feat(web): host_unreachable phase copy for dm_call_undeliverable (TDD)

packages/web/src/utils/callUndeliverableToast.ts

@@ -9,6 +9,9 @@
  * - `reject`: the rejector's relay to the host failed; state was already cleared
  *   locally, so non-terminal info toast only.
  * - `end`: the ender's relay to the host failed; state was already cleared locally.
+ * - `host_unreachable`: the call was terminated by the sentinel worker because the
+ *   host peer became permanently unreachable. Always terminal. A single failure entry
+ *   is expected; multiple fall back to a generic line.
  *
  * Extracted from `useWebSocket.ts` so it can be unit-tested without pulling in
  * the full WS handler graph (livekit / audio deps).
@@ -16,7 +19,7 @@
 export function buildCallUndeliverableToast(
   failures: Array<{ reason: string; peerOrigin?: string; peerLabel?: string }>,
   terminal: boolean,
-  phase: 'start' | 'accept' | 'reject' | 'end' = 'start',
+  phase: 'start' | 'accept' | 'reject' | 'end' | 'host_unreachable' = 'start',
 ): string {
   const primary = failures[0];
   const labelFor = (f: { peerLabel?: string; peerOrigin?: string }) =>
@@ -37,6 +40,21 @@ export function buildCallUndeliverableToast(
     return `Couldn't notify ${labels} that you hung up. Remote participants may see the call for up to 60 seconds.`;
   }
 
+  // host_unreachable: call terminated because the host peer became unreachable.
+  // Terminal is always true in this phase. A single failure entry is expected;
+  // zero or multiple fall back to a generic line.
+  if (phase === 'host_unreachable') {
+    const [f] = failures;
+    if (!f || failures.length !== 1) {
+      return 'Call ended — host instance became unreachable.';
+    }
+    const label = f.peerLabel || f.peerOrigin?.replace(/^https?:\/\//, '') || 'the host instance';
+    if (f.reason === 'peer_rejected') {
+      return `Call ended — this instance is no longer peered with ${label}.`;
+    }
+    return `Call ended — ${label} became unreachable.`;
+  }
+
   // phase === 'start' (default + legacy)
   if (!terminal) {
     const labels = failures.map(labelFor).join(', ');