feat(tasks): add configurable base branch for worktree creation and merging

- Add optional baseBranch parameter to createTask and mergeTask flows
- Add base branch input field in NewTaskDialog with auto-detection
- Pass baseBranch as startPoint to git worktree add command
- Use baseBranch as merge target instead of auto-detected main branch
- Persist baseBranch in Task and PersistedTask types
- Add validation for baseBranch parameter in IPC handlers

Author: Qazi-Cardiex

electron/ipc/git.ts

@@ -337,6 +337,7 @@ export async function createWorktree(
   branchName: string,
   symlinkDirs: string[],
   forceClean = false,
+  startPoint?: string,
 ): Promise<{ path: string; branch: string }> {
   const worktreePath = `${repoRoot}/.worktrees/${branchName}`;
 
@@ -362,7 +363,11 @@ export async function createWorktree(
   }
 
   // Create fresh worktree with new branch
-  await exec('git', ['worktree', 'add', '-b', branchName, worktreePath], { cwd: repoRoot });
+  await exec(
+    'git',
+    ['worktree', 'add', '-b', branchName, worktreePath, ...(startPoint ? [startPoint] : [])],
+    { cwd: repoRoot },
+  );
 
   // Symlink selected directories
   for (const name of symlinkDirs) {
@@ -863,11 +868,12 @@ export async function mergeTask(
   squash: boolean,
   message: string | null,
   cleanup: boolean,
+  targetBranch?: string,
 ): Promise<{ main_branch: string; lines_added: number; lines_removed: number }> {
   const lockKey = await detectRepoLockKey(projectRoot).catch(() => projectRoot);
 
   return withWorktreeLock(lockKey, async () => {
-    const mainBranch = await detectMainBranch(projectRoot);
+    const mainBranch = targetBranch ?? (await detectMainBranch(projectRoot));
     const { linesAdded, linesRemoved } = await computeBranchDiffStats(
       projectRoot,
       mainBranch,

electron/ipc/register.ts

@@ -131,7 +131,14 @@ export function registerAllHandlers(win: BrowserWindow): void {
     validatePath(args.projectRoot, 'projectRoot');
     assertStringArray(args.symlinkDirs, 'symlinkDirs');
     assertOptionalString(args.branchPrefix, 'branchPrefix');
-    const result = createTask(args.name, args.projectRoot, args.symlinkDirs, args.branchPrefix);
+    assertOptionalString(args.baseBranch, 'baseBranch');
+    const result = createTask(
+      args.name,
+      args.projectRoot,
+      args.symlinkDirs,
+      args.branchPrefix,
+      args.baseBranch,
+    );
     result.then((r: { id: string }) => taskNames.set(r.id, args.name)).catch(() => {});
     return result;
   });
@@ -200,7 +207,15 @@ export function registerAllHandlers(win: BrowserWindow): void {
     assertBoolean(args.squash, 'squash');
     assertOptionalString(args.message, 'message');
     assertOptionalBoolean(args.cleanup, 'cleanup');
-    return mergeTask(args.projectRoot, args.branchName, args.squash, args.message, args.cleanup);
+    assertOptionalString(args.targetBranch, 'targetBranch');
+    return mergeTask(
+      args.projectRoot,
+      args.branchName,
+      args.squash,
+      args.message,
+      args.cleanup,
+      args.targetBranch,
+    );
   });
   ipcMain.handle(IPC.GetBranchLog, (_e, args) => {
     validatePath(args.worktreePath, 'worktreePath');

electron/ipc/tasks.ts

@@ -33,10 +33,11 @@ export async function createTask(
   projectRoot: string,
   symlinkDirs: string[],
   branchPrefix: string,
+  baseBranch?: string,
 ): Promise<{ id: string; branch_name: string; worktree_path: string }> {
   const prefix = sanitizeBranchPrefix(branchPrefix);
   const branchName = `${prefix}/${slug(name)}`;
-  const worktree = await createWorktree(projectRoot, branchName, symlinkDirs);
+  const worktree = await createWorktree(projectRoot, branchName, symlinkDirs, false, baseBranch);
   return {
     id: randomUUID(),
     branch_name: worktree.branch,

src/components/NewTaskDialog.tsx

@@ -43,6 +43,7 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
   const [directMode, setDirectMode] = createSignal(false);
   const [skipPermissions, setSkipPermissions] = createSignal(false);
   const [branchPrefix, setBranchPrefix] = createSignal('');
+  const [baseBranch, setBaseBranch] = createSignal('');
   let promptRef!: HTMLTextAreaElement;
   let formRef!: HTMLFormElement;
 
@@ -105,6 +106,7 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
     setLoading(false);
     setDirectMode(false);
     setSkipPermissions(false);
+    setBaseBranch('');
 
     void (async () => {
       if (store.availableAgents.length === 0) {
@@ -194,6 +196,32 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
     setBranchPrefix(pid ? getProjectBranchPrefix(pid) : 'task');
   });
 
