feat: ignition opening with cold start, lamps, crossfade and shader warm-up

docs/overnight/LOG.md

@@ -63,3 +63,11 @@ Run: `npm run build:preview` then serve `dist` (dev server shows a blank page).
 - **Verdict: KEEP with fixes** (Fable, hardware GL): near/far pairs overlapped and the near-right mast clipped, so layout is now aspect-aware with the far mast closer to centre; lamps were white and rungs grey, now hot violet above the bloom threshold; beams brightened and widened with a eased base; hover flash made visible.
 - **Known weaknesses:** lamp cores still tonemap to lavender-white (violet lives in the halo); masts are slivers on phones and modest at 1024 wide; hover flash is a peripheral beat; chirp verified by unit test only.
 - Screenshots: docs/overnight/round7/.
+
+## Round 8: IGNITION (the first three seconds)
+- **What:** the site opens as a film: the first rendered frame is cold (exposure 0.35, lamps off, road stopped) and dissolves over the SSR poster in 0.6 s; dipped lamps at +0.6 s, main beam at +1.0 s with the hero-name sweep; from +1.0 to +3.0 s the road and streaks ease to cruise while the exposure rises and the crane starts; the HUD subline reads IGNITION, then SHIFT START · 02:58, fading out by +4.5 s. html[data-ignition] walks cold → lamps → rolling and is removed. Returning visitors (localStorage nightdrive:route) get the short form; a scroll, nav, dashcam or section change inside 3 s cuts to driving in 0.4 s; deep links skip it; reduced motion, static and data-saver keep the poster only.
+- **Why:** the previous opening was a poster that silently became a lit, cruising scene: a loading state. An ignition beat is a reason for the dark first frame and makes the pull-away the first thing the visitor watches.
+- **Build:** scene/world/ignition.ts, journey/ignition-feed.ts, styles/ignition.css; environment.ts, useHeadlightBeam.ts, car.ts, road.ts. 854 tests (74 files), initial JS 118.23 KB gz (1.8 KB left), CSS 26.73 KB gz, scene chunk 215 KB gz.
+- **Verdict: SHIP** (Fable, hardware GL 1440x900, fresh context): beats land on the spec clock (lamps +0.60, rolling +1.00, sweep +1.05, attribute removed +4.5 s); the dissolve is one exposure pull (the poster darkens with the canvas fade, frame luminance 47.7 → 28 with no step over 15 per 200 ms); rAF p50 16.7 / p95 16.8 ms after the first frame. Fixes made during review: (1) the ignition clock no longer counts the first-frame shader stall, so the cold hold is a real 0.6 s; (2) the poster dims with the dissolve instead of a bright image giving way to a dark one; (3) the hero name is unlit until the sweep (the lamp's idle drift pre-lit letters the hold then darkened); (4) every program is compiled in frame 0 behind the poster by a warm render of the whole scene (hidden objects visible, culling off) through the real post-processing pipeline. renderer.compile() keys programs for the screen and never matched the composer's linear targets, so the car, the sign and the streaks each compiled on first sight: 230-280 ms stalls on the first scroll, which tripped the 250 ms catastrophic-frame downgrade and rebuilt the scene mid-opening (a 350 ms freeze and a brightness pop). After the fix no long task follows the first frame in any scenario; the first scroll cuts cleanly in 0.4 s.
+- **Known weaknesses:** the first frame now lands ~1.7-1.9 s after navigation on a cold GPU (all ~60 programs compile behind the poster in one 1.2 s task; the poster holds, nothing is blank); clicking a nav link inside the opening fires the pre-existing exit-sign flare, one bright frame (mean 80/255) on arrival; the phone opening is quieter (no hero sweep on coarse pointers); the short form's road start is a small 5-point dip in luminance before cruise.
+- Screenshots: docs/overnight/round8/ (01 long contact sheet 1.5-6.0 s, 02 cold frame, 03 lamps on, 04 rolling + sweep, 05 short form, 06 early-scroll cut sheet, 07 phone 390x844).