Fix connect accumulation; add display sinks to enum-devices

- controller_cli: drain semaphore and reset pending_cmd in do_connect
  so stale posts from old connection don't unblock the next command
- protocol: add Proto_Display_Device_Info; extend
  proto_write_enum_devices_response and proto_read_enum_devices_response
  with display section; backward-compatible (absent in older messages)
- node: handle_enum_devices snapshots active Display_Slots under mutex
  and includes them in the response
- controller_cli: on_display callback prints display window info in
  enum-devices output
- query_cli: updated to pass NULL on_display (no display interest)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dev/cli/controller_cli.c

@@ -158,6 +158,31 @@ static void on_standalone(
 		(int)name_len, name);
 }
 
+static const char *scale_name(uint8_t s)
+{
+	switch (s) {
+	case 0: return "stretch";
+	case 1: return "fit";
+	case 2: return "fill";
+	case 3: return "1:1";
+	default: return "?";
+	}
+}
+
+static void on_display(
+	uint16_t stream_id,
+	int16_t win_x, int16_t win_y,
+	uint16_t win_w, uint16_t win_h,
+	uint8_t scale, uint8_t anchor,
+	void *ud)
+{
+	(void)ud;
+	printf("  display  stream=%u  pos=%d,%d  size=%ux%u  scale=%s  anchor=%s\n",
+		stream_id, win_x, win_y, win_w, win_h,
+		scale_name(scale),
+		anchor == 0 ? "center" : "topleft");
+}
+
 static void on_control(
 	uint32_t id, uint8_t type, uint32_t flags,
 	const char *name, uint8_t name_len,
@@ -208,7 +233,7 @@ static void on_frame(struct Transport_Conn *conn,
 		struct Proto_Response_Header hdr;
 		struct App_Error e = proto_read_enum_devices_response(
 			frame->payload, frame->payload_length, &hdr,
-			on_media_device, on_video_node, on_standalone, NULL);
+			on_media_device, on_video_node, on_standalone, on_display, NULL);
 		if (!APP_IS_OK(e)) { app_error_print(&e); }
 		else if (hdr.status != PROTO_STATUS_OK) {
 			fprintf(stderr, "ENUM_DEVICES: status=%u\n", hdr.status);
@@ -452,6 +477,9 @@ static struct Transport_Conn *do_connect(struct Ctrl_State *cs,
 	struct Transport_Conn *old_conn)
 {
 	if (old_conn) { transport_conn_close(old_conn); }
+	/* Reset state — drain stale semaphore posts from the old connection */
+	cs->pending_cmd = 0;
+	while (sem_trywait(&cs->sem) == 0) { /* drain */ }
 	struct Transport_Conn *conn;
 	struct App_Error e = transport_connect(&conn, host, port,
 		TRANSPORT_DEFAULT_MAX_PAYLOAD, on_frame, on_disconnect, cs);

dev/cli/query_cli.c

@@ -195,7 +195,7 @@ static void on_frame(struct Transport_Conn *conn,
 			struct Proto_Response_Header hdr;
 			struct App_Error e = proto_read_enum_devices_response(
 				frame->payload, frame->payload_length, &hdr,
-				on_media_device, on_video_node, on_standalone, NULL);
+				on_media_device, on_video_node, on_standalone, NULL, NULL);
 			if (!APP_IS_OK(e)) { app_error_print(&e); }
 			else if (hdr.status != PROTO_STATUS_OK) {
 				fprintf(stderr, "ENUM_DEVICES failed: status=%u\n", hdr.status);

include/protocol.h

@@ -147,6 +147,18 @@ struct Proto_Standalone_Device_Info {
 	const char *name;
 };
 
+/*
+ * An active display window (video sink role).
+ * stream_id is the stream being displayed; win_* are current geometry.
+ */
+struct Proto_Display_Device_Info {
+	uint16_t stream_id;
+	int16_t  win_x, win_y;
+	uint16_t win_w, win_h;
+	uint8_t  scale;
+	uint8_t  anchor;
+};
+
 struct Proto_Monitor_Info {
 	int32_t    x, y;
 	uint32_t   width, height;
@@ -362,7 +374,8 @@ struct App_Error proto_write_control_response(struct Transport_Conn *conn,
 struct App_Error proto_write_enum_devices_response(struct Transport_Conn *conn,
 	uint16_t request_id, uint16_t status,
 	const struct Proto_Media_Device_Info *media_devices, uint16_t media_count,
-	const struct Proto_Standalone_Device_Info *standalone, uint16_t standalone_count);
+	const struct Proto_Standalone_Device_Info *standalone, uint16_t standalone_count,
+	const struct Proto_Display_Device_Info *displays, uint16_t display_count);
 
 /* CONTROL_RESPONSE: ENUM_CONTROLS */
 struct App_Error proto_write_enum_controls_response(struct Transport_Conn *conn,
@@ -481,6 +494,12 @@ struct App_Error proto_read_enum_devices_response(
 		const char *path,        uint8_t path_len,
 		const char *name,        uint8_t name_len,
 		void *userdata),
+	void (*on_display)(
+		uint16_t stream_id,
+		int16_t  win_x,  int16_t  win_y,
+		uint16_t win_w,  uint16_t win_h,
+		uint8_t  scale,  uint8_t  anchor,
+		void *userdata),
 	void *userdata);
 
 /*

src/modules/protocol/protocol.c

@@ -51,6 +51,14 @@ static struct App_Error wbuf_u16(struct Wbuf *b, uint16_t v) {
 	return APP_OK;
 }
 