+  // Auto-detect base branch when project changes
+  createEffect(() => {
+    const pid = selectedProjectId();
+    const path = pid ? getProjectPath(pid) : undefined;
+    let cancelled = false;
+
+    if (!path) {
+      setBaseBranch('');
+      return;
+    }
+
+    void (async () => {
+      try {
+        const detected = await invoke<string>(IPC.GetMainBranch, { projectRoot: path });
+        if (cancelled) return;
+        setBaseBranch((prev) => (prev === '' ? detected : prev));
+      } catch {
+        /* ignore */
+      }
+    })();
+
+    onCleanup(() => {
+      cancelled = true;
+    });
+  });
+
   // Pre-check direct mode based on project setting
   createEffect(() => {
     const pid = selectedProjectId();
@@ -298,6 +326,7 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
           skipPermissions: agentSupportsSkipPermissions() && skipPermissions(),
         });
       } else {
+        const bb = baseBranch().trim() || undefined;
         taskId = await createTask({
           name: n,
           agentDef: agent,
@@ -307,6 +336,7 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
           branchPrefixOverride: prefix,
           githubUrl: ghUrl,
           skipPermissions: agentSupportsSkipPermissions() && skipPermissions(),
+          baseBranch: bb,
         });
       }
       // Drop flow: prefill prompt without auto-sending
@@ -495,6 +525,45 @@ export function NewTaskDialog(props: NewTaskDialogProps) {
           />
         </Show>
 
+        <Show when={!directMode()}>
+          <div
+            data-nav-field="base-branch"
+            style={{ display: 'flex', 'flex-direction': 'column', gap: '8px' }}
+          >
+            <label
+              style={{
+                'font-size': '11px',
+                color: theme.fgMuted,
+                'text-transform': 'uppercase',
+                'letter-spacing': '0.05em',
+              }}
+            >
+              Base branch{' '}
+              <span style={{ opacity: '0.5', 'text-transform': 'none' }}>(merge target)</span>
+            </label>
+            <input
+              class="input-field"
+              type="text"
+              value={baseBranch()}
+              onInput={(e) => setBaseBranch(e.currentTarget.value)}
+              placeholder="main"
+              style={{
+                background: theme.bgInput,
+                border: `1px solid ${theme.border}`,
+                'border-radius': '8px',
+                padding: '10px 14px',
+                color: theme.fg,
+                'font-size': '13px',
+                'font-family': "'JetBrains Mono', monospace",
+                outline: 'none',
+              }}
+            />
+            <span style={{ 'font-size': '11px', color: theme.fgSubtle, padding: '0 2px' }}>
+              Worktree branches from and merges back into this branch.
+            </span>
+          </div>
+        </Show>
+
         <AgentSelector
           agents={store.availableAgents}
           selectedAgent={selectedAgent()}

src/store/persistence.ts

@@ -66,6 +66,7 @@ export async function saveState(): Promise<void> {
       githubUrl: task.githubUrl,
       savedInitialPrompt: task.savedInitialPrompt,
       planFileName: task.planFileName,
+      baseBranch: task.baseBranch,
     };
   }
 
@@ -91,6 +92,7 @@ export async function saveState(): Promise<void> {
       savedInitialPrompt: task.savedInitialPrompt,
       planFileName: task.planFileName,
       collapsed: true,
+      baseBranch: task.baseBranch,
     };
   }
 
@@ -337,6 +339,7 @@ export async function loadState(): Promise<void> {
           githubUrl: pt.githubUrl,
           savedInitialPrompt: pt.savedInitialPrompt,
           planFileName: pt.planFileName,
+          baseBranch: pt.baseBranch,
         };
 
         s.tasks[taskId] = task;
@@ -404,6 +407,7 @@ export async function loadState(): Promise<void> {
           planFileName: pt.planFileName,
           collapsed: true,
           savedAgentDef: agentDef ?? undefined,
+          baseBranch: pt.baseBranch,
         };
 
         s.tasks[taskId] = task;

src/store/tasks.ts

@@ -57,6 +57,7 @@ export interface CreateTaskOptions {
   branchPrefixOverride?: string;
   githubUrl?: string;
   skipPermissions?: boolean;
+  baseBranch?: string;
 }
 
 export async function createTask(opts: CreateTaskOptions): Promise<string> {
@@ -68,6 +69,7 @@ export async function createTask(opts: CreateTaskOptions): Promise<string> {
     initialPrompt,
     githubUrl,
     skipPermissions,
+    baseBranch,
   } = opts;
   const projectRoot = getProjectPath(projectId);
   if (!projectRoot) throw new Error('Project not found');
@@ -79,6 +81,7 @@ export async function createTask(opts: CreateTaskOptions): Promise<string> {
     projectRoot,
     symlinkDirs,
     branchPrefix,
+    baseBranch,
   });
 
   const agentId = crypto.randomUUID();
@@ -96,6 +99,7 @@ export async function createTask(opts: CreateTaskOptions): Promise<string> {
     skipPermissions: skipPermissions || undefined,
     githubUrl,
     savedInitialPrompt: initialPrompt || undefined,
+    baseBranch: baseBranch || undefined,
   };
 
   const agent: Agent = {
@@ -327,6 +331,7 @@ export async function mergeTask(
     squash: options?.squash ?? false,
     message: options?.message,
     cleanup,
+    targetBranch: task.baseBranch,
   });
   recordMergedLines(mergeResult.lines_added, mergeResult.lines_removed);
 

src/store/types.ts

@@ -52,6 +52,7 @@ export interface Task {
   savedAgentDef?: AgentDef;
   planContent?: string;
   planFileName?: string;
+  baseBranch?: string;
 }
 
 export interface Terminal {
@@ -77,6 +78,7 @@ export interface PersistedTask {
   savedInitialPrompt?: string;
   collapsed?: boolean;
   planFileName?: string;
+  baseBranch?: string;
 }
 
 export interface PersistedTerminal {