diff --git a/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs b/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
index 0f911ad41bf..5d7f6a1b63b 100644
--- a/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
+++ b/desktop/src/features/agents/lib/agentAutocompleteEligibility.test.mjs
@@ -7,6 +7,7 @@ import {
   getMentionableAgentPubkeys,
   getSharedChannelIds,
   isAgentIdentityInAllowedList,
+  isAgentIdentityMentionable,
   isAgentMentionChannelType,
   relayAgentCanRespondInChannel,
   relayAgentIsSharedWithUser,
@@ -21,6 +22,7 @@ const PUB_A = "1".repeat(64);
 const PUB_B = "2".repeat(64);
 const PUB_C = "3".repeat(64);
 const PUB_D = "4".repeat(64);
+const PUB_HEX = "ab".repeat(32);
 
 function coalesce(candidates, options = {}) {
   return coalesceAgentAutocompleteCandidates(candidates, {
@@ -255,6 +257,52 @@ test("isAgentIdentityInAllowedList: keeps people and only explicitly allowed age
   );
 });
 
+test("isAgentIdentityMentionable: keeps people, managed agents, and mentionable relay agents", () => {
+  // Mirrors useMentions: the mentionable set from getMentionableAgentPubkeys
+  // is managed agents (PUB_A, PUB_HEX) plus shared relay agents (PUB_B).
+  const mentionableAgentPubkeys = new Set([PUB_A, PUB_B, PUB_HEX]);
+
+  assert.equal(
+    isAgentIdentityMentionable(
+      { isAgent: false, pubkey: PUB_C },
+      mentionableAgentPubkeys,
+    ),
+    true,
+  );
+  assert.equal(
+    isAgentIdentityMentionable(
+      { isAgent: true, pubkey: PUB_HEX.toUpperCase() },
+      mentionableAgentPubkeys,
+    ),
+    true,
+  );
+  assert.equal(
+    isAgentIdentityMentionable(
+      { isAgent: true, pubkey: PUB_B },
+      mentionableAgentPubkeys,
+    ),
+    true,
+  );
+  assert.equal(
+    isAgentIdentityMentionable(
+      { isAgent: true, pubkey: PUB_C },
+      mentionableAgentPubkeys,
+    ),
+    false,
+  );
+  // Member agent with no usable directory record: isMember does not bypass
+  // the gate — an agent identity outside the mentionable set is filtered
+  // here, before shouldHideAgentFromMentions' member branch can run
+  // (pre-existing behavior, deliberately pinned).
+  assert.equal(
+    isAgentIdentityMentionable(
+      { isAgent: true, isMember: true, pubkey: PUB_D },
+      mentionableAgentPubkeys,
+    ),
+    false,
+  );
+});
+
 test("shouldHideAgentFromMentions: never hides non-agents", () => {
   assert.equal(
     shouldHideAgentFromMentions({
@@ -307,6 +355,10 @@ test("shouldHideAgentFromMentions: hides member agents with an explicit not-invo
   );
 });
 
+// Note: in useMentions' addCandidate flow this member branch only runs for
+// candidates that already passed isAgentIdentityMentionable, which requires
+// mentionable-set membership — so this unit behavior is currently unreachable
+// end-to-end there (see the pinned member-agent case above).
 test("shouldHideAgentFromMentions: shows member agents with unknown invocability (not in directory)", () => {
   assert.equal(
     shouldHideAgentFromMentions({
diff --git a/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts b/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
index 3fb4e23c154..20bb187b626 100644
--- a/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
+++ b/desktop/src/features/agents/lib/agentAutocompleteEligibility.ts
@@ -92,6 +92,25 @@ export function isAgentIdentityInAllowedList(
   );
 }
 
