diff --git a/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs b/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
index 2cb2068d51..a687560bf1 100644
--- a/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
+++ b/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
@@ -110,6 +110,73 @@ test("relayAgentIsSharedWithUser: accepts allowlist agents for the current user"
   );
 });
 
+test("relayAgentIsSharedWithUser: an owner-only agent is invocable by its owner", () => {
+  const agent = {
+    respondTo: "owner-only",
+    respondToAllowlist: [],
+    channelIds: ["general"],
+  };
+  const sharedChannelIds = new Set(["general"]);
+
+  assert.equal(
+    relayAgentIsSharedWithUser(agent, sharedChannelIds, CURRENT_PUBKEY, true),
+    true,
+  );
+  // Someone else's owner-only agent stays out of reach.
+  assert.equal(
+    relayAgentIsSharedWithUser(agent, sharedChannelIds, CURRENT_PUBKEY, false),
+    false,
+  );
+  // Ownership is matched, never assumed: no viewer identity, no admission.
+  assert.equal(
+    relayAgentIsSharedWithUser(agent, sharedChannelIds, null, true),
+    false,
+  );
+});
+
+test("getMentionableAgentPubkeys: admits an owner-only relay agent for its owner", () => {
+  const relayAgents = [
+    {
+      pubkey: PUB_A,
+      respondTo: "owner-only",
+      respondToAllowlist: [],
+      channelIds: ["general"],
+    },
+    {
+      pubkey: PUB_B,
+      respondTo: "owner-only",
+      respondToAllowlist: [],
+      channelIds: ["general"],
+    },
+  ];
+  const call = (overrides) =>
+    getMentionableAgentPubkeys({
+      currentPubkey: CURRENT_PUBKEY,
+      eligibilityScope: { type: "channel", channelId: "general" },
+      managedAgentPubkeys: [],
+      relayAgents,
+      ...overrides,
+    });
+  const profiles = {
+    [PUB_A]: { ownerPubkey: CURRENT_PUBKEY.toUpperCase() },
+    [PUB_B]: { ownerPubkey: OTHER_OWNER_PUBKEY },
+  };
+
+  assert.deepEqual([...call({ profiles })], [PUB_A]);
+  // The owner still only reaches the agent in channels it actually joined.
+  assert.deepEqual(
+    [
+      ...call({
+        eligibilityScope: { type: "channel", channelId: "other" },
+        profiles,
+      }),
+    ],
+    [],
+  );
+  // No owner metadata, no admission -- unchanged from before.
+  assert.deepEqual([...call({})], []);
+});
+
 test("relayAgentCanRespondInChannel: requires exact channel membership and viewer access", () => {
   const agent = {
     respondTo: "allowlist",
diff --git a/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts b/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
index 0abdad82fa..de36873061 100644
--- a/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
+++ b/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
@@ -1,3 +1,5 @@
+import { mergeOwnedAgentPubkeys } from "@/features/agents/knownAgentPubkeys";
+import type { UserProfileLookup } from "@/features/profile/lib/identity";
 import type { Channel, RelayAgent } from "@/shared/api/types";
 import { normalizePubkey } from "@/shared/lib/pubkey";
 
@@ -13,11 +15,21 @@ export function relayAgentIsSharedWithUser(
   agent: Pick<RelayAgent, "channelIds" | "respondTo" | "respondToAllowlist">,
   sharedChannelIds: ReadonlySet<string>,
   currentPubkey?: string | null,
+  isOwnedByViewer = false,
 ) {
   const normalizedCurrentPubkey = currentPubkey
     ? normalizePubkey(currentPubkey)
     : null;
 
+  // `owner-only` names exactly one person who may instruct the agent, so that
+  // person can invoke it. It is also the server default, so an agent created
+  // without an explicit mode used to be invocable by nobody at all. Ownership
+  // is matched, never assumed: an agent whose owner we cannot resolve stays
+  // hidden.
+  if (agent.respondTo === "owner-only") {
+    return isOwnedByViewer && normalizedCurrentPubkey !== null;
+  }
+
   if (agent.respondTo === "allowlist" && normalizedCurrentPubkey) {
     return agent.respondToAllowlist
       .map((pubkey) => normalizePubkey(pubkey))
@@ -34,10 +46,16 @@ export function relayAgentCanRespondInChannel(
   agent: Pick<RelayAgent, "channelIds" | "respondTo" | "respondToAllowlist">,
   channelId: string,
   currentPubkey?: string | null,
+  isOwnedByViewer = false,
 ) {
   return (
     agent.channelIds.includes(channelId) &&
-    relayAgentIsSharedWithUser(agent, new Set([channelId]), currentPubkey)
+    relayAgentIsSharedWithUser(
+      agent,
+      new Set([channelId]),
+      currentPubkey,
+      isOwnedByViewer,
+    )
   );
 }
 
