# AGENTS
## Role
Design and ship deterministic Linux operating-system analyzers that transform container root filesystems into canonical package evidence for SBOM emission.

## Scope
- Provide shared helpers for reading apk, dpkg, and rpm metadata and emitting normalized package identities with provenance.
- Implement analyzer plug-ins for Alpine (apk), Debian (dpkg), and RPM-based distributions that operate on extracted rootfs snapshots.
- Enrich package records with vendor-origin metadata (source packages, declared licenses, CVE hints) and evidence linking files to packages.
- Expose restart-time plug-in manifests so the Scanner.Worker can load analyzers in offline or air-gapped environments.
- Supply deterministic fixtures and a regression harness that verifies analyzer outputs remain stable across runs.

## Participants
- `StellaOps.Scanner.Core` for shared contracts, observability, and plug-in catalog guardrails.
- `StellaOps.Scanner.Worker` which executes analyzers inside the scan pipeline.
- `StellaOps.Scanner.Cache` (future) for layer cache integration; analyzers must be cache-aware via deterministic inputs/outputs.
- `StellaOps.Scanner.Emit` and `StellaOps.Scanner.Diff` rely on analyzer outputs to build SBOMs and change reports.

## Interfaces & Contracts
- Analyzers implement `IOSPackageAnalyzer` (defined in this module) and register via plug-in manifests; they must be restart-time only.
- Input rootfs paths are read-only; analyzers must never mutate files and must tolerate missing metadata gracefully.
- Package records emit canonical purls (`pkg:alpine`, `pkg:deb`, `pkg:rpm`) plus NEVRA/EVR details, source package identifiers, declared licenses, and evidence (file lists with layer attribution placeholders).
- Outputs must be deterministic: ordering is lexicographic, timestamps removed or normalized, hashes (SHA256) calculated when required.

## In/Out of Scope
In scope:
- Linux apk/dpkg/rpm analyzers, shared helpers, plug-in manifests, deterministic regression harness.

Out of scope:
- Windows MSI/SxS analyzers, native (ELF) analyzers, language analyzers, EntryTrace pipeline, or SBOM assembly logic (handled by other guilds).

## Observability & Security Expectations
- Emit structured logs with correlation/job identifiers provided by `StellaOps.Scanner.Core`.
- Surface metrics for package counts, elapsed time, and cache hits (metrics hooks stubbed until Cache module lands).
- Do not perform outbound network calls; operate entirely on provided filesystem snapshot.
- Validate plug-in manifests via `IPluginCatalogGuard` to enforce restart-only loading.

## Tests
- `StellaOps.Scanner.Analyzers.OS.Tests` hosts regression tests with canned rootfs fixtures to verify determinism.
- Fixtures store expected analyzer outputs under `Fixtures/` with golden JSON (normalized, sorted).
- Tests cover apk/dpkg/rpm analyzers, shared helper edge cases, and plug-in catalog enforcement.