Phase 3 of the ADR-0114 expert-capability roadmap. Re-applies every
step of a SolutionTrace from the input graph's initial state and
asserts byte-equal reproduction of answer_value. Pure function; same
(graph, trace) → byte-equal VerifierVerdict.
Why this is distinct from the solver
ADR-0116's solver enforces correctness at construction. ADR-0117's
verifier is a SECOND, INDEPENDENT implementation that re-derives
every value the trace claims. The verifier does NOT call solve(). It
re-implements the operation semantics from ADR-0116 directly inside
_verify_step. If the solver had a bug or was tampered with after the
fact, the verifier catches it.
Six checks per verdict (named, ordered, audit-logged):
1. graph_canonical_hash_matches
2. pack_id_matches
3. pack_lemmas_resolve
4. step_pack_lemma_ids_match_bindings
5. step_replay_matches_before_after
6. answer_value_reproduces
Seven named tamper classes all caught:
- mutated before_value / after_value / operand of any step
- mutated pack_lemma_id of any step
- mutated graph_canonical_hash
- mutated answer_value
- mutated pack_id
- mutated target_before / target_after of transfer step
ADR-0114a obligation update
#3 Replay-equal trace — now discharged at VERIFIER FIDELITY
(was solver-only under ADR-0116). A third party with only
(graph, trace, pack) can reproduce the answer byte-equal.
Five of ten obligations now load-bearing: #3, #4, #9, #10 plus
in-flight #2 (Codex's ADR-0118a OOD generator).
Tests: 62/62 verifier suite green; 67/67 smoke green; existing
solver + parser + schema suites unaffected.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
