Maelstrom decoder consistency: independent acceptance, 2026-10-30

Accepted within the host decoder/adapter scope: candidate 18f9f827f5a83885b90c8eb1489356ccf389a3d3, whose actual tools/maelstrom-original-errno-adapter.cjs SHA-256 is cbe04fef7e98c1ff607251812225b8314fc0aaff2c289331b95839cfe2df2b49 (Git blob 3e8ba249fb31aece02341c046e5675df4cece1fa). No production source was changed by this acceptance.

The independent test imports the actual production decoder and createAdapter. Its first behavioral check starts the adapter, supplies the exact OFF-latch/UOP-bit contradiction, and requires the mode-switch diagnostic error before persistence. It also verifies that an invalid snapshot seals the adapter. Export scalar inputs are synthetic; the decoder and adapter are never replaced by a model.

Run from the repository:

/usr/bin/node --max-old-space-size=192 test/maelstrom-mode-consistency-independent-accept.test.cjs

Task execution used the owned ops.py/limit_contract.py supervisor with recorded admission, Node startup limits, CPU/wall/file/output limits and physical RSS gates. The heap flag is not a total-process memory limit.

New passing coverage:

24 valid direct decodes and 24 contradictory direct decodes: both switch directions, statuses 1/2/3 (events 0/1/2), and other packed bits 0/1/2/3.
24 valid adapter rejection records and 25 invalid adapter observations, including the first production-boundary check. Invalid diagnostics never reach persist; valid switch rejections persist and then raise status rejection.
37 partial-diagnostic checks: missing direct fields, missing/nonfunction export members, and mode exports without the base diagnostic family.
24 legacy checks: undefined/null optional decoder context, absent mode exports, and absent diagnostic families. Legacy contexts cannot establish bit/latched consistency and intentionally keep their additive compatibility behavior.
Seven range/event checks. High unsigned PC/register values remain intact.

Three distinguishing controls mutate only the exact consistency predicate in an in-memory copy of the actual production module; production files stay unchanged. All exit 1:

/usr/bin/node --max-old-space-size=192 test/maelstrom-mode-consistency-independent-accept.test.cjs --control=remove
/usr/bin/node --max-old-space-size=192 test/maelstrom-mode-consistency-independent-accept.test.cjs --control=off-only
/usr/bin/node --max-old-space-size=192 test/maelstrom-mode-consistency-independent-accept.test.cjs --control=on-only

Removal and ON-only enforcement fail at the first adapter assertion: they emit the generic native status rejection instead of the required mode-switch diagnostic error, having accepted the malformed diagnostic into persistence. OFF-only enforcement fails with Missing expected exception at the reverse-direction direct decode (from=1 status=1 other=0). This distinguishes both halves of equality.

The first independent run reached a harness range-check assertion that expected the later packed-range error even though its contradictory UOP bit correctly triggered the earlier consistency guard. The range fixture now keeps bit/latch agreement to isolate upper packed bits. The original failure is retained; this was a test-input correction, not a production counterexample or repair.

Reused evidence, without wholesale replay: coordinator-reviewed canonical receipt /tmp/maelstrom-mode-diagnostic-consistency-repair-oct30/completion-receipt.json SHA-256 5afda1acd302fa7a61fbb4ed92e25ec4db63ccbd48ff29c3c436b92d89330674. It binds the unchanged original counterexample, focused compiled native fixture regression (6 switches, 24 contradictions, 4 adapter cases), repair-removal control, recovered source pins, tested repair patch and remote repair publication. The 13 materialized candidate files were independently checked against dispatch byte/SHA-256 pins and exact candidate tree blob identities. The remote repair ref was also freshly checked at the candidate SHA.

New raw invocation/output evidence, recovery patch, source pins and canonical acceptance completion receipt are retained separately under: /tmp/maelstrom-mode-consistency-repair-independent-accept-oct30/. See completion-receipt.json there for exact acceptance commit/ref and remote verification. The task-owned messageboard note is handed to the coordinator for one append because the standing board exceeds the worker file-size cap.

Full production WAT transformation, full build/binary qualification, guest execution, original-game runtime and gameplay remain UNQUALIFIED. No Boat was allocated or used; no mount argv or guest launch exists to validate. The original causal instruction remains UNKNOWN. This acceptance does not integrate main or authorize deployment.