diff --git a/src/session-manager.ts b/src/session-manager.ts
index 9e528729..48ef0cfd 100644
--- a/src/session-manager.ts
+++ b/src/session-manager.ts
@@ -1,20 +1,60 @@
+/**
+ * @fileoverview Session Manager for coordinating multiple Claude sessions
+ *
+ * Provides lifecycle management for Claude CLI sessions:
+ * - Session creation with working directory configuration
+ * - Event forwarding from individual sessions
+ * - State persistence via StateStore
+ * - Concurrent session limits
+ *
+ * @module session-manager
+ */
+
 import { EventEmitter } from 'node:events';
 import { Session } from './session.js';
 import { getStore } from './state-store.js';
 import { SessionState } from './types.js';
 
+/**
+ * Events emitted by SessionManager
+ */
 export interface SessionManagerEvents {
+  /** Fired when a new session starts successfully */
   sessionStarted: (session: Session) => void;
+  /** Fired when a session stops (graceful or forced) */
   sessionStopped: (sessionId: string) => void;
+  /** Fired when a session encounters an error */
   sessionError: (sessionId: string, error: string) => void;
+  /** Fired when a session produces terminal output */
   sessionOutput: (sessionId: string, output: string) => void;
+  /** Fired when a completion phrase is detected */
   sessionCompletion: (sessionId: string, phrase: string) => void;
 }
 
+/**
+ * Manages multiple Claude sessions with lifecycle coordination.
+ *
+ * @description
+ * SessionManager acts as a coordinator for multiple Claude CLI sessions:
+ * - Enforces concurrent session limits from config
+ * - Forwards session events to subscribers
+ * - Persists session state to disk
+ * - Handles graceful shutdown
+ *
+ * @extends EventEmitter
+ * @fires SessionManagerEvents.sessionStarted
+ * @fires SessionManagerEvents.sessionStopped
+ * @fires SessionManagerEvents.sessionError
+ * @fires SessionManagerEvents.sessionOutput
+ * @fires SessionManagerEvents.sessionCompletion
+ */
 export class SessionManager extends EventEmitter {
   private sessions: Map<string, Session> = new Map();
   private store = getStore();
 
+  /**
+   * Creates a new SessionManager and loads previous session state.
+   */
   constructor() {
     super();
     this.loadFromStore();
@@ -33,6 +73,13 @@ export class SessionManager extends EventEmitter {
     }
   }
 
+  /**
+   * Creates and starts a new Claude session.
+   *
+   * @param workingDir - Working directory for the session
+   * @returns The newly created session
+   * @throws Error if max concurrent sessions limit reached
+   */
   async createSession(workingDir: string): Promise<Session> {
     const config = this.store.getConfig();
 
@@ -71,6 +118,11 @@ export class SessionManager extends EventEmitter {
     return session;
   }
 
+  /**
+   * Stops a session by ID.
+   *
+   * @param id - Session ID to stop
+   */
   async stopSession(id: string): Promise<void> {
     const session = this.sessions.get(id);
     if (!session) {
@@ -89,6 +141,9 @@ export class SessionManager extends EventEmitter {
     this.updateSessionState(session);
   }
 
+  /**
+   * Stops all active sessions.
+   */
   async stopAllSessions(): Promise<void> {
     const stopPromises = Array.from(this.sessions.keys()).map((id) =>
       this.stopSession(id)
@@ -96,26 +151,36 @@ export class SessionManager extends EventEmitter {
     await Promise.all(stopPromises);
   }
 
+  /**
+   * Gets a session by ID.
+   * @param id - Session ID
+   * @returns The session or undefined if not found
+   */
   getSession(id: string): Session | undefined {
     return this.sessions.get(id);
   }
 
+  /** Gets all active sessions. */
   getAllSessions(): Session[] {
     return Array.from(this.sessions.values());
   }
 
+  /** Gets all sessions currently idle (not processing). */
   getIdleSessions(): Session[] {
     return this.getAllSessions().filter((s) => s.isIdle());
   }
 
+  /** Gets all sessions currently busy (processing). */
   getBusySessions(): Session[] {
     return this.getAllSessions().filter((s) => s.isBusy());
   }
 
+  /** Gets the count of active sessions. */
   getSessionCount(): number {
     return this.sessions.size;
   }
 
+  /** Checks if a session exists by ID. */
   hasSession(id: string): boolean {
     return this.sessions.has(id);
   }
@@ -124,10 +189,18 @@ export class SessionManager extends EventEmitter {
     this.store.setSession(session.id, session.toState());
   }
 
+  /** Gets all sessions from persistent storage (including stopped). */
   getStoredSessions(): Record<string, SessionState> {
     return this.store.getSessions();
   }
 
+  /**
+   * Sends input to a session.
+   *
+   * @param sessionId - Session ID to send to
+   * @param input - Input string to send
+   * @throws Error if session not found
+   */
   async sendToSession(sessionId: string, input: string): Promise<void> {
     const session = this.sessions.get(sessionId);
     if (!session) {
@@ -136,11 +209,13 @@ export class SessionManager extends EventEmitter {
     await session.sendInput(input);
   }
 
+  /** Gets the output buffer for a session. */
   getSessionOutput(sessionId: string): string | null {
     const session = this.sessions.get(sessionId);
     return session?.getOutput() ?? null;
   }
 
+  /** Gets the error buffer for a session. */
   getSessionError(sessionId: string): string | null {
     const session = this.sessions.get(sessionId);
     return session?.getError() ?? null;
@@ -150,6 +225,10 @@ export class SessionManager extends EventEmitter {
 // Singleton instance
 let managerInstance: SessionManager | null = null;
 
+/**
+ * Gets or creates the singleton SessionManager instance.
+ * @returns The global SessionManager
+ */
 export function getSessionManager(): SessionManager {
   if (!managerInstance) {
     managerInstance = new SessionManager();