AGENTS

Role

Deterministic merge and reconciliation engine; builds identity graph via aliases; applies precedence (PSIRT/OVAL > NVD; KEV flag only; regional feeds enrich); produces canonical advisory JSON and merge_event audit trail.

Scope

Identity: resolve advisory_key (prefer CVE, else PSIRT/Distro/JVN/BDU/GHSA/ICSA); unify aliases; detect collisions.
Precedence: override rules for affected ranges (vendor PSIRT/OVAL over registry), enrichment-only feeds (CERTs/JVN/RU-CERT), KEV toggles exploitKnown only.
Range comparers: RPM NEVRA comparer (epoch:version-release), Debian EVR comparer, SemVer range resolver; platform-aware selection.
Merge algorithm: stable ordering, pure functions, idempotence; compute beforeHash/afterHash over canonical form; write merge_event.
Conflict reporting: counters and logs for identity conflicts, reference merges, range overrides.

Participants

Storage.Mongo (reads raw mapped advisories, writes merged docs plus merge_event).
Models (canonical types).
Exporters (consume merged canonical).
Core/WebService (jobs: merge:run, maybe per-kind).

Interfaces & contracts

AdvisoryMergeService.MergeAsync(ids or byKind): returns summary {processed, merged, overrides, conflicts}.
Precedence table configurable but with sane defaults: RedHat/Ubuntu/Debian/SUSE > Vendor PSIRT > GHSA/OSV > NVD; CERTs enrich; KEV sets flags.
Range selection uses comparers: NevraComparer, DebEvrComparer, SemVerRange; deterministic tie-breakers.
Provenance propagation merges unique entries; references deduped by (url, type).

Configuration

Precedence overrides bind via feedser:merge:precedence:ranks (dictionary of source → rank, lower wins). Absent entries fall back to defaults.
Operator workflow: update etc/feedser.yaml or environment variables, restart merge job; overrides surface in metrics/logs as AdvisoryOverride entries.

In/Out of scope

In: merge logic, precedence policy, hashing, event records, comparers. Out: fetching/parsing, exporter packaging, signing.

Observability & security expectations

Metrics: merge.delta.count, merge.identity.conflicts, merge.range.overrides, merge.duration_ms.
Logs: decisions (why replaced), keys involved, hashes; avoid dumping large blobs; redact secrets (none expected).

Tests

Author and review coverage in ../StellaOps.Feedser.Merge.Tests.
Shared fixtures (e.g., MongoIntegrationFixture, ConnectorTestHarness) live in ../StellaOps.Feedser.Testing.
Keep fixtures deterministic; match new cases to real-world advisories or regression scenarios.

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