fix(desktop): surface agent rename relay profile sync failure as a warning toast (#2279)

Fixes #1822

## Problem

Renaming an agent via the agent settings dialog performs a local save
(always succeeds) and a best-effort relay kind:0 republish (can fail:
network blip, auth expiry, relay unreachable). On sync failure the
dialog `console.warn`'d the error and closed as a clean success — the
user had no signal that the relay still holds the old name, which breaks
`@mention` resolution and shows the stale name in other agents' `From:`
lines (discovered via #1743).

## Fix

Surface `profileSyncError` as a `toast.warning` in
`AgentInstanceEditDialog`, matching the treatment the create and
persona-save paths already give the same field
(`useManagedAgentActions.ts`, `UserProfilePanelPersonaSubmit.ts`). The
save is not blocked — the local rename is valid and persists, per the
issue's guidance.

The toast points at the retry path that actually works: **restarting the
agent**. Re-saving the same name does not retry — `update_managed_agent`
computes `name_changed` against the already-updated record, so a second
identical save skips the sync — but `start_managed_agent` fires
`reconcile_agent_profile`, which queries the relay's kind:0 and
republishes when the display name diverges.

Scope notes:

- `EditRespondToDialog` (the third caller of the update mutation) never
changes the name, and the Rust side only sets `profile_sync_error` when
the name changed — so no change needed there.
- The alternative fix in the issue (retry-with-backoff in
`sync_managed_agent_profile`) is not taken here;
`reconcile_agent_profile` on agent start already provides self-healing,
and this change makes that path discoverable at the moment of failure.

## Testing

- `just desktop-check` — biome + file-size + px-text + pubkey-truncation
guards clean.
- `just desktop-test` — 3331 passed, 0 failed.
- The handler branch is a straight conditional on the mutation result;
the repo's `.test.mjs` convention covers extracted pure logic, and there
is no extracted logic here to unit-test (consistent with the equivalent
toast branches on the create/persona paths).

---------

Signed-off-by: ayobamiseun <adegokeayobamiseun@gmail.com>
Signed-off-by: npub1mprnacetjua2xx3p5eddmhxyk6wv929ymm5py8kd2xfxurxahspqqlgyta <d8473ee32b973aa31a21a65adddcc4b69cc2a8a4dee8121ecd51926e0cddbc02@buzz.block.builderlab.xyz>
Co-authored-by: npub1mprnacetjua2xx3p5eddmhxyk6wv929ymm5py8kd2xfxurxahspqqlgyta <d8473ee32b973aa31a21a65adddcc4b69cc2a8a4dee8121ecd51926e0cddbc02@buzz.block.builderlab.xyz>

desktop/src/features/agents/ui/AgentInstanceEditDialog.tsx

@@ -1,7 +1,6 @@
 import * as React from "react";
 import { ChevronDown } from "lucide-react";
 import { AnimatePresence, motion, useReducedMotion } from "motion/react";
-
 import { toast } from "sonner";
 
 import {
@@ -83,6 +82,7 @@ import { AgentDefaultsDialog } from "./AgentDefaultsDialog";
 import { useProviderApiKeyFieldState } from "./providerApiKeyFieldState";
 import { resolveModelFieldStatusMessage } from "./agentConfigControls";
 import { AdvancedRequiredBadge } from "./AdvancedRequiredBadge";
+import { showAgentProfileSyncWarning } from "./agentProfileSyncWarning";
 
 const ADVANCED_FIELDS_MOTION_TRANSITION = {
   duration: 0.18,
@@ -101,8 +101,7 @@ export function AgentInstanceEditDialog({
   /** Optional field to scroll/focus when the dialog opens from a card deep-link. */
   initialFocus?: EditAgentFocusTarget;
   open: boolean;
-  /** Present only when the linked definition is editable (non-built-in,
-   * resolved). Caller closes this dialog and enters definition-edit. */
+  /** Present only when the linked definition is editable (non-built-in, resolved). Caller closes this dialog and enters definition-edit. */
   onEditLinkedPersona?: () => void;
   onOpenChange: (open: boolean) => void;
   onUpdated?: (agent: ManagedAgent) => void;
@@ -706,6 +705,7 @@ export function AgentInstanceEditDialog({
           autoRestartOnConfigChange,
         );
       }
+      showAgentProfileSyncWarning(result.agent.name, result.profileSyncError);
       handleOpenChange(false);
       onUpdated?.(result.agent);
       // The auto-restart policy deliberately never fires for a stopped or

desktop/src/features/agents/ui/agentProfileSyncWarning.ts

@@ -0,0 +1,11 @@
+import { toast } from "sonner";
+
+export function showAgentProfileSyncWarning(
+  agentName: string,
+  profileSyncError: string | null,
+) {
+  if (!profileSyncError) return;
+  toast.warning(
+    `${agentName} was saved, but relay profile sync failed: ${profileSyncError}. The relay may still show the old name — restart the agent to retry the sync.`,
+  );
+}