feat: add resource management types and utilities for memory optimization

- Add Disposable, BufferConfig, MemoryMetrics, CleanupRegistration types
- Create src/config/buffer-limits.ts with consolidated buffer size constants
- Create src/config/map-limits.ts with Map size limits to prevent unbounded growth
- Implement BufferAccumulator utility with configurable trim and onTrim callback
- Implement LRUMap with automatic eviction and O(1) operations
- Implement CleanupManager for unified resource cleanup with isStopped guard
- Add comprehensive tests for all new utilities

This lays the foundation for memory leak prevention and performance improvements.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/config/buffer-limits.ts

@@ -0,0 +1,110 @@
+/**
+ * @fileoverview Centralized buffer size limits for memory management.
+ *
+ * These constants define the maximum sizes for various buffers throughout
+ * Claudeman. Consolidating them here ensures consistent limits and makes
+ * it easy to tune memory usage.
+ *
+ * Memory Budget Rationale (for 20 concurrent sessions):
+ * - Terminal buffer: 2MB max × 20 = 40MB worst case
+ * - Text output: 1MB max × 20 = 20MB worst case
+ * - Messages: ~1KB each × 1000 × 20 = 20MB worst case
+ * - Total buffer overhead: ~80MB (acceptable for long-running server)
+ *
+ * @module config/buffer-limits
+ */
+
+// ============================================================================
+// Terminal Buffer Limits
+// ============================================================================
+
+/**
+ * Maximum terminal buffer size in characters.
+ * Contains raw terminal output with ANSI escape sequences.
+ * Reduced from 5MB to 2MB for better render performance.
+ */
+export const MAX_TERMINAL_BUFFER_SIZE = 2 * 1024 * 1024; // 2MB
+
+/**
+ * Size to trim terminal buffer to when max is exceeded.
+ * Keeps the most recent portion to preserve context.
+ */
+export const TRIM_TERMINAL_TO = 1.5 * 1024 * 1024; // 1.5MB
+
+// ============================================================================
+// Text Output Buffer Limits
+// ============================================================================
+
+/**
+ * Maximum text output buffer size in characters.
+ * Contains ANSI-stripped text for search and analysis.
+ */
+export const MAX_TEXT_OUTPUT_SIZE = 1 * 1024 * 1024; // 1MB
+
+/**
+ * Size to trim text output buffer to when max is exceeded.
+ */
+export const TRIM_TEXT_TO = 768 * 1024; // 768KB
+
+// ============================================================================
+// Message Buffer Limits
+// ============================================================================
+
+/**
+ * Maximum number of Claude JSON messages to keep in memory per session.
+ * Older messages are discarded when limit is exceeded.
+ */
+export const MAX_MESSAGES = 1000;
+
+/**
+ * Number of messages to keep when trimming (80% of max).
+ */
+export const TRIM_MESSAGES_TO = 800;
+
+// ============================================================================
+// Line Buffer Limits
+// ============================================================================
+
+/**
+ * Maximum line buffer size in characters.
+ * Prevents unbounded growth for extremely long lines without newlines.
+ */
+export const MAX_LINE_BUFFER_SIZE = 64 * 1024; // 64KB
+
+// ============================================================================
+// Respawn Controller Buffer Limits
+// ============================================================================
+
+/**
+ * Maximum respawn controller buffer size.
+ * Smaller than session buffer since it's only used for idle detection.
+ */
+export const MAX_RESPAWN_BUFFER_SIZE = 1 * 1024 * 1024; // 1MB
+
+/**
+ * Size to trim respawn buffer to when max is exceeded.
+ */
+export const TRIM_RESPAWN_BUFFER_TO = 512 * 1024; // 512KB
+
+// ============================================================================
+// Run Summary Limits
+// ============================================================================
+
+/**
+ * Maximum number of events to keep in run summary.
+ */
+export const MAX_RUN_SUMMARY_EVENTS = 1000;
+
+/**
+ * Number of events to keep when trimming run summary.
+ */
+export const TRIM_RUN_SUMMARY_TO = 800;
+
+// ============================================================================
+// Spawn Message Limits
+// ============================================================================
+
+/**
+ * Maximum messages per spawn communication channel.
+ */
+export const MAX_MESSAGES_PER_CHANNEL = 100;

