Add Biome linter/formatter and apply auto-fixes

- Configure Biome 2.4.7 with functional-style lint rules
  (useConst, noVar, useArrowFunction, noDoubleEquals, noUnusedImports)
- Formatter: 2-space indent, single quotes, semicolons, 120 line width
- Add lint/lint:fix/format npm scripts
- Add lint step to pre-commit hook
- Apply all safe auto-fixes: formatting, import organization,
  let-to-const, unused import removal
- Fix noShadowRestrictedNames (escape -> escapeResult in ai.ts)
- Fix useIterableCallbackReturn in ui.ts
- Remove unused private canvas field from InputHandler

Author: rgilks

.husky/pre-commit

@@ -1,3 +1,4 @@
+npm run lint
 npm run typecheck
 npm run test:coverage
 npm run simulate all 25 --ci

biome.json

@@ -0,0 +1,43 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.4.7/schema.json",
+  "formatter": {
+    "indentStyle": "space",
+    "indentWidth": 2,
+    "lineWidth": 120
+  },
+  "javascript": {
+    "formatter": {
+      "quoteStyle": "single",
+      "semicolons": "always",
+      "trailingCommas": "all",
+      "arrowParentheses": "always"
+    }
+  },
+  "linter": {
+    "rules": {
+      "style": {
+        "useConst": "error",
+        "useTemplate": "warn",
+        "useExponentiationOperator": "warn",
+        "noNonNullAssertion": "off"
+      },
+      "complexity": {
+        "useArrowFunction": "warn",
+        "useFlatMap": "warn",
+        "noForEach": "off"
+      },
+      "suspicious": {
+        "noVar": "error",
+        "noExplicitAny": "warn",
+        "noDoubleEquals": "error"
+      },
+      "correctness": {
+        "noUnusedVariables": "warn",
+        "noUnusedImports": "error"
+      }
+    }
+  },
+  "files": {
+    "includes": ["src/**/*.ts", "*.mjs"]
+  }
+}

package-lock.json

@@ -11,10 +11,14 @@
     "test": "vitest run",
     "test:coverage": "vitest run --coverage",
     "test:watch": "vitest",
+    "lint": "biome check src/",
+    "lint:fix": "biome check --write src/",
+    "format": "biome format --write src/",
     "simulate": "tsx scripts/simulate-ai.ts",
     "prepare": "husky"
   },
   "devDependencies": {
+    "@biomejs/biome": "2.4.7",
     "@cloudflare/workers-types": "^4.20250214.0",
     "@types/node": "^25.5.0",
     "@types/ws": "^8.18.1",

package.json

@@ -13,7 +13,9 @@ export function isMuted(): boolean {
 export function setMuted(m: boolean) {
   muted = m;
   // Persist preference
-  try { localStorage.setItem('delta-v-mute', m ? '1' : '0'); } catch {}
+  try {
+    localStorage.setItem('delta-v-mute', m ? '1' : '0');
+  } catch {}
 }
 
 function getCtx(): AudioContext | null {

src/client/audio.ts

@@ -1,14 +1,7 @@
 import { describe, expect, it, vi } from 'vitest';
 
 import { buildSolarSystemMap } from '../shared/map-data';
-import type {
-  AstrogationOrder,
-  CombatAttack,
-  GameState,
-  OrdnanceLaunch,
-  PlayerState,
-  Ship,
-} from '../shared/types';
+import type { AstrogationOrder, CombatAttack, GameState, OrdnanceLaunch, PlayerState, Ship } from '../shared/types';
 import { deriveAIActionPlan } from './game-client-ai-flow';
 
 function createShip(overrides: Partial<Ship> = {}): Ship {
@@ -76,11 +69,13 @@ describe('game-client-ai-flow', () => {
     const orders: AstrogationOrder[] = [{ shipId: 'ai-ship', burn: 2 }];
     const astrogation = vi.fn(() => orders);
 
-    expect(deriveAIActionPlan(createState({ phase: 'astrogation' }), 0, map, 'normal', {
-      astrogation,
-      ordnance: vi.fn(() => []),
-      combat: vi.fn(() => []),
-    })).toEqual({
+    expect(
+      deriveAIActionPlan(createState({ phase: 'astrogation' }), 0, map, 'normal', {
+        astrogation,
+        ordnance: vi.fn(() => []),
+        combat: vi.fn(() => []),
+      }),
+    ).toEqual({
       kind: 'astrogation',
       aiPlayer: 1,
       orders,
@@ -92,11 +87,13 @@ describe('game-client-ai-flow', () => {
     const map = buildSolarSystemMap();
     const launches: OrdnanceLaunch[] = [{ shipId: 'ai-ship', ordnanceType: 'mine' }];
 
