refactor: codebase cleanup — dead code, regex helper, centralized constants, tests

- Remove unused validateTokenCounts/validateTokensAndCost exports and PlanPhase type alias
- Add execPattern() helper to eliminate 8 repetitive .lastIndex=0 + exec() loops
- Centralize 11 magic number constants into config/ai-defaults.ts and config/server-timing.ts
- Remove stale src/tui from tsconfig.json exclude
- Fix CLAUDE.md inaccuracies (session helpers, app.js line count, module count)
- Add 316 new tests: LRUMap (38), StaleExpirationMap (42), BufferAccumulator (33),
  respawn helpers (142), system-routes expansion (11→61)

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

src/config/ai-defaults.ts

@@ -1,13 +1,17 @@
 /**
- * @fileoverview Default model and context limits for AI-powered checkers.
+ * @fileoverview Default model, context limits, and timing for AI-powered checkers.
  *
- * Centralizes the AI model identifier and context window sizes used by
- * the idle checker, plan checker, respawn controller defaults, and
- * respawn route fallbacks. Change the model here when upgrading.
+ * Centralizes the AI model identifier, context window sizes, and timeout/cooldown
+ * defaults used by the idle checker, plan checker, respawn controller defaults,
+ * and respawn route fallbacks. Change values here when tuning AI check behavior.
  *
  * @module config/ai-defaults
  */
 
+// ============================================================================
+// Model & Context
+// ============================================================================
+
 /** Default model for AI idle and plan checkers */
 export const AI_CHECK_MODEL = 'claude-opus-4-5-20251101';
 
@@ -16,3 +20,39 @@ export const AI_IDLE_CHECK_MAX_CONTEXT = 16000;
 
 /** Max context chars for plan checker (~2k tokens, plan mode UI is compact) */
 export const AI_PLAN_CHECK_MAX_CONTEXT = 8000;
+
+// ============================================================================
+// AI Idle Checker Timing
+// ============================================================================
+
+/** Timeout for AI idle check (90 seconds — thinking can be slow) */
+export const AI_IDLE_CHECK_TIMEOUT_MS = 90_000;
+
+/** Cooldown after WORKING verdict (3 minutes) */
+export const AI_IDLE_CHECK_COOLDOWN_MS = 180_000;
+
+/** Cooldown after AI idle check error (1 minute) */
+export const AI_IDLE_CHECK_ERROR_COOLDOWN_MS = 60_000;
+
+// ============================================================================
+// AI Plan Checker Timing
+// ============================================================================
+
+/** Timeout for AI plan check (60 seconds — allows time for thinking) */
+export const AI_PLAN_CHECK_TIMEOUT_MS = 60_000;
+
+/** Cooldown after NOT_PLAN_MODE verdict (30 seconds) */
+export const AI_PLAN_CHECK_COOLDOWN_MS = 30_000;
+
+/** Cooldown after AI plan check error (30 seconds) */
+export const AI_PLAN_CHECK_ERROR_COOLDOWN_MS = 30_000;
+
+// ============================================================================
+// Shared AI Checker Limits
+// ============================================================================
+
+/** Max consecutive errors before disabling an AI checker */
+export const AI_CHECK_MAX_CONSECUTIVE_ERRORS = 3;
+
+/** Maximum exponential backoff cap for AI checker errors (5 minutes) */
+export const AI_CHECK_MAX_BACKOFF_MS = 5 * 60 * 1000;

src/config/server-timing.ts

@@ -73,3 +73,16 @@ export const MAX_CONSECUTIVE_ERRORS = 5;
 
 /** Error counter reset interval — forgives errors after quiet period (ms) */
 export const ERROR_RESET_MS = 60_000;
+
+// ============================================================================
+// Common Cleanup Intervals
+// ============================================================================
+
+/** Standard 1-minute cleanup/check interval used by multiple subsystems (ms) */
+export const CLEANUP_CHECK_INTERVAL_MS = 60_000;
+
+/** Standard 1-hour max age for stale/completed data (ms) */
+export const STALE_DATA_MAX_AGE_MS = 60 * 60 * 1000;
+
+/** Standard 5-minute inactivity timeout for streams and caches (ms) */
+export const INACTIVITY_TIMEOUT_MS = 5 * 60 * 1000;