# Evidence Task 5C report

## Delivered

- Added `vector.retain_published_generations` (default `3`, validation minimum `1`).
- Retention runs only after publication. It keeps ACTIVE, the newest configured generations,
  and generations referenced by running or resumable failed job checkpoints.
- Cleanup deletes the exact Evidence generation from the vector store before removing its
  immutable filesystem directory. Vector failures retain filesystem metadata for retry and
  produce credential-free partial reports.
- Added idempotent `tht preprocess evidence gc [--dry-run] --json` reconciliation with pristine
  JSON output.
- Materialized document reads now open generation/documents components with directory file
  descriptors and `O_NOFOLLOW`, require a regular file owned by the process with one link, and
  hash the bytes read from the same descriptor against the canonical manifest.
- HTTP generation deletion is pinned to `delete_vector_generation` with exact
  table/kind/generation arguments. Legacy 404 responses fail closed with an actionable,
  sanitized migration message.

## Evidence

- Focused retention, safe-read, CLI, and HTTP contract tests: `51 passed` (Docker-backed direct
  parametrizations excluded from that focused invocation).
- Real Docker pgvector adapter suites: `33 passed`.
- Full harness suite, including Docker-backed tests: `668 passed, 5 deselected`.
- Changed-file Ruff: clean.
- `git diff --check`: clean.

The five deselected tests are the repository's opt-in `l2` tests requiring external services;
they are not local pgvector tests. Test output retains pre-existing Pydantic serialization and
legacy-config deprecation warnings.

## Review fix wave

- Publication is now explicit and durable (`PUBLISHED` marker). Retention candidates require a
  valid generation manifest and publication marker (ACTIVE remains backward-compatible), so
  staged and malformed directories neither consume retention slots nor become deletion targets.
- The policy retains ACTIVE plus exactly `N-1` newest rollback publications, ordered by durable
  publication time and generation id. Running and failed-resumable JobRunner checkpoints protect
  every referenced plan generation.
- `VectorStore` now exposes exact Evidence generation inventory. Direct pgvector uses a constrained
  `SELECT DISTINCT` over `kind='evidence'` and `metadata.vector_generation`; HTTP uses the
  allowlisted `list_evidence_generations` RPC and fails closed on legacy 404. The writer RPC SQL,
  revokes, and grants are packaged in `create_vector_writer_rpc.sql`.
- Explicit GC reconciles the union of published filesystem generations and vector-only orphans,
  preserving vector-before-filesystem deletion and retry semantics.
- `run_as_job` holds the same corpus writer lock across checkpoint recovery, staging, publish, and
  retention. Explicit GC already uses this lock, serializing candidate snapshots with publishers.
- Session artifact consumers no longer receive the corpus source path after validation. They get
  an owned, read-only copy atomically written from the bytes read and hash-validated on the same
  descriptor.

Fresh verification after the fix wave: full harness `672 passed, 5 deselected`; Docker pgvector,
HTTP parity, and migration suites `43 passed`; exact direct inventory/delete integration `1 passed`;
changed-file Ruff and `git diff --check` clean.

## Final hardening verification

- Canonical generation validation is exact (`^gen:[0-9a-f]{32}$`) before HTTP/direct deletion;
  malformed HTTP inventory rows fail closed rather than entering the GC candidate set.
- Added explicit protection coverage for running and failed-resumable JobRunner checkpoints, plus
  a second-GC idempotence assertion for vector-only orphan reconciliation.
- Added deterministic concurrent locking coverage: a job paused after discovery retains the corpus
  writer lock, explicit GC blocks, then completes after publication without deleting the active run.
- Added a descriptor-race regression: replacing the corpus pathname immediately after `read(2)`
  leaves the atomically materialized session-owned copy byte-for-byte equal to the validated ACTIVE
  document and its manifest hash.

Final fresh evidence: Docker pgvector/HTTP/migration suites `48 passed`; full harness `680 passed,
5 external L2 deselected`; changed-file Ruff and `git diff --check` clean.

## Integrated Task 5 dependency fixes

- GC now distinguishes filesystem retention from vector dependencies. ACTIVE and the newest
  `N-1` published manifests keep their directories; every exact generation in their
  `document_generations` maps remains vector-protected even after its old publication directory is
  evicted. Job-protected manifests receive the same dependency treatment.
- The real four-publication Docker lifecycle now includes an unchanged document whose vectors come
  from the first generation. With retention `N=2`, only the final two publication directories remain
  while the first generation's vectors remain searchable from ACTIVE and survive restart/explicit GC.
- Evidence lookup is always wrapped by the ACTIVE-aware searcher. With no corpus/ACTIVE, Evidence
  returns no rows and search packs cannot expose legacy vectors; non-Evidence kinds are unchanged.
- Session artifact resolution holds the corpus writer lock, snapshots the active manifest once, and
  materializes bytes using that exact `manifest_id`, preventing a concurrent publish/retain-1 GC from
  changing or deleting the selected source generation.

Focused unit tests, the updated real Docker lifecycle, changed-file Ruff, and `git diff --check` pass.
The final full harness invocation completed with exit code 0, including the concurrently added DWH
JobRunner tests.