fix(fleet-sync): make control-identity-mismatch sticky and surface in UI (#1117)

Treat 409 CONTROL_IDENTITY_MISMATCH from a replica as a non-retriable
failure instead of looping the same 409 through the 5-minute retry
service forever and silently writing identical failure rows.

Backend
- DatabaseService: add `sticky_error_code`, `sticky_error_expected`,
  `sticky_error_got` columns to `fleet_sync_status` via an idempotent
  migration. New methods setFleetSyncSticky, getFleetSyncStickyCode,
  clearFleetSyncStickyForNode. recordFleetSyncSuccess clears the sticky
  flag on a clean push. getFailedSyncTargets SQL adds
  `AND sticky_error_code IS NULL` so the retry loop skips sticky rows.
- FleetSyncService.executePushToNode: short-circuits at the top when
  sticky is set (covers event-driven pushResourceAsync calls). On a 409
  with code CONTROL_IDENTITY_MISMATCH, records the failure once and
  pins sticky with the expected/got fingerprints carried in the 409 body.
- routes/nodes.ts: new POST /api/nodes/:id/fleet-sync/reset-anchor.
  Admin + paid + node:manage. Proxies POST /api/fleet/role/reanchor to
  the peer with `{override:true}` using the stored Bearer node_proxy
  token. On peer 200, clears every sticky row for the node so the next
  push re-anchors and resumes replication. Distinct 502 / 504 responses
  for peer-rejected / peer-unreachable so the UI can show a useful toast.

Frontend
- New lib/fleetSyncApi.ts + hooks/useFleetSyncStatus.ts. Polling hook
  (30s visibilityInterval) skips fetch when !isPaid.
- NodeManager.tsx: destructive banner per affected node listing both
  fingerprints, with `Reset anchor on peer` and `Remove node` buttons.
  Hidden for community-tier users via empty hook data.
- FleetConfiguration.tsx (Fleet -> Status): read-only `Policy sync`
  SummaryRow per remote node card. In sync / degraded / paused with
  a tooltip; no action buttons (the action lives in NodeManager).

Tests
- fleet-sync-service.test.ts: 4 new cases for sticky-set on first
  mismatch, short-circuit on subsequent pushes, null fingerprints,
  and non-mismatch failures not setting sticky.
- database-fleet-sync-sticky.test.ts (new): 6 cases pinning the DB
  contract incl. retry-loop SQL filter and migration idempotency.
- nodes-fleet-sync-reset-anchor.test.ts (new): 6 cases covering
  happy path, peer 401 -> 502, peer unreachable -> 504, local-node
  rejection, unknown node id, and community-tier 403.

Gate parity (Directive 30): the new POST .../reset-anchor enforces
requireAdmin + requirePaid + node:manage (matches the existing read at
GET /api/fleet/sync-status). UI banner + SummaryRow only render when the
hook returns data, which it only does for paid-tier authed users. No
existing tier-gate file moved; this is greenfield parity.

Auth audit: the peer's POST /api/fleet/role/reanchor route already uses
requireAdmin, which accepts the central's stored node_proxy Bearer
token because authMiddleware maps `scope === 'node_proxy'` to
`req.user = { username: 'node-proxy', role: 'admin', userId: 0 }`.
No widening required.

Backend tsc clean. Frontend tsc -b clean. 59 fleet-sync tests pass; full
backend suite green minus the pre-existing Windows-only file-lock flake
on filesystem-backup.test.ts that reproduces unchanged on main.

frontend/src/components/NodeManager.tsx

@@ -9,7 +9,7 @@ import { Badge } from './ui/badge';
 import { Separator } from './ui/separator';
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from './ui/table';
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from './ui/tooltip';
-import { Plus, Trash2, Wifi, WifiOff, Star, Pencil, Monitor, Globe, Copy, KeyRound, Check, Calendar, RefreshCw, Terminal } from 'lucide-react';
+import { AlertTriangle, Plus, Trash2, Wifi, WifiOff, Star, Pencil, Monitor, Globe, Copy, KeyRound, Check, Calendar, RefreshCw, Terminal } from 'lucide-react';
 import { formatTimeUntil, formatTimeAgo } from '@/lib/relativeTime';
 import { SettingsPrimaryButton } from './settings/SettingsActions';
 import { useMastheadStats } from './settings/MastheadStatsContext';
@@ -17,6 +17,8 @@ import { NodeLabelPicker } from './blueprints/NodeLabelPicker';
 import { useLicense } from '@/context/LicenseContext';
 import { useAuth } from '@/context/AuthContext';
 import { useNodeActions, type NodeTestInfo } from './nodes/useNodeActions';
+import { useFleetSyncStatus } from '@/hooks/useFleetSyncStatus';
+import { resetFleetSyncAnchor, STICKY_CONTROL_IDENTITY_MISMATCH } from '@/lib/fleetSyncApi';
 
 interface NodeSchedulingSummary {
   active_tasks: number;
@@ -60,6 +62,48 @@ export function NodeManager() {
     onTestResult: (result) => setTestResult(result),
   });
 
