test: add regression tests for BUG-4, BUG-6, BUG-7, BUG-F2

Source pattern verification tests:
- BUG-6: webhook calls wrapped in Promise.all (parallel, not sequential)
- BUG-7: SSE maps (spectatorCounts, fightReactions, ssePerIp) cleaned on disconnect
- BUG-4: no raw setTimeout in game code (all use trackedTimeout)
- BUG-F2: no silent .catch(() => {}) in frontend source
43 regression tests total, all passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/engine/regression.test.ts

@@ -4,6 +4,8 @@
  * BUG-1 through BUG-12, BUG-S1 through BUG-S10, BUG-F1 through BUG-F14.
  */
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
+import fs from 'node:fs'
+import path from 'node:path'
 
 // --- Pure function imports (no DB mocking needed) ---
 import { scoreRound, calculateElo, calculateTier } from './scoring.js'
@@ -349,3 +351,96 @@ describe('regression tests — events cleanup', () => {
     unsub()
   })
 })
+
+/** Recursively collect .ts and .vue files from a directory */
+function walkTs(dir: string): string[] {
+  const results: string[] = []
+  if (!fs.existsSync(dir)) return results
+  for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+    const full = path.join(dir, entry.name)
+    if (entry.isDirectory()) {
+      if (entry.name === 'node_modules' || entry.name === 'dist') continue
+      results.push(...walkTs(full))
+    } else if (/\.(ts|vue)$/.test(entry.name)) {
+      results.push(full)
+    }
+  }
+  return results
+}
+
+describe('regression tests — source pattern checks', () => {
+  // BUG-6: Webhook calls must be parallel (Promise.all), not sequential
+  it('BUG-6: bot webhook calls are wrapped in Promise.all', () => {
+    const src = fs.readFileSync(
+      path.resolve(__dirname, 'orchestrator.ts'),
+      'utf-8',
+    )
+    // getBotResponse calls must be inside Promise.all
+    expect(src).toMatch(/Promise\.all\(\[\s*\n?\s*getBotResponse\(/)
+    // trackWebhookResult calls also parallel
+    expect(src).toMatch(/Promise\.all\(\[\s*\n?\s*trackWebhookResult\(/)
+  })
+
+  // BUG-7: SSE maps cleaned on fight end
+  it('BUG-7: SSE maps are cleaned up when spectator disconnects', () => {
+    const src = fs.readFileSync(
+      path.resolve(__dirname, '../routes/fights.ts'),
+      'utf-8',
+    )
+    expect(src).toContain('spectatorCounts.delete(fightId)')
+    expect(src).toContain('fightReactions.delete(fightId)')
+    expect(src).toContain('ssePerIp.delete(clientIp)')
+  })
+
+  // BUG-4: no raw setTimeout in frontend game code (must use trackedTimeout)
+  it('BUG-4: no raw setTimeout in frontend game code', () => {
+    const gameDir = path.resolve(__dirname, '../../../frontend/src/game')
+    const files = walkTs(gameDir)
+    const violations: string[] = []
+
+    for (const file of files) {
+      // Skip test files, TTS (Web Worker), and audio infrastructure (has own tracking)
+      if (file.includes('.test.') || file.includes('.spec.') || file.endsWith('tts.ts') || file.endsWith('tts-worker.ts') || file.includes('/audio/')) continue
+      const src = fs.readFileSync(file, 'utf-8')
+      const lines = src.split('\n')
+      for (let i = 0; i < lines.length; i++) {
+        const line = lines[i]
+        // Allow: trackedTimeout implementations (which wrap raw setTimeout),
+        // sprite load timeout promises, and audio timer implementations
+        if (
+          /(?<!\w)setTimeout\(/.test(line) &&
+          !line.trim().startsWith('//') &&
+          !line.trim().startsWith('*') &&
+          !line.includes('cleanupTimers.delete') && // trackedTimeout impl
+          !line.includes('_audioTimers.delete') && // audio tracked timer impl
+          !line.includes('SPRITE_LOAD_TIMEOUT_MS') // sprite loading timeout
+        ) {
+          violations.push(`${path.relative(gameDir, file)}:${i + 1}: ${line.trim()}`)
+        }
+      }
+    }
+
+    expect(violations).toEqual([])
+  })
+
+  // BUG-F2: no silent .catch(() => {}) swallowing errors
+  it('BUG-F2: no silent .catch(() => {}) in frontend source', () => {
+    const srcDir = path.resolve(__dirname, '../../../frontend/src')
+    const files = walkTs(srcDir)
+    const violations: string[] = []
+
+    for (const file of files) {
+      if (file.includes('.test.') || file.includes('.spec.') || file.includes('node_modules')) continue
+      const src = fs.readFileSync(file, 'utf-8')
+      const lines = src.split('\n')
+      for (let i = 0; i < lines.length; i++) {
+        const line = lines[i]
+        if (/\.catch\(\(\)\s*=>\s*\{\s*\}\)/.test(line)) {
+          violations.push(`${path.relative(srcDir, file)}:${i + 1}: ${line.trim()}`)
+        }
+      }
+    }
+
+    expect(violations).toEqual([])
+  })
+})