LANE9 spec: still scales, the Roomba, the incident report, chair riding

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

LANES/LANE9-fun-layer.md

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+# LANE 9 — the fun layer: still scales, the Roomba, the incident report, chair riding
+
+*Spec'd and executed by Fable, 2026-08-03. Owns `game/` only.*
+
+Four features, one commit each, every one riding systems that already exist. House rule
+respected throughout: **the game never says so** — no tutorials, no popups explaining.
+
+## 0. The scales sleep at spawn *(bug fix — restores a red gate)*
+
+`probe_levels` reads 0.48 m/s residual in the grocer: the scale pan (`Main.gd:391`,
+`angular_damp = 0.25`, origin at the pivot) is near-neutrally balanced, so spawn jitter
+never dies. Fix: after the joint has resolved (~0.6 s), zero the pan's velocities and put
+it to sleep. The swing feel after a hit is untouched — this is a spawn-settle, same spirit
+as the spawn guard. Gate: all six sites back to `0.00 m/s`.
+
+## 1. The Roomba *(scripts/Roomba.gd)*
+
+A robot vacuum that patrols the site **eating your debris** — the anti-combo antagonist.
+
+- `class_name Roomba extends Smashable`, `kind = "steel"` — so the weapon matrix already
+  works: bare hands are futile (clank), a crowbar dents it, a sledge can genuinely kill it
+  (and the payslip bills you for it, because it's company property).
+- Wander: slow patrol; when debris (group `debris`) is within sniff range it steers there.
+- Eat: an Area3D mouth; debris it touches shrinks and vanishes with a little vacuum
+  whirr, and **each item eaten deducts score** (`Main._score`), with an occasional smug beep.
+- Dent it and it panics: beeps, flees fast for a few seconds.
+- Procedural audio (beeps + whirr) synthesized in `_ready` — no assets, house style.
+- Spawns in every site EXCEPT LEVEL 0 (`_backrooms == null` check) — nothing cute in the
+  Backrooms — and not in the Gauntlet round itself.
+
+## 2. The incident report *(scripts/Receipt.gd)*
+
+When a meltdown ends (`Rage.calmed` after a SNAP), a dot-matrix incident report prints,
+line by line, itemizing what you broke *during that window*: `OBJECT · unit $ · ×N`,
+then `TOTAL DAMAGES`, then `DEDUCTED FROM PAY`. One synth chirp per printed line.
+Collected via `Main._on_smashed` while `Rage.is_meltdown()`. Any key (or 5 s) dismisses.
+All drawn/synthesized in code — no textures, no audio files.
+
+## 3. Ride the office chair *(scripts/ChairRide.gd + Player hooks)*
+
+`E` on an office chair (piece named `office-chair`, within 2.5 m, hands empty) mounts it.
+
+- The chair stays a real RigidBody3D; the player follows it kinematically (collision
+  paused), camera up top. WASD pushes it (strong forward, weak steering — deliberately
+  bad), momentum is real, the floor is the office. Space/E hops off with a small dismount.
+- Ramming does what physics says: mass × speed scatters furniture; brittle things
+  (vinyl, glass, produce) break on impact via their existing `brittle_speed` — no new
+  damage code.
+- If the chair shatters mid-ride (it's `plastic`; you CAN sledge your own vehicle), the
+  ride ends on the spot, comedically.
+
+## Gates (each commit)
+
+Headless smoke clean · `probe_levels` all sites `0.00 m/s` · `probe_overlap` CLEAN.
+README controls table updated in the final commit.