src/config/map-limits.ts

@@ -0,0 +1,137 @@
+/**
+ * @fileoverview Centralized Map size limits for memory management.
+ *
+ * These constants define maximum sizes for Maps that track ephemeral data.
+ * Without limits, long-running sessions can accumulate unbounded entries
+ * leading to memory leaks.
+ *
+ * Memory Budget Rationale:
+ * - Assuming average entry size of ~1KB
+ * - MAX_TRACKED_AGENTS=500 × 1KB = ~500KB for agent tracking
+ * - Activity/results per agent × agents = bounded by these limits
+ * - Total Map overhead: <50MB even under heavy load
+ *
+ * @module config/map-limits
+ */
+
+// ============================================================================
+// Agent Tracking Limits
+// ============================================================================
+
+/**
+ * Maximum number of agents to track across all sessions.
+ * Oldest agents are evicted when limit is exceeded (LRU policy).
+ */
+export const MAX_TRACKED_AGENTS = 500;
+
+/**
+ * Maximum activity entries to keep per agent.
+ * Includes tool calls, status updates, progress reports.
+ */
+export const MAX_SUBAGENT_ACTIVITY_PER_AGENT = 100;
+
+/**
+ * Maximum tool results to keep per agent.
+ * Prevents memory growth from long-running agents with many tool calls.
+ */
+export const MAX_TOOL_RESULTS_PER_AGENT = 200;
+
+// ============================================================================
+// Hook Event Limits
+// ============================================================================
+
+/**
+ * Maximum pending hook events to queue.
+ * Prevents unbounded growth if hook processing is slow.
+ */
+export const MAX_PENDING_HOOKS = 50;
+
+// ============================================================================
+// Session Tracking Limits
+// ============================================================================
+
+/**
+ * Maximum concurrent sessions allowed.
+ * Each session consumes significant resources (PTY, buffers, watchers).
+ */
+export const MAX_CONCURRENT_SESSIONS = 50;
+
+/**
+ * Maximum session history entries to keep (for analytics).
+ */
+export const MAX_SESSION_HISTORY = 100;
+
+// ============================================================================
+// SSE Client Limits
+// ============================================================================
+
+/**
+ * Maximum SSE clients per session.
+ * Prevents resource exhaustion from many browser tabs.
+ */
+export const MAX_SSE_CLIENTS_PER_SESSION = 10;
+
+/**
+ * Maximum total SSE clients across all sessions.
+ */
+export const MAX_TOTAL_SSE_CLIENTS = 100;
+
+// ============================================================================
+// File Watcher Limits
+// ============================================================================
+
+/**
+ * Maximum file watchers (FSWatcher) to allow.
+ * Linux default max_user_watches is 8192-65536.
+ * We warn at 80% capacity and evict idle watchers.
+ */
+export const MAX_FILE_WATCHERS = 500;
+
+/**
+ * Warning threshold as percentage of max watchers.
+ */
+export const FILE_WATCHER_WARNING_THRESHOLD = 0.8;
+
+// ============================================================================
+// Task Tracking Limits
+// ============================================================================
+
+/**
+ * Maximum tasks to keep in the task queue.
+ */
+export const MAX_QUEUED_TASKS = 100;
+
+/**
+ * Maximum completed tasks to keep for history.
+ */
+export const MAX_COMPLETED_TASKS_HISTORY = 50;
+
+// ============================================================================
+// Todo Item Limits (Ralph Tracker)
+// ============================================================================
+
+/**
+ * Maximum todo items to track per session.
+ */
+export const MAX_TODOS_PER_SESSION = 500;
+
+/**
+ * TTL for completed todo items before cleanup (1 hour).
+ */
+export const COMPLETED_TODO_TTL_MS = 60 * 60 * 1000;
+
+// ============================================================================
+// Pending Tool Calls Limits
+// ============================================================================
+
+/**
+ * Maximum pending tool calls to track per subagent.
+ * Entries should be cleaned up on tool_result, but this prevents leaks.
+ */
+export const MAX_PENDING_TOOL_CALLS = 100;
+
+/**
+ * TTL for orphaned pending tool calls (5 minutes).
+ * If no tool_result received, entry is cleaned up.
+ */
+export const PENDING_TOOL_CALL_TTL_MS = 5 * 60 * 1000;

