# Immutable Advisory Feed Snapshots

## Module
Replay

## Status
IMPLEMENTED

## Description
The replay infrastructure supports input manifests and determinism tracking which conceptually align with point-in-time query capability, but a dedicated feed snapshotting system with per-provider immutable blobs and point-in-time advisory resolution is not directly implemented as described.

## What's Implemented
- **Input Manifest Resolver**: `src/Replay/StellaOps.Replay.Core/InputManifestResolver.cs` -- resolves input manifests that capture the exact inputs (feed data, SBOM, VEX, policy) used for a verdict, enabling replay with identical inputs. This provides partial snapshot functionality by recording what feed data was consumed.
- **Determinism Verifier**: `src/Replay/StellaOps.Replay.Core/DeterminismVerifier.cs` -- verifies that replaying a verdict with the same inputs produces the same output, which indirectly validates feed data consistency.
- **Replay Executor**: `src/Replay/StellaOps.Replay.Core/ReplayExecutor.cs` -- executes verdict replay using captured input manifests, consuming the recorded feed data rather than live feeds.
- **Policy Simulation Input Lock**: `src/Replay/StellaOps.Replay.Core/PolicySimulationInputLock.cs` -- locks policy simulation inputs to prevent mutation during replay, ensuring deterministic execution.
- **Replay Job Queue**: `src/Replay/StellaOps.Replay.Core/ReplayJobQueue.cs` -- manages replay job scheduling and execution.
- **Trace Anonymizer**: `src/Replay/StellaOps.Replay.Anonymization/TraceAnonymizer.cs` -- anonymizes replay traces for sharing without exposing sensitive feed data.
- **Verdict Replay Endpoints**: `src/Replay/StellaOps.Replay.WebService/VerdictReplayEndpoints.cs` -- API endpoints for triggering and querying verdict replays.

## What's Missing
- **Per-Provider Feed Snapshots**: No system exists to capture immutable snapshots of advisory feeds on a per-provider basis (e.g., NVD snapshot at epoch T, GHSA snapshot at epoch T). The input manifest records which feed data was used but does not create addressable, immutable blob snapshots.
- **Point-in-Time Advisory Resolution**: No API exists to query "what was the advisory state for CVE-X at time T?" across all providers. Feed data is consumed in real-time; historical queries require replaying from input manifests.
- **Feed Snapshot Storage**: No dedicated content-addressable storage for feed snapshots (e.g., immutable blobs with digest-based retrieval). Feed data flows through the pipeline but is not persisted as versioned snapshots.
- **Snapshot Epoch Registry**: No registry that maps epoch identifiers to feed snapshot digests, enabling O(1) lookup of historical feed state.
- **Snapshot Attestation**: No attestation mechanism for feed snapshots that proves the snapshot was captured at a specific time and has not been tampered with.

## Implementation Plan
- Design a per-provider feed snapshot format (content-addressable blob with provider ID, epoch timestamp, digest)
- Implement a snapshot capture service that creates immutable blobs when feed data is ingested, storing them in content-addressable storage
- Build a snapshot epoch registry mapping epoch IDs to snapshot digests for all providers
- Add point-in-time advisory resolution API that resolves advisory state by looking up the appropriate epoch snapshot
- Add snapshot attestation (signed digest + timestamp) for tamper-evidence
- Integrate with the existing `InputManifestResolver` so replay can reference snapshots by epoch/digest rather than inline data

## Related Documentation
- Replay infrastructure: `src/Replay/StellaOps.Replay.Core/`
- Feed ingestion (Concelier): `src/Concelier/`
- Feed processing (Excititor): `src/Excititor/`
- Determinism testing: `src/__Tests/__Libraries/StellaOps.Testing.Determinism/`