait(false);
+
+            if (!manifestExists)
+            {
+                danglingIds.Add(entry.Id);
+            }
+        }
+
+        if (danglingIds.Count == 0)
+        {
+            return 0;
+        }
+
+        var danglingFilter = Builders<VexCacheEntryRecord>.Filter.In(x => x.Id, danglingIds);
+        var result = await _cache.DeleteManyAsync(danglingFilter, cancellationToken).ConfigureAwait(false);
+
+        var removed = (int)result.DeletedCount;
+        _logger.LogWarning("Removed {Count} cache entries referencing missing export manifests.", removed);
+
+        return removed;
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/MongoVexConsensusStore.cs

@@ -0,0 +1,46 @@
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using MongoDB.Driver;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+public sealed class MongoVexConsensusStore : IVexConsensusStore
+{
+    private readonly IMongoCollection<VexConsensusRecord> _collection;
+
+    public MongoVexConsensusStore(IMongoDatabase database)
+    {
+        ArgumentNullException.ThrowIfNull(database);
+        VexMongoMappingRegistry.Register();
+        _collection = database.GetCollection<VexConsensusRecord>(VexMongoCollectionNames.Consensus);
+    }
+
+    public async ValueTask<VexConsensus?> FindAsync(string vulnerabilityId, string productKey, CancellationToken cancellationToken)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(vulnerabilityId);
+        ArgumentException.ThrowIfNullOrWhiteSpace(productKey);
+        var id = VexConsensusRecord.CreateId(vulnerabilityId, productKey);
+        var filter = Builders<VexConsensusRecord>.Filter.Eq(x => x.Id, id);
+        var record = await _collection.Find(filter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
+        return record?.ToDomain();
+    }
+
+    public async ValueTask<IReadOnlyCollection<VexConsensus>> FindByVulnerabilityAsync(string vulnerabilityId, CancellationToken cancellationToken)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(vulnerabilityId);
+        var filter = Builders<VexConsensusRecord>.Filter.Eq(x => x.VulnerabilityId, vulnerabilityId.Trim());
+        var records = await _collection.Find(filter).ToListAsync(cancellationToken).ConfigureAwait(false);
+        return records.ConvertAll(static record => record.ToDomain());
+    }
+
+    public async ValueTask SaveAsync(VexConsensus consensus, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(consensus);
+        var record = VexConsensusRecord.FromDomain(consensus);
+        var filter = Builders<VexConsensusRecord>.Filter.Eq(x => x.Id, record.Id);
+        await _collection.ReplaceOneAsync(filter, record, new ReplaceOptions { IsUpsert = true }, cancellationToken).ConfigureAwait(false);
+    }
+
+}

src/StellaOps.Vexer.Storage.Mongo/MongoVexExportStore.cs

@@ -1,46 +1,150 @@
+using System;
+using System.ComponentModel.DataAnnotations;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Options;
 using MongoDB.Driver;
+using MongoDB.Driver.Core.Clusters;
 using StellaOps.Vexer.Core;
 
 namespace StellaOps.Vexer.Storage.Mongo;
 
 public sealed class MongoVexExportStore : IVexExportStore
 {
-    private readonly IMongoCollection<VexExportManifestRecord> _collection;
+    private readonly IMongoClient _client;
+    private readonly IMongoCollection<VexExportManifestRecord> _exports;
+    private readonly IMongoCollection<VexCacheEntryRecord> _cache;
+    private readonly VexMongoStorageOptions _options;
 
-    public MongoVexExportStore(IMongoDatabase database)
+    public MongoVexExportStore(
+        IMongoClient client,
+        IMongoDatabase database,
+        IOptions<VexMongoStorageOptions> options)
     {
+        _client = client ?? throw new ArgumentNullException(nameof(client));
         ArgumentNullException.ThrowIfNull(database);
+        ArgumentNullException.ThrowIfNull(options);
+
+        _options = options.Value;
+        Validator.ValidateObject(_options, new ValidationContext(_options), validateAllProperties: true);
+
         VexMongoMappingRegistry.Register();
-        _collection = database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports);
+        _exports = database.GetCollection<VexExportManifestRecord>(VexMongoCollectionNames.Exports);
-        EnsureIndexes(_collection);
+        _cache = database.GetCollection<VexCacheEntryRecord>(VexMongoCollectionNames.Cache);
     }
 
     public async ValueTask<VexExportManifest?> FindAsync(VexQuerySignature signature, VexExportFormat format, CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(signature);
-        var id = VexExportManifestRecord.CreateId(signature, format);
+        var cacheId = VexCacheEntryRecord.CreateId(signature, format);
-        var filter = Builders<VexExportManifestRecord>.Filter.Eq(x => x.Id, id);
+        var cacheFilter = Builders<VexCacheEntryRecord>.Filter.Eq(x => x.Id, cacheId);
-        var entity = await _collection.Find(filter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
+        var cacheRecord = await _cache.Find(cacheFilter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
-        return entity?.ToDomain();
+
+        if (cacheRecord is null)
+        {
+            return null;
+        }
+
+        if (cacheRecord.ExpiresAt is DateTime expiresAt && expiresAt <= DateTime.UtcNow)
+        {
+            await _cache.DeleteOneAsync(cacheFilter, cancellationToken).ConfigureAwait(false);
+            return null;
+        }
+
+        var manifestId = VexExportManifestRecord.CreateId(signature, format);
+        var manifestFilter = Builders<VexExportManifestRecord>.Filter.Eq(x => x.Id, manifestId);
+        var manifest = await _exports.Find(manifestFilter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
+
+        if (manifest is null)
+        {
+            await _cache.DeleteOneAsync(cacheFilter, cancellationToken).ConfigureAwait(false);
+            return null;
+        }
+
+        if (!string.IsNullOrWhiteSpace(cacheRecord.ManifestId) &&
+            !string.Equals(cacheRecord.ManifestId, manifest.Id, StringComparison.Ordinal))
+        {
+            await _cache.DeleteOneAsync(cacheFilter, cancellationToken).ConfigureAwait(false);
+            return null;
+        }
+
+        return manifest.ToDomain();
     }
 
     public async ValueTask SaveAsync(VexExportManifest manifest, CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(manifest);
-        var entity = VexExportManifestRecord.FromDomain(manifest);
+
-        var filter = Builders<VexExportManifestRecord>.Filter.Eq(x => x.Id, entity.Id);
+        using var session = await _client.StartSessionAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
-        await _collection.ReplaceOneAsync(filter, entity, new ReplaceOptions { IsUpsert = true }, cancellationToken)
+        var supportsTransactions = session.Client.Cluster.Description.Type != ClusterType.Standalone;
-            .ConfigureAwait(false);
+
+        var startedTransaction = false;
+        if (supportsTransactions)
+        {
+            try
+            {
+                session.StartTransaction();
+                startedTransaction = true;
+            }
+            catch (NotSupportedException)
+            {
+                supportsTransactions = false;
+            }
         }
 
