--- id: CB-WP-0005 title: "Make the instruments count assertions, then fix what they expose" status: proposed state_hub_workstream_id: "0b95a1e3-7780-43d0-81e9-072ef7978734" --- # Purpose `research/CB-RES-0004-replay-and-kernel-coverage.md` (v2, after an adversarial review that rejected v1 with four blocking findings): > **Every coverage instrument in this project counts names. None counts > assertions.** Four of the seven defects found this pass are named in the > source and inert, so no name-based check finds them. Two are mutation-proven: AM-7's `hash-identical` clause survives folding a 100k-event log from an unrelated genesis state, and K9's `through` field survives `Snapshot::take` discarding it entirely. `evidence/CB-EV-0001` carries **`AM-7 replay | met, 2,290×`** for the first of those. [ADR-0005](../decisions/ADR-0005-assertion-coverage-and-replay.md) decides the response. This workplan executes it in four phases: teach the instruments to count assertions, correct the record they falsified, implement what they expose, then measure whether any of it worked. **Headline numbers are expected to get worse before they get better.** A pass that widened every denominator and reported the same percentages would have proved the instruments still count names. Per InnerLoop §Step 4 no target moves in the commit that measures it. ## Phase A — teach the instruments to count assertions ## Task: spec→code link over every numbered spec and every crate ```task id: CB-WP-0005-T01 status: done priority: high state_hub_task_id: "d47338c6-eb2e-4443-aad2-0b08c2d91895" ``` `tools/rule-coverage.py` hardcodes `AGGREGATE = "games/ground/src/lib.rs"` and `RULE_RE = \*\*(GR-[A-Z]+\d+)` against `GroundRules.md` alone. The reviewer's finding: a ~10-line generalization would have surfaced K10, K14 and K18 the day AM-1b shipped. Deliver: `AGGREGATE` becomes a list of source roots; rule patterns become per-spec; the link runs over **every numbered spec × every crate**. Three constraints from ADR-0005 §5, all of which must be visible in the output: 1. The kernel denominator **reports and does not feed the exit code until 2026-08-31**, after which it binds. The date lives in the tool and the tool prints the days remaining — an open-ended "gate it later" is how AM-4's targets went unratified for four workplans. 2. **Replicate the zero-rules positive control** on every new denominator. The existing arm refuses to report over zero rules, a defect it was fixed for; a kernel regex matching nothing must abort, not print `0/0 (100%)`. 3. State the limit in the output, as the GR arm already does: this counts names. It is the cheap half. **Predicted:** K10, K14, K18 reported unlinked on the first run. **Refuted if** any numbered rule in any spec is still unnamed in source after the pass and the tool does not say so. **Delivered, and the prediction held on the first run:** ```text AM-1b kernel spec->code link: 15/18 (83%) K-rules named across 10 source files NOTE: link only — K-rules are kernel invariants with no scenario mechanism; and this counts names, not assertions gate: reporting only for 31 more day(s), binds 2026-08-31 (ADR-0005 §5) unlinked (declared in the spec, named nowhere in source): K10 K14 K18 ``` `AGGREGATE` is now a list of source roots, rule patterns are per-spec, and the link runs over every numbered spec × every crate. The binding date lives in the tool and the days remaining are printed every run. The kernel figures (`k_rules`, `k_linked`, `k_unlinked`) are registered facts, so they are under `make facts-check` from the day they first exist rather than after they drift. **The self-test passed while the tool was completely broken.** A `print(` inside `say()` was rewritten to `say(`, so every real `make coverage` died with `RecursionError` — while `--self-test` reported all-ok, because it only ever called `kernel_arm(quiet=True)` and never executed the reporting path. That is this task's own thesis in miniature: **the control named the behaviour and did not assert it.** Fixed by exercising the loud path under `redirect_stdout` and asserting it prints, and verified by re-breaking `say()` and confirming the two new checks go red. Seventh instance of the harness-does-nothing shape, found in the tool written to find that shape. **A limit of `facts-check` surfaced here and is recorded, not patched:** the check is line-based, so a tagged value that prose-wraps onto the next line fails. It cost three edits to place two tags. Reported for T07 — either the checker spans a paragraph, or the rule is stated as "tagged values must not wrap". ## Task: M-D1-MUT — one mutation per acceptance row ```task id: CB-WP-0005-T02 status: done priority: high state_hub_task_id: "c88f2696-ca12-44df-add3-0db3d2819c08" ``` The task this workplan exists for. Name-based checks catch 3 of the 7 defects; this catches the other 4. Deliver `make mutation-check`: for each of the twelve AM-* acceptance rows, a committed fixture that **inverts the row's stated property** and an assertion that the suite goes **red**. A row whose mutation leaves the suite green is a row backed by nothing. Per ADR-0005 §1, `adapted:mutation-testing` — the denominator is acceptance rows, not source lines, because the failure mode here is not an untested branch but a headline number backed by nothing. **The escape hatch is closed in advance:** a row for which no mutation can be written is recorded `unmutatable` **with the reason** and **counts against** the metric. A row nobody can invert asserts nothing. Carries `--self-test`. Its own positive control is the one that matters: a mutation harness that fails to apply its mutation reports every row as `unmutatable` and looks thorough — this project has six harness-does- nothing instances and one of them is being fixed in T03. **Predicted: 9 of 12 rows turn red.