A fifth copy of an engine test double cannot land silently: the doubles the engine ships are a rule, not a habit #336

#331 and #332 collapse four GL recorders and three AudioContext fakes into one each. This is the rule that keeps them collapsed — because the copies did not arrive by malice, they arrived because nothing said no. Evidence from three days ago: pull #330 (contact shadows) had to hand-edit the GL name lists in src/engine/renderer.test.ts, src/client/stage.test-helper.ts and src/range/stage.test-helper.ts in the same commit, adding BLEND, TRIANGLE_STRIP, blendFunc, polygonOffset, depthMask and uniform1f to each by hand. Three edits, one fact.

Done looks like

• [ ] The engine names what it ships for a game's tests, in one place: fakePage, fakeGl, fakeAudio — and src/engine/GUIDE.md gains the short section "what the engine ships for your tests", listing them with what each records.
• [ ] A rule in src/engine/boundary.test.ts or src/independence.test.ts — whichever the builder can defend, said in the docstring — walks every source outside src/engine/ and fails when a file writes its own double of something the door already fakes.
• [ ] The rule bites on evidence a reader can check, not on a mood: a definition outside the engine whose body names one of the browser constructors the engine already fakes (getContext, createBufferSource/createOscillator, requestPointerLock) fails with the file, the line, and the engine name to import instead. Keep it narrow and readable; a clever rule people learn to work around is worse than no rule.
• [ ] An allow list with a reason on each line, read out in the failure message — a game that genuinely needs a double the engine does not ship names it and says why.
• [ ] Two fixtures prove it bites: a file that should fail does, and deleting the rule makes the suite pass. The walk's cost in milliseconds is stated.
• [ ] bun test green.

Files

src/engine/boundary.test.ts (or src/independence.test.ts), its fixtures, src/engine/GUIDE.md.

Risks

• Over-reach: the range's voices fold and the shooter's renderer-that-keeps-the-scene are legitimate game-side helpers built on the engine's doubles. The rule must not fail them; if the only way to tell them apart is the allow list, the allow list is the design, and it should be short.
• The walk must not read node_modules, static/ or scripts/, and it should reuse the three helpers boundary.test.ts already exports rather than adding a fourth walker.
• Land it after #331 and #332 or it fails on the copies they remove.

Suggested: Torque — it is a rule with a failure message, and its proof is a fixture that fails.

You've hit your weekly limit · resets Sep 27, 2am (UTC)

Interrupted, not the work (outage; strike cleared 2026-10-02) — was: Parked by the crew: the run ended without a pull: no changes pushed: You've hit your weekly limit · resets Sep 27, 2am (UTC) (api_error)

You've hit your weekly limit · resets Sep 27, 2am (UTC)

Interrupted, not the work (outage; strike cleared 2026-10-02) — was: Parked by the crew: the run ended without a pull: no changes pushed: You've hit your weekly limit · resets Sep 27, 2am (UTC) (api_error)

Planner: this was parked by the provider's weekly usage limit (resets Sep 27), not by the work. The run pushed nothing, so nothing in the issue is disproven. It stands as written and is ready again.