-    private static void EnsureIndexes(IMongoCollection<VexExportManifestRecord> collection)
+        try
         {
-        var keys = Builders<VexExportManifestRecord>.IndexKeys
+            var manifestRecord = VexExportManifestRecord.FromDomain(manifest);
-            .Ascending(x => x.QuerySignature)
+            var manifestFilter = Builders<VexExportManifestRecord>.Filter.Eq(x => x.Id, manifestRecord.Id);
-            .Ascending(x => x.Format);
+
-        var model = new CreateIndexModel<VexExportManifestRecord>(keys);
+            await _exports
-        _ = collection.Indexes.CreateOne(model);
+                .ReplaceOneAsync(
+                    session,
+                    manifestFilter,
+                    manifestRecord,
+                    new ReplaceOptions { IsUpsert = true },
+                    cancellationToken)
+                .ConfigureAwait(false);
+
+            var cacheEntry = CreateCacheEntry(manifest);
+            var cacheRecord = VexCacheEntryRecord.FromDomain(cacheEntry);
+            var cacheFilter = Builders<VexCacheEntryRecord>.Filter.Eq(x => x.Id, cacheRecord.Id);
+
+            await _cache
+                .ReplaceOneAsync(
+                    session,
+                    cacheFilter,
+                    cacheRecord,
+                    new ReplaceOptions { IsUpsert = true },
+                    cancellationToken)
+                .ConfigureAwait(false);
+
+            if (startedTransaction)
+            {
+                await session.CommitTransactionAsync(cancellationToken).ConfigureAwait(false);
+            }
+        }
+        catch
+        {
+            if (startedTransaction && session.IsInTransaction)
+            {
+                await session.AbortTransactionAsync(cancellationToken).ConfigureAwait(false);
+            }
+            throw;
+        }
+    }
+
+    private VexCacheEntry CreateCacheEntry(VexExportManifest manifest)
+    {
+        var expiresAt = manifest.CreatedAt + _options.ExportCacheTtl;
+        return new VexCacheEntry(
+            manifest.QuerySignature,
+            manifest.Format,
+            manifest.Artifact,
+            manifest.CreatedAt,
+            manifest.SizeBytes,
+            manifestId: manifest.ExportId,
+            gridFsObjectId: null,
+            expiresAt: expiresAt);
     }
 }

src/StellaOps.Vexer.Storage.Mongo/MongoVexProviderStore.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using MongoDB.Driver;
+using StellaOps.Vexer.Core;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+public sealed class MongoVexProviderStore : IVexProviderStore
+{
+    private readonly IMongoCollection<VexProviderRecord> _collection;
+
+    public MongoVexProviderStore(IMongoDatabase database)
+    {
+        ArgumentNullException.ThrowIfNull(database);
+        VexMongoMappingRegistry.Register();
+        _collection = database.GetCollection<VexProviderRecord>(VexMongoCollectionNames.Providers);
+    }
+
+    public async ValueTask<VexProvider?> FindAsync(string id, CancellationToken cancellationToken)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(id);
+        var filter = Builders<VexProviderRecord>.Filter.Eq(x => x.Id, id.Trim());
+        var record = await _collection.Find(filter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
+        return record?.ToDomain();
+    }
+
+    public async ValueTask<IReadOnlyCollection<VexProvider>> ListAsync(CancellationToken cancellationToken)
+    {
+        var records = await _collection.Find(FilterDefinition<VexProviderRecord>.Empty)
+            .Sort(Builders<VexProviderRecord>.Sort.Ascending(x => x.Id))
+            .ToListAsync(cancellationToken)
+            .ConfigureAwait(false);
+
+        return records.ConvertAll(static record => record.ToDomain());
+    }
+
+    public async ValueTask SaveAsync(VexProvider provider, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(provider);
+        var record = VexProviderRecord.FromDomain(provider);
+        var filter = Builders<VexProviderRecord>.Filter.Eq(x => x.Id, record.Id);
+        await _collection.ReplaceOneAsync(filter, record, new ReplaceOptions { IsUpsert = true }, cancellationToken).ConfigureAwait(false);
+    }
+}

src/StellaOps.Vexer.Storage.Mongo/MongoVexRawStore.cs

@@ -1,33 +1,130 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Options;
+using MongoDB.Bson;
 using MongoDB.Driver;
+using MongoDB.Driver.Core.Clusters;
+using MongoDB.Driver.GridFS;
 using StellaOps.Vexer.Core;
 
 namespace StellaOps.Vexer.Storage.Mongo;
 
 public sealed class MongoVexRawStore : IVexRawStore
 {
+    private readonly IMongoClient _client;
     private readonly IMongoCollection<VexRawDocumentRecord> _collection;
+    private readonly GridFSBucket _bucket;
+    private readonly VexMongoStorageOptions _options;
 
-    public MongoVexRawStore(IMongoDatabase database)
+    public MongoVexRawStore(
+        IMongoClient client,
+        IMongoDatabase database,
+        IOptions<VexMongoStorageOptions> options)
     {
-        if (database is null)
+        _client = client ?? throw new ArgumentNullException(nameof(client));
-        {
+        ArgumentNullException.ThrowIfNull(database);
-            throw new ArgumentNullException(nameof(database));
+        ArgumentNullException.ThrowIfNull(options);
-        }
+
+        _options = options.Value;
+        Validator.ValidateObject(_options, new ValidationContext(_options), validateAllProperties: true);
 
