feat(gridlock): isometric neon city-builder with pure simulation core

[cloudygetty-ai]

GRIDLOCK — Everything runs through you.

A SimCity-style isometric city-builder at games/gridlock/. Open index.html — no build step, no dependencies, no server.

What makes it not-SimCity

Three pressures turn zoning from painting into a decision:

1. Adjacency synergy — 11 rules where the same building is worth materially more or less depending on what it touches. Commerce beside housing sells more (+8%/neighbour, cap 4). Housing beside a foundry loses approval. A server farm on the waterfront dumps heat into the bay. The inspector shows what a tile would score before you commit.
2. The Heat Index — generators, factories, and server farms emit heat. Past 55 it raises city-wide cooling demand and costs approval; past 88 the city is in crisis and the map takes a red cast. Parks, sky gardens, and carbon scrubbers pull it back.
3. Crisis cards — 12 condition-triggered cards that pause the world and force a trade with no clean answer (Grid Surge, Heatwave, Corporate Bid, Transit Strike, Arrival Wave, Data Breach, Ground Tremor, Smog Alert, Blackout Riots…). Unseen cards are 3× as likely, so the deck stays surprising.

The three chains

road ──▶ power ──▶ water ──▶ live. A structure produces nothing unless all three hold. Utility rationing is deterministic and priority-ordered — water plants and clinics stay lit, factories brown out first — and water resolves after power, so an unpowered pump makes no water and the cascade runs one way.

Architecture

• config/ is data only; core/ is a pure simulation: tickMonth(state) → state, no DOM, no clock, no Math.random. It runs headless under node --test, which is what makes any of this testable.
• Every stochastic decision draws from (seed, rollCount), so a save file replays exactly and crisis outcomes are reproducible.
• Buildings are catalog entries — adding one to config/buildings.js makes it appear in the palette, on the map, and in the economy with no other code change. The renderer draws all 31 structures procedurally; there is no art pipeline.
• HEALTH / PRESSURE / EFFICIENCY telemetry behind ` or ?debug=1. A built-out city ticks in <1ms and draws in ~3ms at 58fps.

Tests

77 tests, no framework and no dependencies: placement rules, road connectivity and orphan islands, rationing order, synergy caps, tick purity/determinism, crisis gating, directive streaks, and a 10-year fixture-district balance regression (fills up, pays for itself, stays cool; dirty industry demonstrably overheats it; severing a street takes the district offline).

Two real bugs were caught and fixed during verification:

• Grid Surge fired every single month — its condition compared power.ratio (clamped at 1) against 1.05. There is now a test asserting no crisis condition does this.
• Structures stranded from the road graph were invisible — the sim was correct but silent, so the HUD now shows a pulsing N CUT OFF chip alongside BROWNOUT / WATER SHORT / GRIDLOCK / DEFICIT / OVERHEATING.

Verification

• npm run test:gridlock — 77/77 pass
• Browser-driven smoke test in headless Chromium: intro → build a district by dragging → run at 3× → resolve a live crisis → cycle overlays → save/load round-trip. No console errors (the only network failure is Google Fonts being blocked in the sandbox; fallback stacks are in place).
• Repo type-check / lint / jest are unaffected — tsconfig includes only src/**, eslint targets only .ts,.tsx, and jest's testRegex does not match .mjs. (Those commands fail in this container only because node_modules is not installed.)

Also included

• /gridlock route in vercel.json (plus static passthrough for games/**)
• An isolated, dependency-free CI job on Node 20 for the simulation core
• npm run test:gridlock at the repo root

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