** Deliberately beatable in both directions — **12 of 12 refutes CB-RES-0004** (the instruments were better than claimed, the finding shrinks to three absent rules, and M-D1-MUT was not worth its CI cost); **3 of 12 means the pass is under-scoped and must stop and re-plan** rather than proceed to Phase C. **Delivered. Measured: 4 of 14 rows enforced. The prediction is badly unmet.** ```text M-D1-MUT: 4/14 rows enforced PARTIAL 2 (AM-7, AM-8 — some clauses live, some inert) unmutatable 8 (no property to invert, reason stated per row) SURVIVED 0 ``` **First correction: there are 14 acceptance rows, not 12.** ADR-0005 and this workplan both said twelve; AM-4 splits into a/b/c. The 9-of-12 (75%) prediction is evaluated as ≥10 of 14 on the same basis. Measured 4 (29%). **Second correction, and the one that matters: my first run reported two SURVIVED rows, and both were my own bad mutations.** - AM-8: `pub struct NullRng;` → `pub struct NullRng {}` — semantically identical, a no-op. - AM-12: renaming `max_age_days` in the price sheet — CA-17 reads it with `.get("max_age_days", 90)`, so removing it changes nothing. Both would have been published as *"this row asserts nothing"* — a false accusation against code that is in fact fine. Replaced with real inversions (inject a per-construction counter into the ChaCha seed; revert the AC-9 output resolution to the first-wins bug it was fixed for), after which both go red. **T08's question — "is writing a weak mutation the new grep?" — is answered on the first attempt: yes, demonstrably.** **The finding is larger than the workplan assumed.** 8 of 14 rows are `unmutatable`: AM-2, AM-3, AM-4c, AM-5, AM-6, AM-9, AM-10, AM-11 have no instrument at all. AM-6 is the sharpest — **nothing in the workspace compares any number to 100,000 events/s**, the headline throughput claim. The problem is not three unimplemented rules; it is that **more than half the acceptance table has nothing behind it.** Harness controls that earned their place: a stale find-string reports `HARNESS-BROKEN` rather than silently scoring the baseline as the mutant; a red baseline reports `inconclusive` rather than `red`; the tree is restored in a `finally` and the restoration is verified. `make mutation-check` is deliberately **not** in `make all` — it rebuilds the workspace once per mutated row. `--self-test` is in `make self-tests`. **Stop condition: see the note in T07 and the decision recorded there.** ## Phase B — correct the record ## Task: correct three committed verdicts and restore the fourth ```task id: CB-WP-0005-T03 status: todo priority: high state_hub_task_id: "87fa2245-5f27-48af-906e-18affa41efcf" ``` Per ADR-0005 §4. Corrections are made **in place with a dated note**, not silently edited — the correction trail is the artifact. | row | committed | corrected to | |---|---|---| | AM-7 replay | `met, 2,290×` | timing clause **met**; `hash-identical` clause **withdrawn**, mutation-proven unmeasured, and the fold spans multiple game seeds so it is not a replay | | AM-10 foreign types | `met` | **withdrawn as written** — no `cb-*-api` crate, so the population is empty; re-stated as a K6 determinism row, M-D4-LEAK marked **unmeasured** | | AM-11 impl pairs | `met, narrow` | **unmet** until a shared conformance suite exists; the pair exists, the suite does not, and the metric is a bool over the suite | | AM-1b | *absent from the scoreboard* | **added**, at its real value | The last one is the point of the phase. `make coverage` prints `49/58` two lines below the `100%` the scoreboard carried, and the scoreboard kept the flattering half. Update `specs/GameKernel.md` §5 and `specs/MetricsAndScenarios.md` §1 to match, and tag the new figures under `make facts-check` so they cannot drift. ## Phase C — implement what the instruments expose ## Task: K9 and K11 — durable log, LogStore port, real conformance suite ```task id: CB-WP-0005-T04 status: todo priority: high state_hub_task_id: "35876b28-97ac-4379-bb71-72e74c4116d4" ``` **K9** currently round-trips a `BTreeMap` with `EventSeq(17)` as a literal. Deliver the real property: *snapshot at seq N + events N+1..M ≡ genesis fold*, on `GroundState`, hash-compared. **K11** — append-only, length-prefixed, versioned framing, with a truncated tail **detected**. Reimplemented, not assimilated (ADR-0005 §2): ~100 lines against a format Kafka and EventStore converged on independently. Charged to **AM-4a** (shipped runtime, 1.5% headroom) and adds no dependency. **The port** (ADR-0005 §3): a `LogStore` trait with a shared `fn conformance(…)` driven by an in-memory impl **and** a file-backed impl. Retro-fit the same shape to `KernelRng`, whose pair is currently exercised by two separate non-shared tests — which is why AM-11 was never earned. Negative controls, not optional: truncate by one byte → reject; corrupt the length prefix → reject. K11's