         VexMongoMappingRegistry.Register();
         _collection = database.GetCollection<VexRawDocumentRecord>(VexMongoCollectionNames.Raw);
-        EnsureIndexes(_collection);
+        _bucket = new GridFSBucket(database, new GridFSBucketOptions
+        {
+            BucketName = _options.RawBucketName,
+            ReadConcern = database.Settings.ReadConcern,
+            ReadPreference = database.Settings.ReadPreference,
+            WriteConcern = database.Settings.WriteConcern,
+        });
     }
 
     public async ValueTask StoreAsync(VexRawDocument document, CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(document);
-        var record = VexRawDocumentRecord.FromDomain(document);
+
-        var filter = Builders<VexRawDocumentRecord>.Filter.Eq(x => x.Id, record.Id);
+        var threshold = _options.GridFsInlineThresholdBytes;
-        await _collection.ReplaceOneAsync(filter, record, new ReplaceOptions { IsUpsert = true }, cancellationToken)
+        var useInline = threshold == 0 || document.Content.Length <= threshold;
+        string? newGridId = null;
+        string? oldGridIdToDelete = null;
+
+        if (!useInline)
+        {
+            newGridId = await UploadToGridFsAsync(document, cancellationToken).ConfigureAwait(false);
+        }
+
+        using var session = await _client.StartSessionAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
+        var supportsTransactions = session.Client.Cluster.Description.Type != ClusterType.Standalone;
+
+        var startedTransaction = false;
+        if (supportsTransactions)
+        {
+            try
+            {
+                session.StartTransaction();
+                startedTransaction = true;
+            }
+            catch (NotSupportedException)
+            {
+                supportsTransactions = false;
+            }
+        }
+
+        try
+        {
+            var filter = Builders<VexRawDocumentRecord>.Filter.Eq(x => x.Id, document.Digest);
+            var existing = await _collection
+                .Find(session, filter)
+                .FirstOrDefaultAsync(cancellationToken)
                 .ConfigureAwait(false);
+
+            var record = VexRawDocumentRecord.FromDomain(document, includeContent: useInline);
+            record.GridFsObjectId = useInline ? null : newGridId;
+
+            await _collection
+                .ReplaceOneAsync(
+                    session,
+                    filter,
+                    record,
+                    new ReplaceOptions { IsUpsert = true },
+                    cancellationToken)
+                .ConfigureAwait(false);
+
+            if (existing?.GridFsObjectId is string oldGridId && !string.IsNullOrWhiteSpace(oldGridId))
+            {
+                if (useInline || !string.Equals(newGridId, oldGridId, StringComparison.Ordinal))
+                {
+                    oldGridIdToDelete = oldGridId;
+                }
+            }
+
+            if (startedTransaction)
+            {
+                await session.CommitTransactionAsync(cancellationToken).ConfigureAwait(false);
+            }
+        }
+        catch
+        {
+            if (startedTransaction && session.IsInTransaction)
+            {
+                await session.AbortTransactionAsync(cancellationToken).ConfigureAwait(false);
+            }
+
+            if (!useInline && !string.IsNullOrWhiteSpace(newGridId))
+            {
+                await DeleteFromGridFsAsync(newGridId, cancellationToken).ConfigureAwait(false);
+            }
+
+            throw;
+        }
+
+        if (!string.IsNullOrWhiteSpace(oldGridIdToDelete))
+        {
+            await DeleteFromGridFsAsync(oldGridIdToDelete!, cancellationToken).ConfigureAwait(false);
+        }
     }
 
     public async ValueTask<VexRawDocument?> FindByDigestAsync(string digest, CancellationToken cancellationToken)
@@ -37,17 +134,66 @@ public sealed class MongoVexRawStore : IVexRawStore
             throw new ArgumentException("Digest must be provided.", nameof(digest));
         }
 
-        var filter = Builders<VexRawDocumentRecord>.Filter.Eq(x => x.Id, digest.Trim());
+        var trimmed = digest.Trim();
+        var filter = Builders<VexRawDocumentRecord>.Filter.Eq(x => x.Id, trimmed);
         var record = await _collection.Find(filter).FirstOrDefaultAsync(cancellationToken).ConfigureAwait(false);
-        return record?.ToDomain();
+        if (record is null)
+        {
+            return null;
         }
 
-    private static void EnsureIndexes(IMongoCollection<VexRawDocumentRecord> collection)
+        if (!string.IsNullOrWhiteSpace(record.GridFsObjectId))
         {
-        var keys = Builders<VexRawDocumentRecord>.IndexKeys
+            var bytes = await DownloadFromGridFsAsync(record.GridFsObjectId, cancellationToken).ConfigureAwait(false);
-            .Ascending(x => x.ProviderId)
+            return record.ToDomain(new ReadOnlyMemory<byte>(bytes));
-            .Ascending(x => x.SourceUri);
+        }
-        var model = new CreateIndexModel<VexRawDocumentRecord>(keys);
+
-        _ = collection.Indexes.CreateOne(model);
+        return record.ToDomain();
+    }
+
+    private async Task<string?> UploadToGridFsAsync(VexRawDocument document, CancellationToken cancellationToken)
+    {
+        using var stream = new MemoryStream(document.Content.ToArray(), writable: false);
+        var metadata = new BsonDocument
+        {
+            { "providerId", document.ProviderId },
+            { "format", document.Format.ToString().ToLowerInvariant() },
+            { "sourceUri", document.SourceUri.ToString() },
+            { "retrievedAt", document.RetrievedAt.UtcDateTime },
+        };
+
+        var options = new GridFSUploadOptions { Metadata = metadata };
+        var objectId = await _bucket
+            .UploadFromStreamAsync(document.Digest, stream, options, cancellationToken)
+            .ConfigureAwait(false);
+
+        return objectId.ToString();
+    }
+
+    private async Task DeleteFromGridFsAsync(string gridFsObjectId, CancellationToken cancellationToken)
+    {
+        if (!ObjectId.TryParse(gridFsObjectId, out var objectId))
+        {
+            return;
+        }
+
+        try
+        {
+            await _bucket.DeleteAsync(objectId, cancellationToken).ConfigureAwait(false);
+        }
+        catch (GridFSFileNotFoundException)
+        {
+            // file already removed by TTL or manual cleanup
+        }
+    }
+
+    private async Task<byte[]> DownloadFromGridFsAsync(string gridFsObjectId, CancellationToken cancellationToken)
+    {
+        if (!ObjectId.TryParse(gridFsObjectId, out var objectId))
+        {
+            return Array.Empty<byte>();
+        }
+
+        return await _bucket.DownloadAsBytesAsync(objectId, cancellationToken: cancellationToken).ConfigureAwait(false);
     }
 }

src/StellaOps.Vexer.Storage.Mongo/Properties/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("StellaOps.Vexer.Storage.Mongo.Tests")]

src/StellaOps.Vexer.Storage.Mongo/ServiceCollectionExtensions.cs

@@ -1,4 +1,6 @@
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Storage.Mongo.Migrations;
 
 namespace StellaOps.Vexer.Storage.Mongo;
 
