The mandatory lookback before CMB-d (3+ PRs on one surface; next-phase boundary). A 5-dimension
read-only fan-out audit over the 10-item checklist found the CMB-a/b/c substrate composes cleanly:
25 solid / 4 drift / 8 gap / 1 reader hazard. Doc:
docs/analysis/cmb-lookback-review-2026-06-08.md.
Fixes the one real hazard (H3): a query attributing the answer to a SINGLE agent ('how many words
does Alice type' with a distractor second rate) wrongly claimed the substantive
combine_mode_ambiguous — a hygiene over-claim that would corrupt the shared router in CMB-d. The
combined-query gate now excludes single-agent 'does <Agent>' attribution (_SINGLE_AGENT_QUERY) and
steps aside as not_combined_rate_shaped; the genuinely-combined forms ('do they' / 'are produced' /
'does it') still yield combine_mode_ambiguous. Pinned by gold cmb-16 + a reader test.
The review also resolves the CMB-d failure-family classification (input_shape:
not_combined_rate_shaped; must_remain_refused incl. rate_unit_mismatch — DECISIVELY, the reader has
no dimension representation so it cannot tell convertible from incompatible units; proposal_allowed:
combine_mode_ambiguous, missing_second_rate) and enumerates the live CMB-d registry preconditions
(not_combined_rate_shaped mapping, rate_unit_mismatch/non_integer_solution string collisions,
non_positive_net_rate family, Organ/ALL_REASONS extension). Provenance false-alarm (stale local main
checkout) noted + verified against origin/main.
gold 19/19 (6/5/8); reader 11/0/0 + 8 refused-correct; solver 6/0 + 5/0; 0 hygiene breaches; 123
tests; serving + R1/R2/R3 unchanged.
solve_combined_rate(CombinedRateProblem) -> int | Refusal over effective_rate = rate_a +/- rate_b.
effective_rate query returns the net (even <=0); quantity/time queries need a positive net rate
(non_positive_net_rate) and exact division (non_integer_solution). Pure integer arithmetic, no
float/Fraction (CMB v1 crosses no units). Off-serving. Graded by a new run_solver lane in
evals/combined_rate_oracle against the committed gold.
Adversarial 5-lens(+adjudicator) verification returned fix_first; both real hazards fixed:
- wrong=0 breach: negative known-slot inputs (time<0/quantity<0) bypassed the eff<=0 guard and
produced negative answers. FIXED UPSTREAM in model.py __post_init__ — rate_a/rate_b and the known
time/quantity are now positive ints, so the illegal state is unrepresentable and the solver can
never receive a negative-yielding path. Added model + gold (cmb-07d eff<0/time) + lane coverage.
- doc overclaim: the solver lane does NOT grade 'two independent paths' (both solver and the
oracle's _canonical_outcome delegate to model.effective_rate). Corrected both docstrings to name
the true anchor (committed gold + inline-computed literal tests) and added a difference-mode
inline-computed test.
R3-vac came back SOLID (separate PR). gold 18/18 (6/5/7); solver lane 6/0 + 5/0; 36 CMB tests;
router-hygiene + serving unchanged.
