T04: adversarial review round + survey corrections + ADR-0002 (reimplement, assimilate patterns)

history/260731-game-kernel-response.md

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+# 2026-07-31 — response to adversarial challenge: CB-RES-0001 (T04)
+
+One round, per InnerLoop §Step 2. Each finding answered with evidence or
+conceded. New measurements were run before answering B1/S1/S4; harness
+gained `--disable-undo` and `--single-run` flags.
+
+## B1 (blocking) — "architectural, not a tuning artifact": **partially conceded, empirically resolved**
+
+The reviewer was right that the claim was untested and the `disableUndo`
+flag unacknowledged. We reran the harness both ways:
+
+| moves | with undo (moves/s) | disableUndo (moves/s) |
+|---:|---:|---:|
+| 5,000 | 1,439–1,930* | 1,118 |
+| 10,000 | 1,605 | 1,076 |
+| 20,000 | 870 | 942 |
+| 40,000 | — | 733 |
+| 100,000 | DNF @300 s | **DNF @240 s** |
+
+\* run-to-run variance on this machine is large (1,930 vs 1,439 for the
+same config); now noted in the survey's risks.
+
+Verdict on the finding: the undo stack **is** the dominant superlinear term
+at small N (concede: it is a documented one-line flag, and the original
+"not a tuning artifact" sentence was an overclaim — retracted). But
+degradation **persists with undo disabled** (−34% from 5k→40k, RSS
+100→232 MB, and 100k still does not finish), consistent with the client's
+unbounded redux log/deltalog, which has no client-side off switch in
+0.50.2. The survey now reports both datasets and attributes the two
+mechanisms separately. The D3-scaling row is restated against the
+disableUndo (best-case) configuration: 0.66× at 40k vs 5k.
+
+## S1 (significant) — memory methodology: **conceded, fixed**
+
+`--single-run` mode now measures RSS immediately after the main run in a
+fresh process with no warmup/determinism clients. New indicative figures:
+100 MB RSS after 5k moves (disableUndo, isolated) rising to 232 MB after
+40k. The old 224 MB row is withdrawn; memory rows are labeled *indicative*
+(raw RSS includes Node baseline; heap delta not isolated).
+
+## S2 (significant) — omitted candidates: **conceded, added**
+
+OpenSpiel and Ludii added as cited candidates; BGA Studio and Colyseus
+added as one-line secondary references. The verdict's "what none of them
+do" paragraph was re-checked against OpenSpiel specifically and reworded:
+OpenSpiel *does* cover simultaneous-move + imperfect-information semantics
+with deterministic replay via action histories — what it lacks is the
+production layer (client visibility projections, networking, snapshots,
+embeddable boundary), and that is now stated precisely instead of the
+blanket claim.
+
+## S3 (significant) — unsourced D3 ceiling: **conceded, relabeled**
+
+The 10⁵–10⁶ events/s range stays as an *estimate* flag, and the headline
+≥100k events/s + flat-scaling figure is now explicitly labeled a
+**stipulated engineering target**, not a competitor-derived baseline. A
+measured Rust comparator remains an open follow-up (noted in the survey);
+until then, parity-cap applies to any evidence row leaning on that number.
+
+## S4 (significant) — `updatePlayerID` in the timed loop: **answered with a control**
+
+Measured in isolation: ~466,000 calls/s (~2 µs/call) vs ~500–1,100 µs per
+applied move — contamination < 0.5%. Left in the loop (it is part of
+driving multi-player turns through one client); provenance note added.
+
+## M1–M4 (minor) — all conceded
+
+- M1: traceability row demoted from baseline table to an observation.
+- M2: LOC corrected to ~36 and marked gameable/secondary.
+- M3: provenance now states hidden-info (`playerView`) and hand depletion
+  are unexercised by the workload; commit/reveal shape only.
+- M4: maturity figures kept with the npm-checkable fact primary.
+
+## Net effect on the survey
+
+Status remains draft → **approved** (per this round's disposition:
+"approvable with corrections", all corrections applied). The central
+comparative conclusions survive: boardgame.io is the closest semantic
+comparator but inactive, heavyweight for what it does, and degrades with
+history even in its best configuration; the surpass opportunity is the
+combination of production projection/networking, flat-cost replay, and an
+embeddable boundary — now stated with OpenSpiel explicitly in view.