src/types.ts

@@ -11,6 +11,77 @@
  * - Inner loop tracking (Ralph Wiggum detection)
  */
 
+// ========== Resource Management Types ==========
+
+/**
+ * Interface for objects that hold resources requiring explicit cleanup.
+ * Implementing classes should release timers, watchers, and other resources in dispose().
+ */
+export interface Disposable {
+  /** Release all held resources. Safe to call multiple times. */
+  dispose(): void;
+  /** Whether this object has been disposed */
+  readonly isDisposed: boolean;
+}
+
+/**
+ * Configuration for buffer accumulator instances.
+ * Used for terminal buffers, text output, and other size-limited string storage.
+ */
+export interface BufferConfig {
+  /** Maximum buffer size in bytes before trimming */
+  maxSize: number;
+  /** Size to trim to when maxSize is exceeded */
+  trimSize: number;
+  /** Optional callback invoked when buffer is trimmed */
+  onTrim?: (trimmedBytes: number) => void;
+}
+
+/**
+ * Memory metrics for monitoring and debugging.
+ * Extends Node.js process.memoryUsage() with application-specific tracking.
+ */
+export interface MemoryMetrics {
+  /** Heap memory used by V8 (bytes) */
+  heapUsed: number;
+  /** Total heap size allocated by V8 (bytes) */
+  heapTotal: number;
+  /** Memory used by C++ objects bound to JavaScript (bytes) */
+  external: number;
+  /** Memory used by ArrayBuffers and SharedArrayBuffers (bytes) */
+  arrayBuffers: number;
+  /** Sizes of tracked Maps by name */
+  mapSizes: Record<string, number>;
+  /** Number of active timers (setTimeout/setInterval) */
+  timerCount: number;
+  /** Number of active file system watchers */
+  watcherCount: number;
+  /** Timestamp when metrics were collected */
+  timestamp: number;
+}
+
+/**
+ * Resource types that can be registered for cleanup.
+ */
+export type CleanupResourceType = 'timer' | 'interval' | 'watcher' | 'listener' | 'stream';
+
+/**
+ * Registration entry for a cleanup resource.
+ * Used by CleanupManager to track and dispose resources.
+ */
+export interface CleanupRegistration {
+  /** Unique identifier for this registration */
+  id: string;
+  /** Type of resource */
+  type: CleanupResourceType;
+  /** Human-readable description for debugging */
+  description: string;
+  /** Cleanup function to call on dispose */
+  cleanup: () => void;
+  /** Timestamp when registered */
+  registeredAt: number;
+}
+
 // ========== Core Status Types ==========
 
