fix: handle repos with no commits in getCurrentBranch

git rev-parse --abbrev-ref HEAD fails with exit code 128 on freshly
initialized repos with no commits. This error bubbled up through
workspace listing and showed a toast error on every app launch for
users with empty git repos.

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

@@ -21,7 +21,7 @@ import type { WorkspaceGitService } from "./workspace-git-service.js";
 import { normalizeWorkspaceId as normalizePersistedWorkspaceId } from "./workspace-registry-model.js";
 import { createAgentWorktree } from "./worktree-bootstrap.js";
 import type { TerminalManager } from "../terminal/terminal-manager.js";
-import { resolveRepositoryDefaultBranch } from "../utils/checkout-git.js";
+import { getCurrentBranch, resolveRepositoryDefaultBranch } from "../utils/checkout-git.js";
 import { expandTilde } from "../utils/path.js";
 import {
   computeWorktreePath,
@@ -35,8 +35,7 @@ import {
   validateBranchSlug,
   type WorktreeConfig,
 } from "../utils/worktree.js";
-import { runGitCommand } from "../utils/run-git-command.js";
-import { READ_ONLY_GIT_ENV, toCheckoutError } from "./checkout-git-utils.js";
+import { toCheckoutError } from "./checkout-git-utils.js";
 const SAFE_GIT_REF_PATTERN = /^[A-Za-z0-9._\/-]+$/;
 
 export type NormalizedGitOptions = {
@@ -153,11 +152,7 @@ export async function buildAgentSessionConfig(
     if (normalized.createNewBranch) {
       targetBranch = normalized.newBranchName!;
     } else {
-      const { stdout } = await runGitCommand(["rev-parse", "--abbrev-ref", "HEAD"], {
-        cwd,
-        env: READ_ONLY_GIT_ENV,
-      });
-      targetBranch = stdout.trim();
+      targetBranch = (await getCurrentBranch(cwd)) ?? "";
     }
 
     if (!targetBranch) {

packages/server/src/utils/checkout-git.test.ts

@@ -18,6 +18,7 @@ import {
   __setGhPathForTests,
   __setPullRequestStatusCacheTtlForTests,
   commitAll,
+  getCurrentBranch,
   getCheckoutDiff,
   getCheckoutShortstat,
   getPullRequestStatus,
@@ -84,6 +85,15 @@ describe("checkout git utilities", () => {
     );
   });
 
+  it("returns null for getCurrentBranch in a repo with no commits", async () => {
+    const emptyRepo = join(tempDir, "empty-repo");
+    execSync(`mkdir -p ${emptyRepo}`);
+    execSync("git init -b main", { cwd: emptyRepo });
+
+    const branch = await getCurrentBranch(emptyRepo);
+    expect(branch).toBeNull();
+  });
+
   it("handles status/diff/commit in a normal repo", async () => {
     writeFileSync(join(repoDir, "file.txt"), "updated\n");
 

packages/server/src/utils/checkout-git.ts

@@ -525,12 +525,16 @@ async function requireGitRepo(cwd: string): Promise<void> {
 }
 
 export async function getCurrentBranch(cwd: string): Promise<string | null> {
-  const { stdout } = await runGitCommand(["rev-parse", "--abbrev-ref", "HEAD"], {
-    cwd,
-    env: READ_ONLY_GIT_ENV,
-  });
-  const branch = stdout.trim();
-  return branch.length > 0 ? branch : null;
+  try {
+    const { stdout } = await runGitCommand(["rev-parse", "--abbrev-ref", "HEAD"], {
+      cwd,
+      env: READ_ONLY_GIT_ENV,
+    });
+    const branch = stdout.trim();
+    return branch.length > 0 ? branch : null;
+  } catch {
+    return null;
+  }
 }
 
 async function getWorktreeRoot(cwd: string): Promise<string | null> {