Audit Snapshot (Step 12)

The final gate. After this skill runs, the change is frozen, replayable, and regulator-defensible for 6 years.

Core mental model

A bundle is not "all the files we had lying around" — it is a time capsule that, opened by a stranger 4 years from now during a regulatory audit, must allow them to:

1. Reconstruct what the AI did — every prompt, every model, every tool call
2. Reconstruct what the code became — base commit + diff, with hashes
3. Reconstruct what the data was — synthetic fixtures + fingerprints, no real patients
4. Reconstruct who approved what — signatures + compliance report
5. Verify nothing has been tampered with — hash chain + WORM ROOT_SHA256

If a stranger cannot do this in 4 hours, the bundle is invalid.

What this skill produces

1. <artifact-storage>/AUDIT_BUNDLE_<change-id>_<archived_at>.tar.gz — the canonical bundle (structure defined in openspec/templates/AUDIT_BUNDLE.spec.md)
2. WORM record in mcp-audit-log with ROOT_SHA256, change_id, archived_at, signers
3. Optional: a one-page archive_summary.md for stakeholder readout

When NOT to use this skill

Skip for:

• Mid-change snapshots (no concept of mid-archive — bundles are final)
• Changes that haven't passed Step 10 with High = 0
• Pure documentation-only changes (still log an L1 lightweight entry, but skip full bundle if the org policy permits — usually it doesn't, default to full)

Active context bundle

Always load first

1. This SKILL.md
2. openspec/templates/AUDIT_BUNDLE.spec.md — canonical structure
3. openspec/templates/LINEAGE_GRAPH.schema.json — invariants to enforce
4. reference/hash-chain-protocol.md — exact hash computation order

Load on demand

• reference/replay-sanity-check.md — self-test routine before sealing
• reference/encryption-protocol.md — for desensitize_map.json.enc
• reference/signature-protocol.md — committee signatures (M3+)

Workflow

Phase 1 · Pre-flight verification (≤ 5 min)

Refuse to proceed if any of these are false:

• Step 7 Verify passed
• Step 8 code review closed
• Step 9 mocking tests passed
• Step 10 COMPLIANCE_REPORT.md exists with High = 0
• Step 11 (if applicable) closed all High items
• COMPLIANCE_TAG.md exists and is signed
• MODEL_ALLOWLIST.json exists and was active during the change

Phase 2 · Lineage graph generation

Walk the change directory and synthesize lineage/LINEAGE_GRAPH.json:

• Node types: prd / tdd / spec / task / code_module / code_file / test_case / test_data / model_call / skill_call / deploy_artifact
• Edges: derives_from / implements / tests / verifies / calls / produces / depends_on / desensitizes / audits
• Enforce all 4 invariants before sealing:
  • all_code_traceable_to_spec
  • all_l4_fields_pass_desensitize
  • all_model_calls_in_allowlist
  • no_real_phi_in_test_data

Any invariant false → stop; this is a structural bug in the change, not a packaging problem.

Phase 3 · Materials collection

Collect into a staging directory:

staging/
├── manifest.json               (populated in Phase 4)
├── prompts/                    (from change-scoped session JSONL slices)
├── changes/                    (proposal/design/specs/tasks + diff.patch)
├── compliance/                 (COMPLIANCE_TAG, MODEL_ALLOWLIST, COMPLIANCE_REPORT, desensitize_map.enc)
├── test_data/                  (synthetic/, fingerprints.txt, source_declaration.md)
├── lineage/                    (LINEAGE_GRAPH.json, skill_call_chain.json)
├── verification/               (verify_report.md, test_results.xml, coverage.json)
├── models/                     (model_versions.json, routing_log.jsonl)
└── signatures/                 (filled in Phase 6)

Phase 4 · Manifest population

Fill manifest.json per AUDIT_BUNDLE.spec.md section 2:

• schema_version, change_id, archived_at, archived_by, compliance_tier
• models_used (from routing_log)
• duration_total_seconds, skill_calls_count, tool_calls_count, prompt/completion tokens
• phi_detector_blocks (count of blocks during the change lifecycle)
• compliance_gate_outcome (must have high_risk = 0, passed = true)
• hashes (filled in Phase 5)