 /** Status of a Claude session */

src/utils/buffer-accumulator.ts

@@ -0,0 +1,190 @@
+/**
+ * @fileoverview High-performance buffer accumulator for string data.
+ *
+ * This utility reduces GC pressure by avoiding repeated string concatenation (`+=`).
+ * Instead, chunks are pushed to an array and joined only when needed.
+ * Automatically trims when size limits are exceeded.
+ *
+ * @module utils/buffer-accumulator
+ */
+
+import type { BufferConfig } from '../types.js';
+
+/**
+ * High-performance buffer accumulator using array-based collection.
+ *
+ * Features:
+ * - Efficient append via array push (avoids O(n) string concat)
+ * - Lazy join on read (consolidates only when accessed)
+ * - Automatic trimming when max size exceeded
+ * - Optional callback on trim for logging/metrics
+ *
+ * @example
+ * ```typescript
+ * const buffer = new BufferAccumulator({
+ *   maxSize: 2 * 1024 * 1024,  // 2MB
+ *   trimSize: 1.5 * 1024 * 1024,  // Trim to 1.5MB
+ *   onTrim: (bytes) => console.log(`Trimmed ${bytes} bytes`)
+ * });
+ *
+ * buffer.append('chunk1');
+ * buffer.append('chunk2');
+ * console.log(buffer.value);  // Joins and returns full content
+ * ```
+ */
+export class BufferAccumulator {
+  private chunks: string[] = [];
+  private totalLength: number = 0;
+  private readonly maxSize: number;
+  private readonly trimSize: number;
+  private readonly onTrim?: (trimmedBytes: number) => void;
+
+  /**
+   * Creates a new BufferAccumulator.
+   *
+   * @param config - Buffer configuration with max/trim sizes
+   */
+  constructor(config: BufferConfig);
+  /**
+   * Creates a new BufferAccumulator with simple size parameters.
+   *
+   * @param maxSize - Maximum buffer size before trimming
+   * @param trimSize - Size to trim to when max is exceeded
+   */
+  constructor(maxSize: number, trimSize: number);
+  constructor(configOrMaxSize: BufferConfig | number, trimSize?: number) {
+    if (typeof configOrMaxSize === 'number') {
+      this.maxSize = configOrMaxSize;
+      this.trimSize = trimSize!;
+      this.onTrim = undefined;
+    } else {
+      this.maxSize = configOrMaxSize.maxSize;
+      this.trimSize = configOrMaxSize.trimSize;
+      this.onTrim = configOrMaxSize.onTrim;
+    }
+  }
+
+  /**
+   * Append data to the buffer.
+   * Automatically trims if maxSize is exceeded.
+   *
+   * @param data - String data to append
+   */
+  append(data: string): void {
+    if (!data) return;
+    this.chunks.push(data);
+    this.totalLength += data.length;
+
+    // Trim if exceeded max size
+    if (this.totalLength > this.maxSize) {
+      this.trim();
+    }
+  }
+
+  /**
+   * Get the full buffer content.
+   * Consolidates chunks on access for efficient subsequent reads.
+   */
+  get value(): string {
+    if (this.chunks.length === 0) return '';
+    if (this.chunks.length === 1) return this.chunks[0];
+
+    // Consolidate chunks on access
+    const result = this.chunks.join('');
+    this.chunks = [result];
+    return result;
+  }
+
+  /**
+   * Get current buffer length without joining chunks.
+   */
+  get length(): number {
+    return this.totalLength;
+  }
+
+  /**
+   * Check if buffer is empty.
+   */
+  get isEmpty(): boolean {
+    return this.totalLength === 0;
+  }
+
+  /**
+   * Clear the buffer completely.
+   */
+  clear(): void {
+    this.chunks = [];
+    this.totalLength = 0;
+  }
+
+  /**
+   * Set buffer to a specific value, replacing all content.
+   *
+   * @param value - New buffer content
+   */
+  set(value: string): void {
+    this.chunks = value ? [value] : [];
+    this.totalLength = value?.length || 0;
+  }
+
+  /**
+   * Get the last N characters from the buffer.
+   * Useful for checking recent content without reading the entire buffer.
+   *
+   * @param n - Number of characters to get from the end
+   * @returns The last N characters (or entire buffer if smaller)
+   */
+  tail(n: number): string {
+    if (n >= this.totalLength) {
+      return this.value;
+    }
+    const full = this.value;
+    return full.slice(-n);
+  }
+
+  /**
+   * Check if buffer ends with a specific string.
+   *
+   * @param suffix - String to check for
+   * @returns True if buffer ends with the suffix
+   */
+  endsWith(suffix: string): boolean {
+    if (!suffix) return true;  // All strings end with empty string
+    if (suffix.length > this.totalLength) return false;
+    return this.tail(suffix.length) === suffix;
+  }
+
+  /**
+   * Search for a pattern in the buffer (from the end).
+   *
+   * @param pattern - String or RegExp to search for
+   * @param fromEnd - Number of characters from end to search within (default: entire buffer)
+   * @returns True if pattern is found
+   */
+  contains(pattern: string | RegExp, fromEnd?: number): boolean {
+    const searchIn = fromEnd ? this.tail(fromEnd) : this.value;
+    if (typeof pattern === 'string') {
+      return searchIn.includes(pattern);
+    }
+    return pattern.test(searchIn);
+  }
+
+  /**
+   * Trim buffer to keep only the most recent data.
+   * Called automatically when maxSize is exceeded.
+   */
+  private trim(): void {
+    const full = this.chunks.join('');
+    const trimmedBytes = full.length - this.trimSize;
+    const trimmed = full.slice(-this.trimSize);
+    this.chunks = [trimmed];
+    this.totalLength = trimmed.length;
+
+    // Notify callback if configured
+    if (this.onTrim && trimmedBytes > 0) {
+      this.onTrim(trimmedBytes);
+    }
+  }
+}
+
+export default BufferAccumulator;

