feat: Implement branch picker (#222)

Author: charlesvien

apps/array/src/main/preload.ts

@@ -282,6 +282,12 @@ contextBridge.exposeInMainWorld("electronAPI", {
   }> => ipcRenderer.invoke("get-diff-stats", repoPath),
   getCurrentBranch: (repoPath: string): Promise<string | undefined> =>
     ipcRenderer.invoke("get-current-branch", repoPath),
+  getDefaultBranch: (repoPath: string): Promise<string> =>
+    ipcRenderer.invoke("get-default-branch", repoPath),
+  getAllBranches: (repoPath: string): Promise<string[]> =>
+    ipcRenderer.invoke("get-all-branches", repoPath),
+  createBranch: (repoPath: string, branchName: string): Promise<void> =>
+    ipcRenderer.invoke("create-branch", repoPath, branchName),
   discardFileChanges: (
     repoPath: string,
     filePath: string,

apps/array/src/main/services/git.ts

@@ -153,6 +153,36 @@ export const getDefaultBranch = async (
   }
 };
 
+export const getAllBranches = async (
+  directoryPath: string,
+): Promise<string[]> => {
+  try {
+    const { stdout } = await execAsync(
+      'git branch --list --format="%(refname:short)"',
+      {
+        cwd: directoryPath,
+      },
+    );
+    return stdout
+      .trim()
+      .split("\n")
+      .filter(Boolean)
+      .map((branch) => branch.trim())
+      .filter((branch) => !branch.startsWith("array/"));
+  } catch {
+    return [];
+  }
+};
+
+export const createBranch = async (
+  directoryPath: string,
+  branchName: string,
+): Promise<void> => {
+  await execAsync(`git checkout -b "${branchName}"`, {
+    cwd: directoryPath,
+  });
+};
+
 const getChangedFiles = async (directoryPath: string): Promise<Set<string>> => {
   const changedFiles = new Set<string>();
 
@@ -785,6 +815,37 @@ export function registerGitIpc(
     },
   );
 
+  ipcMain.handle(
+    "get-default-branch",
+    async (
+      _event: IpcMainInvokeEvent,
+      directoryPath: string,
+    ): Promise<string> => {
+      return getDefaultBranch(directoryPath);
+    },
+  );
+
+  ipcMain.handle(
+    "get-all-branches",
+    async (
+      _event: IpcMainInvokeEvent,
+      directoryPath: string,
+    ): Promise<string[]> => {
+      return getAllBranches(directoryPath);
+    },
+  );
+
+  ipcMain.handle(
+    "create-branch",
+    async (
+      _event: IpcMainInvokeEvent,
+      directoryPath: string,
+      branchName: string,
+    ): Promise<void> => {
+      return createBranch(directoryPath, branchName);
+    },
+  );
+
   ipcMain.handle(
     "discard-file-changes",
     async (

apps/array/src/main/services/workspace/workspaceService.ts

@@ -84,7 +84,8 @@ export class WorkspaceService {
   async createWorkspace(
     options: CreateWorkspaceOptions,
   ): Promise<WorkspaceInfo> {
-    const { taskId, mainRepoPath, folderId, folderPath, mode } = options;
+    const { taskId, mainRepoPath, folderId, folderPath, mode, branch } =
+      options;
     log.info(
       `Creating workspace for task ${taskId} in ${mainRepoPath} (mode: ${mode})`,
     );
@@ -117,6 +118,25 @@ export class WorkspaceService {
 
     // Root mode: skip worktree creation entirely
     if (mode === "root") {
+      // try to create the branch, if it already exists just switch to it
+      if (branch) {
+        try {
+          log.info(`Creating/switching to branch ${branch} for task ${taskId}`);
+          try {
+            await execAsync(`git checkout -b "${branch}"`, { cwd: folderPath });
+            log.info(`Created and switched to new branch ${branch}`);
+          } catch (_error) {
+            await execAsync(`git checkout "${branch}"`, { cwd: folderPath });
+            log.info(`Switched to existing branch ${branch}`);
+          }
+        } catch (error) {
+          log.error(`Failed to create/switch to branch ${branch}:`, error);
+          throw new Error(
+            `Failed to create/switch to branch ${branch}: ${String(error)}`,
+          );
+        }
+      }
+
       // Save task association without worktree
       const associations = getTaskAssociations();
       const existingIndex = associations.findIndex((a) => a.taskId === taskId);
@@ -219,7 +239,9 @@ export class WorkspaceService {
     let worktree: WorktreeInfo;
 
     try {
-      worktree = await worktreeManager.createWorktree();
+      worktree = await worktreeManager.createWorktree({
+        baseBranch: branch ?? undefined,
+      });
       log.info(
         `Created worktree: ${worktree.worktreeName} at ${worktree.worktreePath}`,
       );

apps/array/src/renderer/features/folder-picker/components/FolderPicker.tsx

@@ -61,19 +61,15 @@ export function FolderPicker({
         onClick={handleOpenFilePicker}
       >
         <Flex justify="between" align="center" gap="2" width="100%">
-          <Flex
-            align="center"
-            gap="2"
-            width="250px"
-            style={{ minWidth: 0, flex: 1 }}
-          >
+          <Flex align="center" gap="2">
             <FolderIcon size={16} weight="regular" style={{ flexShrink: 0 }} />
             <Text
               size={size}
               style={{
                 overflow: "hidden",
                 textOverflow: "ellipsis",
                 whiteSpace: "nowrap",
+                maxWidth: "120px",
               }}
               truncate
             >
@@ -90,13 +86,8 @@ export function FolderPicker({
     <DropdownMenu.Root>
       <DropdownMenu.Trigger>
         <Button color="gray" variant="outline" size={size}>
-          <Flex justify="between" align="center" gap="2" width="100%">
-            <Flex
-              align="center"
-              gap="2"
-              width="250px"
-              style={{ minWidth: 0, flex: 1 }}
-            >
+          <Flex justify="between" align="center" gap="2">
+            <Flex align="center" gap="2" style={{ minWidth: 0 }}>
               <FolderIcon
                 size={16}
                 weight="regular"