fix(desktop): relay-scope the channel agent reuse finders

Complete the cross-community reuse fix on the *creation* path. The attach
guards (commit b49523e7f) stopped a foreign-relay agent from being
silently attached, but the reuse finders that decide "reuse existing vs
create new" were still relay-unfiltered: a persona/generic agent pinned to
community A's relay would surface as a reuse candidate while Desktop viewed
community B, so creating a B agent could return the deaf A agent instead of
a fresh B one — user-visible wrongness (Eva's scope call).

Relay-scope all three reuse finders with the existing
`agentBelongsToRelay` helper:

1. `findReusablePersonaAgent` / `findReusableGenericAgent` gain a REQUIRED
   `activeRelayUrl` and filter candidates to the active community's relay
   before preference selection. A foreign-relay candidate is excluded, so
   the caller falls through to creating a fresh agent on the active relay.
2. `findReusableAgent` (the routing wrapper) threads `activeRelayUrl`
   through to both finders.
3. Both consumers pass it: `provisionChannelManagedAgent`'s context (via
   `createChannelManagedAgents(..., activeRelayUrl)` and the provision
   mutation hook) and the `useReusableAgentDetection` UI guardrail, each
   sourcing the relay from `useActiveRelayUrl()`.

The param is REQUIRED so the compiler finds every caller and no future
call can silently bypass the scope. `agentBelongsToRelay` stays permissive
for blank pins / blank active relay, so existing tests and legacy blank-pin
records are unaffected.

Four unit tests cover the new behavior: a B-pinned persona/generic
candidate is excluded when the active relay is A (fresh agent created, no
error), a same-relay candidate is still reused, and the wrapper routes the
foreign-relay persona case to a fresh agent. 42/42 agentReuse tests pass;
tsc --noEmit and biome check clean.

Stacked on wren/agents-every-community-successor (commit #4 on b49523e7f).

Co-authored-by: npub17jjz49l9jjmhhk7cac63j8yt9z555n9cw8vk7v5jz4vzw4ppld5qgj57cc <f4a42a97e594b77bdbd8ee35191c8b28a94a4cb871d96f32921558275421fb68@sprout-oss.stage.blox.sqprod.co>
Signed-off-by: npub17jjz49l9jjmhhk7cac63j8yt9z555n9cw8vk7v5jz4vzw4ppld5qgj57cc <f4a42a97e594b77bdbd8ee35191c8b28a94a4cb871d96f32921558275421fb68@sprout-oss.stage.blox.sqprod.co>

desktop/src/features/agents/agentReuse.test.mjs

@@ -308,6 +308,71 @@ test("findReusableGenericAgent: command matching uses normalization", () => {
   assert.equal(result, agent);
 });
 
+test("findReusablePersonaAgent: excludes agent pinned to a different relay", () => {
+  const agent = makeAgent({
+    personaId: "persona-1",
+    pubkey: PUB_A,
+    relayUrl: "wss://relay-a.example",
+  });
+  const channelMembers = new Set([PUB_B]);
+  const result = findReusablePersonaAgent(
+    [agent],
+    "persona-1",
+    channelMembers,
+    "wss://relay-b.example",
+  );
+  assert.equal(result, undefined);
+});
+
+test("findReusablePersonaAgent: reuses agent pinned to the active relay", () => {
+  const agent = makeAgent({
+    personaId: "persona-1",
+    pubkey: PUB_A,
+    relayUrl: "wss://relay-b.example",
+  });
+  const channelMembers = new Set([PUB_B]);
+  const result = findReusablePersonaAgent(
+    [agent],
+    "persona-1",
+    channelMembers,
+    "wss://relay-b.example",
+  );
+  assert.equal(result, agent);
+});
+
+test("findReusableGenericAgent: excludes agent pinned to a different relay", () => {
+  const agent = makeAgent({
+    agentCommand: "goose",
+    personaId: null,
+    systemPrompt: null,
+    relayUrl: "wss://relay-a.example",
+  });
+  const channelMembers = new Set([PUB_B]);
+  const result = findReusableGenericAgent(
+    [agent],
+    "goose",
+    channelMembers,
+    "wss://relay-b.example",
+  );
+  assert.equal(result, undefined);
+});
+
+test("findReusableAgent: foreign-relay persona candidate yields fresh agent (no reuse)", () => {
+  const agent = makeAgent({
+    personaId: "p1",
+    pubkey: PUB_A,
+    relayUrl: "wss://relay-a.example",
+  });
+  const channelMembers = new Set([PUB_B]);
+  const result = findReusableAgent(
+    [agent],
+    channelMembers,
+    { personaId: "p1", command: "goose" },
+    "wss://relay-b.example",
+  );
+  assert.equal(result, undefined);
+});
+
 test("findReusableAgent: routes to persona search when personaId provided", () => {
   const agent = makeAgent({ personaId: "p1", pubkey: PUB_A });
   const channelMembers = new Set([PUB_B]);

