Replace quiescence detection with process tree inspection

Detect idle state by checking if kiro-cli-chat has tool children
rather than relying purely on output quiescence. Fixes premature
idle detection during long-running processes like remote builds.

internal/backend/tmux/helpers.go

@@ -109,6 +109,44 @@ func getPanePID(target string) (int, error) {
 	return pid, err
 }
 
+// hasToolChildren checks if kiro-cli-chat has any child processes (tool executions)
+func hasToolChildren(panePID int) bool {
+	// Find kiro-cli-chat PID in the process tree: pane -> bash -> kiro-cli -> kiro-cli-chat
+	chatPID := findKiroChatPID(panePID)
+	if chatPID == 0 {
+		return false
+	}
+	// Check if kiro-cli-chat has any children
+	cmd := exec.Command("pgrep", "-P", fmt.Sprintf("%d", chatPID))
+	return cmd.Run() == nil
+}
+
+// findKiroChatPID traverses the process tree to find kiro-cli-chat
+func findKiroChatPID(panePID int) int {
+	// pane (kiro-cli-term) -> bash -> kiro-cli -> kiro-cli-chat
+	bashPID := findChildByName(panePID, "bash")
+	if bashPID == 0 {
+		return 0
+	}
+	kiroPID := findChildByName(bashPID, "kiro-cli")
+	if kiroPID == 0 {
+		return 0
+	}
+	return findChildByName(kiroPID, "kiro-cli-chat")
+}
+
+// findChildByName finds a child process with the given name
+func findChildByName(parentPID int, name string) int {
+	cmd := exec.Command("pgrep", "-P", fmt.Sprintf("%d", parentPID), "-x", name)
+	out, err := cmd.Output()
+	if err != nil {
+		return 0
+	}
+	var pid int
+	fmt.Sscanf(strings.TrimSpace(string(out)), "%d", &pid)
+	return pid
+}
+
 // makeNonBlocking sets a file descriptor to non-blocking mode
 func makeNonBlocking(fd int) error {
 	return syscall.SetNonblock(fd, true)

internal/backend/tmux/session.go

@@ -336,7 +336,10 @@ func (s *Session) Send(ctx context.Context, prompt string) (string, error) {
 
 func (s *Session) waitForComplete(ctx context.Context, prompt string) error {
 	const minContent = 50
-	const quiescence = 400 * time.Millisecond
+	const quiescence = 300 * time.Millisecond
+	const pollInterval = 100 * time.Millisecond
+
+	var quiesceStart time.Time
 
 	for {
 		select {
@@ -349,10 +352,29 @@ func (s *Session) waitForComplete(ctx context.Context, prompt string) error {
 				return fmt.Errorf("session closed")
 			}
 			s.output.Write(data)
+			quiesceStart = time.Time{} // Reset quiescence on new data
 
-		case <-time.After(quiescence):
-			if s.output.Len() > minContent {
-				debug.Log("[session %s] quiescence detected, %d bytes", s.id, s.output.Len())
+		case <-time.After(pollInterval):
+			// Check if we have minimum content
+			if s.output.Len() < minContent {
+				continue
+			}
+
+			// Check process tree: if kiro-cli-chat has tool children, still running
+			if hasToolChildren(s.pid) {
+				quiesceStart = time.Time{} // Reset quiescence
+				continue
+			}
+
+			// No tool children - start or continue quiescence timer
+			if quiesceStart.IsZero() {
+				quiesceStart = time.Now()
+				continue
+			}
+
+			// Check if quiescence period has passed
+			if time.Since(quiesceStart) >= quiescence {
+				debug.Log("[session %s] idle detected (no tool children, %d bytes)", s.id, s.output.Len())
 				return nil
 			}
 		}