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.

backend/src/__tests__/database-fleet-sync-sticky.test.ts

@@ -0,0 +1,129 @@
+/**
+ * Pins the DatabaseService sticky-error wiring used by the F-16 fix:
+ *   - setFleetSyncSticky writes the code + expected + got fingerprints.
+ *   - getFleetSyncStickyCode reads them back.
+ *   - getFailedSyncTargets excludes sticky rows (the retry loop must not pick them up).
+ *   - recordFleetSyncSuccess clears the sticky on success (operator reset → push resumes).
+ *   - clearFleetSyncStickyForNode clears every resource for one node id (used by the reset endpoint).
+ */
+import { describe, it, expect, beforeAll, afterAll, beforeEach } from 'vitest';
+import { setupTestDb, cleanupTestDb } from './helpers/setupTestDb';
+
+let tmpDir: string;
+let DatabaseService: typeof import('../services/DatabaseService').DatabaseService;
+let nodeId: number;
+let siblingId: number;
+
+beforeAll(async () => {
+  tmpDir = await setupTestDb();
+  ({ DatabaseService } = await import('../services/DatabaseService'));
+  const db = DatabaseService.getInstance();
+  nodeId = db.addNode({
+    name: 'sticky-target',
+    type: 'remote',
+    compose_dir: '/app/compose',
+    is_default: false,
+    api_url: 'https://sticky.example',
+    api_token: 'tok',
+    mode: 'proxy',
+  });
+  siblingId = db.addNode({
+    name: 'sticky-sibling',
+    type: 'remote',
+    compose_dir: '/app/compose',
+    is_default: false,
+    api_url: 'https://sibling-sticky.example',
+    api_token: 'tok',
+    mode: 'proxy',
+  });
+});
+
+afterAll(() => {
+  cleanupTestDb(tmpDir);
+});
+
+beforeEach(() => {
+  const db = DatabaseService.getInstance();
+  // Wipe stale rows from prior tests in this file so each case starts clean.
+  db.getDb().prepare('DELETE FROM fleet_sync_status WHERE node_id IN (?, ?)').run(nodeId, siblingId);
+});
+
+describe('fleet_sync_status sticky-error column', () => {
+  it('setFleetSyncSticky persists the code and fingerprints', () => {
+    const db = DatabaseService.getInstance();
+    db.setFleetSyncSticky(nodeId, 'scan_policies', 'CONTROL_IDENTITY_MISMATCH', 'aaa111', 'bbb222');
+
+    const row = db.getFleetSyncStatuses().find(
+      (s) => s.node_id === nodeId && s.resource === 'scan_policies',
+    );
+    expect(row).toBeDefined();
+    expect(row!.sticky_error_code).toBe('CONTROL_IDENTITY_MISMATCH');
+    expect(row!.sticky_error_expected).toBe('aaa111');
+    expect(row!.sticky_error_got).toBe('bbb222');
+    expect(db.getFleetSyncStickyCode(nodeId, 'scan_policies')).toBe('CONTROL_IDENTITY_MISMATCH');
+  });
+
+  it('setFleetSyncSticky upserts when no row exists yet', () => {
+    const db = DatabaseService.getInstance();
+    // Pre-state: no row.
+    expect(db.getFleetSyncStickyCode(nodeId, 'cve_suppressions')).toBeNull();
+
+    db.setFleetSyncSticky(nodeId, 'cve_suppressions', 'CONTROL_IDENTITY_MISMATCH', null, null);
+
+    expect(db.getFleetSyncStickyCode(nodeId, 'cve_suppressions')).toBe('CONTROL_IDENTITY_MISMATCH');
+  });
+
+  it('getFailedSyncTargets excludes rows where sticky_error_code is set', () => {
+    const db = DatabaseService.getInstance();
+    db.recordFleetSyncFailure(nodeId, 'scan_policies', 'timeout');
+    db.recordFleetSyncFailure(siblingId, 'scan_policies', 'connection refused');
+    // Mark only `nodeId` as sticky; the sibling stays retriable.
+    db.setFleetSyncSticky(nodeId, 'scan_policies', 'CONTROL_IDENTITY_MISMATCH', null, null);
+
+    const retriable = db.getFailedSyncTargets('scan_policies', 24 * 60 * 60_000);
+    const retriableIds = retriable.map((r) => r.node_id);
+    expect(retriableIds).toContain(siblingId);
+    expect(retriableIds).not.toContain(nodeId);
+  });
+
+  it('recordFleetSyncSuccess clears the sticky flag (operator-reset round-trip)', () => {
+    const db = DatabaseService.getInstance();
+    db.setFleetSyncSticky(nodeId, 'scan_policies', 'CONTROL_IDENTITY_MISMATCH', 'aaa', 'bbb');
+    expect(db.getFleetSyncStickyCode(nodeId, 'scan_policies')).toBe('CONTROL_IDENTITY_MISMATCH');
+
+    db.recordFleetSyncSuccess(nodeId, 'scan_policies');
+
+    expect(db.getFleetSyncStickyCode(nodeId, 'scan_policies')).toBeNull();
+    const row = db.getFleetSyncStatuses().find(
+      (s) => s.node_id === nodeId && s.resource === 'scan_policies',
+    );
+    expect(row!.sticky_error_expected).toBeNull();
+    expect(row!.sticky_error_got).toBeNull();
+  });
+
+  it('clearFleetSyncStickyForNode clears every resource for one node, leaves siblings untouched', () => {
+    const db = DatabaseService.getInstance();
+    db.setFleetSyncSticky(nodeId, 'scan_policies', 'CONTROL_IDENTITY_MISMATCH', null, null);
+    db.setFleetSyncSticky(nodeId, 'cve_suppressions', 'CONTROL_IDENTITY_MISMATCH', null, null);
+    db.setFleetSyncSticky(siblingId, 'scan_policies', 'CONTROL_IDENTITY_MISMATCH', null, null);
+
+    db.clearFleetSyncStickyForNode(nodeId);
+
+    expect(db.getFleetSyncStickyCode(nodeId, 'scan_policies')).toBeNull();
+    expect(db.getFleetSyncStickyCode(nodeId, 'cve_suppressions')).toBeNull();
+    expect(db.getFleetSyncStickyCode(siblingId, 'scan_policies')).toBe('CONTROL_IDENTITY_MISMATCH');
+  });
+
+  it('migrateFleetSyncStickyError is idempotent (running twice does not error)', () => {
+    // The constructor already runs the migration once at boot. Manually
+    // invoke the private method twice via index access to confirm
+    // tryAddColumn's idempotency contract holds for this migration.
+    const db = DatabaseService.getInstance() as unknown as {
+      migrateFleetSyncStickyError: () => void;
+    };
+    expect(() => {
+      db.migrateFleetSyncStickyError();
+      db.migrateFleetSyncStickyError();
+    }).not.toThrow();
+  });
+});