+  const { statuses: syncStatuses, refresh: refreshSyncStatuses } = useFleetSyncStatus();
+  const [resettingAnchor, setResettingAnchor] = useState<number | null>(null);
+
+  // Per-node aggregate of CONTROL_IDENTITY_MISMATCH sticky errors. All resources
+  // for one peer share the same root cause (the peer's cached fingerprint), so
+  // collapse to one entry per node id and surface a single banner.
+  const anchorMismatches = useMemo(() => {
+    const byNode = new Map<number, { expected: string | null; got: string | null; resources: string[] }>();
+    for (const row of syncStatuses) {
+      if (row.sticky_error_code !== STICKY_CONTROL_IDENTITY_MISMATCH) continue;
+      const existing = byNode.get(row.node_id);
+      if (existing) {
+        existing.resources.push(row.resource);
+        if (!existing.expected && row.sticky_error_expected) existing.expected = row.sticky_error_expected;
+        if (!existing.got && row.sticky_error_got) existing.got = row.sticky_error_got;
+      } else {
+        byNode.set(row.node_id, {
+          expected: row.sticky_error_expected,
+          got: row.sticky_error_got,
+          resources: [row.resource],
+        });
+      }
+    }
+    return Array.from(byNode.entries()).map(([nodeId, agg]) => {
+      const node = nodes.find((n) => n.id === nodeId);
+      return { nodeId, node, ...agg };
+    }).filter((entry) => entry.node !== undefined);
+  }, [syncStatuses, nodes]);
+
+  const handleResetAnchor = async (nodeId: number) => {
+    setResettingAnchor(nodeId);
+    try {
+      await resetFleetSyncAnchor(nodeId);
+      toast.success('Anchor reset. Security policy sync will resume on the next push.');
+      refreshSyncStatuses();
+    } catch (error) {
+      toast.error((error as Error).message || 'Failed to reset anchor on peer');
+    } finally {
+      setResettingAnchor(null);
+    }
+  };
+
   const fetchSchedulingSummary = useCallback(async () => {
     try {
       const res = await apiFetch('/nodes/scheduling-summary', { localOnly: true });
@@ -188,6 +232,51 @@ export function NodeManager() {
         )}
       </div>
 
+      {/* Sync issues: surfaces FleetSync sticky errors (currently CONTROL_IDENTITY_MISMATCH). */}
+      {anchorMismatches.length > 0 && (
+        <div className="space-y-3">
+          {anchorMismatches.map(({ nodeId, node, expected, got, resources }) => (
+            <div
+              key={nodeId}
+              className="rounded-lg border border-destructive/40 bg-destructive/10 p-3 text-sm text-destructive flex items-start gap-3 shadow-card-bevel"
+            >
+              <AlertTriangle className="h-4 w-4 mt-0.5 shrink-0" strokeWidth={1.75} />
+              <div className="min-w-0 flex-1 space-y-2">
+                <div className="font-medium">
+                  Node "{node?.name ?? `id ${nodeId}`}" is anchored to another central
+                </div>
+                <div className="text-xs leading-relaxed text-destructive/90">
+                  Security policy sync is paused for {resources.join(', ')}.
+                  {expected && got && (
+                    <> This peer is anchored to <span className="font-mono">{expected}</span>; this central is <span className="font-mono">{got}</span>.</>
+                  )}
+                  {' '}Reset the anchor on the peer to resume sync, or remove the node from this fleet.
+                </div>
+                <div className="flex flex-wrap items-center gap-2 pt-1">
+                  <Button
+                    size="sm"
+                    variant="destructive"
+                    onClick={() => handleResetAnchor(nodeId)}
+                    disabled={resettingAnchor === nodeId}
+                  >
+                    {resettingAnchor === nodeId ? 'Resetting...' : 'Reset anchor on peer'}
+                  </Button>
+                  {node && !node.is_default && (
+                    <Button
+                      size="sm"
+                      variant="outline"
+                      onClick={() => openDelete(node)}
+                    >
+                      Remove node
+                    </Button>
+                  )}
+                </div>
+              </div>
+            </div>
+          ))}
+        </div>
+      )}
+
       {/* Nodes Table */}
       <div className="rounded-md border overflow-x-auto w-full">
         <Table>