🤖 fix: register background executors for existing workspaces after restart

- Add ensureExecutorRegistered() called from getOrCreateSession()
- Add Config.getWorkspaceMetadataSync() for sync metadata lookup
- Make registerExecutor() idempotent (no-op if already registered)

Without this fix, background execution tools failed for all pre-existing
workspaces after app restart with 'No executor registered' error.

Author: ethanndickson

src/node/config.ts

@@ -360,6 +360,33 @@ export class Config {
     return workspaceMetadata;
   }
 
+  /**
+   * Get workspace metadata by ID synchronously.
+   * Used for executor registration when creating sessions for existing workspaces.
+   * Only returns workspaces that have complete metadata in config (not legacy).
+   */
+  getWorkspaceMetadataSync(workspaceId: string): WorkspaceMetadata | null {
+    const config = this.loadConfigOrDefault();
+
+    for (const [projectPath, projectConfig] of config.projects) {
+      for (const workspace of projectConfig.workspaces) {
+        // Only check new format workspaces (have id and name in config)
+        if (workspace.id === workspaceId && workspace.name) {
+          return {
+            id: workspace.id,
+            name: workspace.name,
+            projectName: this.getProjectName(projectPath),
+            projectPath,
+            createdAt: workspace.createdAt,
+            runtimeConfig: workspace.runtimeConfig ?? DEFAULT_RUNTIME_CONFIG,
+          };
+        }
+      }
+    }
+
+    return null;
+  }
+
   /**
    * Add a workspace to config.json (single source of truth for workspace metadata).
    * Creates project entry if it doesn't exist.

src/node/services/backgroundProcessManager.ts

@@ -33,10 +33,14 @@ export class BackgroundProcessManager {
 
   /**
    * Register an executor for a workspace.
-   * Called when workspace is created - local workspaces get LocalBackgroundExecutor,
-   * SSH workspaces get SSHBackgroundExecutor.
+   * Called when workspace is created or session is started for existing workspace.
+   * Local workspaces get LocalBackgroundExecutor, SSH workspaces get SSHBackgroundExecutor.
+   * Idempotent - no-op if executor already registered.
    */
   registerExecutor(workspaceId: string, executor: BackgroundExecutor): void {
+    if (this.executors.has(workspaceId)) {
+      return; // Already registered
+    }
     log.debug(`BackgroundProcessManager.registerExecutor(${workspaceId})`);
     this.executors.set(workspaceId, executor);
   }
@@ -194,7 +198,7 @@ export class BackgroundProcessManager {
       proc.exitTime ??= Date.now();
       // Ensure handle is cleaned up even on error
       if (proc.handle) {
-        await proc.handle.dispose().catch(() => {});
+        await proc.handle.dispose();
       }
       return { success: true };
     }

src/node/services/ipcMain.ts

@@ -121,6 +121,25 @@ export class IpcMain {
     return new LocalBackgroundExecutor(this.bashExecutionService);
   }
 
+  /**
+   * Ensure a background executor is registered for a workspace.
+   * Called when creating sessions for existing workspaces (after app restart).
+   * No-op if executor already registered or workspace not found (new workspace being created).
+   */
+  private ensureExecutorRegistered(workspaceId: string): void {
+    // Look up workspace metadata synchronously from config
+    const metadata = this.config.getWorkspaceMetadataSync(workspaceId);
+    if (!metadata) {
+      // Workspace not in config yet - executor will be registered by creation path
+      return;
+    }
+
+    const runtime = createRuntime(metadata.runtimeConfig);
+    const executor = this.createBackgroundExecutor(metadata.runtimeConfig, runtime);
+    // registerExecutor is idempotent - no-op if already registered
+    this.backgroundProcessManager.registerExecutor(workspaceId, executor);
+  }
+
   /**
    * Initialize the service. Call this after construction.
    * This is separate from the constructor to support async initialization.
@@ -420,6 +439,9 @@ export class IpcMain {
       return session;
     }
 
+    // Ensure executor is registered for existing workspaces (handles app restart case)
+    this.ensureExecutorRegistered(trimmed);
+
     session = new AgentSession({
       workspaceId: trimmed,
       config: this.config,

src/node/services/localBackgroundExecutor.ts

@@ -88,8 +88,8 @@ class LocalBackgroundHandle implements BackgroundHandle {
     }
   }
 
-  async isRunning(): Promise<boolean> {
-    return this.disposable.child.exitCode === null;
+  isRunning(): Promise<boolean> {
+    return Promise.resolve(this.disposable.child.exitCode === null);
   }
 
   async terminate(): Promise<void> {
@@ -126,8 +126,8 @@ class LocalBackgroundHandle implements BackgroundHandle {
     this.terminated = true;
   }
 
-  async dispose(): Promise<void> {
-    this.disposable[Symbol.dispose]();
+  dispose(): Promise<void> {
+    return Promise.resolve(this.disposable[Symbol.dispose]());
   }
 
   /** Get the child process (for spawn event waiting) */