Here’s a tight, first‑time‑friendly blueprint for two Stella Ops UX pillars—**Triage & Exceptions** and **Knowledge Snapshots & Merge Semantics**—with just enough background plus concrete specs your PMs/devs can ship.

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# Triage & Exceptions (quiet‑by‑design)

**Why it matters (plain English):** Most scanners drown users in alerts. “Quiet‑by‑design” shows only *provable, reachable* risks and lets you create **auditable exceptions** (temporary waivers) that auto‑feed compliance packs.

**User flow**

1. **Inbox grouped by exploit path**

   * Group key = `(artifact → package → vulnerable symbol → runtime path)`.
   * Each group shows: risk score, blast radius (count of dependents), EPSS/CVSS, and a “Proof” button.
2. **Open a path → Proof bundle**

   * **Reach subgraph** (who calls what).
   * **Symbol map** (function/offsets; source or binary map).
   * **VEX claims** (vendor/distro/internal) with trust score + signatures.
3. **Raise Exception** (time‑boxed)

   * **Required fields:** attested reason (dropdown + free text), expiry date, recheck policy (e.g., “fail build if new reachable path appears”, “fail if EPSS > X”).
   * **Attestation:** DSSE‑signed exception object, OCI‑attached to artifact digest.
   * Auto‑lands in **Audit Pack** (PDF/JSON bundle) and **Timeline**.

**Data model (C# POCO sketch)**

```csharp
record ExploitPathId(string ArtifactDigest, string PackagePurl, string CveId, string Symbol, string EntryPathHash);

record ExceptionObj(
    string Id, ExploitPathId Path, string ReasonCode, string ReasonText,
    DateTimeOffset IssuedAt, DateTimeOffset ExpiresAt,
    RecheckPolicy Policy, EvidenceRef[] Evidence, AttestationMeta Att);
```

**RecheckPolicy (examples)**

* `ReachGraphChange=Block`
* `EPSSAbove=0.5`
* `EnvScope=prod-only`
* `UnknownsAbove=N → Block`

**UI essentials**

* **Inbox:** 3‑pane (List • Details • Proof).
* **Proof drawer:** collapsible reach subgraph; one‑click JSON export.
* **Exception modal:** expiry presets (7/30/90 days), reason templates (backport, feature‑flag‑off, compensating control).

**APIs (REST-ish)**

* `GET /triage/inbox?scope=env:prod&quiet=true`
* `GET /triage/path/{id}/proof`
* `POST /exceptions` (body = ExceptionObj sans AttestationMeta; server returns DSSE envelope)
* `GET /audit-packs/{releaseDigest}`

**Guardrails**

* Exceptions must **never** outlive a release line by default (force renewal).
* Creating an exception **requires evidence hooks** (see below).
* Build gates read exceptions; if proof no longer holds (reach diff changed), gate fails.

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# Knowledge Snapshots & Merge Semantics

**Plain English:** Take a sealed “photo” of everything you *know* at a point in time—SBOM, VEX, attestations, policies—so audits and incident reviews can be replayed exactly.

**Lifecycle: Snapshot → Seal → Export**

1. **Snapshot**

   * Capture: SBOM (CycloneDX 1.6 + SPDX 3.0.1), VEX docs, reach subgraphs, exception objects, policies, trust scores, feed versions, rules hashes.
2. **Seal**

   * Compute **Manifest of Manifests** (Merkle root) + DSSE signature (with PQ option).
   * Store to **Authority** (Postgres) and attach to image digest (OCI ref).
3. **Export**

   * Produce a single **Replay Bundle** (`.stella-replay.tgz`): data + `REPLAY.yaml` (inputs, versions, lattice rules).
   * Offline‑ready.

**Policy pane with merge semantics**

* Default preview: **vendor ⊕ distro ⊕ internal** (not “vendor > distro > internal”).
* **Lattice rules** define resolution (e.g., `NOT_AFFECTED ⊕ AFFECTED → AFFECTED unless Evidence(feature_flag_off)`).
* **Evidence hooks (required):**

  * “Not affected because feature X off” → must include **feature‑flag attestation** (env‑scoped, signed).
  * “Backported patch” → must include **patch‑index** mapping (`fixed‑symbols`, commit OIDs).
  * “Compensating control” → must include **control attestation** (control ID, monitoring link, SLO).

**UI essentials**

* **Snapshot panel:** shows inputs (feed versions, rules hash), diff vs last snapshot, “Seal & Export” button.
* **Policy pane:** interactive merge preview; failed hooks highlighted with “Add evidence” CTA.
* **Replay check:** “Verify determinism” runs local re‑eval; shows PASS/FAIL badge.

**APIs**

* `POST /snapshots` → returns `SnapshotId` + content hashes
* `POST /snapshots/{id}/seal` → returns DSSE + Merkle root
* `GET /snapshots/{id}/export` → stream bundle
* `POST /policy/preview` (inputs: sources+claims) → resolved verdict + missing-evidence list

**Storage**

* **Postgres** = system of record (immutable rows for sealed snapshots).
* **Valkey** (optional) = cache (diffs, precomputed subgraphs).
* **OCI** = distribution of attestations & snapshots alongside images.

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# PM & Dev acceptance checklist (short)

* **Triage Inbox**

  * [ ] Groups by exploit path, not by CVE alone.
  * [ ] Proof bundle includes reach subgraph + symbol map + VEX claims.
  * [ ] Exception modal enforces reason + expiry + recheck policy + evidence.
  * [ ] Exceptions are DSSE‑signed and appear in Audit Pack.

* **Knowledge Snapshot**

  * [ ] Snapshot records *all* inputs (feeds, rules, versions, hashes).
  * [ ] Seal produces a verifiable Merkle root + DSSE.
  * [ ] Export bundle replays deterministically offline.
  * [ ] Policy pane supports lattice merges + evidence hooks with blocking states.

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# Tiny implementation notes (.NET 10)

* Use **record structs** for small immutable IDs; keep hash fields as `ReadOnlyMemory<byte>`.
* Attest with **in‑toto/DSSE**; provide PQ toggle (Dilithium/Falcon) at key‑policy level.
* Graphs: store **reach subgraph** as compressed adjacency lists; index by `(digest, symbol)`.

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If you want, I can turn this into: (a) Swagger stubs, (b) EF Core schema + migrations, or (c) a Figma‑ready UI spec with screen flows and copy.