Add radio channel property with stereo/mono/left/right

client/public/version.js

@@ -1,3 +1,3 @@
 // Maintainer-controlled web client version.
 // Format: YYYY.MM.DD Rn (example: 2026.02.20 R2)
-window.CHGRID_WEB_VERSION = "2026.02.21 R77";
+window.CHGRID_WEB_VERSION = "2026.02.21 R78";

client/src/main.ts

@@ -93,6 +93,7 @@ const EDITABLE_ITEM_PROPERTY_KEYS = new Set([
   'title',
   'streamUrl',
   'enabled',
+  'channel',
   'volume',
   'effect',
   'effectValue',
@@ -100,8 +101,11 @@ const EDITABLE_ITEM_PROPERTY_KEYS = new Set([
   'sides',
   'number',
 ]);
+const RADIO_CHANNEL_OPTIONS = ['stereo', 'mono', 'left', 'right'] as const;
+type RadioChannelMode = (typeof RADIO_CHANNEL_OPTIONS)[number];
 const OPTION_ITEM_PROPERTY_VALUES: Partial<Record<string, string[]>> = {
   effect: EFFECT_SEQUENCE.map((effect) => effect.id),
+  channel: [...RADIO_CHANNEL_OPTIONS],
 };
 const APP_BASE_URL = import.meta.env.BASE_URL || '/';
 function withBase(path: string): string {
@@ -352,7 +356,7 @@ function beginItemSelection(context: 'pickup' | 'delete' | 'edit' | 'use' | 'ins
 function getEditableItemPropertyKeys(item: WorldItem): string[] {
   const keys = ['title'];
   if (item.type === 'radio_station') {
-    keys.push('streamUrl', 'enabled', 'volume', 'effect', 'effectValue');
+    keys.push('streamUrl', 'enabled', 'channel', 'volume', 'effect', 'effectValue');
   } else if (item.type === 'dice') {
     keys.push('sides', 'number');
   } else if (item.type === 'wheel') {
@@ -486,6 +490,12 @@ function normalizeRadioEffectValue(effectValue: unknown): number {
   return clampEffectLevel(effectValue);
 }
 
+function normalizeRadioChannel(channel: unknown): RadioChannelMode {
+  if (typeof channel !== 'string') return 'stereo';
+  const normalized = channel.trim().toLowerCase() as RadioChannelMode;
+  return (RADIO_CHANNEL_OPTIONS as readonly string[]).includes(normalized) ? normalized : 'stereo';
+}
+
 function applyRadioEffect(
   output: ItemRadioOutput,
   audioCtx: AudioContext,
@@ -575,6 +585,7 @@ function updateRadioStationSpatialAudio(): void {
     const normalizedVolume = Number.isFinite(volume) ? Math.max(0, Math.min(100, volume)) / 100 : 0.5;
     const effect = normalizeRadioEffect(item.params.effect);
     const effectValue = normalizeRadioEffectValue(item.params.effectValue);
+    const channel = normalizeRadioChannel(item.params.channel);
     applyRadioEffect(output, audioCtx, effect, effectValue);
     if (!streamUrl || !enabled) {
       output.gain.gain.linearRampToValueAtTime(0, audioCtx.currentTime + 0.05);
@@ -593,7 +604,15 @@ function updateRadioStationSpatialAudio(): void {
     }
     output.gain.gain.linearRampToValueAtTime(gainValue * normalizedVolume, audioCtx.currentTime + 0.1);
     if (output.panner) {
-      output.panner.pan.linearRampToValueAtTime(Math.max(-1, Math.min(1, panValue)), audioCtx.currentTime + 0.1);
+      let resolvedPan = Math.max(-1, Math.min(1, panValue));
+      if (channel === 'mono') {
+        resolvedPan = 0;
+      } else if (channel === 'left') {
+        resolvedPan = -1;
+      } else if (channel === 'right') {
+        resolvedPan = 1;
+      }
+      output.panner.pan.linearRampToValueAtTime(resolvedPan, audioCtx.currentTime + 0.1);
     }
   }
 }
@@ -733,6 +752,7 @@ function getItemPropertyValue(item: WorldItem, key: string): string {
   if (key === 'capabilities') return item.capabilities.join(', ') || 'none';
   if (key === 'useSound') return item.useSound ?? 'none';
   if (key === 'enabled') return item.params.enabled === false ? 'off' : 'on';
+  if (key === 'channel') return normalizeRadioChannel(item.params.channel);
   if (key === 'effect') return normalizeRadioEffect(item.params.effect);
   if (key === 'effectValue') return String(normalizeRadioEffectValue(item.params.effectValue));
   const globalValue = ITEM_TYPE_GLOBAL_PROPERTIES[item.type]?.[key];