backend/src/__tests__/fleet-sync-service.test.ts

@@ -16,6 +16,8 @@ const {
   mockInsertAuditLog,
   mockRecordFleetSyncSuccess,
   mockRecordFleetSyncFailure,
+  mockSetFleetSyncSticky,
+  mockGetFleetSyncStickyCode,
   mockGetSystemState,
   mockSetSystemState,
   mockTransaction,
@@ -33,6 +35,8 @@ const {
   mockInsertAuditLog: vi.fn(),
   mockRecordFleetSyncSuccess: vi.fn(),
   mockRecordFleetSyncFailure: vi.fn(),
+  mockSetFleetSyncSticky: vi.fn(),
+  mockGetFleetSyncStickyCode: vi.fn().mockReturnValue(null),
   mockGetSystemState: vi.fn().mockReturnValue(null),
   mockSetSystemState: vi.fn(),
   mockTransaction: vi.fn().mockImplementation((fn: () => unknown) => fn()),
@@ -53,6 +57,8 @@ vi.mock('../services/DatabaseService', () => ({
       insertAuditLog: mockInsertAuditLog,
       recordFleetSyncSuccess: mockRecordFleetSyncSuccess,
       recordFleetSyncFailure: mockRecordFleetSyncFailure,
+      setFleetSyncSticky: mockSetFleetSyncSticky,
+      getFleetSyncStickyCode: mockGetFleetSyncStickyCode,
       getSystemState: mockGetSystemState,
       setSystemState: mockSetSystemState,
       transaction: mockTransaction,
@@ -90,6 +96,7 @@ import { FleetSyncService, LOCAL_IDENTITY_SENTINEL } from '../services/FleetSync
 beforeEach(() => {
   vi.clearAllMocks();
   mockGetSystemState.mockReturnValue(null);
+  mockGetFleetSyncStickyCode.mockReturnValue(null);
 });
 
