diff --git a/pkg/agent/instance.go b/pkg/agent/instance.go
index 110dc11a7..358a38a19 100644
--- a/pkg/agent/instance.go
+++ b/pkg/agent/instance.go
@@ -206,16 +206,21 @@ func resolvePlanFallbacks(agentCfg *config.AgentConfig, defaults *config.AgentDe
 }
 
 // ActivateWorktree creates a worktree for a session.
-// Path: <workspace>/.picoclaw/worktrees/<branch-basename>/
-func (ai *AgentInstance) ActivateWorktree(sessionKey, taskName string) (*git.WorktreeInfo, error) {
-	repoRoot := git.FindRepoRoot(ai.Workspace)
+// projectDir is the git repository to create the worktree in.
+// If empty, falls back to ai.Workspace.
+// Path: <projectDir>/.picoclaw/worktrees/<branch-basename>/
+func (ai *AgentInstance) ActivateWorktree(sessionKey, taskName, projectDir string) (*git.WorktreeInfo, error) {
+	if projectDir == "" {
+		projectDir = ai.Workspace
+	}
+	repoRoot := git.FindRepoRoot(projectDir)
 	if repoRoot == "" {
-		return nil, fmt.Errorf("workspace is not a git repository")
+		return nil, fmt.Errorf("directory is not a git repository: %s", projectDir)
 	}
 
 	branchName := git.SanitizeBranchName(taskName)
 	baseName := git.BranchBaseName(branchName)
-	wtPath := filepath.Join(ai.Workspace, ".picoclaw", "worktrees", baseName)
+	wtPath := filepath.Join(repoRoot, ".picoclaw", "worktrees", baseName)
 
 	wt, err := git.CreateWorktree(repoRoot, wtPath, branchName)
 	if err != nil {
diff --git a/pkg/agent/loop.go b/pkg/agent/loop.go
index 5f5c759e7..a49a74eb0 100644
--- a/pkg/agent/loop.go
+++ b/pkg/agent/loop.go
@@ -307,7 +307,8 @@ func (al *AgentLoop) Run(ctx context.Context) error {
 					if taskName == "" {
 						taskName = "plan-execution"
 					}
-					if wt, err := agent.ActivateWorktree(msg.SessionKey, taskName); err != nil {
+					planDir := agent.ContextBuilder.GetPlanWorkDir()
+					if wt, err := agent.ActivateWorktree(msg.SessionKey, taskName, planDir); err != nil {
 						logger.WarnCF("agent", "Worktree activation skipped", map[string]any{"error": err.Error()})
 					} else {
 						logger.InfoCF("agent", "Worktree activated", map[string]any{"branch": wt.Branch})
@@ -2111,7 +2112,8 @@ func (al *AgentLoop) runLLMIteration(
 			// Heartbeat lazy worktree: create worktree on first write-tool call
 			if opts.Background && isWriteTool(tc.Name) && !agent.IsInWorktree(opts.SessionKey) {
 				taskName := "heartbeat-" + time.Now().Format("20060102")
-				if wt, err := agent.ActivateWorktree(opts.SessionKey, taskName); err == nil {
+				hbDir := agent.ContextBuilder.GetPlanWorkDir()
+				if wt, err := agent.ActivateWorktree(opts.SessionKey, taskName, hbDir); err == nil {
 					logger.InfoCF("agent", "Heartbeat worktree created", map[string]any{"branch": wt.Branch})
 				}
 			}