feat(backend): wire terminal manager into the daemon at /mux

Construct the tmux runtime and a terminal.Manager fed by the CDC
broadcaster, and hand it to httpd.New so the /mux WebSocket surface goes
live. httpd.New now runs after the CDC substrate so the broadcaster exists
when the manager subscribes; the listener still binds before running.json
is written, preserving fail-fast on port conflict. The manager is closed on
shutdown alongside the CDC pipeline and lifecycle stack.

backend/internal/terminal/manager.go

@@ -284,9 +284,9 @@ func (c *connState) handleSubscribe() {
 			Type: msgSnapshot,
 			Session: &sessionUpdate{
 				Seq:       e.Seq,
+				ProjectID: e.ProjectID,
 				SessionID: e.SessionID,
-				EventType: e.EventType,
-				Revision:  e.Revision,
+				EventType: string(e.Type),
 			},
 		})
 	})

backend/internal/terminal/manager_test.go

@@ -127,7 +127,7 @@ func TestServeForwardsSessionChannelFromCDC(t *testing.T) {
 	conn.in <- clientMsg{Ch: chSubscribe, Type: msgSubscribe}
 	// Give the subscription time to register before publishing.
 	eventually(t, time.Second, func() bool {
-		bc.Publish(cdc.Event{Seq: 9, SessionID: "s1", EventType: "session_updated", Revision: 4})
+		bc.Publish(cdc.Event{Seq: 9, ProjectID: "p1", SessionID: "s1", Type: cdc.EventSessionUpdated})
 		select {
 		case m := <-conn.out:
 			return m.Ch == chSessions && m.Session != nil && m.Session.Seq == 9

backend/internal/terminal/protocol.go

@@ -65,7 +65,7 @@ type serverMsg struct {
 // change_log payload blob; the client refetches detail over the REST surface.
 type sessionUpdate struct {
 	Seq       int64  `json:"seq"`
-	SessionID string `json:"sessionId"`
+	ProjectID string `json:"projectId"`
+	SessionID string `json:"sessionId,omitempty"`
 	EventType string `json:"eventType"`
-	Revision  int64  `json:"revision"`
 }

backend/internal/terminal/protocol_test.go

@@ -33,7 +33,7 @@ func TestServerMsgSessionFrameWireShape(t *testing.T) {
 		Ch:   chSessions,
 		Type: msgSnapshot,
 		Session: &sessionUpdate{
-			Seq: 7, SessionID: "s1", EventType: "session_updated", Revision: 3,
+			Seq: 7, ProjectID: "p1", SessionID: "s1", EventType: "session_updated",
 		},
 	}
 	raw, err := json.Marshal(msg)
@@ -41,7 +41,7 @@ func TestServerMsgSessionFrameWireShape(t *testing.T) {
 		t.Fatalf("marshal: %v", err)
 	}
 	// Golden wire shape the client depends on.
-	want := `{"ch":"sessions","type":"snapshot","session":{"seq":7,"sessionId":"s1","eventType":"session_updated","revision":3}}`
+	want := `{"ch":"sessions","type":"snapshot","session":{"seq":7,"projectId":"p1","sessionId":"s1","eventType":"session_updated"}}`
 	if string(raw) != want {
 		t.Fatalf("wire shape:\n got %s\nwant %s", raw, want)
 	}

backend/main.go

@@ -12,10 +12,12 @@ import (
 	"os/signal"
 	"syscall"
 
+	"github.com/aoagents/agent-orchestrator/backend/internal/adapters/runtime/tmux"
 	"github.com/aoagents/agent-orchestrator/backend/internal/config"
 	"github.com/aoagents/agent-orchestrator/backend/internal/httpd"
 	"github.com/aoagents/agent-orchestrator/backend/internal/runfile"
 	"github.com/aoagents/agent-orchestrator/backend/internal/storage/sqlite"
+	"github.com/aoagents/agent-orchestrator/backend/internal/terminal"
 )
 
 func main() {
@@ -42,11 +44,6 @@ func run() error {
 		return fmt.Errorf("daemon already running (pid %d, port %d); refusing to start", live.PID, live.Port)
 	}
 
-	srv, err := httpd.New(cfg, log, nil)
-	if err != nil {
-		return err
-	}
-
 	// Open the durable store and bring up the CDC substrate: the DB triggers
 	// capture changes into change_log, the poller tails it, and the broadcaster
 	// fans events out to the SSE transport. The LCM/Session Manager and the HTTP
@@ -70,6 +67,19 @@ func run() error {
 		return err
 	}
 
+	// Terminal streaming: the tmux runtime supplies the PTY-attach command and
+	// liveness; the CDC broadcaster feeds the session-state channel. The manager
+	// is handed to httpd, which mounts it at /mux. Raw PTY bytes never flow
+	// through the CDC change_log — only session-state events do.
+	runtimeAdapter := tmux.New(tmux.Options{})
+	termMgr := terminal.NewManager(runtimeAdapter, cdcPipe.Broadcaster, log)
+	defer termMgr.Close()
+
+	srv, err := httpd.New(cfg, log, termMgr)
+	if err != nil {
+		return err
+	}
+
 	// Bring up the Lifecycle Manager (sole store writer) and the reaper (OBSERVE
 	// timer). This makes the write path live end-to-end: LCM write -> store -> DB
 	// trigger -> change_log -> poller -> broadcaster. The collaborators it needs