* fix(engine): length-prefix witness fields to close domain-separation collision
The BLAKE3 trust witness concatenated model_version, calibration_version,
and privacy_decision boundary-to-boundary, with the variable-length evidence
list lacking an explicit count. A string straddling a field boundary (e.g. a
per-room adapter id absorbing the leading bytes of the calibration epoch, or a
model_version absorbing a trailing evidence ref) collided with a different
trust decision — silently un-distinguishing two distinct privacy-relevant
inputs and defeating the ADR-137 tamper/drift audit guarantee. model_version
is operator-influenceable via the adapter id (ADR-150 §3.4), so the ambiguity
was reachable.
Fix: domain-tag the hash and length-prefix every field (8-byte LE length),
plus an explicit evidence count. Pinned by two fails-on-old tests:
witness_distinguishes_model_calibration_boundary and
witness_distinguishes_evidence_model_boundary.
Co-Authored-By: claude-flow <ruv@ruv.net>
* test(engine): pin privacy monotonicity, fail-closed boundaries; de-magic constants
Review hardening for the governed-trust cycle (no behavior change):
- forced_contradiction_never_relaxes_class: property test over all 5 privacy
modes proving a forced contradiction only ever raises the emitted class byte
(more restrictive) and a clean cycle emits exactly the base class — the
ADR-141/120 information-only-removed invariant.
- empty_cycle_fails_closed: a zero-frame cycle errors (fusion NoFrames),
emits no SemanticState, and does not advance the cycle counter.
- single_node_cycle_is_well_formed: characterizes the n=1 boundary (no mesh,
no directional, base class, witness still emitted) — documents single-node
sensing as a valid non-demoting mode, not a bypass.
- De-magicked the engine-construction literals (coherence accept gate, ADR-143
SLAM discovery + static-anchor thresholds) into named documented consts,
value-identical, pinned by engine_constants_match_prior_values.
Co-Authored-By: claude-flow <ruv@ruv.net>
* docs(engine-review): record witness domain-separation fix + monotonicity clean bill
CHANGELOG [Unreleased] Security entry and review notes appended to ADR-137
(witness domain-separation fix) and ADR-141 (privacy monotonicity confirmed
clean over all 5 modes, fail-closed boundaries pinned).
Co-Authored-By: claude-flow <ruv@ruv.net>
d2089c342a