Phase 5 · Hash chain computation

Per reference/hash-chain-protocol.md:

1. Walk staging directory in deterministic sorted order (canonical UTF-8 sort)
2. For each file compute sha256, append sha256:<hex> <relpath> to signatures/hash_chain.txt
3. After all per-file hashes, compute ROOT_SHA256 = sha256 of concatenated hash lines
4. Write ROOT_SHA256: sha256:<hex> as the final line of hash_chain.txt
5. Populate manifest.json.hashes with per-file hashes

Phase 6 · Signature collection

• Tech committee signature: signatures/tech_committee.sig
• Compliance committee signature: signatures/compliance_committee.sig
• During M1-M2 (transition): single QA Lead signature placeholder, marked transitional: true
• From M3: both committees sign

Phase 7 · Sealing

1. Re-validate manifest against schema
2. Re-validate LINEAGE_GRAPH against schema (all 4 invariants true)
3. Tar+gz the staging directory: AUDIT_BUNDLE_<change_id>_<archived_at>.tar.gz
4. Compute sha256 of the .tar.gz file itself; this is the "outer" bundle hash
5. Atomic write to artifact storage location

Phase 8 · WORM commit

Send to mcp-audit-log:

{
  "event": "audit_bundle_sealed",
  "change_id": "...",
  "archived_at": "...",
  "root_sha256": "sha256:...",
  "outer_sha256": "sha256:...",
  "bundle_location": "...",
  "signers": ["tech_committee:...", "compliance_committee:..."],
  "schema_version": "1.0"
}

If the WORM commit fails, do not delete the local bundle — escalate to Harness Engineer + Compliance Officer for manual reconciliation.

Phase 9 · Self-replay sanity check

Per reference/replay-sanity-check.md:

1. Extract bundle to temp location
2. Verify manifest hashes match recomputed sha256s
3. Pick one prompt from prompts/, validate JSONL structure
4. Pick one model_call from routing_log.jsonl, validate model_id ∈ manifest.models_used
5. Apply changes/diff.patch to base commit in scratch repo, expect clean apply
6. Re-run one test_case from verification/test_results.xml against synthetic test_data, expect match

If any check fails → bundle is malformed → escalate.

Hard gate checklist

• All Phase 1 preconditions satisfied
• LINEAGE_GRAPH 4 invariants all true
• Manifest passes JSON schema validation
• hash_chain.txt complete with ROOT_SHA256
• Signatures present per committee policy
• Bundle tar.gz atomically written
• WORM commit succeeded (with retry on transient failure, fail-loud after retries)
• Self-replay sanity check passed

Common failure modes

1. Empty prompts/ directory: change had no Claude Code prompts (manual coding). Bundle still required — fill with prompts/no_prompts_declaration.md explaining. Don't pretend.
2. Hash chain non-determinism: file walk in OS-dependent order produces different ROOT_SHA256 each run. Mitigation: explicit sorted iteration.
3. Missing model_versions.json: routing log says "claude-opus" but version field is empty. Audit fails because monitor cannot reproduce. Mitigation: routing log writer must record model: id + version + deployment always.
4. Encrypted map with lost key: desensitize_map.json.enc exists but KMS key has been rotated/deleted. Recovery impossible. Mitigation: KMS key rotation policy must include audit-bundle keys in retention.
5. Schema drift: bundle written with v1.0 spec, opened during audit when v2.0 is current. Mitigation: manifest carries schema_version; auditor tool must support N-2 schemas.
6. WORM "best effort" failure mode: audit-log MCP returns ok despite actually not persisting. Mitigation: WORM commit must return a receipt (storage URI + receipt hash); skill must verify receipt before declaring success.

Integration

• Triggered by: completion of Step 11 (or Step 10 if no remediation needed)
• Triggers: ends the change lifecycle; opens permission for next change in the sequence

Output handoff

Return:

• Path to AUDIT_BUNDLE.tar.gz
• ROOT_SHA256
• WORM receipt
• Self-replay sanity-check result

Hand to openspec-archive-change for final OpenSpec state transition.