Districts that remember you, and roads worth staying on

Area heat. Road heat alone rewarded a strange kind of play: work one part of
town hard but take a different street every time, and nothing ever got hot. A
second, coarser pool now accrues from being inside a district at all — on-road
or off — and bleeds into every road running through it, including ones never
driven. Deliberately capped below the barricade threshold: a hot district gets
roads patrolled, but concrete still takes somebody actually using that road. It
also decays slower than road heat, because one patrol re-secures a road while a
district's reputation lingers.

Surfaces. Off the route the car now makes about 40% of its road top speed, loses
grip and scrubs momentum in a fifth of the distance, so the road hierarchy is
something you feel rather than something the map merely claims. A first tuning
made off-road a 12 km/h crawl, which removed the choice instead of pricing it —
going round a checkpoint cross-country has to stay a legitimate move.

Speed. Heat scales with how fast you were going, not just how far, and stops
rewarding ever-higher speed past a point so the answer is never one exact number
on the clock. With the road classes, that makes the routing decision real: the
trunk fast and noticed, or the lanes slow and ignored.

Save format goes to v2 for the district pool; older saves are refused rather
than half-restored. Also fixes a population test that hardcoded densities since
tuned, and README claims about patrols and AI that Phase 6 made untrue.

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

src/ui/hud.ts

@@ -24,6 +24,8 @@ export interface HudModel {
     /** False while on the verge — still counts as using the road. */
     onTarmac: boolean;
     value: number;
+    /** Standing of the district, which feeds every road through it. */
+    area: number;
     level: HeatLevel | null;
   };
   quest: {
@@ -113,6 +115,7 @@ export function createHud(seed: number) {
             : `#${model.heat.segmentId} ${model.heat.onTarmac ? '(on road)' : '(alongside)'}`
         }`,
         `[debug] heat ${bar(model.heat.value)} ${model.heat.level ?? '—'}`,
+        `[debug] area ${bar(model.heat.area)}`,
         '',
         `seed ${seed}`,
         `WASD drive · space handbrake · R respawn · M sound ${model.muted ? 'off' : 'on'}`,