 describe('FleetSyncService.getRole', () => {
@@ -594,3 +601,102 @@ describe('FleetSyncService.formatError redaction', () => {
     expect(failure[2]).toContain('[redacted-jwt]');
   });
 });
+
+describe('FleetSyncService CONTROL_IDENTITY_MISMATCH sticky handling', () => {
+  function makeMismatchError(expected: string, got: string) {
+    return async () => {
+      const { AxiosError } = await import('axios');
+      const err = new AxiosError('Request failed with status code 409');
+      (err as unknown as { response: unknown }).response = {
+        status: 409,
+        statusText: 'Conflict',
+        data: {
+          error: `Control identity mismatch: replica is anchored to "${expected}", push from "${got}"`,
+          code: 'CONTROL_IDENTITY_MISMATCH',
+          expected,
+          got,
+        },
+      };
+      throw err;
+    };
+  }
+
+  it('sets the sticky flag carrying the expected/got fingerprints on first mismatch', async () => {
+    mockGetNodes.mockReturnValue([
+      { id: 7, type: 'remote', api_url: 'https://peer.example', api_token: 'tok', name: 'peer', mode: 'proxy' },
+    ]);
+    mockGetLocalScanPolicies.mockReturnValue([]);
+    mockGetFleetSyncStickyCode.mockReturnValue(null);
+    mockAxiosPost.mockImplementation(makeMismatchError('cb45a2eff9db81d8', '555f8d1f7e7e71e3'));
+
+    await FleetSyncService.getInstance().pushResource('scan_policies');
+
+    expect(mockRecordFleetSyncFailure).toHaveBeenCalledTimes(1);
+    expect(mockSetFleetSyncSticky).toHaveBeenCalledTimes(1);
+    expect(mockSetFleetSyncSticky).toHaveBeenCalledWith(
+      7,
+      'scan_policies',
+      'CONTROL_IDENTITY_MISMATCH',
+      'cb45a2eff9db81d8',
+      '555f8d1f7e7e71e3',
+    );
+  });
+
+  it('short-circuits subsequent pushes when sticky is already set; no HTTP call, no failure record', async () => {
+    mockGetNodes.mockReturnValue([
+      { id: 7, type: 'remote', api_url: 'https://peer.example', api_token: 'tok', name: 'peer', mode: 'proxy' },
+    ]);
+    mockGetLocalScanPolicies.mockReturnValue([]);
+    // Sticky already set from a prior push.
+    mockGetFleetSyncStickyCode.mockReturnValue('CONTROL_IDENTITY_MISMATCH');
+
+    await FleetSyncService.getInstance().pushResource('scan_policies');
+
+    expect(mockAxiosPost).not.toHaveBeenCalled();
+    expect(mockRecordFleetSyncFailure).not.toHaveBeenCalled();
+    expect(mockRecordFleetSyncSuccess).not.toHaveBeenCalled();
+    expect(mockSetFleetSyncSticky).not.toHaveBeenCalled();
+  });
+
+  it('tolerates a missing expected/got payload (passes null through)', async () => {
+    mockGetNodes.mockReturnValue([
+      { id: 7, type: 'remote', api_url: 'https://peer.example', api_token: 'tok', name: 'peer', mode: 'proxy' },
+    ]);
+    mockGetLocalScanPolicies.mockReturnValue([]);
+    mockGetFleetSyncStickyCode.mockReturnValue(null);
+    mockAxiosPost.mockImplementation(async () => {
+      const { AxiosError } = await import('axios');
+      const err = new AxiosError('Request failed with status code 409');
+      (err as unknown as { response: unknown }).response = {
+        status: 409,
+        statusText: 'Conflict',
+        data: { error: 'mismatch', code: 'CONTROL_IDENTITY_MISMATCH' },
+      };
+      throw err;
+    });
+
+    await FleetSyncService.getInstance().pushResource('scan_policies');
+
+    expect(mockSetFleetSyncSticky).toHaveBeenCalledWith(
+      7,
+      'scan_policies',
+      'CONTROL_IDENTITY_MISMATCH',
+      null,
+      null,
+    );
+  });
+
+  it('does not set sticky for non-mismatch failures (network errors, 500s)', async () => {
+    mockGetNodes.mockReturnValue([
+      { id: 7, type: 'remote', api_url: 'https://peer.example', api_token: 'tok', name: 'peer', mode: 'proxy' },
+    ]);
+    mockGetLocalScanPolicies.mockReturnValue([]);
+    mockGetFleetSyncStickyCode.mockReturnValue(null);
+    mockAxiosPost.mockRejectedValue(new Error('ECONNREFUSED'));
+
+    await FleetSyncService.getInstance().pushResource('scan_policies');
+
+    expect(mockRecordFleetSyncFailure).toHaveBeenCalledTimes(1);
+    expect(mockSetFleetSyncSticky).not.toHaveBeenCalled();
+  });
+});

