# Evidence Task 2 Report

## Status

Implemented filesystem and explicit-manifest HTTP Evidence source adapters, typed source
configuration with legacy compatibility, and factory construction.

## Delivered behavior

- Filesystem discovery is deterministic and rooted at a strict canonical directory.
- Symlink/path escapes are rejected before content is exposed.
- Discovery hashing and acquisition reads enforce a configurable byte limit.
- Filesystem fingerprints are content SHA-256 values; stable IDs derive from relative paths.
- HTTP accepts only explicit `http`/`https` manifest entries and keeps transport URLs private.
- HTTP provenance strips query strings/fragments, while config and adapter representations hide
  signed or secret-bearing transport URLs.
- HTTP acquisition uses separate connect/read timeouts, streaming byte limits, bounded redirects,
  private redirect rejection, and safe transient/permanent error classification.
- HTTP fingerprints prefer a deterministic ETag digest, then Last-Modified, then content SHA-256.
- `build_evidence_sources(cfg)` supports both typed `evidence.sources` entries and the legacy
  `source_root` plus `evidence_dir` filesystem configuration.

## TDD and verification

- RED: focused tests initially failed during collection because the adapter package did not exist.
- GREEN: `15 passed` for filesystem, HTTP, and resource-config tests.
- Full harness: `548 passed, 5 deselected`.
- Changed-file Ruff: clean.
- Repository-wide Ruff remains non-clean due to 34 pre-existing findings in unrelated test files;
  no unrelated lint files were modified.

## Notes

The approved `SourceObject` namespace grammar does not permit raw quoted ETags such as
`etag:"abc"`. The adapter therefore uses `etag:<sha256-of-opaque-etag>`: it preserves ETag-based
change identity without weakening the canonical contract or exposing validator contents.

## Review hardening follow-up

Four review findings were closed in a separate follow-up commit:

- Filesystem access now anchors a persistent descriptor at the canonical root and walks each
  component with `openat` semantics (`dir_fd`, `O_NOFOLLOW`, and `O_DIRECTORY`). The regular-file
  check, bounded read, metadata, and hash all use the opened descriptor. Acquisition reopens by
  the same path-safe mechanism and rejects a changed fingerprint. Deterministic tests swap both a
  leaf and an ancestor to symlinks at open time.
- HTTP network policy defaults to public hosts only. Initial URLs and every redirect reject
  userinfo, mixed public/private IPv4/IPv6 answers fail closed, and the connected peer must be a
  public member of the previously validated DNS answer set before any body bytes are consumed.
  Explicit `allow_private_hosts: true` is required for trusted private deployments and local tests.
- Every HTTP response is closed in a `finally` block, including redirects, status failures,
  policy failures, oversized bodies, and mid-stream exceptions.
- ETag and Last-Modified values remain adapter-internal. Repeated discovery and acquisition send
  conditional headers; a 304 reuses only previously verified cached bytes and identity. The LRU
  content cache has an explicit byte bound (`max_cache_bytes`). Validators are not forwarded
  across redirect origins.