Bumper Cars rules: a tested `bumper-cars/floor.js` where you steer a car on a walled floor and shove three seeded rivals into the wall without a head-on bump, from plain data, in a two-file pull with a test file that runs in under a second #329

Bumper Cars rules are in, as a two-file pull: bumper-cars/floor.js and bumper-cars/floor.test.mjs. Nothing else is touched. bun test bumper-cars/floor.test.mjs passes all 12 tests in 65 ms, with no page, renderer or server. bun x tsc --noEmit printed only its usage text, so I can't say it was clean. I didn't run scripts/gate.ts.

The rules

• Floor: 9×9, ringed by the wall. You start at (4,8) facing north, with 3 lives and a round of 60 ticks.
• Rivals: three, each with a seeded start square, heading and 4-turn repeating pattern. All randomness comes from the seed via mulberry32.
• Turns: steer(state, 'left'|'right'|'straight') sets your next turn. An unknown turn returns unknown-turn, and a round already over returns round-over. Both hand back the same state object.
• Tick order: step(state) moves your car first, then rivals 1, 2 and 3. It returns {ok, state, why, events}.
• Wall: a car that would leave the floor stays put and turns right.
• Bumps:

- A back or side bump shoves the rival one square the way you were going, and you take its square. - A shove off the floor scores 10, counts as a wall shove, and the rival is placed again at a seeded free square. - A head-on bump costs a life, and you stay put and turn about.

• End of round:

- A loss comes when lives hit 0: "Round lost: out of lives at tick N, score S". - A win comes when the ticks run out: "Round won: score S, K wall shoves".

Choices the issue left open

• A shove into another car does nothing, and you stay put.
• A rival that moves into you head-on costs you a life. Any other blocked rival move just turns it right.
• Rivals don't shove anyone.

Not done: the page and the catalogue entry. The issue left them for a later pull.

The check wasn't run, so the "took longer than 600s" caveat doesn't arise.

🤖 Generated with Claude Code

Closes #320

Bumper Cars rules are in, as a two-file pull: bumper-cars/floor.js and bumper-cars/floor.test.mjs. Nothing else is touched. bun test bumper-cars/floor.test.mjs passes all 12 tests in 65 ms, with no page, renderer or server. bun x tsc --noEmit printed only its usage text, so I can't say it was clean. I didn't run scripts/gate.ts.

The rules

• Floor: 9×9, ringed by the wall. You start at (4,8) facing north, with 3 lives and a round of 60 ticks.
• Rivals: three, each with a seeded start square, heading and 4-turn repeating pattern. All randomness comes from the seed via mulberry32.
• Turns: steer(state, 'left'|'right'|'straight') sets your next turn. An unknown turn returns unknown-turn, and a round already over returns round-over. Both hand back the same state object.
• Tick order: step(state) moves your car first, then rivals 1, 2 and 3. It returns {ok, state, why, events}.
• Wall: a car that would leave the floor stays put and turns right.
• Bumps:

- A back or side bump shoves the rival one square the way you were going, and you take its square. - A shove off the floor scores 10, counts as a wall shove, and the rival is placed again at a seeded free square. - A head-on bump costs a life, and you stay put and turn about.

• End of round:

- A loss comes when lives hit 0: "Round lost: out of lives at tick N, score S". - A win comes when the ticks run out: "Round won: score S, K wall shoves".

Choices the issue left open

• A shove into another car does nothing, and you stay put.
• A rival that moves into you head-on costs you a life. Any other blocked rival move just turns it right.
• Rivals don't shove anyone.

Not done: the page and the catalogue entry. The issue left them for a later pull.

The check wasn't run, so the "took longer than 600s" caveat doesn't arise.

🤖 Generated with Claude Code

I've pushed the changes to the same branch, covering every point except the type check, which has nothing to run in this clone. bun test bumper-cars/floor.test.mjs passes 20 tests (12 before) in 54 ms, with no page or server.

1. Untested behaviours. Each of these now has a test that fails without the rule:

• A rival driving head-on into your car costs a life. A second test ends the round with the loss line from that rival's move.
• A shove into another car is refused. You stay put and a blocked event is returned.
• A rival blocked by your side or back, or by another rival, stays put and turns right. Only a head-on costs you a life.
• Rivals stop moving once lives hit 0 within the tick. A control case shows the same rival moving when a life is left.
• The singular wording is pinned for "1 life", "1 wall shove" and the win line.
• The events from step are asserted exactly, with their car and score fields, for wall, shove, wall-shove, head-on and blocked. A tick with no bump returns [].

2. Checks.

• bun x tsc --noEmit: this clone has no package.json, no tsconfig.json and no node_modules. bun install has nothing to install and tsc just prints its usage text. There is no type check to run here.
• bun scripts/gate.ts: it doesn't exist here; scripts/ holds only og.mjs. I didn't run it.

3. Minor.

• Parking: the set helper now fills any rival slot a test doesn't give from an explicit PARKED list, with one square and heading per slot. The vague comment and the index-coupled corner list are gone.
• Exports: PATTERN and DIRS are no longer exported from floor.js.

I disagree with nothing in the review.

🤖 Generated with Claude Code

Declined: I found nothing to fix, so I didn't push. The deploy log you sent stops partway through the playtests, at sandcastle, and shows no failing test. Run log: https://forge.open-platform.sh/trevato/pixel-plays/runs/01m6gjhcbn6mpen1522vfx4sk4