Limit DM task inference to one agent participant

desktop/src/features/channels/ui/ChannelPane.helpers.test.mjs

@@ -104,6 +104,18 @@ test("DM task agent inference requires exactly one other known agent", () => {
     [],
   );
 
+  assert.deepEqual(
+    getDmTaskAgentPubkeys({
+      channel: channel({
+        channelType: "dm",
+        participantPubkeys: ["human", "agent-one", "human-two"],
+      }),
+      currentPubkey: "human",
+      knownAgentPubkeys,
+    }),
+    [],
+  );
+
   assert.deepEqual(
     getDmTaskAgentPubkeys({
       channel: channel({

desktop/src/features/channels/ui/ChannelPane.helpers.ts

@@ -110,15 +110,22 @@ export function getDmTaskAgentPubkeys({
   const normalizedCurrentPubkey = currentPubkey
     ? normalizePubkey(currentPubkey)
     : null;
+  const otherParticipants = new Map<string, string>();
 
-  return singleKnownAgentPubkey(
-    channel.participantPubkeys.filter(
-      (pubkey) =>
-        !normalizedCurrentPubkey ||
-        normalizePubkey(pubkey) !== normalizedCurrentPubkey,
-    ),
-    knownAgentPubkeys,
-  );
+  for (const pubkey of channel.participantPubkeys) {
+    const normalized = normalizePubkey(pubkey);
+    if (normalizedCurrentPubkey && normalized === normalizedCurrentPubkey) {
+      continue;
+    }
+
+    otherParticipants.set(normalized, pubkey);
+  }
+
+  if (otherParticipants.size !== 1) {
+    return [];
+  }
+
+  return singleKnownAgentPubkey(otherParticipants.values(), knownAgentPubkeys);
 }
 
 export function getThreadTaskAgentPubkeys({