+static struct App_Error wbuf_i16(struct Wbuf *b, int16_t v) {
+	struct App_Error e = wbuf_grow(b, 2);
+	if (!APP_IS_OK(e)) { return e; }
+	put_i16(b->data, b->len, v);
+	b->len += 2;
+	return APP_OK;
+}
+
 static struct App_Error wbuf_u32(struct Wbuf *b, uint32_t v) {
 	struct App_Error e = wbuf_grow(b, 4);
 	if (!APP_IS_OK(e)) { return e; }
@@ -366,7 +374,8 @@ struct App_Error proto_write_get_control_response(struct Transport_Conn *conn,
 struct App_Error proto_write_enum_devices_response(struct Transport_Conn *conn,
 	uint16_t request_id, uint16_t status,
 	const struct Proto_Media_Device_Info *media_devices, uint16_t media_count,
-	const struct Proto_Standalone_Device_Info *standalone, uint16_t standalone_count)
+	const struct Proto_Standalone_Device_Info *standalone, uint16_t standalone_count,
+	const struct Proto_Display_Device_Info *displays, uint16_t display_count)
 {
 	struct Wbuf b;
 	struct App_Error e = wbuf_init(&b, 128);
@@ -402,6 +411,18 @@ struct App_Error proto_write_enum_devices_response(struct Transport_Conn *conn,
 		e = wbuf_str8(&b, standalone[i].name); if (!APP_IS_OK(e)) { goto fail; }
 	}
 
+	e = wbuf_u16(&b, display_count); if (!APP_IS_OK(e)) { goto fail; }
+	for (uint16_t i = 0; i < display_count; i++) {
+		const struct Proto_Display_Device_Info *d = &displays[i];
+		e = wbuf_u16(&b, d->stream_id); if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_i16(&b, d->win_x);     if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_i16(&b, d->win_y);     if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_u16(&b, d->win_w);     if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_u16(&b, d->win_h);     if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_u8 (&b, d->scale);     if (!APP_IS_OK(e)) { goto fail; }
+		e = wbuf_u8 (&b, d->anchor);    if (!APP_IS_OK(e)) { goto fail; }
+	}
+
 	e = transport_send_frame(conn, PROTO_MSG_CONTROL_RESPONSE, b.data, b.len);
 fail:
 	wbuf_free(&b);
@@ -705,6 +726,12 @@ struct App_Error proto_read_enum_devices_response(
 		const char *path,        uint8_t path_len,
 		const char *name,        uint8_t name_len,
 		void *userdata),
+	void (*on_display)(
+		uint16_t stream_id,
+		int16_t  win_x,  int16_t  win_y,
+		uint16_t win_w,  uint16_t win_h,
+		uint8_t  scale,  uint8_t  anchor,
+		void *userdata),
 	void *userdata)
 {
 	struct Cursor c;
@@ -759,6 +786,26 @@ struct App_Error proto_read_enum_devices_response(
 		if (on_standalone) { on_standalone(path, path_len, name, name_len, userdata); }
 	}
 
+	/* Display section — optional; absent in messages from older nodes */
+	if (c.ok && c.pos + 2 <= c.len) {
+		uint16_t display_count = cur_u16(&c);
+		CUR_CHECK(c);
+		for (uint16_t i = 0; i < display_count; i++) {
+			uint16_t stream_id = cur_u16(&c);
+			int16_t  win_x     = (int16_t)cur_u16(&c);
+			int16_t  win_y     = (int16_t)cur_u16(&c);
+			uint16_t win_w     = cur_u16(&c);
+			uint16_t win_h     = cur_u16(&c);
+			uint8_t  scale     = cur_u8(&c);
+			uint8_t  anchor    = cur_u8(&c);
+			CUR_CHECK(c);
+			if (on_display) {
+				on_display(stream_id, win_x, win_y,
+					win_w, win_h, scale, anchor, userdata);
+			}
+		}
+	}
+
 	return APP_OK;
 }
 

src/node/main.c

@@ -829,10 +829,31 @@ static void handle_enum_devices(struct Node *node,
 		standalone_count++;
 	}
 
+	struct Proto_Display_Device_Info disp_infos[MAX_DISPLAYS];
+	int disp_count = 0;
+	for (int i = 0; i < MAX_DISPLAYS; i++) {
+		struct Display_Slot *d = &node->displays[i];
+		pthread_mutex_lock(&d->mutex);
+		int snap = d->allocated && d->wanted_state == DISP_OPEN;
+		struct Proto_Display_Device_Info info = {
+			.stream_id = d->stream_id,
+			.win_x     = (int16_t)d->win_x,
+			.win_y     = (int16_t)d->win_y,
+			.win_w     = (uint16_t)d->win_w,
+			.win_h     = (uint16_t)d->win_h,
+			.scale     = (uint8_t)d->scale,
+			.anchor    = (uint8_t)d->anchor,
+		};
+		pthread_mutex_unlock(&d->mutex);
+		if (!snap) { continue; }
+		disp_infos[disp_count++] = info;
+	}
+
 	struct App_Error e = proto_write_enum_devices_response(conn,
 		request_id, PROTO_STATUS_OK,
 		mdevs, (uint16_t)node->devices.media_count,
-		standalone, (uint16_t)standalone_count);
+		standalone, (uint16_t)standalone_count,
+		disp_infos, (uint16_t)disp_count);
 	if (!APP_IS_OK(e)) { app_error_print(&e); }
 }