backend/src/__tests__/nodes-fleet-sync-reset-anchor.test.ts

@@ -0,0 +1,158 @@
+/**
+ * Tests for POST /api/nodes/:id/fleet-sync/reset-anchor (F-16 fix).
+ *
+ * The endpoint proxies the peer's reanchor endpoint and clears every
+ * sticky-error row for the node on success. Covers:
+ *   - happy path: 200 from peer → sticky rows cleared, 200 returned.
+ *   - peer 401/403 → 502 with helpful message.
+ *   - peer unreachable → 504.
+ *   - missing/non-proxy node → 400.
+ *   - non-paid tier → 403.
+ */
+import { describe, it, expect, beforeAll, afterAll, beforeEach, vi } from 'vitest';
+import request from 'supertest';
+import jwt from 'jsonwebtoken';
+import { setupTestDb, cleanupTestDb, TEST_USERNAME, TEST_JWT_SECRET } from './helpers/setupTestDb';
+
+let tmpDir: string;
+let app: import('express').Express;
+let authHeader: string;
+let peerNodeId: number;
+
+const originalFetch = globalThis.fetch;
+
+beforeAll(async () => {
+  tmpDir = await setupTestDb();
+  ({ app } = await import('../index'));
+  const token = jwt.sign({ username: TEST_USERNAME }, TEST_JWT_SECRET, { expiresIn: '1m' });
+  authHeader = `Bearer ${token}`;
+
+  // Seed a proxy-mode remote node and a sticky row for it. Tests then drive
+  // the route handler and assert side effects on the test DB.
+  const { DatabaseService } = await import('../services/DatabaseService');
+  const db = DatabaseService.getInstance();
+  peerNodeId = db.addNode({
+    name: 'sticky-peer',
+    type: 'remote',
+    compose_dir: '/app/compose',
+    is_default: false,
+    api_url: 'http://192.168.1.99:1852',
+    api_token: 'peer-token',
+    mode: 'proxy',
+  });
+  db.setFleetSyncSticky(
+    peerNodeId,
+    'scan_policies',
+    'CONTROL_IDENTITY_MISMATCH',
+    'cb45a2eff9db81d8',
+    '555f8d1f7e7e71e3',
+  );
+});
+
+afterAll(() => {
+  globalThis.fetch = originalFetch;
+  cleanupTestDb(tmpDir);
+});
+
+beforeEach(async () => {
+  vi.restoreAllMocks();
+  globalThis.fetch = originalFetch;
+  // Re-establish the paid-tier spy after restoreAllMocks. Individual tests
+  // can override with `mockReturnValue('community')` to exercise the tier
+  // gate's deny path.
+  const { LicenseService } = await import('../services/LicenseService');
+  vi.spyOn(LicenseService.getInstance(), 'getTier').mockReturnValue('paid');
+});
+
+describe('POST /api/nodes/:id/fleet-sync/reset-anchor', () => {
+  it('proxies to the peer reanchor, clears sticky rows, returns 200', async () => {
+    const fetchSpy = vi.fn().mockResolvedValue(
+      new Response(JSON.stringify({ success: true }), { status: 200 }),
+    );
+    globalThis.fetch = fetchSpy as unknown as typeof fetch;
+
+    const res = await request(app)
+      .post(`/api/nodes/${peerNodeId}/fleet-sync/reset-anchor`)
+      .set('Authorization', authHeader)
+      .send({});
+
+    expect(res.status).toBe(200);
+    expect(res.body.success).toBe(true);
+    expect(fetchSpy).toHaveBeenCalledTimes(1);
+    const [url, init] = fetchSpy.mock.calls[0] as [string, RequestInit];
+    expect(url).toBe('http://192.168.1.99:1852/api/fleet/role/reanchor');
+    expect(init.method).toBe('POST');
+    expect((init.headers as Record<string, string>).Authorization).toBe('Bearer peer-token');
+    expect(JSON.parse(init.body as string)).toEqual({ override: true });
+
+    const { DatabaseService } = await import('../services/DatabaseService');
+    const sticky = DatabaseService.getInstance().getFleetSyncStickyCode(peerNodeId, 'scan_policies');
