refactor: split god files into focused modules (phase 4, steps 2-4)

Split 3 large files into 11 focused sub-modules via composition:

ralph-tracker.ts (3,868 → ~2,400 LOC):
- ralph-plan-tracker.ts: plan task tracking, checkpoints, history
- ralph-fix-plan-watcher.ts: @fix_plan.md file watching
- ralph-stall-detector.ts: iteration stall detection
- ralph-status-parser.ts: RALPH_STATUS block parsing, circuit breaker

respawn-controller.ts (3,611 → ~3,200 LOC):
- respawn-patterns.ts: pure pattern detection functions
- respawn-adaptive-timing.ts: adaptive timing with percentile calc
- respawn-metrics.ts: cycle metrics tracking + aggregation
- respawn-health.ts: pure health scoring functions

session.ts (2,418 → ~1,800 LOC):
- session-cli-builder.ts: CLI argument construction
- session-auto-ops.ts: auto-compact/clear automation
- session-task-cache.ts: task description LRU cache

All external APIs preserved via delegation. Events forwarded
through parent classes. Zero behavioral changes — all 436 tests pass.

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

src/respawn-patterns.ts

@@ -0,0 +1,131 @@
+/**
+ * @fileoverview Pure utility functions for terminal pattern detection in respawn controller.
+ *
+ * Extracted from respawn-controller.ts for modularity. These are stateless functions
+ * and constants used to detect completion messages, working patterns, and token counts
+ * in terminal output.
+ *
+ * @module respawn-patterns
+ */
+
+import { TOKEN_PATTERN } from './utils/index.js';
+
+// ========== Constants ==========
+
+/**
+ * Pattern to detect completion messages from Claude Code.
+ * Requires "Worked for" prefix to avoid false positives from bare time durations
+ * in regular text (e.g., "wait for 5s", "run for 2m").
+ *
+ * Matches: "Worked for 2m 46s", "Worked for 46s", "Worked for 1h 2m 3s"
+ * Does NOT match: "wait for 5s", "run for 2m", "for 3s the system..."
+ */
+const COMPLETION_TIME_PATTERN = /\bWorked\s+for\s+\d+[hms](\s*\d+[hms])*/i;
+
+/**
+ * Patterns indicating Claude is ready for input (legacy fallback).
+ * Used as secondary signals, not primary detection.
+ */
+export const PROMPT_PATTERNS = [
+  '❯', // Standard prompt
+  '\u276f', // Unicode variant
+  '⏵', // Claude Code prompt variant
+];
+
+/**
+ * Patterns indicating Claude is actively working.
+ * When detected, resets all idle detection timers.
+ * Note: ✻ and ✽ removed - they appear in completion messages too.
+ */
+export const WORKING_PATTERNS = [
+  'Thinking',
+  'Writing',
+  'Reading',
+  'Running',
+  'Searching',
+  'Editing',
+  'Creating',
+  'Deleting',
+  'Analyzing',
+  'Executing',
+  'Synthesizing',
+  'Brewing', // Claude's processing indicators
+  'Compiling',
+  'Building',
+  'Installing',
+  'Fetching',
+  'Downloading',
+  'Processing',
+  'Generating',
+  'Loading',
+  'Starting',
+  'Updating',
+  'Checking',
+  'Validating',
+  'Testing',
+  'Formatting',
+  'Linting',
+  '⠋',
+  '⠙',
+  '⠹',
+  '⠸',
+  '⠼',
+  '⠴',
+  '⠦',
+  '⠧',
+  '⠇',
+  '⠏', // Spinner chars
+  '◐',
+  '◓',
+  '◑',
+  '◒', // Alternative spinners
+  '⣾',
+  '⣽',
+  '⣻',
+  '⢿',
+  '⡿',
+  '⣟',
+  '⣯',
+  '⣷', // Braille spinners
+];
+
+/**
+ * Check if data contains a completion message pattern.
+ * Matches "Worked for Xh Xm Xs" time duration patterns.
+ *
+ * @param data - Raw terminal output data
+ * @returns True if completion message pattern is found
+ */
+export function isCompletionMessage(data: string): boolean {
+  return COMPLETION_TIME_PATTERN.test(data);
+}
+
+/**
+ * Check if a rolling window of terminal output contains working patterns.
+ * The rolling window catches patterns split across chunks (e.g., "Thin" + "king").
+ *
+ * @param window - Rolling window of recent terminal output (already includes current data)
+ * @returns True if any working pattern is found in the window
+ */
+export function hasWorkingPattern(window: string): boolean {
+  return WORKING_PATTERNS.some((pattern) => window.includes(pattern));
+}
+
+/**
+ * Extract token count from data if present.
+ * Parses patterns like "123.4k tokens" or "1.5M tokens".
+ *
+ * @param data - Raw terminal output data
+ * @returns Parsed token count, or null if no token pattern found
+ */
+export function extractTokenCount(data: string): number | null {
+  const match = data.match(TOKEN_PATTERN);
+  if (!match) return null;
+
+  let count = parseFloat(match[1]);
+  const suffix = match[2]?.toLowerCase();
+  if (suffix === 'k') count *= 1000;
+  else if (suffix === 'm') count *= 1000000;
+
+  return Math.round(count);
+}