fix: Cache 2-way audio detection to avoid re-probing (#2716)

- Closes: #2299

src/go2rtc/audio.ts

@@ -1,3 +1,6 @@
+import { add } from 'date-fns';
+
+import { ExpiringEqualityCache } from '../cache/expiring-cache';
 import type { EnabledProxyConfig } from '../config/schema/common/proxy';
 import { homeAssistantSignAndFetch } from '../ha/fetch';
 import type { HomeAssistant } from '../ha/types';
@@ -6,20 +9,17 @@ import type { Endpoint } from '../types';
 import { errorToConsole } from '../utils/basic';
 import { go2RTCStreamInfoSchema, type Go2RTCStreamInfo } from './types';
 
-const getGo2RTCStreamMetadata = async (
-  hass: HomeAssistant,
-  endpoint: Endpoint,
-  timeoutSeconds: number,
-): Promise<Go2RTCStreamInfo | null> => {
-  try {
-    return await homeAssistantSignAndFetch(hass, endpoint, go2RTCStreamInfoSchema, {
-      timeoutSeconds,
-    });
-  } catch (e) {
-    errorToConsole(e);
-    return null;
-  }
-};
+// Cache 2-way capabilities: these only changes when go2rtc configuration or
+// camera hardware changes.
+const TWO_WAY_AUDIO_CACHE_SECONDS = 5 * 60;
+
+// Page-scoped because Home Assistant builds a new card on dashboard navigation,
+// and every fetch makes go2rtc connect to the camera.
+// See: https://github.com/dermotduffy/advanced-camera-card/issues/2299
+const twoWayAudioSupportCache = new ExpiringEqualityCache<
+  string,
+  Promise<boolean | null>
+>();
 
 const streamSupports2WayAudio = (streamInfo: Go2RTCStreamInfo | null): boolean => {
   if (!streamInfo?.producers) {
@@ -35,18 +35,35 @@ const streamSupports2WayAudio = (streamInfo: Go2RTCStreamInfo | null): boolean =
   );
 };
 
-/**
- * Fetch go2rtc metadata and determine if the stream supports 2-way audio.
- * Handles proxy transformation if proxy config requires it.
- * Returns false if the endpoint is not available or fetch fails.
- *
- * Note: Caller is responsible for checking if live_provider is 'go2rtc' before calling.
- *
- * @param hass Home Assistant instance.
- * @param go2rtcMetadataEndpoint The go2rtc metadata endpoint.
- * @param proxyConfig The resolved proxy configuration for live streams.
- * @returns True if supports 2-way audio, false otherwise.
- */
+const fetch2WayAudioSupport = async (
+  hass: HomeAssistant,
+  metadataFetchTimeoutSeconds: number,
+  go2rtcMetadataEndpoint: Endpoint,
+  proxyConfig?: EnabledProxyConfig,
+): Promise<boolean | null> => {
+  const endpoint = await createProxiedEndpointIfNecessary(
+    hass,
+    go2rtcMetadataEndpoint,
+    proxyConfig,
+    { openLimit: 1 },
+  );
+  if (!endpoint) {
+    return null;
+  }
+
+  try {
+    return streamSupports2WayAudio(
+      await homeAssistantSignAndFetch(hass, endpoint, go2RTCStreamInfoSchema, {
+        timeoutSeconds: metadataFetchTimeoutSeconds,
+      }),
+    );
+  } catch (e) {
+    errorToConsole(e);
+    return null;
+  }
+};
+
+// Caller must verify the live provider is go2rtc before calling.
 export const supports2WayAudio = async (
   hass: HomeAssistant,
   metadataFetchTimeoutSeconds: number,
@@ -57,20 +74,30 @@ export const supports2WayAudio = async (
     return false;
   }
 
-  const endpoint = await createProxiedEndpointIfNecessary(
-    hass,
-    go2rtcMetadataEndpoint,
-    proxyConfig,
-    { openLimit: 1 },
-  );
-  if (!endpoint) {
-    return false;
+  const key = go2rtcMetadataEndpoint.endpoint;
+  const cachedPromise = twoWayAudioSupportCache.get(key);
+  if (cachedPromise) {
+    return (await cachedPromise) ?? false;
   }
 
-  const streamInfo = await getGo2RTCStreamMetadata(
+  const request = fetch2WayAudioSupport(
     hass,
-    endpoint,
     metadataFetchTimeoutSeconds,
+    go2rtcMetadataEndpoint,
+    proxyConfig,
   );
-  return streamSupports2WayAudio(streamInfo);
+  twoWayAudioSupportCache.set(
+    key,
+    request,
+    add(new Date(), { seconds: TWO_WAY_AUDIO_CACHE_SECONDS }),
+  );
+
+  const isSupported = await request;
+
+  // Inconclusive results are evicted so the next caller retries.
+  if (isSupported === null) {
+    twoWayAudioSupportCache.delete(key);
+  }
+
+  return isSupported ?? false;
 };