+    expect(sticky).toBeNull();
+  });
+
+  it('returns 502 with a helpful message when peer responds 401', async () => {
+    const { DatabaseService } = await import('../services/DatabaseService');
+    DatabaseService.getInstance().setFleetSyncSticky(
+      peerNodeId, 'cve_suppressions', 'CONTROL_IDENTITY_MISMATCH', 'aaa', 'bbb',
+    );
+    const fetchSpy = vi.fn().mockResolvedValue(
+      new Response(JSON.stringify({ error: 'Admin access required.' }), { status: 401 }),
+    );
+    globalThis.fetch = fetchSpy as unknown as typeof fetch;
+
+    const res = await request(app)
+      .post(`/api/nodes/${peerNodeId}/fleet-sync/reset-anchor`)
+      .set('Authorization', authHeader)
+      .send({});
+
+    expect(res.status).toBe(502);
+    expect(res.body.error).toMatch(/Admin access required/);
+    // Sticky rows must remain set so the operator can retry.
+    const sticky = DatabaseService.getInstance().getFleetSyncStickyCode(peerNodeId, 'cve_suppressions');
+    expect(sticky).toBe('CONTROL_IDENTITY_MISMATCH');
+  });
+
+  it('returns 504 when the peer is unreachable', async () => {
+    const fetchSpy = vi.fn().mockRejectedValue(new Error('connect ECONNREFUSED'));
+    globalThis.fetch = fetchSpy as unknown as typeof fetch;
+
+    const res = await request(app)
+      .post(`/api/nodes/${peerNodeId}/fleet-sync/reset-anchor`)
+      .set('Authorization', authHeader)
+      .send({});
+
+    expect(res.status).toBe(504);
+    expect(res.body.error).toMatch(/unreachable/i);
+  });
+
+  it('returns 400 for a local node', async () => {
+    const { DatabaseService } = await import('../services/DatabaseService');
+    const local = DatabaseService.getInstance().getNodes().find((n) => n.type === 'local');
+    expect(local).toBeTruthy();
+    const res = await request(app)
+      .post(`/api/nodes/${local!.id}/fleet-sync/reset-anchor`)
+      .set('Authorization', authHeader)
+      .send({});
+    expect(res.status).toBe(400);
+  });
+
+  it('returns 404 for an unknown node id', async () => {
+    const res = await request(app)
+      .post('/api/nodes/9999/fleet-sync/reset-anchor')
+      .set('Authorization', authHeader)
+      .send({});
+    expect(res.status).toBe(404);
+  });
+
+  it('returns 403 (PAID_REQUIRED) when the license is community-tier', async () => {
+    const { LicenseService } = await import('../services/LicenseService');
+    vi.spyOn(LicenseService.getInstance(), 'getTier').mockReturnValue('community');
+
+    const res = await request(app)
+      .post(`/api/nodes/${peerNodeId}/fleet-sync/reset-anchor`)
+      .set('Authorization', authHeader)
+      .send({});
+    expect(res.status).toBe(403);
+    expect(res.body.code).toBe('PAID_REQUIRED');
+  });
+});

backend/src/routes/nodes.ts

@@ -4,7 +4,7 @@ import crypto from 'crypto';
 import { authMiddleware } from '../middleware/auth';
 import { requirePermission } from '../middleware/permissions';
 import { rejectApiTokenScope } from '../middleware/apiTokenScope';
-import { requireAdmiral } from '../middleware/tierGates';
+import { requireAdmin, requireAdmiral, requirePaid } from '../middleware/tierGates';
 import { enrollmentLimiter } from '../middleware/rateLimiters';
 import { DatabaseService } from '../services/DatabaseService';
 import { NodeRegistry } from '../services/NodeRegistry';
@@ -354,6 +354,93 @@ nodesRouter.post('/:id/uncordon', (req: Request, res: Response) => {
   }
 });
 