@@ -6,8 +8,17 @@ public static class VexMongoServiceCollectionExtensions
 {
     public static IServiceCollection AddVexerMongoStorage(this IServiceCollection services)
     {
+        services.AddOptions<VexMongoStorageOptions>();
+
         services.AddSingleton<IVexRawStore, MongoVexRawStore>();
         services.AddSingleton<IVexExportStore, MongoVexExportStore>();
+        services.AddSingleton<IVexProviderStore, MongoVexProviderStore>();
+        services.AddSingleton<IVexConsensusStore, MongoVexConsensusStore>();
+        services.AddSingleton<IVexCacheIndex, MongoVexCacheIndex>();
+        services.AddSingleton<IVexCacheMaintenance, MongoVexCacheMaintenance>();
+        services.AddSingleton<IVexMongoMigration, VexInitialIndexMigration>();
+        services.AddSingleton<VexMongoMigrationRunner>();
+        services.AddHostedService<VexMongoMigrationHostedService>();
         return services;
     }
 }

src/StellaOps.Vexer.Storage.Mongo/StellaOps.Vexer.Storage.Mongo.csproj

@@ -9,6 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="8.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="8.0.0" />
     <PackageReference Include="MongoDB.Driver" Version="2.22.0" />
     <PackageReference Include="MongoDB.Driver.GridFS" Version="2.22.0" />
   </ItemGroup>

src/StellaOps.Vexer.Storage.Mongo/TASKS.md

@@ -3,6 +3,8 @@ If you are working on this file you need to read docs/ARCHITECTURE_VEXER.md and
 | Task | Owner(s) | Depends on | Notes |
 |---|---|---|---|
 |VEXER-STORAGE-01-001 – Collection schemas & class maps|Team Vexer Storage|VEXER-CORE-01-001|DONE (2025-10-15) – Added Mongo mapping registry with raw/export entities and service registration groundwork.|
-|VEXER-STORAGE-01-002 – Migrations & indices bootstrap|Team Vexer Storage|VEXER-STORAGE-01-001|TODO – Add bootstrapper creating indices (claims by vulnId/product, exports by querySignature, etc.) and migrations for existing deployments.|
+|VEXER-STORAGE-01-002 – Migrations & indices bootstrap|Team Vexer Storage|VEXER-STORAGE-01-001|**DONE (2025-10-16)** – Add bootstrapper creating indices (claims by vulnId/product, exports by querySignature, etc.) and migrations for existing deployments.<br>2025-10-16: Introduced migration runner + hosted service, initial index migration covers raw/providers/consensus/exports/cache, and tests use Mongo2Go to verify execution.|
-|VEXER-STORAGE-01-003 – Repository layer & transactional flows|Team Vexer Storage|VEXER-STORAGE-01-001|TODO – Provide repository APIs for ingest upserts, export registration, cache lookups, and GridFS raw storage with deterministic transactions.|
+|VEXER-STORAGE-01-003 – Repository layer & transactional flows|Team Vexer Storage|VEXER-STORAGE-01-001|**DONE (2025-10-16)** – Added GridFS-backed raw store with transactional upserts (including fallback for non-replicaset Mongo), export/cache repository coordination, and coverage verifying cache TTL + GridFS round-trips.|
-|VEXER-STORAGE-01-004 – Provider/consensus/cache mappings|Team Vexer Storage|VEXER-STORAGE-01-001|TODO – Implement Bson class maps and collections for providers, consensus snapshots, and cache index (including GridFS linkage).|
+|VEXER-STORAGE-01-004 – Provider/consensus/cache mappings|Team Vexer Storage|VEXER-STORAGE-01-001|**DONE (2025-10-16)** – Registered MongoDB class maps for provider/consensus/cache records with forward-compatible field handling and added coverage ensuring GridFS-linked cache entries round-trip cleanly.|
+|VEXER-STORAGE-02-001 – Statement events & scoring signals|Team Vexer Storage|VEXER-CORE-02-001|TODO – Add immutable `vex.statements` collection, extend consensus documents with severity/KEV/EPSS fields, build indices for `policyRevisionId`/`generatedAt`, and script migrations/backfill guidance for Phase 1 rollout.|
+|VEXER-STORAGE-MONGO-08-001 – Session + causal consistency hardening|Team Vexer Storage|VEXER-STORAGE-01-003|TODO – Register Mongo client/database with majority read/write concerns, expose scoped session helper enabling causal consistency, thread session handles through raw/export/consensus/cache stores (including GridFS reads), and extend integration tests to verify read-your-write semantics during replica-set failover.|

src/StellaOps.Vexer.Storage.Mongo/VexMongoMappingRegistry.cs

@@ -15,15 +15,51 @@ public static class VexMongoMappingRegistry
             return;
         }
 
-        if (!BsonSerializer.IsSerializerRegistered(typeof(byte[])))
+        try
         {
-            BsonSerializer.RegisterSerializer(new ByteArraySerializer());
+            BsonSerializer.RegisterSerializer(typeof(byte[]), new ByteArraySerializer());
         }
+        catch
+        {
+            // serializer already registered – safe to ignore
+        }
+
+        RegisterClassMaps();
+    }
+
+    private static void RegisterClassMaps()
+    {
+        RegisterClassMap<VexProviderRecord>();
+        RegisterClassMap<VexProviderDiscoveryDocument>();
+        RegisterClassMap<VexProviderTrustDocument>();
+        RegisterClassMap<VexCosignTrustDocument>();
+        RegisterClassMap<VexConsensusRecord>();
+        RegisterClassMap<VexProductDocument>();
+        RegisterClassMap<VexConsensusSourceDocument>();
+        RegisterClassMap<VexConsensusConflictDocument>();
+        RegisterClassMap<VexConfidenceDocument>();
+        RegisterClassMap<VexCacheEntryRecord>();
+    }
+
+    private static void RegisterClassMap<TDocument>()
+        where TDocument : class
+    {
+        if (BsonClassMap.IsClassMapRegistered(typeof(TDocument)))
+        {
+            return;
+        }
+
+        BsonClassMap.RegisterClassMap<TDocument>(classMap =>
+        {
+            classMap.AutoMap();
+            classMap.SetIgnoreExtraElements(true);
+        });
     }
 }
 
 public static class VexMongoCollectionNames
 {
+    public const string Migrations = "vex.migrations";
     public const string Providers = "vex.providers";
     public const string Raw = "vex.raw";
     public const string Claims = "vex.claims";

src/StellaOps.Vexer.Storage.Mongo/VexMongoModels.cs

@@ -3,11 +3,13 @@ using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Globalization;
 using System.Linq;
+using MongoDB.Bson;
 using MongoDB.Bson.Serialization.Attributes;
 using StellaOps.Vexer.Core;
 
 namespace StellaOps.Vexer.Storage.Mongo;
 