desktop/src/features/agents/agentReuse.ts

@@ -1,3 +1,4 @@
+import { agentBelongsToRelay } from "@/features/agents/agentRelayScope";
 import type { ManagedAgent } from "@/shared/api/types";
 
 /** Inline normalization — avoids runtime dependency on @/shared/lib/pubkey. */
@@ -50,11 +51,13 @@ export function findReusablePersonaAgent(
   agents: ManagedAgent[],
   personaId: string,
   channelMemberPubkeys: ReadonlySet<string>,
+  activeRelayUrl: string | null | undefined,
 ): ManagedAgent | undefined {
   const candidates = agents.filter(
     (agent) =>
       agent.personaId === personaId &&
-      !channelMemberPubkeys.has(normalizePubkey(agent.pubkey)),
+      !channelMemberPubkeys.has(normalizePubkey(agent.pubkey)) &&
+      agentBelongsToRelay(agent.relayUrl, activeRelayUrl),
   );
   return pickPreferredManagedAgent(candidates);
 }
@@ -63,13 +66,15 @@ export function findReusableGenericAgent(
   agents: ManagedAgent[],
   command: string,
   channelMemberPubkeys: ReadonlySet<string>,
+  activeRelayUrl: string | null | undefined,
 ): ManagedAgent | undefined {
   const candidates = agents.filter(
     (agent) =>
       !agent.personaId &&
       !agent.systemPrompt?.trim() &&
       commandsMatch(agent.agentCommand, command) &&
-      !channelMemberPubkeys.has(normalizePubkey(agent.pubkey)),
+      !channelMemberPubkeys.has(normalizePubkey(agent.pubkey)) &&
+      agentBelongsToRelay(agent.relayUrl, activeRelayUrl),
   );
   return pickPreferredManagedAgent(candidates);
 }
@@ -86,12 +91,14 @@ export function findReusableAgent(
     systemPrompt?: string;
     command: string;
   },
+  activeRelayUrl: string | null | undefined,
 ): ManagedAgent | undefined {
   if (input.personaId) {
     return findReusablePersonaAgent(
       agents,
       input.personaId,
       channelMemberPubkeys,
+      activeRelayUrl,
     );
   }
   if (!input.systemPrompt?.trim()) {
@@ -99,6 +106,7 @@ export function findReusableAgent(
       agents,
       input.command,
       channelMemberPubkeys,
+      activeRelayUrl,
     );
   }
   return undefined;

