fix: improve state detection accuracy and notification UX

- Hook reads JSON from stdin (not env vars) matching Claude Code protocol
- end_turn = Idle (not NeedsInput); real questions come from hooks
- Permission prompt (stale tool_use) never becomes Idle
- Notifications auto-expire after 10s (--expire-time)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

main.go

@@ -149,7 +149,7 @@ func main() {
 		runI3Bar(sockPath)
 
 	case "hook":
-		event := parseHookEnv()
+		event := parseHookStdin()
 		if event.HookEventName == "" {
 			os.Exit(0)
 		}

notify.go

@@ -22,6 +22,7 @@ func (n *ExecNotifier) Notify(title, body string) error {
 	return exec.CommandContext(ctx, "notify-send",
 		"--urgency=critical",
 		"--app-name=vmux",
+		"--expire-time=10000",
 		title,
 		body,
 	).Run()

setup.go

@@ -7,15 +7,11 @@ import (
 	"path/filepath"
 )
 
-// parseHookEnv builds a HookEvent from Claude Code hook environment variables.
-func parseHookEnv() HookEvent {
-	return HookEvent{
-		SessionID:        os.Getenv("SESSION_ID"),
-		Cwd:              os.Getenv("SESSION_CWD"),
-		HookEventName:    os.Getenv("HOOK_EVENT_NAME"),
-		NotificationType: os.Getenv("NOTIFICATION_TYPE"),
-		ToolName:         os.Getenv("TOOL_NAME"),
-	}
+// parseHookStdin reads a HookEvent from stdin (Claude Code sends JSON on stdin).
+func parseHookStdin() HookEvent {
+	var event HookEvent
+	json.NewDecoder(os.Stdin).Decode(&event)
+	return event
 }
 
 // runSetup adds vmux hooks to ~/.claude/settings.json (idempotent).

state.go

@@ -20,34 +20,35 @@ func DetectState(messages []JSONLMessage, now time.Time) SessionState {
 
 	last := messages[len(messages)-1]
 
-	// Check idle threshold first
+	age := time.Duration(0)
 	if ts, err := time.Parse(time.RFC3339, last.Timestamp); err == nil {
-		if now.Sub(ts) > IdleThreshold {
-			return Idle
-		}
+		age = now.Sub(ts)
 	}
 
 	if last.Type == "assistant" && last.Message != nil {
 		switch last.Message.StopReason {
 		case "end_turn":
-			return NeedsInput
+			return Idle
 		case "tool_use":
 			for _, block := range last.Message.Content {
 				if block.Type == "tool_use" && block.Name == "AskUserQuestion" {
 					return NeedsInput
 				}
 			}
-			// If tool_use is stale (no new JSONL activity), Claude is likely
-			// waiting for a permission prompt approval.
-			if ts, err := time.Parse(time.RFC3339, last.Timestamp); err == nil {
-				if now.Sub(ts) > PermissionStallThreshold {
-					return NeedsInput
-				}
+			// Stale tool_use = permission prompt waiting for approval.
+			// Never becomes Idle: a pending permission is always NeedsInput.
+			if age > PermissionStallThreshold {
+				return NeedsInput
 			}
 			return Working
 		}
 	}
 
+	// Non-assistant messages (progress, user): idle if old enough
+	if age > IdleThreshold {
+		return Idle
+	}
+
 	if last.Type == "progress" {
 		return Working
 	}

state_test.go

@@ -8,6 +8,8 @@ import (
 var testNow = time.Date(2026, 3, 23, 12, 0, 30, 0, time.UTC)
 
 func TestDetectState_EndTurnText(t *testing.T) {
+	// end_turn = Claude finished, prompt waiting. This is Idle, not NeedsInput.
+	// Real NeedsInput comes from hooks (Stop, Notification) or AskUserQuestion.
 	msgs := []JSONLMessage{{
 		Type:      "assistant",
 		Timestamp: "2026-03-23T12:00:00Z",
@@ -19,8 +21,8 @@ func TestDetectState_EndTurnText(t *testing.T) {
 	}}
 
 	state := DetectState(msgs, testNow)
-	if state != NeedsInput {
-		t.Errorf("expected NeedsInput, got %v", state)
+	if state != Idle {
+		t.Errorf("expected Idle for end_turn, got %v", state)
 	}
 }
 
@@ -84,6 +86,24 @@ func TestDetectState_ToolUseStale(t *testing.T) {
 	}
 }
 
+func TestDetectState_ToolUseStaleNeverIdle(t *testing.T) {
+	// A tool_use older than IdleThreshold should still be NeedsInput, not Idle
+	msgs := []JSONLMessage{{
+		Type:      "assistant",
+		Timestamp: "2026-03-23T11:58:00Z", // 2min30s before testNow (> IdleThreshold)
+		Message: &MessagePayload{
+			Role:       "assistant",
+			Content:    []ContentBlock{{Type: "tool_use", Name: "Bash"}},
+			StopReason: "tool_use",
+		},
+	}}
+
+	state := DetectState(msgs, testNow)
+	if state != NeedsInput {
+		t.Errorf("expected NeedsInput for very old tool_use (permission), got %v", state)
+	}
+}
+
 func TestDetectState_Progress(t *testing.T) {
 	msgs := []JSONLMessage{{
 		Type:      "progress",