feat(02-01): add Unix socket server, poll loop, and stop handler

- Daemon struct with Start/Stop/Wait lifecycle
- Unix socket server handling list/label/stop actions
- Poll loop scanning /proc every 5s
- Stale socket cleanup before listen
- Connection dispatch with JSON encoding
- Tests with -race: StartStop, ListOverSocket, LabelOverSocket, UnknownAction

daemon_test.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"encoding/json"
+	"net"
 	"os"
 	"path/filepath"
 	"testing"
@@ -173,7 +175,151 @@ func TestRegistryUpdateTimestamp(t *testing.T) {
 	}
 }
 
-// Placeholder to verify file exists
-func init() {
-	_ = os.TempDir()
+// sendRequest dials the daemon socket, sends a Request, and decodes the Response.
+func sendRequest(t *testing.T, sockPath string, req Request) Response {
+	t.Helper()
+	conn, err := net.Dial("unix", sockPath)
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	defer conn.Close()
+
+	if err := json.NewEncoder(conn).Encode(req); err != nil {
+		t.Fatalf("encode: %v", err)
+	}
+
+	var resp Response
+	if err := json.NewDecoder(conn).Decode(&resp); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	return resp
+}
+
+// newTestDaemon creates a daemon using temp dirs (no real /proc or claude dir).
+func newTestDaemon(t *testing.T) *Daemon {
+	t.Helper()
+	dir := t.TempDir()
+	sockPath := filepath.Join(dir, "vmux.sock")
+	procDir := filepath.Join(dir, "proc")   // empty, no processes
+	claudeDir := filepath.Join(dir, "claude")
+	labelsPath := filepath.Join(dir, "labels.json")
+
+	os.MkdirAll(procDir, 0o755)
+	os.MkdirAll(claudeDir, 0o755)
+
+	labels, err := NewLabelStore(labelsPath)
+	if err != nil {
+		t.Fatalf("labels: %v", err)
+	}
+
+	return NewDaemon(sockPath, procDir, claudeDir, labels)
+}
+
+func TestDaemonStartStop(t *testing.T) {
+	d := newTestDaemon(t)
+
+	if err := d.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+
+	// Send stop via socket
+	resp := sendRequest(t, d.sockPath, Request{Action: "stop"})
+	if !resp.OK {
+		t.Errorf("stop resp.OK = false, error = %q", resp.Error)
+	}
+
+	// Daemon should stop within a short time
+	done := make(chan struct{})
+	go func() {
+		d.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		// ok
+	case <-time.After(2 * time.Second):
+		t.Fatal("daemon did not stop within 2s")
+	}
+}
+
+func TestDaemonListOverSocket(t *testing.T) {
+	d := newTestDaemon(t)
+
+	if err := d.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	defer d.Stop()
+
+	// Populate registry after Start (initial scan clears unknown sessions)
+	d.registry.Update(SessionInfo{
+		PID:       42,
+		SessionID: "test-sess",
+		State:     "Working",
+		Cwd:       "/tmp/test",
+	})
+
+	resp := sendRequest(t, d.sockPath, Request{Action: "list"})
+	if !resp.OK {
+		t.Fatalf("list resp.OK = false, error = %q", resp.Error)
+	}
+	if len(resp.Sessions) != 1 {
+		t.Fatalf("sessions len = %d, want 1", len(resp.Sessions))
+	}
+	if resp.Sessions[0].SessionID != "test-sess" {
+		t.Errorf("session_id = %q, want %q", resp.Sessions[0].SessionID, "test-sess")
+	}
+}
+
+func TestDaemonLabelOverSocket(t *testing.T) {
+	d := newTestDaemon(t)
+
+	if err := d.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	defer d.Stop()
+
+	// Populate registry after Start (initial scan clears unknown sessions)
+	d.registry.Update(SessionInfo{
+		PID:       42,
+		SessionID: "test-sess",
+		State:     "Working",
+		Cwd:       "/tmp/test",
+	})
+
+	// Set label
+	args, _ := json.Marshal(LabelArgs{SessionID: "test-sess", Label: "review MR"})
+	resp := sendRequest(t, d.sockPath, Request{Action: "label", Args: args})
+	if !resp.OK {
+		t.Fatalf("label resp.OK = false, error = %q", resp.Error)
+	}
+
+	// Verify label appears in list
+	resp = sendRequest(t, d.sockPath, Request{Action: "list"})
+	if !resp.OK {
+		t.Fatalf("list resp.OK = false, error = %q", resp.Error)
+	}
+	if len(resp.Sessions) != 1 {
+		t.Fatalf("sessions len = %d, want 1", len(resp.Sessions))
+	}
+	if resp.Sessions[0].Label != "review MR" {
+		t.Errorf("label = %q, want %q", resp.Sessions[0].Label, "review MR")
+	}
+}
+
+func TestDaemonUnknownAction(t *testing.T) {
+	d := newTestDaemon(t)
+
+	if err := d.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	defer d.Stop()
+
+	resp := sendRequest(t, d.sockPath, Request{Action: "bogus"})
+	if resp.OK {
+		t.Error("expected OK=false for unknown action")
+	}
+	if resp.Error == "" {
+		t.Error("expected error message for unknown action")
+	}
 }