@@ -46,33 +64,57 @@ export type AgentEligibilityScope =
   | { type: "channel"; channelId: string }
   | { type: "managed-only" };
 
+const EMPTY_CHANNEL_IDS: ReadonlySet<string> = new Set();
+
 export function getMentionableAgentPubkeys({
   currentPubkey,
   eligibilityScope,
   managedAgentPubkeys,
+  profiles,
   relayAgents,
-  sharedChannelIds,
+  sharedChannelIds = EMPTY_CHANNEL_IDS,
 }: {
   currentPubkey?: string | null;
   eligibilityScope: AgentEligibilityScope;
   managedAgentPubkeys: Iterable<string>;
+  /**
+   * Profile metadata, the only place an agent's owner is published: the relay
+   * directory (`RelayAgent`) carries no owner field. Omit it and `owner-only`
+   * agents stay hidden, which is the pre-existing behaviour.
+   */
+  profiles?: UserProfileLookup;
   relayAgents: readonly RelayAgent[] | undefined;
-  sharedChannelIds: ReadonlySet<string>;
+  /** Read only by the `community` scope; the others derive their own. */
+  sharedChannelIds?: ReadonlySet<string>;
 }) {
   const pubkeys = new Set(
     [...managedAgentPubkeys].map((pubkey) => normalizePubkey(pubkey)),
   );
+  const ownedAgentPubkeys = mergeOwnedAgentPubkeys(
+    undefined,
+    profiles,
+    currentPubkey,
+  );
 
   for (const agent of relayAgents ?? []) {
+    const isOwnedByViewer = ownedAgentPubkeys.has(
+      normalizePubkey(agent.pubkey),
+    );
     const isAllowed =
       eligibilityScope.type === "managed-only"
         ? false
         : eligibilityScope.type === "community"
-          ? relayAgentIsSharedWithUser(agent, sharedChannelIds, currentPubkey)
+          ? relayAgentIsSharedWithUser(
+              agent,
+              sharedChannelIds,
+              currentPubkey,
+              isOwnedByViewer,
+            )
           : relayAgentCanRespondInChannel(
               agent,
               eligibilityScope.channelId,
               currentPubkey,
+              isOwnedByViewer,
             );
     if (isAllowed) {
       pubkeys.add(normalizePubkey(agent.pubkey));
diff --git a/desktop/src/features/messages/lib/useMentions.ts b/desktop/src/features/messages/lib/useMentions.ts
index cd52b1bebf..fc77658433 100644
--- a/desktop/src/features/messages/lib/useMentions.ts
+++ b/desktop/src/features/messages/lib/useMentions.ts
@@ -5,10 +5,7 @@ import {
   useRelayAgentsQuery,
   useTeamsQuery,
 } from "@/features/agents/hooks";
-import {
-  useChannelMembersQuery,
-  useChannelsQuery,
-} from "@/features/channels/hooks";
+import { useChannelMembersQuery } from "@/features/channels/hooks";
 import { useIsArchivedPredicate } from "@/features/identity-archive/hooks";
 import type { MentionSuggestion } from "@/features/messages/ui/MentionAutocomplete";
 import {
@@ -16,7 +13,6 @@ import {
   coalesceAutocompleteCandidatesByKey,
   filterCachedAgentSuggestions,
   getMentionableAgentPubkeys,
-  getSharedChannelIds,
   isAgentIdentityInAllowedList,
   isAgentMentionChannelType,
   shouldHideAgentFromMentions,
@@ -107,7 +103,6 @@ export function useMentions(
   const isArchivedDiscovery = useIsArchivedPredicate();
   const managedAgentsQuery = useManagedAgentsQuery();
   const relayAgentsQuery = useRelayAgentsQuery();
-  const channelsQuery = useChannelsQuery();
   const personasQuery = usePersonasQuery();
   const teamsQuery = useTeamsQuery();
   const managedAgentDirectoryReady =
@@ -190,10 +185,6 @@ export function useMentions(
       ),
     [relayAgentsQuery.data],
   );
-  const sharedChannelIds = React.useMemo(
-    () => getSharedChannelIds(channelsQuery.data),
-    [channelsQuery.data],
-  );
   const mentionChannelId = isAgentMentionChannelType(options?.channelType)
     ? channelId
     : null;
@@ -205,15 +196,15 @@ export function useMentions(
           ? { type: "channel", channelId: mentionChannelId }
           : { type: "managed-only" },
         managedAgentPubkeys,
+        profiles,
         relayAgents: relayAgentsQuery.data,
-        sharedChannelIds,
       }),
     [
       currentPubkey,
       managedAgentPubkeys,
       mentionChannelId,
+      profiles,
       relayAgentsQuery.data,
-      sharedChannelIds,
     ],
   );
   const personaNameByPubkey = React.useMemo(() => {