+/**
+ * Managed-list membership alone cannot admit remote agents: managed agents
+ * are never minted from relay events (see apply_inbound_managed_agent), so a
+ * shared relay agent has no local record on this device. Mention candidacy
+ * therefore checks the mentionable set from getMentionableAgentPubkeys —
+ * locally managed agents plus directory-mentionable relay agents, the same
+ * eligibility `useNewMessageRecipients` already trusts. An agent identity
+ * outside that set stays hidden.
+ */
+export function isAgentIdentityMentionable(
+  candidate: { isAgent?: boolean; pubkey: string },
+  mentionableAgentPubkeys: ReadonlySet<string>,
+) {
+  return (
+    candidate.isAgent !== true ||
+    mentionableAgentPubkeys.has(normalizePubkey(candidate.pubkey))
+  );
+}
+
 export function shouldHideAgentFromMentions({
   isAgent,
   isMember,
diff --git a/desktop/src/features/agents/lib/personaCatalogRelay.test.mjs b/desktop/src/features/agents/lib/personaCatalogRelay.test.mjs
index ef516f4b01c..c02644c0129 100644
--- a/desktop/src/features/agents/lib/personaCatalogRelay.test.mjs
+++ b/desktop/src/features/agents/lib/personaCatalogRelay.test.mjs
@@ -367,7 +367,7 @@ test("test_foreign_entry_with_no_local_copy_stays_unselected", () => {
     BOB,
   );
 
-  assert.equal(personas[0].id, "catalog:" + ALICE + ":reviewer");
+  assert.equal(personas[0].id, `catalog:${ALICE}:reviewer`);
   assert.equal(personas[0].isActive, false);
 });
 
@@ -388,7 +388,7 @@ test("test_catalog_source_match_is_scoped_to_the_publishing_owner", () => {
     ALICE,
   );
 
-  assert.equal(personas[0].id, "catalog:" + BOB + ":reviewer");
+  assert.equal(personas[0].id, `catalog:${BOB}:reviewer`);
   assert.equal(personas[0].isActive, false);
 });
 
diff --git a/desktop/src/features/messages/lib/useMentions.ts b/desktop/src/features/messages/lib/useMentions.ts
index cd52b1bebf3..daf1a4ae49e 100644
--- a/desktop/src/features/messages/lib/useMentions.ts
+++ b/desktop/src/features/messages/lib/useMentions.ts
@@ -17,7 +17,7 @@ import {
   filterCachedAgentSuggestions,
   getMentionableAgentPubkeys,
   getSharedChannelIds,
-  isAgentIdentityInAllowedList,
+  isAgentIdentityMentionable,
   isAgentMentionChannelType,
   shouldHideAgentFromMentions,
   uniqueAutocompleteLabels,
@@ -255,7 +255,7 @@ export function useMentions(
       if (isArchivedDiscovery(pubkey)) {
         return;
       }
-      if (!isAgentIdentityInAllowedList(candidate, mentionableAgentPubkeys)) {
+      if (!isAgentIdentityMentionable(candidate, mentionableAgentPubkeys)) {
         return;
       }
       if (
diff --git a/desktop/tests/e2e/mentions.spec.ts b/desktop/tests/e2e/mentions.spec.ts
index ed00e8c3556..cfa7bb63d18 100644
--- a/desktop/tests/e2e/mentions.spec.ts
+++ b/desktop/tests/e2e/mentions.spec.ts
@@ -250,6 +250,9 @@ test("@ trigger prioritizes channel members before runnable personas and other m
 
   const dropdown = autocomplete(page);
   await expect(dropdown).toBeVisible();
+  // alice is a shared relay agent (directory respond_to: "anyone" with a
+  // shared channel) and a channel member: mentionable even though she is
+  // not locally managed.
   await expect(dropdown.getByText("alice")).toBeVisible();
   await expect(dropdown.getByText("bob")).toBeVisible();
   await expect(dropdown.getByText("Fizz")).toBeVisible();
@@ -280,8 +283,10 @@ test("@ trigger prioritizes channel members before runnable personas and other m
   expect(bobIndex).toBeGreaterThanOrEqual(0);
   expect(charlieIndex).toBeGreaterThanOrEqual(0);
   expect(outsiderIndex).toEqual(-1);
-  expect(aliceIndex).toBeLessThan(fizzIndex);
   expect(bobIndex).toBeLessThan(fizzIndex);
+  // alice is a channel member, so she sorts in the member tier ahead of
+  // personas and non-member managed agents.
+  expect(aliceIndex).toBeLessThan(fizzIndex);
   expect(fizzIndex).toBeLessThan(charlieIndex);
 });