src/utils/cleanup-manager.ts

@@ -0,0 +1,330 @@
+/**
+ * @fileoverview Centralized resource cleanup manager.
+ *
+ * Tracks timers, intervals, watchers, and other resources that need explicit
+ * cleanup. Provides a unified dispose() method that safely cleans up all
+ * registered resources, even on partial failures.
+ *
+ * @module utils/cleanup-manager
+ */
+
+import { v4 as uuidv4 } from 'uuid';
+import type { Disposable, CleanupRegistration, CleanupResourceType } from '../types.js';
+
+/**
+ * Options for setTimeout/setInterval with automatic cleanup.
+ */
+export interface TimerOptions {
+  /** Human-readable description for debugging */
+  description?: string;
+}
+
+/**
+ * Centralized manager for tracking and disposing resources.
+ *
+ * Implements the Disposable interface for hierarchical cleanup.
+ * All registered resources are cleaned up when dispose() is called.
+ *
+ * Features:
+ * - Tracks timers, intervals, watchers, and custom cleanup functions
+ * - isStopped guard to prevent callbacks firing after disposal
+ * - Safe disposal that continues even if individual cleanups fail
+ * - Debug logging for resource tracking
+ *
+ * @example
+ * ```typescript
+ * class MyService implements Disposable {
+ *   private cleanup = new CleanupManager();
+ *
+ *   start() {
+ *     // Timer automatically cleared on dispose
+ *     this.cleanup.setTimeout(() => {
+ *       if (this.cleanup.isStopped) return;  // Guard
+ *       this.doWork();
+ *     }, 5000, { description: 'work timer' });
+ *   }
+ *
+ *   dispose() {
+ *     this.cleanup.dispose();
+ *   }
+ *
+ *   get isDisposed() { return this.cleanup.isDisposed; }
+ * }
+ * ```
+ */
+export class CleanupManager implements Disposable {
+  private registrations = new Map<string, CleanupRegistration>();
+  private _isDisposed = false;
+  private readonly debugMode: boolean;
+
+  /**
+   * Creates a new CleanupManager.
+   *
+   * @param debug - Enable debug logging for resource tracking
+   */
+  constructor(debug = false) {
+    this.debugMode = debug;
+  }
+
+  /**
+   * Whether this manager has been disposed.
+   * Check this before executing callbacks to prevent zombie operations.
+   */
+  get isDisposed(): boolean {
+    return this._isDisposed;
+  }
+
+  /**
+   * Alias for isDisposed - check before executing async callbacks.
+   */
+  get isStopped(): boolean {
+    return this._isDisposed;
+  }
+
+  /**
+   * Number of currently registered resources.
+   */
+  get resourceCount(): number {
+    return this.registrations.size;
+  }
+
+  /**
+   * Get counts by resource type for metrics/debugging.
+   */
+  get resourceCounts(): Record<CleanupResourceType, number> {
+    const counts: Record<CleanupResourceType, number> = {
+      timer: 0,
+      interval: 0,
+      watcher: 0,
+      listener: 0,
+      stream: 0,
+    };
+
+    for (const reg of this.registrations.values()) {
+      counts[reg.type]++;
+    }
+
+    return counts;
+  }
+
+  /**
+   * Schedule a timeout that will be automatically cleared on dispose.
+   *
+   * @param callback - Function to call when timeout fires
+   * @param delay - Delay in milliseconds
+   * @param options - Optional configuration
+   * @returns Timer ID for manual clearing if needed
+   */
+  setTimeout(
+    callback: () => void,
+    delay: number,
+    options?: TimerOptions
+  ): string {
+    const id = uuidv4();
+    const timeoutId = setTimeout(() => {
+      // Remove registration when timer fires naturally
+      this.registrations.delete(id);
+      // Don't execute if already stopped
+      if (this._isDisposed) return;
+      callback();
+    }, delay);
+
+    this.register({
+      id,
+      type: 'timer',
+      description: options?.description || `setTimeout(${delay}ms)`,
+      cleanup: () => clearTimeout(timeoutId),
+      registeredAt: Date.now(),
+    });
+
+    return id;
+  }
+
+  /**
+   * Schedule an interval that will be automatically cleared on dispose.
+   *
+   * @param callback - Function to call on each interval
+   * @param delay - Interval in milliseconds
+   * @param options - Optional configuration
+   * @returns Interval ID for manual clearing if needed
+   */
+  setInterval(
+    callback: () => void,
+    delay: number,
+    options?: TimerOptions
+  ): string {
+    const id = uuidv4();
+    const intervalId = setInterval(() => {
+      // Don't execute if stopped
+      if (this._isDisposed) return;
+      callback();
+    }, delay);
+
+    this.register({
+      id,
+      type: 'interval',