+[BsonIgnoreExtraElements]
 internal sealed class VexRawDocumentRecord
 {
     [BsonId]
@@ -26,9 +28,13 @@ internal sealed class VexRawDocumentRecord
 
     public byte[] Content { get; set; } = Array.Empty<byte>();
 
+    [BsonRepresentation(BsonType.ObjectId)]
+    public string? GridFsObjectId { get; set; }
+        = null;
+
     public Dictionary<string, string> Metadata { get; set; } = new(StringComparer.Ordinal);
 
-    public static VexRawDocumentRecord FromDomain(VexRawDocument document)
+    public static VexRawDocumentRecord FromDomain(VexRawDocument document, bool includeContent = true)
         => new()
         {
             Id = document.Digest,
@@ -37,22 +43,26 @@ internal sealed class VexRawDocumentRecord
             SourceUri = document.SourceUri.ToString(),
             RetrievedAt = document.RetrievedAt.UtcDateTime,
             Digest = document.Digest,
-            Content = document.Content.ToArray(),
+            Content = includeContent ? document.Content.ToArray() : Array.Empty<byte>(),
             Metadata = document.Metadata.ToDictionary(kvp => kvp.Key, kvp => kvp.Value, StringComparer.Ordinal),
         };
 
     public VexRawDocument ToDomain()
+        => ToDomain(new ReadOnlyMemory<byte>(Content ?? Array.Empty<byte>()));
+
+    public VexRawDocument ToDomain(ReadOnlyMemory<byte> content)
         => new(
             ProviderId,
             Enum.Parse<VexDocumentFormat>(Format, ignoreCase: true),
             new Uri(SourceUri),
             RetrievedAt,
             Digest,
-            new ReadOnlyMemory<byte>(Content ?? Array.Empty<byte>()),
+            content,
             (Metadata ?? new Dictionary<string, string>(StringComparer.Ordinal))
                 .ToImmutableDictionary(StringComparer.Ordinal));
 }
 
+[BsonIgnoreExtraElements]
 internal sealed class VexExportManifestRecord
 {
     [BsonId]
@@ -162,5 +172,401 @@ internal sealed class VexExportManifestRecord
     }
 
