fix(worktrees): default to HEAD when no startPoint provided

- Use git reset --hard HEAD by default when startPoint is not provided or is HEAD
- Preserve resetting to the provided startPoint when a concrete value is supplied

packages/ui/src/components/session/GitHubPullRequestPickerDialog.tsx

@@ -328,7 +328,9 @@ export function GitHubPullRequestPickerDialog({
       throw new Error(`Local branch already exists: ${preferredBranch}`);
     }
 
-    const session = await createWorktreeSessionForNewBranchExact(projectDirectory, preferredBranch, headCommitish);
+    const session = await createWorktreeSessionForNewBranchExact(projectDirectory, preferredBranch, headCommitish, {
+      kind: 'pr',
+    });
     if (!session?.id) {
       throw new Error('Failed to create PR worktree session');
     }
@@ -341,12 +343,12 @@ export function GitHubPullRequestPickerDialog({
 
     // Switch the new worktree to the PR branch and delete the SDK-created opencode/* branch immediately.
     // This makes the worktree directly operate on the PR branch.
-    const originalBranch = (meta?.branch || session.branch || '').replace(/^refs\/heads\//, '').trim();
     const commands: string[] = [
       // Create local branch from the fetched PR head commit.
       `git -C ${JSON.stringify(worktreeDir)} switch -c ${JSON.stringify(preferredBranch)} ${JSON.stringify(headCommitish)}`,
     ];
-    if (originalBranch && originalBranch.startsWith('opencode/')) {
+    const originalBranch = (meta?.branch || session.branch || '').replace(/^refs\/heads\//, '').trim();
+    if (meta?.kind === 'pr' && originalBranch && originalBranch.startsWith('opencode/')) {
       commands.push(`git -C ${JSON.stringify(projectDirectory)} branch -D ${JSON.stringify(originalBranch)}`);
     }
 
@@ -394,6 +396,7 @@ export function GitHubPullRequestPickerDialog({
       branch: preferredBranch,
       label: preferredBranch,
       createdFromBranch: pr.base,
+      kind: 'pr' as const,
     });
 
     return { id: session.id };

packages/ui/src/lib/worktreeSessionCreator.ts

@@ -99,6 +99,7 @@ export async function createWorktreeSession(): Promise<{ id: string } | null> {
     const createdMetadata = {
       ...metadata,
       createdFromBranch: startPoint ?? 'HEAD',
+      kind: 'standard' as const,
     };
 
     // Get worktree status
@@ -271,6 +272,7 @@ export async function createWorktreeSessionForBranch(
     const createdMetadata = {
       ...metadata,
       createdFromBranch: branchName,
+      kind: 'standard' as const,
     };
 
     // Get worktree status
@@ -394,7 +396,7 @@ export async function createWorktreeSessionForNewBranch(
   projectDirectory: string,
   preferredBranchName: string,
   startPoint: string,
-  options?: { allowSuffix?: boolean }
+  options?: { allowSuffix?: boolean; kind?: 'pr' | 'standard' }
 ): Promise<{ id: string; branch: string } | null> {
   if (isCreatingWorktreeSession) {
     return null;
@@ -425,6 +427,7 @@ export async function createWorktreeSessionForNewBranch(
     }
 
     const allowSuffix = options?.allowSuffix !== false;
+    const kind = options?.kind ?? 'standard';
 
     const projectRef = resolveProjectRef(projectDirectory);
     if (!projectRef) {
@@ -444,6 +447,7 @@ export async function createWorktreeSessionForNewBranch(
       const createdMetadata = {
         ...metadata,
         createdFromBranch: start,
+        kind,
       };
 
         const status = await getWorktreeStatus(metadata.path).catch(() => undefined);
@@ -543,7 +547,11 @@ export async function createWorktreeSessionForNewBranch(
 export async function createWorktreeSessionForNewBranchExact(
   projectDirectory: string,
   branchName: string,
-  startPoint: string
+  startPoint: string,
+  options?: { kind?: 'pr' | 'standard' }
 ): Promise<{ id: string; branch: string } | null> {
-  return createWorktreeSessionForNewBranch(projectDirectory, branchName, startPoint, { allowSuffix: false });
+  return createWorktreeSessionForNewBranch(projectDirectory, branchName, startPoint, {
+    allowSuffix: false,
+    kind: options?.kind,
+  });
 }

packages/ui/src/lib/worktrees/worktreeManager.ts

@@ -71,6 +71,8 @@ export const buildSdkStartCommand = (args: {
   const startPoint = typeof args.startPoint === 'string' ? args.startPoint.trim() : '';
   if (startPoint && startPoint !== 'HEAD') {
     commands.push(`git reset --hard ${shellQuote(startPoint)}`);
+  } else {
+    commands.push('git reset --hard HEAD');
   }
 
   for (const raw of args.setupCommands) {

packages/ui/src/stores/useMultiRunStore.ts

@@ -170,6 +170,7 @@ export const useMultiRunStore = create<MultiRunStore>()(
               const enrichedMetadata = {
                 ...worktreeMetadata,
                 createdFromBranch: startPoint ?? 'HEAD',
+                kind: 'standard' as const,
               };
 
               // Session title format: groupSlug/provider/model (or groupSlug/provider/model/index for duplicates)

packages/ui/src/types/worktree.ts

@@ -18,6 +18,8 @@ export interface WorktreeMetadata {
   /** SDK worktree name (slug), if available. */
   name?: string;
 
+  kind?: 'pr' | 'standard';
+
   /**
    * Branch/ref this worktree was created from (intended integration target).
    * For SDK worktrees this is typically the user-selected base branch.