+      description: options?.description || `setInterval(${delay}ms)`,
+      cleanup: () => clearInterval(intervalId),
+      registeredAt: Date.now(),
+    });
+
+    return id;
+  }
+
+  /**
+   * Register a custom cleanup function.
+   *
+   * @param type - Type of resource for categorization
+   * @param cleanup - Function to call on dispose
+   * @param description - Human-readable description
+   * @returns Registration ID for manual removal if needed
+   */
+  registerCleanup(
+    type: CleanupResourceType,
+    cleanup: () => void,
+    description: string
+  ): string {
+    const id = uuidv4();
+    this.register({
+      id,
+      type,
+      description,
+      cleanup,
+      registeredAt: Date.now(),
+    });
+    return id;
+  }
+
+  /**
+   * Register a file system watcher for cleanup.
+   *
+   * @param watcher - Object with close() method (FSWatcher, chokidar, etc.)
+   * @param description - Human-readable description
+   * @returns Registration ID
+   */
+  registerWatcher(
+    watcher: { close: () => void },
+    description: string
+  ): string {
+    return this.registerCleanup('watcher', () => watcher.close(), description);
+  }
+
+  /**
+   * Register an event listener for cleanup.
+   *
+   * @param emitter - Object with removeListener/off method
+   * @param event - Event name
+   * @param listener - Listener function
+   * @param description - Human-readable description
+   * @returns Registration ID
+   */
+  registerListener<T extends { removeListener?: (event: string, listener: () => void) => void; off?: (event: string, listener: () => void) => void }>(
+    emitter: T,
+    event: string,
+    listener: () => void,
+    description: string
+  ): string {
+    return this.registerCleanup('listener', () => {
+      if (emitter.removeListener) {
+        emitter.removeListener(event, listener);
+      } else if (emitter.off) {
+        emitter.off(event, listener);
+      }
+    }, description);
+  }
+
+  /**
+   * Register a stream for cleanup.
+   *
+   * @param stream - Object with destroy() or close() method
+   * @param description - Human-readable description
+   * @returns Registration ID
+   */
+  registerStream(
+    stream: { destroy?: () => void; close?: () => void },
+    description: string
+  ): string {
+    return this.registerCleanup('stream', () => {
+      if (stream.destroy) {
+        stream.destroy();
+      } else if (stream.close) {
+        stream.close();
+      }
+    }, description);
+  }
+
+  /**
+   * Manually remove a registered resource.
+   *
+   * @param id - Registration ID returned from register methods
+   * @returns True if resource was found and removed
+   */
+  unregister(id: string): boolean {
+    const reg = this.registrations.get(id);
+    if (!reg) return false;
+
+    try {
+      reg.cleanup();
+    } catch (err) {
+      this.debug(`Error cleaning up ${reg.type} "${reg.description}": ${err}`);
+    }
+
+    this.registrations.delete(id);
+    return true;
+  }
+
+  /**
+   * Dispose all registered resources.
+   * Safe to call multiple times (idempotent).
+   * Continues cleanup even if individual resources fail.
+   */
+  dispose(): void {
+    if (this._isDisposed) return;
+    this._isDisposed = true;
+
+    const errors: Array<{ description: string; error: unknown }> = [];
+
+    for (const reg of this.registrations.values()) {
+      try {
+        reg.cleanup();
+        this.debug(`Cleaned up ${reg.type}: ${reg.description}`);
+      } catch (err) {
+        errors.push({ description: reg.description, error: err });
+        this.debug(`Error cleaning up ${reg.type} "${reg.description}": ${err}`);
+      }
+    }
+
+    this.registrations.clear();
+
+    if (errors.length > 0) {
+      console.error(`[CleanupManager] ${errors.length} errors during disposal:`,
+        errors.map(e => e.description).join(', '));
+    }
+  }
+
+  /**
+   * Get all current registrations for debugging.
+   */
+  getRegistrations(): CleanupRegistration[] {
+    return Array.from(this.registrations.values());
+  }
+
+  /**
+   * Internal: Register a cleanup entry.
+   */
+  private register(reg: CleanupRegistration): void {
+    this.registrations.set(reg.id, reg);
+    this.debug(`Registered ${reg.type}: ${reg.description}`);
+  }
+
+  /**
+   * Internal: Debug logging.
+   */
+  private debug(message: string): void {
+    if (this.debugMode) {
+      console.log(`[CleanupManager] ${message}`);
+    }
+  }
+}
+
+export default CleanupManager;

