diff --git a/src/mux-interface.ts b/src/mux-interface.ts
index 6007e472..cc3d5e60 100644
--- a/src/mux-interface.ts
+++ b/src/mux-interface.ts
@@ -61,6 +61,8 @@ export interface CreateSessionOptions {
   claudeMode?: ClaudeMode;
   allowedTools?: string;
   openCodeConfig?: OpenCodeConfig;
+  /** When restoring after reboot, resume a previous Claude conversation by its session ID */
+  resumeSessionId?: string;
 }
 
 /** Options for respawning a dead pane. */
diff --git a/src/session.ts b/src/session.ts
index 210f3eb4..8e6051ab 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -324,6 +324,7 @@ export class Session extends EventEmitter {
 
   // OpenCode configuration (only for mode === 'opencode')
   private _openCodeConfig: OpenCodeConfig | undefined;
+  private _resumeSessionId: string | undefined;
 
   // Session color for visual differentiation
   private _color: import('./types.js').SessionColor = 'default';
@@ -382,6 +383,8 @@ export class Session extends EventEmitter {
       allowedTools?: string;
       /** OpenCode configuration (only for mode === 'opencode') */
       openCodeConfig?: OpenCodeConfig;
+      /** Resume a previous Claude conversation (used after server reboot) */
+      resumeSessionId?: string;
     }
   ) {
     super();
@@ -398,12 +401,10 @@ export class Session extends EventEmitter {
     this.createdAt = config.createdAt || Date.now();
     this.mode = config.mode || 'claude';
     this._name = config.name || '';
+    this._resumeSessionId = config.resumeSessionId;
     this._lastActivityAt = this.createdAt;
-    // Set claudeSessionId immediately — Codeman always passes --session-id ${this.id}
-    // to Claude CLI, so the Claude session ID always matches the Codeman session ID.
-    // This ensures subagent matching works even for recovered sessions (where
-    // startInteractive() hasn't been called yet).
-    this._claudeSessionId = this.id;
+    // Set claudeSessionId — when resuming, the Claude conversation ID is the resumed one.
+    this._claudeSessionId = config.resumeSessionId || this.id;
     this._mux = config.mux || null;
     this._useMux = config.useMux ?? (this._mux !== null && this._mux.isAvailable());
     this._muxSession = config.muxSession || null;
@@ -792,6 +793,7 @@ export class Session extends EventEmitter {
       cliAccountType: this._cliAccountType || undefined,
       cliLatestVersion: this._cliLatestVersion || undefined,
       openCodeConfig: this._openCodeConfig,
+      resumeSessionId: this._resumeSessionId,
     };
   }
 
@@ -936,6 +938,7 @@ export class Session extends EventEmitter {
             claudeMode: this._claudeMode,
             allowedTools: this._allowedTools,
             openCodeConfig: this._openCodeConfig,
+            resumeSessionId: this._resumeSessionId,
           });
           console.log('[Session] Created mux session:', this._muxSession.muxName);
           // No extra sleep — createSession() already waits for tmux readiness
diff --git a/src/tmux-manager.ts b/src/tmux-manager.ts
index 1551649a..9dff494f 100644
--- a/src/tmux-manager.ts
+++ b/src/tmux-manager.ts
@@ -200,12 +200,17 @@ function buildSpawnCommand(options: {
   claudeMode?: ClaudeMode;
   allowedTools?: string;
   openCodeConfig?: OpenCodeConfig;
+  resumeSessionId?: string;
 }): string {
   if (options.mode === 'claude') {
     // Validate model to prevent command injection
     const safeModel = options.model && /^[a-zA-Z0-9._-]+$/.test(options.model) ? options.model : undefined;
     const modelFlag = safeModel ? ` --model ${safeModel}` : '';
-    return `claude${buildClaudePermissionFlags(options.claudeMode, options.allowedTools)} --session-id "${options.sessionId}"${modelFlag}`;
+    // Use --resume to restore a previous conversation, otherwise --session-id for new sessions
+    const safeResumeId =
+      options.resumeSessionId && /^[a-f0-9-]+$/.test(options.resumeSessionId) ? options.resumeSessionId : undefined;
+    const sessionFlag = safeResumeId ? ` --resume "${safeResumeId}"` : ` --session-id "${options.sessionId}"`;
+    return `claude${buildClaudePermissionFlags(options.claudeMode, options.allowedTools)}${sessionFlag}${modelFlag}`;
   }
   if (options.mode === 'opencode') {
     return buildOpenCodeCommand(options.openCodeConfig);
@@ -370,7 +375,18 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
    * In test mode: creates an in-memory session only (no real tmux session).
    */
   async createSession(options: CreateSessionOptions): Promise<MuxSession> {
-    const { sessionId, workingDir, mode, name, niceConfig, model, claudeMode, allowedTools, openCodeConfig } = options;
+    const {
+      sessionId,
+      workingDir,
+      mode,
+      name,
+      niceConfig,
+      model,
+      claudeMode,
+      allowedTools,
+      openCodeConfig,
+      resumeSessionId,
+    } = options;
     const muxName = `codeman-${sessionId.slice(0, 8)}`;
 
     if (!isValidMuxName(muxName)) {
@@ -433,6 +449,7 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
       claudeMode,
       allowedTools,
       openCodeConfig,
+      resumeSessionId,
     });
 
     const config = niceConfig || DEFAULT_NICE_CONFIG;
diff --git a/src/types/session.ts b/src/types/session.ts
index 69728070..01cf3584 100644
--- a/src/types/session.ts
+++ b/src/types/session.ts
@@ -143,6 +143,8 @@ export interface SessionState {
   cliLatestVersion?: string;
   /** OpenCode-specific configuration (only for mode === 'opencode') */
   openCodeConfig?: OpenCodeConfig;
+  /** Claude conversation session ID to resume after reboot (set by restore script) */
+  resumeSessionId?: string;
 }
 
 /**
diff --git a/src/web/schemas.ts b/src/web/schemas.ts
index 0cd8e588..6922dc15 100644
--- a/src/web/schemas.ts
+++ b/src/web/schemas.ts
@@ -125,6 +125,12 @@ export const CreateSessionSchema = z.object({
   name: z.string().max(100).optional(),
   envOverrides: safeEnvOverridesSchema,
   openCodeConfig: OpenCodeConfigSchema,
+  /** Resume a previous Claude conversation by its session ID (used for reboot recovery) */
+  resumeSessionId: z
+    .string()
+    .max(100)
+    .regex(/^[a-f0-9-]+$/, 'resumeSessionId must be a valid UUID')
+    .optional(),
 });
 
 /**