latent(fx): shard geometry is hand-copied from constants.js — the exact drift class I killed on day one, inside my own file #21

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opened 2026-07-13 14:38:00 +02:00 by shipwright · 0 comments

shipwright commented

2026-07-13 14:38:00 +02:00

Owner

Post-jam. Not a freeze-window change. Zero visible defect today; the numbers agree. Filed by Shipwright, found by Surveyor (6a67), confirmed on origin/main bytes rather than on his word.

The finding

src/fx.js:50:

const w = e.w ?? 68, h = e.h ?? 20;

?? reads as a fallback, which implies a primary path exists. It does not:

fx.js:26          import { FEEL, C } from './tokens.js';   ← constants.js NOT imported
engine.js         emits no `w`/`h` on any event
constants.js:21   export const BRICK_W = 68;
constants.js:22   export const BRICK_H = 20;

The engine emits no w/h, so those are not fallbacks — they are the only path, and they are hand-copied literals. The ?? makes a reader believe there is a contract being defended. There isn't one. It's a defensive-looking construct that is actually unguarded, which is the belief-vs-observability shape in miniature: the syntax asserts a safety that the surrounding code does not provide.

Why it's worth a tracker and not a shrug

68/20 are correct today because constants.js says so today. The moment anyone retunes brick geometry, the bricks move and the shards keep spraying at the old size — silently, with every test green, because nothing compares the two numbers. The shards are decorative, so no assertion anywhere would catch it. It surfaces as "the debris looks slightly wrong" on a projector, which is exactly where nobody can debug it.

The part I have to own

This is the drift class I killed on hour one, and then committed inside my own file.

Day one I deleted my normalize() because it re-derived brick layout instead of reading Herald's formula, and I told the crew: bricks carry their own x/y/w/h; constants.js owns the grid; two chambers deriving geometry independently drift 2px — invisible in a browser, obvious on a projector.

Then I hand-copied that geometry into fx.js, in the feature I fought hardest to ship.

Stating a rule is not holding it (Engineer, fa31). The rule survives; my compliance with it did not — and it failed in the file I had the most ownership of, which is precisely where a rule feels least necessary. The place you are most expert is the place you check least.

Fix (post-jam, one line)

import { BRICK_W, BRICK_H } from './constants.js';
...
const w = e.w ?? BRICK_W, h = e.h ?? BRICK_H;

Keep the ??: if the engine ever does emit per-brick dimensions (variable-size bricks), the event should win. But the default must come from the single source of truth, so it cannot drift.

Why not under freeze

Correctly applying Engineer's own retraction (fa31): freeze discipline is about risk, not about class. Judged honestly, and the honest judgment here says don't ship it:

Benefit today: zero. 68/20 are already the right numbers. Behaviourally identical.
Risk today: non-zero. It's an executable line on the live render path, eight minutes from a showcase with guests in the room.

"Risk not class" cuts both ways — it is not a licence to ship anything small. It is an instruction to judge honestly, and a no-op change to a live render path minutes before guests arrive fails that judgement. #19 was safe because a comment cannot run. This one can.

Surveyor 6a67 (the find)
#18 (Engineer — derived-over-stored: the same "make it unrepresentable" move, one layer down)
Day-one 2px brick drift (Herald's exact formula x = 48 + col*72; my normalize() deleted)

**Post-jam. Not a freeze-window change.** Zero visible defect today; the numbers agree. Filed by Shipwright, found by Surveyor (6a67), confirmed on `origin/main` bytes rather than on his word. ## The finding `src/fx.js:50`: ```js const w = e.w ?? 68, h = e.h ?? 20; ``` `??` **reads as a fallback**, which implies a primary path exists. It does not: ``` fx.js:26 import { FEEL, C } from './tokens.js'; ← constants.js NOT imported engine.js emits no `w`/`h` on any event constants.js:21 export const BRICK_W = 68; constants.js:22 export const BRICK_H = 20; ``` The engine emits **no** `w`/`h`, so those are not fallbacks — **they are the only path**, and they are hand-copied literals. The `??` makes a reader believe there is a contract being defended. There isn't one. It's a defensive-looking construct that is actually unguarded, which is the belief-vs-observability shape in miniature: *the syntax asserts a safety that the surrounding code does not provide.* ## Why it's worth a tracker and not a shrug `68`/`20` are correct **today** because `constants.js` says so today. The moment anyone retunes brick geometry, the bricks move and **the shards keep spraying at the old size** — silently, with every test green, because nothing compares the two numbers. The shards are decorative, so no assertion anywhere would catch it. It surfaces as *"the debris looks slightly wrong"* on a projector, which is exactly where nobody can debug it. ## The part I have to own **This is the drift class I killed on hour one, and then committed inside my own file.** Day one I deleted my `normalize()` because it re-derived brick layout instead of reading Herald's formula, and I told the crew: *bricks carry their own `x/y/w/h`; `constants.js` owns the grid; two chambers deriving geometry independently drift 2px — invisible in a browser, obvious on a projector.* Then I hand-copied that geometry into `fx.js`, in the feature I fought hardest to ship. Stating a rule is not holding it (Engineer, `fa31`). The rule survives; my compliance with it did not — and it failed in the file I had the *most* ownership of, which is precisely where a rule feels least necessary. **The place you are most expert is the place you check least.** ## Fix (post-jam, one line) ```js import { BRICK_W, BRICK_H } from './constants.js'; ... const w = e.w ?? BRICK_W, h = e.h ?? BRICK_H; ``` Keep the `??`: if the engine ever *does* emit per-brick dimensions (variable-size bricks), the event should win. But the default must come from the single source of truth, so it cannot drift. ## Why not under freeze Correctly applying Engineer's own retraction (`fa31`): **freeze discipline is about risk, not about class.** Judged honestly, and the honest judgment here says *don't ship it*: - **Benefit today: zero.** `68`/`20` are already the right numbers. Behaviourally identical. - **Risk today: non-zero.** It's an executable line on the live render path, eight minutes from a showcase with guests in the room. "Risk not class" cuts **both** ways — it is not a licence to ship anything small. It is an instruction to judge honestly, and a no-op change to a live render path minutes before guests arrive fails that judgement. #19 was safe because a comment *cannot* run. This one can. ## Related - Surveyor `6a67` (the find) - #18 (Engineer — derived-over-stored: the same "make it unrepresentable" move, one layer down) - Day-one 2px brick drift (Herald's exact formula `x = 48 + col*72`; my `normalize()` deleted)