desktop/src/features/agents/channelAgents.ts

@@ -299,6 +299,7 @@ export async function provisionChannelManagedAgent(
   context?: {
     managedAgents?: ManagedAgent[];
     channelMemberPubkeys?: ReadonlySet<string>;
+    activeRelayUrl?: string | null;
   },
 ): Promise<ProvisionChannelManagedAgentResult> {
   const trimmedName = input.name.trim();
@@ -319,6 +320,7 @@ export async function provisionChannelManagedAgent(
       context.managedAgents,
       input.personaId,
       context.channelMemberPubkeys,
+      context.activeRelayUrl,
     );
     if (reusable) {
       // Apply the caller's respondTo settings so the user's permission
@@ -359,6 +361,7 @@ export async function provisionChannelManagedAgent(
       context.managedAgents,
       input.runtime.command,
       context.channelMemberPubkeys,
+      context.activeRelayUrl,
     );
     if (reusable) {
       const needsRespondToUpdate =
@@ -464,7 +467,7 @@ export async function createChannelManagedAgents(
   const channelMemberPubkeys = new Set(
     members.map((m) => normalizePubkey(m.pubkey)),
   );
-  const context = { managedAgents, channelMemberPubkeys };
+  const context = { managedAgents, channelMemberPubkeys, activeRelayUrl };
 
   // Sequential loop: each agent must be fully created and its relay membership
   // written before the next starts. Concurrent writes to the replaceable

desktop/src/features/agents/hooks.ts

@@ -711,6 +711,7 @@ export function useProvisionChannelManagedAgentMutation(
   channelId: string | null,
 ) {
   const queryClient = useQueryClient();
+  const activeRelayUrl = useActiveRelayUrl();
 
   return useMutation({
     mutationFn: async (
@@ -731,6 +732,7 @@ export function useProvisionChannelManagedAgentMutation(
         channelMemberPubkeys: new Set(
           members.map((member) => normalizePubkey(member.pubkey)),
         ),
+        activeRelayUrl,
       });
     },
     onSuccess: (result) => {

desktop/src/features/channels/ui/useReusableAgentDetection.ts

@@ -5,6 +5,7 @@ import {
   useManagedAgentsQuery,
 } from "@/features/agents/hooks";
 import { useChannelMembersQuery } from "@/features/channels/hooks";
+import { useActiveRelayUrl } from "@/features/communities/useCommunities";
 import { normalizePubkey } from "@/shared/lib/pubkey";
 import type { AcpRuntime, ManagedAgent } from "@/shared/api/types";
 
@@ -25,6 +26,7 @@ export function useReusableAgentDetection(
 ): ManagedAgent | undefined {
   const managedAgentsQuery = useManagedAgentsQuery();
   const channelMembersQuery = useChannelMembersQuery(channelId, enabled);
+  const activeRelayUrl = useActiveRelayUrl();
 
   return React.useMemo(() => {
     const agents = managedAgentsQuery.data;
@@ -36,10 +38,15 @@ export function useReusableAgentDetection(
 
     // For persona selection: check the first selected persona
     if (selectedPersonas.length === 1 && !includeGeneric) {
-      return findReusableAgent(agents, memberPubkeys, {
-        personaId: selectedPersonas[0].id,
-        command: selectedRuntime.command,
-      });
+      return findReusableAgent(
+        agents,
+        memberPubkeys,
+        {
+          personaId: selectedPersonas[0].id,
+          command: selectedRuntime.command,
+        },
+        activeRelayUrl,
+      );
     }
 
     // For generic agent with no custom prompt
@@ -48,10 +55,15 @@ export function useReusableAgentDetection(
       selectedPersonas.length === 0 &&
       !customPrompt.trim()
     ) {
-      return findReusableAgent(agents, memberPubkeys, {
-        command: selectedRuntime.command,
-        systemPrompt: customPrompt,
-      });
+      return findReusableAgent(
+        agents,
+        memberPubkeys,
+        {
+          command: selectedRuntime.command,
+          systemPrompt: customPrompt,
+        },
+        activeRelayUrl,
+      );
     }
 
     return undefined;
@@ -62,5 +74,6 @@ export function useReusableAgentDetection(
     selectedPersonas,
     includeGeneric,
     customPrompt,
+    activeRelayUrl,
   ]);
 }