feat(adr-0181-p3): audio_core_v1 pack + AudioProjectionHead (gate-closed) (#467)
PR-3 of ADR-0181. Externalises the PR-2 in-code operator registry to a
versioned, checksum-locked pack and wires the sensorium adapter. Mounts
gate-closed until the PR-4 eval gates pass. No core mutation (ADR-0013).
Pack (packs/audio/audio_core_v1/):
- manifest.json canonical params, resampling config, gating defaults, ordering
- operators.jsonl the 8 elliptic operators (byte-equivalent to DEFAULT_OPERATOR_REGISTRY)
- basis_map.json alias→index over the six elliptic planes {6,7,8,10,11,13}
- resample_fir_v1.npy pinned odd-length symmetric windowed-sinc low-pass (unit DC)
- checksums.json sha256 of every artifact
Loader (packs/audio/loader.py) — trust boundary (ADR-0051 / CLAUDE.md §Security):
- _validate_pack_id rejects traversal/separators/dotfiles before any path join
- fail-closed checksum verification: every file re-hashed vs checksums.json
- resolved path must stay under the packs root (defense in depth)
- JSON format (matches every other CORE pack loader; spec §6.1 TOML was
illustrative; no tomllib dependency added)
Adapter (sensorium/adapters/audio.py):
- AudioProjectionHead wraps AudioCompiler; project(AudioSignal)->(32,) f32
- make_audio_pack loads+verifies the pack, builds a gate-closed ModalityPack
Tests (19): PR-2↔PR-3 registry byte-parity via manifest_sha256, elliptic-only
operators, FIR integrity, fail-closed checksum mismatch, path-traversal guard,
gate-closed refusal, mount-time unitarity (+ bad-unitarity blocks mount),
gate-engage requires checksum_verified, engaged pack projects (32,) f32.
All audio 32 + arch-invariants 40 + smoke 67 green.
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