server/app/item_catalog.py

@@ -20,7 +20,7 @@ ITEM_DEFINITIONS: dict[ItemType, ItemDefinition] = {
         default_title="radio",
         capabilities=("editable", "carryable", "deletable", "usable"),
         use_sound=None,
-        default_params={"streamUrl": "", "enabled": True, "volume": 50, "effect": "off", "effectValue": 50},
+        default_params={"streamUrl": "", "enabled": True, "channel": "stereo", "volume": 50, "effect": "off", "effectValue": 50},
     ),
     "dice": ItemDefinition(
         default_title="Dice",

server/app/server.py

@@ -49,6 +49,7 @@ LOGGER = logging.getLogger("chgrid.server")
 PACKET_LOGGER = logging.getLogger("chgrid.server.packet")
 CLIENT_PACKET_ADAPTER = TypeAdapter(ClientPacket)
 RADIO_EFFECT_IDS = {"reverb", "echo", "flanger", "high_pass", "low_pass", "off"}
+RADIO_CHANNEL_IDS = {"stereo", "mono", "left", "right"}
 
 
 class SignalingServer:
@@ -615,6 +616,18 @@ class SignalingServer:
                         return
                     next_params["effect"] = effect
 
+                    channel = str(next_params.get("channel", "stereo")).strip().lower()
+                    if channel not in RADIO_CHANNEL_IDS:
+                        await self._send_item_result(
+                            client,
+                            False,
+                            "update",
+                            "channel must be one of stereo, mono, left, right.",
+                            item.id,
+                        )
+                        return
+                    next_params["channel"] = channel
+
                     try:
                         effect_value = int(next_params.get("effectValue", 50))
                     except (TypeError, ValueError):

server/tests/test_item_use_cooldown.py

@@ -82,3 +82,38 @@ async def test_radio_use_toggles_enabled(monkeypatch: pytest.MonkeyPatch) -> Non
     assert send_payloads[-1].ok is True
 
     assert any(getattr(packet, "type", "") == "item_upsert" for packet in broadcast_payloads)
+
+
+@pytest.mark.asyncio
+async def test_radio_channel_update_validates(monkeypatch: pytest.MonkeyPatch) -> None:
+    server = SignalingServer("127.0.0.1", 8765, None, None)
+    ws = _fake_ws()
+    client = ClientConnection(websocket=ws, id="u1", nickname="tester", x=5, y=6)
+    server.clients[ws] = client
+    item = server.item_service.default_item(client, "radio_station")
+    server.item_service.add_item(item)
+
+    send_payloads: list[object] = []
+
+    async def fake_send(websocket: ServerConnection, packet: object) -> None:
+        send_payloads.append(packet)
+
+    async def fake_broadcast(packet: object, exclude: ServerConnection | None = None) -> None:
+        return
+
+    monkeypatch.setattr(server, "_send", fake_send)
+    monkeypatch.setattr(server, "_broadcast", fake_broadcast)
+
+    await server._handle_message(
+        client,
+        json.dumps({"type": "item_update", "itemId": item.id, "params": {"channel": "left"}}),
+    )
+    assert send_payloads[-1].ok is True
+    assert item.params.get("channel") == "left"
+
+    await server._handle_message(
+        client,
+        json.dumps({"type": "item_update", "itemId": item.id, "params": {"channel": "invalid"}}),
+    )
+    assert send_payloads[-1].ok is False
+    assert "channel must be one of" in send_payloads[-1].message.lower()