+/**
+ * Reset the FleetSync control anchor on a remote peer.
+ *
+ * Proxies POST /api/fleet/role/reanchor to the peer using its stored
+ * Bearer token. A successful reanchor clears every sticky-error row for
+ * this node so the next push (event-driven or via the 5-minute retry
+ * service) re-attempts cleanly and the peer accepts the central's
+ * fingerprint as the new anchor.
+ *
+ * Surfaces UI affordance for the F-16 audit (mesh-e2e-2026-05-17.md):
+ * when a peer was previously enrolled by a different central, FleetSync
+ * keeps 409'ing every reconcile tick; the sticky flag halts retries and
+ * this endpoint is the single one-click recovery for the operator.
+ */
+nodesRouter.post('/:id/fleet-sync/reset-anchor', async (req: Request, res: Response) => {
+  if (rejectApiTokenScope(req, res, NODE_SCOPE_MESSAGE)) return;
+  const nodeIdParam = req.params.id as string;
+  if (!requirePermission(req, res, 'node:manage', 'node', nodeIdParam)) return;
+  if (!requirePaid(req, res)) return;
+  // Reset-anchor is symmetric with `/api/fleet/sync-status` (admin-only).
+  // Keeping read and write gated at the same role avoids a banner-invisible-to-the-actor
+  // gap where a node-admin could call reset without ever seeing why.
+  if (!requireAdmin(req, res)) return;
+  try {
+    const id = parseInt(nodeIdParam, 10);
+    if (!Number.isFinite(id) || id <= 0) {
+      res.status(400).json({ error: 'Invalid node id' });
+      return;
+    }
+    const node = DatabaseService.getInstance().getNode(id);
+    if (!node) {
+      res.status(404).json({ error: 'Node not found' });
+      return;
+    }
+    if (node.type !== 'remote' || node.mode !== 'proxy') {
+      res.status(400).json({ error: 'Reset anchor only applies to proxy-mode remote nodes' });
+      return;
+    }
+    if (!node.api_url || !node.api_token) {
+      res.status(400).json({ error: 'Node is missing api_url or api_token' });
+      return;
+    }
+
+    const baseUrl = node.api_url.replace(/\/$/, '');
+    let peerResponse: globalThis.Response;
+    try {
+      peerResponse = await fetch(`${baseUrl}/api/fleet/role/reanchor`, {
+        method: 'POST',
+        headers: {
+          Authorization: `Bearer ${node.api_token}`,
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify({ override: true }),
+        signal: AbortSignal.timeout(15_000),
+      });
+    } catch (networkErr) {
+      const message = getErrorMessage(networkErr, 'Failed to reach peer');
+      console.warn(`[Nodes] Reset anchor unreachable for node ${id}: ${message}`);
+      res.status(504).json({ error: `Peer unreachable: ${message}` });
+      return;
+    }
+
+    if (!peerResponse.ok) {
+      const status = peerResponse.status;
+      const body = await peerResponse.json().catch(() => ({}));
+      const peerError = (body as { error?: string })?.error
+        ?? `Peer returned HTTP ${status}`;
+      if (status === 401 || status === 403) {
+        console.warn(`[Nodes] Reset anchor rejected by peer ${id}: ${peerError}`);
+        res.status(502).json({
+          error: `Peer rejected the reanchor request: ${peerError}. The node's API token may need to be regenerated.`,
+        });
+        return;
+      }
+      res.status(502).json({ error: peerError });
+      return;
+    }
+
+    DatabaseService.getInstance().clearFleetSyncStickyForNode(id);
+    console.log(`[Nodes] Fleet-sync anchor reset on node ${id} ("${node.name}")`);
+    res.json({ success: true });
+  } catch (error: unknown) {
+    console.error('Failed to reset fleet-sync anchor:', error);
+    res.status(500).json({ error: getErrorMessage(error, 'Failed to reset fleet-sync anchor') });
+  }
+});
+
 nodesRouter.post('/:id/test', async (req: Request, res: Response) => {
   try {
     const id = parseInt(req.params.id as string);

backend/src/services/DatabaseService.ts

@@ -555,6 +555,9 @@ export interface FleetSyncStatus {
     last_success_at: number | null;
     last_failure_at: number | null;
     last_error: string | null;
+    sticky_error_code: string | null;
+    sticky_error_expected: string | null;
+    sticky_error_got: string | null;
 }
 
 export interface CveSuppression {
@@ -659,6 +662,7 @@ export class DatabaseService {
         this.migrateAddNodeCordonFields();
         this.migrateAddBlueprintPinnedNode();
         this.migrateAutoHealNodeId();
+        this.migrateFleetSyncStickyError();
 