src/utils/index.ts

@@ -0,0 +1,11 @@
+/**
+ * @fileoverview Utility module exports.
+ *
+ * This module re-exports all utility classes and functions for easy import.
+ *
+ * @module utils
+ */
+
+export { BufferAccumulator } from './buffer-accumulator.js';
+export { LRUMap, type LRUMapOptions } from './lru-map.js';
+export { CleanupManager, type TimerOptions } from './cleanup-manager.js';

src/utils/lru-map.ts

@@ -0,0 +1,214 @@
+/**
+ * @fileoverview LRU (Least Recently Used) Map implementation.
+ *
+ * Extends the built-in Map with automatic eviction when a maximum size is
+ * exceeded. Uses Map's insertion-order iteration for O(1) LRU eviction.
+ *
+ * @module utils/lru-map
+ */
+
+/**
+ * Configuration options for LRUMap.
+ */
+export interface LRUMapOptions<K, V> {
+  /** Maximum number of entries before eviction */
+  maxSize: number;
+  /** Optional callback when an entry is evicted */
+  onEvict?: (key: K, value: V) => void;
+}
+
+/**
+ * A Map with automatic LRU (Least Recently Used) eviction.
+ *
+ * When the map exceeds maxSize, the oldest entries are evicted.
+ * Access via get() refreshes an entry's position (moves to most recent).
+ *
+ * Uses JavaScript Map's insertion-order guarantee for efficient LRU behavior.
+ * All operations are O(1) amortized.
+ *
+ * @example
+ * ```typescript
+ * const cache = new LRUMap<string, number>({
+ *   maxSize: 100,
+ *   onEvict: (key, value) => console.log(`Evicted ${key}`)
+ * });
+ *
+ * cache.set('a', 1);
+ * cache.set('b', 2);
+ * cache.get('a');  // Refreshes 'a', making 'b' the oldest
+ * // When full, 'b' would be evicted first
+ * ```
+ */
+export class LRUMap<K, V> extends Map<K, V> {
+  private readonly maxSize: number;
+  private readonly onEvict?: (key: K, value: V) => void;
+
+  /**
+   * Creates a new LRUMap.
+   *
+   * @param options - Configuration options
+   */
+  constructor(options: LRUMapOptions<K, V>) {
+    super();
+    this.maxSize = options.maxSize;
+    this.onEvict = options.onEvict;
+  }
+
+  /**
+   * Set a key-value pair.
+   * If key exists, updates value and refreshes position.
+   * If adding new entry would exceed maxSize, evicts oldest entries.
+   *
+   * @param key - Key to set
+   * @param value - Value to associate
+   * @returns this (for chaining)
+   */
+  override set(key: K, value: V): this {
+    // If key exists, delete first to refresh position
+    if (super.has(key)) {
+      super.delete(key);
+    }
+
+    // Add the entry (will be at end = most recent)
+    super.set(key, value);
+
+    // Evict oldest entries if over capacity
+    while (super.size > this.maxSize) {
+      const oldestKey = super.keys().next().value;
+      if (oldestKey !== undefined) {
+        const oldestValue = super.get(oldestKey)!;
+        super.delete(oldestKey);
+        this.onEvict?.(oldestKey, oldestValue);
+      }
+    }
+
+    return this;
+  }
+
+  /**
+   * Get a value and refresh its position (mark as most recently used).
+   *
+   * @param key - Key to look up
+   * @returns Value if found, undefined otherwise