     public static string CreateId(VexQuerySignature signature, VexExportFormat format)
-        => string.Create(CultureInfo.InvariantCulture, $"{signature.Value}|{format.ToString().ToLowerInvariant()}");
+        => string.Format(CultureInfo.InvariantCulture, "{0}|{1}", signature.Value, format.ToString().ToLowerInvariant());
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexProviderRecord
+{
+    [BsonId]
+    public string Id { get; set; } = default!;
+
+    public string DisplayName { get; set; } = default!;
+
+    public string Kind { get; set; } = default!;
+
+    public List<string> BaseUris { get; set; } = new();
+
+    public VexProviderDiscoveryDocument? Discovery { get; set; }
+        = null;
+
+    public VexProviderTrustDocument? Trust { get; set; }
+        = null;
+
+    public bool Enabled { get; set; }
+        = true;
+
+    public static VexProviderRecord FromDomain(VexProvider provider)
+        => new()
+        {
+            Id = provider.Id,
+            DisplayName = provider.DisplayName,
+            Kind = provider.Kind.ToString().ToLowerInvariant(),
+            BaseUris = provider.BaseUris.Select(uri => uri.ToString()).ToList(),
+            Discovery = VexProviderDiscoveryDocument.FromDomain(provider.Discovery),
+            Trust = VexProviderTrustDocument.FromDomain(provider.Trust),
+            Enabled = provider.Enabled,
+        };
+
+    public VexProvider ToDomain()
+    {
+        var uris = BaseUris?.Select(uri => new Uri(uri)) ?? Enumerable.Empty<Uri>();
+        return new VexProvider(
+            Id,
+            DisplayName,
+            Enum.Parse<VexProviderKind>(Kind, ignoreCase: true),
+            uris,
+            Discovery?.ToDomain(),
+            Trust?.ToDomain(),
+            Enabled);
+    }
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexProviderDiscoveryDocument
+{
+    public string? WellKnownMetadata { get; set; }
+        = null;
+
+    public string? RolIeService { get; set; }
+        = null;
+
+    public static VexProviderDiscoveryDocument? FromDomain(VexProviderDiscovery? discovery)
+        => discovery is null
+            ? null
+            : new VexProviderDiscoveryDocument
+            {
+                WellKnownMetadata = discovery.WellKnownMetadata?.ToString(),
+                RolIeService = discovery.RolIeService?.ToString(),
+            };
+
+    public VexProviderDiscovery ToDomain()
+        => new(
+            WellKnownMetadata is null ? null : new Uri(WellKnownMetadata),
+            RolIeService is null ? null : new Uri(RolIeService));
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexProviderTrustDocument
+{
+    public double Weight { get; set; }
+        = 1.0;
+
+    public VexCosignTrustDocument? Cosign { get; set; }
+        = null;
+
+    public List<string> PgpFingerprints { get; set; } = new();
+
+    public static VexProviderTrustDocument? FromDomain(VexProviderTrust? trust)
+        => trust is null
+            ? null
+            : new VexProviderTrustDocument
+            {
+                Weight = trust.Weight,
+                Cosign = trust.Cosign is null ? null : VexCosignTrustDocument.FromDomain(trust.Cosign),
+                PgpFingerprints = trust.PgpFingerprints.ToList(),
+            };
+
+    public VexProviderTrust ToDomain()
+        => new(
+            Weight,
+            Cosign?.ToDomain(),
+            PgpFingerprints);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexCosignTrustDocument
+{
+    public string Issuer { get; set; } = default!;
+
+    public string IdentityPattern { get; set; } = default!;
+
+    public static VexCosignTrustDocument FromDomain(VexCosignTrust trust)
+        => new()
+        {
+            Issuer = trust.Issuer,
+            IdentityPattern = trust.IdentityPattern,
+        };
+
+    public VexCosignTrust ToDomain()
+        => new(Issuer, IdentityPattern);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexConsensusRecord
+{
+    [BsonId]
+    public string Id { get; set; } = default!;
+
+    public string VulnerabilityId { get; set; } = default!;
+
+    public VexProductDocument Product { get; set; } = default!;
+
+    public string Status { get; set; } = default!;
+
+    public DateTime CalculatedAt { get; set; }
+        = DateTime.SpecifyKind(DateTime.UtcNow, DateTimeKind.Utc);
+
+    public List<VexConsensusSourceDocument> Sources { get; set; } = new();
+
+    public List<VexConsensusConflictDocument> Conflicts { get; set; } = new();
+
+    public string? PolicyVersion { get; set; }
+        = null;
+
+    public string? PolicyRevisionId { get; set; }
+        = null;
+
+    public string? PolicyDigest { get; set; }
+        = null;
+
+    public string? Summary { get; set; }
+        = null;
+
+    public static string CreateId(string vulnerabilityId, string productKey)
+        => string.Format(CultureInfo.InvariantCulture, "{0}|{1}", vulnerabilityId.Trim(), productKey.Trim());
+
+    public static VexConsensusRecord FromDomain(VexConsensus consensus)
+        => new()
+        {
+            Id = CreateId(consensus.VulnerabilityId, consensus.Product.Key),
+            VulnerabilityId = consensus.VulnerabilityId,
+            Product = VexProductDocument.FromDomain(consensus.Product),
+            Status = consensus.Status.ToString().ToLowerInvariant(),
+            CalculatedAt = consensus.CalculatedAt.UtcDateTime,
+            Sources = consensus.Sources.Select(VexConsensusSourceDocument.FromDomain).ToList(),
+            Conflicts = consensus.Conflicts.Select(VexConsensusConflictDocument.FromDomain).ToList(),
+            PolicyVersion = consensus.PolicyVersion,
+            PolicyRevisionId = consensus.PolicyRevisionId,
+            PolicyDigest = consensus.PolicyDigest,
+            Summary = consensus.Summary,
+        };
+
+    public VexConsensus ToDomain()
+        => new(
+            VulnerabilityId,
+            Product.ToDomain(),
+            Enum.Parse<VexConsensusStatus>(Status, ignoreCase: true),
+            new DateTimeOffset(CalculatedAt, TimeSpan.Zero),
+            Sources.Select(static source => source.ToDomain()),
+            Conflicts.Select(static conflict => conflict.ToDomain()),
+            PolicyVersion,
+            Summary,
+            PolicyRevisionId,
+            PolicyDigest);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexProductDocument
+{
+    public string Key { get; set; } = default!;
+
+    public string? Name { get; set; }
+        = null;
+
+    public string? Version { get; set; }
+        = null;
+
+    public string? Purl { get; set; }
+        = null;
+
+    public string? Cpe { get; set; }
+        = null;
+
+    public List<string> ComponentIdentifiers { get; set; } = new();
+
+    public static VexProductDocument FromDomain(VexProduct product)
+        => new()
+        {
+            Key = product.Key,
+            Name = product.Name,
+            Version = product.Version,
+            Purl = product.Purl,
+            Cpe = product.Cpe,
+            ComponentIdentifiers = product.ComponentIdentifiers.ToList(),
+        };
+
+    public VexProduct ToDomain()
+        => new(
+            Key,
+            Name,
+            Version,
+            Purl,
+            Cpe,
+            ComponentIdentifiers);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexConsensusSourceDocument
+{
+    public string ProviderId { get; set; } = default!;
+
+    public string Status { get; set; } = default!;
+
+    public string DocumentDigest { get; set; } = default!;
+
+    public double Weight { get; set; }
+        = 0;
+
+    public string? Justification { get; set; }
+        = null;
+
+    public string? Detail { get; set; }
+        = null;
+
+    public VexConfidenceDocument? Confidence { get; set; }
+        = null;
+
+    public static VexConsensusSourceDocument FromDomain(VexConsensusSource source)
+        => new()
+        {
+            ProviderId = source.ProviderId,
+            Status = source.Status.ToString().ToLowerInvariant(),
+            DocumentDigest = source.DocumentDigest,
+            Weight = source.Weight,
+            Justification = source.Justification?.ToString().ToLowerInvariant(),
+            Detail = source.Detail,
+            Confidence = source.Confidence is null ? null : VexConfidenceDocument.FromDomain(source.Confidence),
+        };
+
+    public VexConsensusSource ToDomain()
+        => new(
+            ProviderId,
+            Enum.Parse<VexClaimStatus>(Status, ignoreCase: true),
+            DocumentDigest,
+            Weight,
+            string.IsNullOrWhiteSpace(Justification) ? null : Enum.Parse<VexJustification>(Justification, ignoreCase: true),
+            Detail,
+            Confidence?.ToDomain());
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexConsensusConflictDocument
+{
+    public string ProviderId { get; set; } = default!;
+
+    public string Status { get; set; } = default!;
+
+    public string DocumentDigest { get; set; } = default!;
+
+    public string? Justification { get; set; }
+        = null;
+
+    public string? Detail { get; set; }
+        = null;
+
+    public string? Reason { get; set; }
+        = null;
+
+    public static VexConsensusConflictDocument FromDomain(VexConsensusConflict conflict)
+        => new()
+        {
+            ProviderId = conflict.ProviderId,
+            Status = conflict.Status.ToString().ToLowerInvariant(),
+            DocumentDigest = conflict.DocumentDigest,
+            Justification = conflict.Justification?.ToString().ToLowerInvariant(),
+            Detail = conflict.Detail,
+            Reason = conflict.Reason,
+        };
+
+    public VexConsensusConflict ToDomain()
+        => new(
+            ProviderId,
+            Enum.Parse<VexClaimStatus>(Status, ignoreCase: true),
+            DocumentDigest,
+            string.IsNullOrWhiteSpace(Justification) ? null : Enum.Parse<VexJustification>(Justification, ignoreCase: true),
+            Detail,
+            Reason);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexConfidenceDocument
+{
+    public string Level { get; set; } = default!;
+
+    public double? Score { get; set; }
+        = null;
+
+    public string? Method { get; set; }
+        = null;
+
+    public static VexConfidenceDocument FromDomain(VexConfidence confidence)
+        => new()
+        {
+            Level = confidence.Level,
+            Score = confidence.Score,
+            Method = confidence.Method,
+        };
+
+    public VexConfidence ToDomain()
+        => new(Level, Score, Method);
+}
+
+[BsonIgnoreExtraElements]
+internal sealed class VexCacheEntryRecord
+{
+    [BsonId]
+    public string Id { get; set; } = default!;
+
+    public string QuerySignature { get; set; } = default!;
+
+    public string Format { get; set; } = default!;
+
+    public string ArtifactAlgorithm { get; set; } = default!;
+
+    public string ArtifactDigest { get; set; } = default!;
+
+    public DateTime CreatedAt { get; set; }
+        = DateTime.SpecifyKind(DateTime.UtcNow, DateTimeKind.Utc);
+
+    public long SizeBytes { get; set; }
+        = 0;
+
+    public string? ManifestId { get; set; }
+        = null;
+
+    [BsonRepresentation(BsonType.ObjectId)]
+    public string? GridFsObjectId { get; set; }
+        = null;
+
+    public DateTime? ExpiresAt { get; set; }
+        = null;
+
+    public static string CreateId(VexQuerySignature signature, VexExportFormat format)
+        => string.Format(CultureInfo.InvariantCulture, "{0}|{1}", signature.Value, format.ToString().ToLowerInvariant());
+
+    public static VexCacheEntryRecord FromDomain(VexCacheEntry entry)
+        => new()
+        {
+            Id = CreateId(entry.QuerySignature, entry.Format),
+            QuerySignature = entry.QuerySignature.Value,
+            Format = entry.Format.ToString().ToLowerInvariant(),
+            ArtifactAlgorithm = entry.Artifact.Algorithm,
+            ArtifactDigest = entry.Artifact.Digest,
+            CreatedAt = entry.CreatedAt.UtcDateTime,
+            SizeBytes = entry.SizeBytes,
+            ManifestId = entry.ManifestId,
+            GridFsObjectId = entry.GridFsObjectId,
+            ExpiresAt = entry.ExpiresAt?.UtcDateTime,
+        };
+
+    public VexCacheEntry ToDomain()
+    {
+        var signature = new VexQuerySignature(QuerySignature);
+        var artifact = new VexContentAddress(ArtifactAlgorithm, ArtifactDigest);
+        var createdAt = new DateTimeOffset(DateTime.SpecifyKind(CreatedAt, DateTimeKind.Utc));
+        var expires = ExpiresAt.HasValue
+            ? new DateTimeOffset(DateTime.SpecifyKind(ExpiresAt.Value, DateTimeKind.Utc))
+            : (DateTimeOffset?)null;
+
+        return new VexCacheEntry(
+            signature,
+            Enum.Parse<VexExportFormat>(Format, ignoreCase: true),
+            artifact,
+            createdAt,
+            SizeBytes,
+            ManifestId,
+            GridFsObjectId,
+            expires);
+    }
 }

