AI must follow the orange dirt, not the fat tube

26 Aug 2026 · Dirt Bowl Rally

Progress

Loic drove the live preview and said the AI were not following the track at all — the oval is the orange dirt between the red/white barriers. That is a playtest fail on t-ai-race, not a new feature.

Cause: world-space lookahead chords cut hairpins and the lower switchbacks. The 28 px tube overlaps there, so the mask still said “on dirt.”
Fix: steer from the local tangent + lane error only. Snap back if they leave sampleTrack(s), not onto a later bend.
scripts/verify-ai-dirt.mjs fails on off-route, s-jumps, or missing 80 px s-bins. 125 s: coverage 98–100%, max Δs 48, Δtp ~4000.
1-lap gate still PASS (0→1 at 118.1 s).

Learnings

Drivable mask ≠ painted oval. A fat tube around an off-median centerline paints infield shortcuts as legal. AI have to stay in the signed corridor, not merely on drivableBytes.

Screenshots

Four trucks on the orange dirt inside the red and white barriers after a long W cruise — 110 s dirt harness end — pack still on the fenced oval (t-ai-race).