feat: implement initial commit creation for empty git repositories

- Added a function to ensure that a git repository has at least one commit before executing worktree commands. This function creates an empty initial commit with a predefined message if the repository is empty.
- Updated the create route handler to call this function, ensuring smooth operation when adding worktrees to repositories without existing commits.
- Introduced integration tests to verify the creation of the initial commit when no commits are present in the repository.

apps/server/src/routes/worktree/common.ts

@@ -13,6 +13,9 @@ import {
 const logger = createLogger("Worktree");
 const execAsync = promisify(exec);
 
+export const AUTOMAKER_INITIAL_COMMIT_MESSAGE =
+  "chore: automaker initial commit";
+
 /**
  * Normalize path separators to forward slashes for cross-platform consistency.
  * This ensures paths from `path.join()` (backslashes on Windows) match paths
@@ -73,3 +76,30 @@ export function logWorktreeError(
 // Re-export shared utilities
 export { getErrorMessageShared as getErrorMessage };
 export const logError = createLogError(logger);
+
+/**
+ * Ensure the repository has at least one commit so git commands that rely on HEAD work.
+ * Returns true if an empty commit was created, false if the repo already had commits.
+ */
+export async function ensureInitialCommit(repoPath: string): Promise<boolean> {
+  try {
+    await execAsync("git rev-parse --verify HEAD", { cwd: repoPath });
+    return false;
+  } catch {
+    try {
+      await execAsync(
+        `git commit --allow-empty -m "${AUTOMAKER_INITIAL_COMMIT_MESSAGE}"`,
+        { cwd: repoPath }
+      );
+      logger.info(
+        `[Worktree] Created initial empty commit to enable worktrees in ${repoPath}`
+      );
+      return true;
+    } catch (error) {
+      const reason = getErrorMessageShared(error);
+      throw new Error(
+        `Failed to create initial git commit. Please commit manually and retry. ${reason}`
+      );
+    }
+  }
+}

apps/server/src/routes/worktree/routes/create.ts

@@ -12,7 +12,13 @@ import { exec } from "child_process";
 import { promisify } from "util";
 import path from "path";
 import { mkdir } from "fs/promises";
-import { isGitRepo, getErrorMessage, logError, normalizePath } from "../common.js";
+import {
+  isGitRepo,
+  getErrorMessage,
+  logError,
+  normalizePath,
+  ensureInitialCommit,
+} from "../common.js";
 import { trackBranch } from "./branch-tracking.js";
 
 const execAsync = promisify(exec);
@@ -93,6 +99,9 @@ export function createCreateHandler() {
         return;
       }
 
+      // Ensure the repository has at least one commit so worktree commands referencing HEAD succeed
+      await ensureInitialCommit(projectPath);
+
       // First, check if git already has a worktree for this branch (anywhere)
       const existingWorktree = await findExistingWorktreeForBranch(projectPath, branchName);
       if (existingWorktree) {