src/StellaOps.Vexer.Storage.Mongo/VexMongoStorageOptions.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+
+namespace StellaOps.Vexer.Storage.Mongo;
+
+/// <summary>
+/// Configuration controlling Mongo-backed storage for Vexer repositories.
+/// </summary>
+public sealed class VexMongoStorageOptions : IValidatableObject
+{
+    private const int DefaultInlineThreshold = 256 * 1024;
+    private static readonly TimeSpan DefaultCacheTtl = TimeSpan.FromHours(12);
+
+    /// <summary>
+    /// Name of the GridFS bucket used for raw VEX payloads that exceed <see cref="GridFsInlineThresholdBytes"/>.
+    /// </summary>
+    public string RawBucketName { get; set; } = "vex.raw";
+
+    /// <summary>
+    /// Inline raw document payloads smaller than this threshold; larger payloads are stored in GridFS.
+    /// </summary>
+    public int GridFsInlineThresholdBytes { get; set; } = DefaultInlineThreshold;
+
+    /// <summary>
+    /// Default TTL applied to export cache entries (absolute expiration).
+    /// </summary>
+    public TimeSpan ExportCacheTtl { get; set; } = DefaultCacheTtl;
+
+    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+    {
+        if (string.IsNullOrWhiteSpace(RawBucketName))
+        {
+            yield return new ValidationResult("Raw bucket name must be provided.", new[] { nameof(RawBucketName) });
+        }
+
+        if (GridFsInlineThresholdBytes < 0)
+        {
+            yield return new ValidationResult("GridFS inline threshold must be non-negative.", new[] { nameof(GridFsInlineThresholdBytes) });
+        }
+
+        if (ExportCacheTtl <= TimeSpan.Zero)
+        {
+            yield return new ValidationResult("Export cache TTL must be greater than zero.", new[] { nameof(ExportCacheTtl) });
+        }
+    }
+}