         // Reset the cache once at end of constructor in case any migration
         // populated it via getGlobalSettings() and a subsequent migration
@@ -1581,6 +1585,12 @@ export class DatabaseService {
         this.tryAddColumn('blueprints', 'pinned_node_id', 'INTEGER');
     }
 
+    private migrateFleetSyncStickyError(): void {
+        this.tryAddColumn('fleet_sync_status', 'sticky_error_code', 'TEXT');
+        this.tryAddColumn('fleet_sync_status', 'sticky_error_expected', 'TEXT');
+        this.tryAddColumn('fleet_sync_status', 'sticky_error_got', 'TEXT');
+    }
+
     private migrateAutoHealNodeId(): void {
         const markerKey = 'migration_auto_heal_node_scope_v1';
         const markerDone = this.getGlobalSettings()[markerKey] === '1';
@@ -3931,11 +3941,15 @@ export class DatabaseService {
         const now = Date.now();
         this.db
             .prepare(
-                `INSERT INTO fleet_sync_status (node_id, resource, last_success_at, last_failure_at, last_error)
-                 VALUES (?, ?, ?, NULL, NULL)
+                `INSERT INTO fleet_sync_status (node_id, resource, last_success_at, last_failure_at, last_error,
+                                                 sticky_error_code, sticky_error_expected, sticky_error_got)
+                 VALUES (?, ?, ?, NULL, NULL, NULL, NULL, NULL)
                  ON CONFLICT(node_id, resource) DO UPDATE SET
                    last_success_at = excluded.last_success_at,
-                   last_error = NULL`,
+                   last_error = NULL,
+                   sticky_error_code = NULL,
+                   sticky_error_expected = NULL,
+                   sticky_error_got = NULL`,
             )
             .run(nodeId, resource, now);
     }
@@ -3953,6 +3967,64 @@ export class DatabaseService {
             .run(nodeId, resource, now, error);
     }
 
+    /**
+     * Mark a (node, resource) pair as having hit a non-retriable failure. The
+     * retry service skips sticky rows and the push paths short-circuit before
+     * any HTTP call. The first such failure still records `last_failure_at` +
+     * `last_error` via `recordFleetSyncFailure`; the sticky write is additive.
+     *
+     * `expected` and `got` carry the fingerprints from a 409
+     * CONTROL_IDENTITY_MISMATCH response so the UI can render
+     * "anchored to <expected>, this central is <got>" without parsing the
+     * error string.
+     */
+    public setFleetSyncSticky(
+        nodeId: number,
+        resource: string,
+        code: string,
+        expected: string | null,
+        got: string | null,
+    ): void {
+        this.db
+            .prepare(
+                `INSERT INTO fleet_sync_status (node_id, resource, sticky_error_code,
+                                                 sticky_error_expected, sticky_error_got)
+                 VALUES (?, ?, ?, ?, ?)
+                 ON CONFLICT(node_id, resource) DO UPDATE SET
+                   sticky_error_code = excluded.sticky_error_code,
+                   sticky_error_expected = excluded.sticky_error_expected,
+                   sticky_error_got = excluded.sticky_error_got`,
+            )
+            .run(nodeId, resource, code, expected, got);
+    }
+
+    public getFleetSyncStickyCode(nodeId: number, resource: string): string | null {
+        const row = this.db
+            .prepare(
+                `SELECT sticky_error_code FROM fleet_sync_status
+                 WHERE node_id = ? AND resource = ?`,
+            )
+            .get(nodeId, resource) as { sticky_error_code: string | null } | undefined;
+        return row?.sticky_error_code ?? null;
+    }
+
+    /**
+     * Clear every sticky-error row for one node id. Used by the
+     * reset-anchor endpoint after the peer has acknowledged a reanchor; the
+     * next push attempt re-tries normally.
+     */
+    public clearFleetSyncStickyForNode(nodeId: number): void {
+        this.db
+            .prepare(
+                `UPDATE fleet_sync_status
+                 SET sticky_error_code = NULL,
+                     sticky_error_expected = NULL,
+                     sticky_error_got = NULL
+                 WHERE node_id = ?`,
+            )
+            .run(nodeId);
+    }
+
     public getFailedSyncTargets(resource: string, maxAgeMs: number): FleetSyncStatus[] {
         const cutoff = Date.now() - maxAgeMs;
         return this.db
@@ -3960,7 +4032,8 @@ export class DatabaseService {
                 `SELECT * FROM fleet_sync_status
                  WHERE resource = ?
                    AND (last_failure_at IS NOT NULL AND last_failure_at > ?)
-                   AND (last_success_at IS NULL OR last_success_at < last_failure_at)`,
+                   AND (last_success_at IS NULL OR last_success_at < last_failure_at)
+                   AND sticky_error_code IS NULL`,
             )
             .all(resource, cutoff) as FleetSyncStatus[];
     }

