fix(server): await git worktree creation before responding to client

Move createAgentWorktree() from the fire-and-forget background function
into handleCreatePaseoWorktreeRequest so the worktree directory exists
on disk before the client receives the response and navigates. Fixes
ENOENT race when the app queries checkout status on a path that hasn't
been created yet. Setup commands (npm install, etc.) remain background.

packages/server/src/server/session.ts

@@ -173,7 +173,7 @@ import { ScheduleService } from "./schedule/service.js";
 import {
   assertSafeGitRef as assertWorktreeSafeGitRef,
   buildAgentSessionConfig as buildWorktreeAgentSessionConfig,
-  createPaseoWorktreeInBackground as createWorktreeInBackgroundSession,
+  runWorktreeSetupInBackground as runWorktreeSetupInBackgroundSession,
   handleCreatePaseoWorktreeRequest as handleCreateWorktreeRequest,
   handlePaseoWorktreeArchiveRequest as handleWorktreeArchiveRequest,
   handlePaseoWorktreeListRequest as handleWorktreeListRequest,
@@ -6157,20 +6157,19 @@ export class Session {
         registerPendingWorktreeWorkspace: (options) =>
           this.registerPendingWorktreeWorkspace(options),
         sessionLogger: this.sessionLogger,
-        createPaseoWorktreeInBackground: (options) => this.createPaseoWorktreeInBackground(options),
+        runWorktreeSetupInBackground: (options) => this.runWorktreeSetupInBackground(options),
       },
       request,
     );
   }
 
-  private async createPaseoWorktreeInBackground(options: {
+  private async runWorktreeSetupInBackground(options: {
     requestCwd: string;
     repoRoot: string;
-    baseBranch: string;
     slug: string;
     worktreePath: string;
   }): Promise<void> {
-    return createWorktreeInBackgroundSession(
+    return runWorktreeSetupInBackgroundSession(
       {
         paseoHome: this.paseoHome,
         emitWorkspaceUpdateForCwd: (cwd) => this.emitWorkspaceUpdateForCwd(cwd),

packages/server/src/server/worktree-session.ts

@@ -109,10 +109,9 @@ type HandleCreatePaseoWorktreeRequestDependencies = {
     branchName: string;
   }) => Promise<PersistedWorkspaceRecord>;
   sessionLogger: Logger;
-  createPaseoWorktreeInBackground: (options: {
+  runWorktreeSetupInBackground: (options: {
     requestCwd: string;
     repoRoot: string;
-    baseBranch: string;
     slug: string;
     worktreePath: string;
   }) => Promise<void>;
@@ -575,6 +574,15 @@ export async function handleCreatePaseoWorktreeRequest(
       worktreePath,
       branchName: normalizedSlug,
     });
+
+    await createAgentWorktree({
+      cwd: repoRoot,
+      branchName: normalizedSlug,
+      baseBranch,
+      worktreeSlug: normalizedSlug,
+      paseoHome: dependencies.paseoHome,
+    });
+
     const descriptor = await dependencies.describeWorkspaceRecord(workspace);
     dependencies.emit({
       type: "create_paseo_worktree_response",
@@ -586,10 +594,9 @@ export async function handleCreatePaseoWorktreeRequest(
       },
     });
 
-    void dependencies.createPaseoWorktreeInBackground({
+    void dependencies.runWorktreeSetupInBackground({
       requestCwd: request.cwd,
       repoRoot,
-      baseBranch,
       slug: normalizedSlug,
       worktreePath,
     });
@@ -611,12 +618,11 @@ export async function handleCreatePaseoWorktreeRequest(
   }
 }
 
-export async function createPaseoWorktreeInBackground(
+export async function runWorktreeSetupInBackground(
   dependencies: CreatePaseoWorktreeInBackgroundDependencies,
   options: {
     requestCwd: string;
     repoRoot: string;
-    baseBranch: string;
     slug: string;
     worktreePath: string;
   },
@@ -624,14 +630,6 @@ export async function createPaseoWorktreeInBackground(
   let setupTerminalId: string | null = null;
 
   try {
-    await createAgentWorktree({
-      cwd: options.repoRoot,
-      branchName: options.slug,
-      baseBranch: options.baseBranch,
-      worktreeSlug: options.slug,
-      paseoHome: dependencies.paseoHome,
-    });
-
     const setupCommands = getWorktreeSetupCommands(options.worktreePath);
     if (setupCommands.length > 0 && dependencies.terminalManager) {
       const runtimeEnv = await resolveWorktreeRuntimeEnv({
@@ -667,7 +665,7 @@ export async function createPaseoWorktreeInBackground(
         worktreePath: options.worktreePath,
         setupTerminalId,
       },
-      "Background worktree creation failed",
+      "Background worktree setup failed",
     );
   } finally {
     await dependencies.emitWorkspaceUpdateForCwd(options.worktreePath);