release: final v2.2.2 hardening

[noctem-o]

Motivation

• Preserve provenance and correctness: ensure replay mode preserves the original transcript policy_digest so replayed runs cannot lose the policy identity committed in the baseline record.
• Security/harness correctness: ensure live ordeal runs that record precomputed fixture responses still evaluate and honour policy before committing executed vs phantom entries.
• Transparency: update README wording to disclose that --nix-provenance=auto|on may run bounded local Nix commands for diagnostic provenance while keeping provenance-only / witness-root invariants.
• Release prep: bump package version for a patch release to 2.2.2 and add a short changelog entry.

Description

• Implemented replay digest preservation by adding replay_policy_digest: Option<String> to ToolTranscript, setting it in new_replay(...), leaving it None in new_live(...), and returning the preserved digest from into_record() when present; this preserves policy_digest during replay. (changed: src/tooling.rs)
• Added a policy-aware precomputed-response execution path ToolTranscript::execute_with_precomputed_response(...) which normalizes tool names, allocates tool_call_idx exactly once, evaluates the current PolicyEngine before recording, records PhantomEntry on Block/Phantom, and records actual ToolCall only on Allow; switched run_ordeal live path to use this method. (changed: src/tooling.rs, src/ordeal.rs)
• Tests added to cover the fixes: replay_preserves_policy_digest (replay digest preservation) and two ordeal tests verifying live precomputed responses under allow and block policies. (changed: tests/replay_phantom.rs, tests/ordeal.rs)
• README tweak: clarify that --nix-provenance=auto|on may run bounded local Nix commands for diagnostic provenance (closed stdin, timeout-bounded, output-capped) and does not alter witness root computation. (changed: README.md)
• Version bump and changelog: Cargo.toml package version set to 2.2.2, root [[package]] entry in Cargo.lock set to 2.2.2, and concise CHANGELOG.md entry added for 2.2.2. Dependency versions were not changed. (changed: Cargo.toml, Cargo.lock, CHANGELOG.md)

Testing

• Formatting/linters: cargo fmt --check succeeded and cargo clippy --locked --all-targets -- -D warnings succeeded.
• Unit/integration test suite: cargo test --locked succeeded (all tests passed, including the new tests replay_preserves_policy_digest, ordeal_live_precomputed_allow_records_executed_calls, and ordeal_live_precomputed_block_records_phantom_not_entry).
• Ordeal golden check: cargo run --locked -- ordeal check --golden goldens/ordeal_witness_root.txt succeeded and matched the golden.
• Demo/drift workflow: cargo run --locked -- demo drift --seed 1 --threads 1 --fault-profile ci --out-dir demo_out --clean succeeded and produced run outputs.
• Verify workflows: cargo run --locked -- verify --witness demo_out/drift/baseline_faults failed in this ephemeral environment with failed to read witness file (os error 2) due to CLI invocation expectations for the local demo output layout, while cargo run --locked -- verify --witness demo_out/drift/baseline_faults --recompute-witness-root succeeded and confirmed matched=true on recompute.
• Action pins: bash scripts/check_action_pins.sh succeeded (all actions pinned).
• cargo dist validation: cargo dist is not installed in this environment (no such command), so cargo dist build was not run here and dist validation is deferred to the release/tag environment.

Notes and non-goals (explicit)

• No changes to witness-root algorithm, witness domain separators, schema constants, canonicalization semantics, or verifier acceptance semantics were made.
• No release tag/publish was performed in this PR; maintainers should create the annotated tag after CI passes.

Manual maintainer release instructions after merge

1. Wait for main CI to pass.
2. Create tag: git tag -a v2.2.2 -m "Cogitator v2.2.2".
3. Push tag: git push origin v2.2.2.
4. Watch the GitHub Actions Release workflow and confirm artifacts/installers and provenance attestation.

If any reviewer hits issues around witness roots or policy digests, treat them as P0 blockers (do not merge until resolved).

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