operative clause is *detection*. ## Task: K10 — the replay bundle and `--replay` ```task id: CB-WP-0005-T05 status: todo priority: high state_hub_task_id: "8592b6e7-8b83-4b47-b310-90e16a35eb6a" ``` INTENT design decision **8 of 10**, unimplemented. `cb-sim` has no flag parsing at all, so `--replay` has nowhere to go yet. D2 note carried from the review: this is **not** "a directory of four files". `scenario.rs` creates an `EventLog`, appends to it and never reads it — the one production instantiation of the K11 log is a write-only sink. `Pass` carries the *end* state, not an initial snapshot, and failures are a formatted `String`, not structured expected-vs-actual. Plumb the log out of `execute`, capture an initial snapshot, restructure `RunOutcome::Failed`. The bundle writer is **dev-only** behind the `scenarios` feature and is charged to **AM-4b** (9.4% headroom), not AM-4a. **Four controls, from ADR-0005 §6, verbatim and all required:** 1. a committed **deliberately-failing fixture** scenario, plus an assertion that bundles produced `> 0` and equals expected failures — all 21 scenarios pass today, so a corpus sweep verifies zero bundles and prints `ok`; 2. the comparison hash **read out of the bundle**, written by the first process — never recomputed in the second, which is `assert_eq!(h, h)` and the AM-7 defect exactly; 3. truncate-by-one-byte and corrupt-length-prefix rejection; 4. a **mutated-seed** control: change the manifest seed and the replay must fail to reproduce. A round-trip that cannot fail proves nothing. ## Task: K14 and K18 — implement, or amend the spec and say why ```task id: CB-WP-0005-T06 status: todo priority: medium state_hub_task_id: "774b1c8a-71c1-4e0a-91b1-0247a3e397cf" ``` Both are named nowhere in source, and both have an honest second option that must be considered rather than assumed away. **K14** — "one commit window per Select". `CommitWindow` exists, has zero non-test users, and `games/ground` does not import it; GROUND collects selections in its own aggregate. Either wire GROUND through the runtime primitive as K14 requires, **or** amend K14 to describe what the kernel actually guarantees and record why the primitive stays. A dead abstraction certified by a test that exercises only itself is worse than no abstraction — it is an AM-11-shaped claim waiting to be quoted. **K18** — "Criterion benches driving the same scenario format". The bench hardcodes commands in Rust and never touches `ScenarioFile`, and `benchmarks/` contains only `baselines/model-prices.toml` against a spec that says benches live there. Either drive the bench from scenario files, **or** amend K18 and MetricsAndScenarios §3 to match reality. Whichever way each goes, the outcome is a rule and an implementation that agree. Deleting a rule to make a gate green is forbidden; deleting a rule *with an argument*, recorded, is a legitimate outcome and the more likely one for K18. ## Phase D — measure it, then say what the loop should change ## Task: control loop — did the numbers get worse, then better? ```task id: CB-WP-0005-T07 status: todo priority: high state_hub_task_id: "a34baa46-fbfd-473b-9e15-811e17697791" ``` Commit `evidence/CB-EV-0004-assertion-coverage.md`. Three tests, all reported: 1. **Did the denominators widen?** Name coverage before and after, per spec. A widened denominator that reports the same percentage is the result to publish — it would mean the instruments still count names. 2. **M-D1-MUT against the 9-of-12 prediction.** Report unmet if unmet; no target moves in the commit that measures it. State which rows are `unmutatable` and why. 3. **Did quality hold?** `make all` green with the new gates; and the honest question this pass raises — did widening the instruments surface *new* defects, or only the seven already known? Finding none would be evidence the sweep was as complete as CB-RES-0004 claims, which is a stronger claim than it sounds and should be stated as such. Normalize per unit of work, as CB-WP-0004 T05 established: report share of pass alongside absolute figures, and use `cb-cost --since` to window this pass against the last. ## Task: retrospective and InnerLoop v1.4 ```task id: CB-WP-0005-T08 status: todo priority: medium state_hub_task_id: "3add7e1e-2082-44ef-9287-742c90e5c958" ``` One loop change is already earned and should be written whatever else this pass finds. InnerLoop §Step 2's "numbers" row says the reviewer must *reproduce the number independently* — satisfiable by re-running the command that prints it, which is exactly what does **not** find this class. The reviewer found AM-7 by opening a test out of curiosity, and said so. > **v1.4:** the reviewer must read the assertion behind every quoted > acceptance number and **mutate it**, not re-run the command that prints > it. This is the **second** instance of a verification step inheriting the author's blindness — CB-WP-0002's dedup blind spot was the first. Both fixes replace re-derivation with adversarial execution. Record whether that generalizes. The question to answer honestly: **CB-WP-0004 concluded that tooling recovers capacity only where it removes the manual path. Does the same test predict which gates work?** `env-test` and `task-done` removed the manual path and held. Does a mutation gate remove the manual path — or is writing a weak mutation the new `grep`?