+   */
+  override get(key: K): V | undefined {
+    if (!super.has(key)) {
+      return undefined;
+    }
+
+    // Delete and re-insert to move to end (most recent)
+    const value = super.get(key)!;
+    super.delete(key);
+    super.set(key, value);
+    return value;
+  }
+
+  /**
+   * Check if a key exists WITHOUT refreshing its position.
+   * Use this when you want to check existence without affecting LRU order.
+   *
+   * @param key - Key to check
+   * @returns True if key exists
+   */
+  override has(key: K): boolean {
+    return super.has(key);
+  }
+
+  /**
+   * Peek at a value WITHOUT refreshing its position.
+   * Use this when you want to read without affecting LRU order.
+   *
+   * @param key - Key to peek
+   * @returns Value if found, undefined otherwise
+   */
+  peek(key: K): V | undefined {
+    return super.get(key);
+  }
+
+  /**
+   * Get the oldest entry (next to be evicted) without removing it.
+   *
+   * @returns [key, value] of oldest entry, or undefined if empty
+   */
+  oldest(): [K, V] | undefined {
+    const first = super.entries().next();
+    if (first.done) return undefined;
+    return first.value;
+  }
+
+  /**
+   * Get the newest entry (most recently accessed).
+   *
+   * @returns [key, value] of newest entry, or undefined if empty
+   */
+  newest(): [K, V] | undefined {
+    let last: [K, V] | undefined;
+    for (const entry of super.entries()) {
+      last = entry;
+    }
+    return last;
+  }
+
+  /**
+   * Evict entries older than a specific timestamp.
+   * Assumes values have a timestamp property or are numbers representing time.
+   *
+   * @param maxAge - Maximum age in milliseconds
+   * @param getTimestamp - Function to extract timestamp from value
+   * @returns Number of entries evicted
+   */
+  expireOlderThan(maxAge: number, getTimestamp: (value: V) => number): number {
+    const now = Date.now();
+    const cutoff = now - maxAge;
+    let evicted = 0;
+
+    // Iterate from oldest to newest
+    for (const [key, value] of super.entries()) {
+      if (getTimestamp(value) < cutoff) {
+        super.delete(key);
+        this.onEvict?.(key, value);
+        evicted++;
+      } else {
+        // Since entries are ordered, once we find a non-expired one,
+        // all subsequent entries are also non-expired
+        break;
+      }
+    }
+
+    return evicted;
+  }
+
+  /**
+   * Get all keys in order from oldest to newest.
+   *
+   * @returns Array of keys
+   */
+  keysInOrder(): K[] {
+    return Array.from(super.keys());
+  }
+
+  /**
+   * Get all values in order from oldest to newest.
+   *
+   * @returns Array of values
+   */
+  valuesInOrder(): V[] {
+    return Array.from(super.values());
+  }
+
+  /**
+   * Get the maximum size limit.
+   */
+  get maxEntries(): number {
+    return this.maxSize;
+  }
+
+  /**
+   * Get the number of free slots before eviction would occur.
+   */
+  get freeSlots(): number {
+    return Math.max(0, this.maxSize - super.size);
+  }
+}
+
+export default LRUMap;