src/StellaOps.Vexer.WebService.Tests/StatusEndpointTests.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Net.Http.Json;
+using System.IO;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Mongo2Go;
+using MongoDB.Driver;
+using StellaOps.Vexer.Attestation.Signing;
+using StellaOps.Vexer.Policy;
+using StellaOps.Vexer.Core;
+using StellaOps.Vexer.Export;
+using StellaOps.Vexer.WebService;
+
+namespace StellaOps.Vexer.WebService.Tests;
+
+public sealed class StatusEndpointTests : IClassFixture<WebApplicationFactory<Program>>, IDisposable
+{
+    private readonly WebApplicationFactory<Program> _factory;
+    private readonly MongoDbRunner _runner;
+
+    public StatusEndpointTests(WebApplicationFactory<Program> factory)
+    {
+        _runner = MongoDbRunner.Start();
+        _factory = factory.WithWebHostBuilder(builder =>
+        {
+            builder.ConfigureAppConfiguration((_, config) =>
+            {
+                var rootPath = Path.Combine(Path.GetTempPath(), "vexer-offline-tests");
+                Directory.CreateDirectory(rootPath);
+                var settings = new Dictionary<string, string?>
+                {
+                    ["Vexer:Storage:Mongo:RawBucketName"] = "vex.raw",
+                    ["Vexer:Storage:Mongo:GridFsInlineThresholdBytes"] = "256",
+                    ["Vexer:Artifacts:FileSystem:RootPath"] = rootPath,
+                };
+                config.AddInMemoryCollection(settings!);
+            });
+
+            builder.ConfigureServices(services =>
+            {
+                services.AddSingleton<IMongoClient>(_ => new MongoClient(_runner.ConnectionString));
+                services.AddSingleton(provider => provider.GetRequiredService<IMongoClient>().GetDatabase("vexer-web-tests"));
+                services.AddSingleton<IVexSigner, FakeSigner>();
+                services.AddSingleton<IVexPolicyEvaluator, FakePolicyEvaluator>();
+                services.AddSingleton<IVexExportDataSource, FakeExportDataSource>();
+            });
+        });
+    }
+
+    [Fact]
+    public async Task StatusEndpoint_ReturnsArtifactStores()
+    {
+        var client = _factory.CreateClient();
+        var response = await client.GetAsync("/vexer/status");
+        var raw = await response.Content.ReadAsStringAsync();
+        Assert.True(response.IsSuccessStatusCode, raw);
+
+        var payload = System.Text.Json.JsonSerializer.Deserialize<StatusResponse>(raw);
+        Assert.NotNull(payload);
+        Assert.NotEmpty(payload!.ArtifactStores);
+    }
+
+    public void Dispose()
+    {
+        _runner.Dispose();
+    }
+
+    private sealed class StatusResponse
+    {
+        public string[] ArtifactStores { get; set; } = Array.Empty<string>();
+    }
+
+    private sealed class FakeSigner : IVexSigner
+    {
+        public ValueTask<VexSignedPayload> SignAsync(ReadOnlyMemory<byte> payload, CancellationToken cancellationToken)
+            => ValueTask.FromResult(new VexSignedPayload("signature", "key"));
+    }
+
+    private sealed class FakePolicyEvaluator : IVexPolicyEvaluator
+    {
+        public string Version => "test";
+
+        public VexPolicySnapshot Snapshot => VexPolicySnapshot.Default;
+
+        public double GetProviderWeight(VexProvider provider) => 1.0;
+
+        public bool IsClaimEligible(VexClaim claim, VexProvider provider, out string? rejectionReason)
+        {
+            rejectionReason = null;
+            return true;
+        }
+    }
+
+    private sealed class FakeExportDataSource : IVexExportDataSource
+    {
+        public ValueTask<VexExportDataSet> FetchAsync(VexQuery query, CancellationToken cancellationToken)
+        {
+            var dataset = new VexExportDataSet(ImmutableArray<VexConsensus>.Empty, ImmutableArray<VexClaim>.Empty, ImmutableArray<string>.Empty);
+            return ValueTask.FromResult(dataset);
+        }
+    }
+}

src/StellaOps.Vexer.WebService.Tests/StellaOps.Vexer.WebService.Tests.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Update="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.8" />
+    <PackageReference Update="Mongo2Go" Version="3.1.3" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\StellaOps.Vexer.WebService\StellaOps.Vexer.WebService.csproj" />
+  </ItemGroup>
+</Project>

src/StellaOps.Vexer.WebService/Program.cs

@@ -0,0 +1,89 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.Options;
+using StellaOps.Vexer.Attestation.Extensions;
+using StellaOps.Vexer.Attestation;
+using StellaOps.Vexer.Attestation.Transparency;
+using StellaOps.Vexer.ArtifactStores.S3.Extensions;
+using StellaOps.Vexer.Export;
+using StellaOps.Vexer.Storage.Mongo;
+
+var builder = WebApplication.CreateBuilder(args);
+var configuration = builder.Configuration;
+var services = builder.Services;
+
+services.AddOptions<VexMongoStorageOptions>()
+    .Bind(configuration.GetSection("Vexer:Storage:Mongo"))
+    .ValidateOnStart();
+
+services.AddVexerMongoStorage();
+services.AddVexExportEngine();
+services.AddVexExportCacheServices();
+services.AddVexAttestation();
+services.Configure<VexAttestationClientOptions>(configuration.GetSection("Vexer:Attestation:Client"));
+
+var rekorSection = configuration.GetSection("Vexer:Attestation:Rekor");
+if (rekorSection.Exists())
+{
+    services.AddVexRekorClient(opts => rekorSection.Bind(opts));
+}
+
+var fileSystemSection = configuration.GetSection("Vexer:Artifacts:FileSystem");
+if (fileSystemSection.Exists())
+{
+    services.AddVexFileSystemArtifactStore(opts => fileSystemSection.Bind(opts));
+}
+else
+{
+    services.AddVexFileSystemArtifactStore(_ => { });
+}
+
+var s3Section = configuration.GetSection("Vexer:Artifacts:S3");
+if (s3Section.Exists())
+{
+    services.AddVexS3ArtifactClient(opts => s3Section.GetSection("Client").Bind(opts));
+    services.AddSingleton<IVexArtifactStore, S3ArtifactStore>(provider =>
+    {
+        var options = new S3ArtifactStoreOptions();
+        s3Section.GetSection("Store").Bind(options);
+        return new S3ArtifactStore(
+            provider.GetRequiredService<IS3ArtifactClient>(),
+            Microsoft.Extensions.Options.Options.Create(options),
+            provider.GetRequiredService<Microsoft.Extensions.Logging.ILogger<S3ArtifactStore>>());
+    });
+}
+
+var offlineSection = configuration.GetSection("Vexer:Artifacts:OfflineBundle");
+if (offlineSection.Exists())
+{
+    services.AddVexOfflineBundleArtifactStore(opts => offlineSection.Bind(opts));
+}
+
+services.AddEndpointsApiExplorer();
+services.AddHealthChecks();
+services.AddSingleton(TimeProvider.System);
+
+var app = builder.Build();
+
+app.MapGet("/vexer/status", async (HttpContext context,
+    IEnumerable<IVexArtifactStore> artifactStores,
+    IOptions<VexMongoStorageOptions> mongoOptions,
+    TimeProvider timeProvider) =>
+{
+    var payload = new StatusResponse(
+        timeProvider.GetUtcNow(),
+        mongoOptions.Value.RawBucketName,
+        mongoOptions.Value.GridFsInlineThresholdBytes,
+        artifactStores.Select(store => store.GetType().Name).ToArray());
+
+    context.Response.ContentType = "application/json";
+    await System.Text.Json.JsonSerializer.SerializeAsync(context.Response.Body, payload);
+});
+
+app.MapHealthChecks("/vexer/health");
+
+app.Run();
+
+public partial class Program;
+
+internal sealed record StatusResponse(DateTimeOffset UtcNow, string MongoBucket, int InlineThreshold, string[] ArtifactStores);