backend/src/services/FleetSyncService.ts

@@ -449,12 +449,38 @@ export class FleetSyncService {
         return next;
     }
 
+    /**
+     * Concurrency note: the sticky-set in the CONTROL_IDENTITY_MISMATCH catch
+     * branch is best-effort against an operator-initiated reset that lands
+     * during a push's HTTP round-trip. The reset endpoint clears
+     * `sticky_error_code` to NULL; if this push's 409 arrives after that
+     * clear, it will re-pin the row. The operator clicks Reset again. The
+     * window is bounded by one HTTP round-trip per resource; no lock or
+     * generation counter is justified.
+     */
     private async executePushToNode(
         node: Node & { id: number },
         resource: FleetResource,
         partial: Omit<FleetSyncPayload, 'targetIdentity'>,
     ): Promise<void> {
         const db = DatabaseService.getInstance();
+
+        // Sticky-error short-circuit. When a previous push hit a non-retriable
+        // failure (today: CONTROL_IDENTITY_MISMATCH), every subsequent push
+        // would re-issue the same 409 and re-spam the log every 5 minutes. The
+        // sticky flag is cleared by either (a) the operator resetting the
+        // anchor via POST /api/nodes/:id/fleet-sync/reset-anchor, or (b) a
+        // successful push to the same node (recordFleetSyncSuccess clears
+        // it). Until then, skip the HTTP call entirely.
+        if (db.getFleetSyncStickyCode(node.id, resource)) {
+            if (isDebugEnabled()) {
+                console.debug(
+                    `[FleetSync:debug] Skipping ${resource} push to "${node.name}": sticky error blocks retries.`,
+                );
+            }
+            return;
+        }
+
         const apiUrl = node.api_url ?? '';
         const baseUrl = apiUrl.replace(/\/$/, '');
         const payload: FleetSyncPayload = { ...partial, targetIdentity: apiUrl };
@@ -479,7 +505,7 @@ export class FleetSyncService {
             // healthy; suppress the failure record so it does not surface as
             // an alert in the sync-status panel.
             if (err instanceof AxiosError && err.response?.status === 409) {
-                const data = err.response.data as { code?: string } | undefined;
+                const data = err.response.data as { code?: string; expected?: string; got?: string } | undefined;
                 if (data?.code === SYNC_ERROR_CODES.staleSyncPush) {
                     if (isDebugEnabled()) {
                         console.debug(
@@ -488,6 +514,26 @@ export class FleetSyncService {
                     }
                     return;
                 }
+                // CONTROL_IDENTITY_MISMATCH is permanent until the operator
+                // explicitly resets the peer anchor. Record the failure once
+                // (last_error + last_failure_at) plus a sticky flag so the
+                // retry service and event-driven push path skip subsequent
+                // attempts.
+                if (data?.code === SYNC_ERROR_CODES.controlIdentityMismatch) {
+                    const message = this.formatError(err);
+                    console.warn(
+                        `[FleetSync] Failed to push ${resource} to "${node.name}" (${baseUrl}): ${message}`,
+                    );
+                    db.recordFleetSyncFailure(node.id, resource, message);
+                    db.setFleetSyncSticky(
+                        node.id,
+                        resource,
+                        SYNC_ERROR_CODES.controlIdentityMismatch,
+                        typeof data.expected === 'string' ? data.expected : null,
+                        typeof data.got === 'string' ? data.got : null,
+                    );
+                    return;
+                }
             }
             const message = this.formatError(err);
             console.warn(