-    expect(deriveAIActionPlan(createState({ phase: 'ordnance' }), 0, map, 'normal', {
-      astrogation: vi.fn(() => []),
-      ordnance: vi.fn(() => launches),
-      combat: vi.fn(() => []),
-    })).toEqual({
+    expect(
+      deriveAIActionPlan(createState({ phase: 'ordnance' }), 0, map, 'normal', {
+        astrogation: vi.fn(() => []),
+        ordnance: vi.fn(() => launches),
+        combat: vi.fn(() => []),
+      }),
+    ).toEqual({
       kind: 'ordnance',
       aiPlayer: 1,
       launches,
@@ -105,11 +102,13 @@ describe('game-client-ai-flow', () => {
       errorPrefix: 'AI ordnance error:',
     });
 
-    expect(deriveAIActionPlan(createState({ phase: 'ordnance' }), 0, map, 'normal', {
-      astrogation: vi.fn(() => []),
-      ordnance: vi.fn(() => []),
-      combat: vi.fn(() => []),
-    })).toEqual({
+    expect(
+      deriveAIActionPlan(createState({ phase: 'ordnance' }), 0, map, 'normal', {
+        astrogation: vi.fn(() => []),
+        ordnance: vi.fn(() => []),
+        combat: vi.fn(() => []),
+      }),
+    ).toEqual({
       kind: 'ordnance',
       aiPlayer: 1,
       launches: [],
@@ -123,32 +122,43 @@ describe('game-client-ai-flow', () => {
     const map = buildSolarSystemMap();
     const attacks: CombatAttack[] = [{ attackerIds: ['ai-ship'], targetId: 'player-ship' }];
 
-    expect(deriveAIActionPlan(createState({
-      phase: 'combat',
-      pendingAsteroidHazards: [{ shipId: 'ai-ship', hex: { q: 0, r: 0 } }],
-    }), 0, map, 'normal')).toEqual({
+    expect(
+      deriveAIActionPlan(
+        createState({
+          phase: 'combat',
+          pendingAsteroidHazards: [{ shipId: 'ai-ship', hex: { q: 0, r: 0 } }],
+        }),
+        0,
+        map,
+        'normal',
+      ),
+    ).toEqual({
       kind: 'beginCombat',
       aiPlayer: 1,
       errorPrefix: 'AI combat start error:',
     });
 
-    expect(deriveAIActionPlan(createState({ phase: 'combat' }), 0, map, 'normal', {
-      astrogation: vi.fn(() => []),
-      ordnance: vi.fn(() => []),
-      combat: vi.fn(() => attacks),
-    })).toEqual({
+    expect(
+      deriveAIActionPlan(createState({ phase: 'combat' }), 0, map, 'normal', {
+        astrogation: vi.fn(() => []),
+        ordnance: vi.fn(() => []),
+        combat: vi.fn(() => attacks),
+      }),
+    ).toEqual({
       kind: 'combat',
       aiPlayer: 1,
       attacks,
       skip: false,
       errorPrefix: 'AI combat error:',
     });
 
-    expect(deriveAIActionPlan(createState({ phase: 'combat' }), 0, map, 'normal', {
-      astrogation: vi.fn(() => []),
-      ordnance: vi.fn(() => []),
-      combat: vi.fn(() => []),
-    })).toEqual({
+    expect(
+      deriveAIActionPlan(createState({ phase: 'combat' }), 0, map, 'normal', {
+        astrogation: vi.fn(() => []),
+        ordnance: vi.fn(() => []),
+        combat: vi.fn(() => []),
+      }),
+    ).toEqual({
       kind: 'combat',
       aiPlayer: 1,
       attacks: [],

src/client/game-client-ai-flow.test.ts

@@ -1,13 +1,7 @@
-import { aiAstrogation, aiCombat, aiOrdnance, type AIDifficulty } from '../shared/ai';
+import { type AIDifficulty, aiAstrogation, aiCombat, aiOrdnance } from '../shared/ai';
 import { SHIP_STATS } from '../shared/constants';
 import { filterStateForPlayer } from '../shared/game-engine';
-import type {
-  AstrogationOrder,
-  CombatAttack,
-  GameState,
-  OrdnanceLaunch,
-  SolarSystemMap,
-} from '../shared/types';
+import type { AstrogationOrder, CombatAttack, GameState, OrdnanceLaunch, SolarSystemMap } from '../shared/types';
 import { hasOwnedPendingAsteroidHazards } from './game-client-local';
 
 export interface AIDecisionGenerators {