diff --git a/app/api/sync/reconcile-tickets/route.ts b/app/api/sync/reconcile-tickets/route.ts
new file mode 100644
index 0000000..bffdc5a
--- /dev/null
+++ b/app/api/sync/reconcile-tickets/route.ts
@@ -0,0 +1,31 @@
+/**
+ * Ticket Reconciliation API Endpoint
+ * POST /api/sync/reconcile-tickets - Trigger a stale-ticket reconciliation pass.
+ * Public per middleware.ts (matches /api/sync/incremental). Fire-and-forget.
+ */
+
+import { NextRequest, NextResponse } from 'next/server';
+import { reconcileStaleTickets } from '@/lib/services/ticket-reconciliation-service';
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json().catch(() => ({}));
+    const triggeredBy = body.triggeredBy || 'api';
+
+    // Non-blocking — same pattern as /api/sync/incremental.
+    reconcileStaleTickets().catch((error) => {
+      console.error('[RECONCILE] Ticket reconciliation failed:', error);
+    });
+
+    return NextResponse.json({
+      message: 'Ticket reconciliation started',
+      triggeredBy,
+    });
+  } catch (error) {
+    console.error('Failed to start ticket reconciliation:', error);
+    return NextResponse.json(
+      { error: 'Failed to start ticket reconciliation' },
+      { status: 500 }
+    );
+  }
+}
diff --git a/lib/services/ticket-reconciliation-service.ts b/lib/services/ticket-reconciliation-service.ts
new file mode 100644
index 0000000..c859df6
--- /dev/null
+++ b/lib/services/ticket-reconciliation-service.ts
@@ -0,0 +1,151 @@
+/**
+ * Ticket Reconciliation Service (STOPGAP)
+ *
+ * Nightly backstop for drift between the postgres `tickets` mirror and Autotask.
+ * Webhooks can drop events and the incremental sync's high-water-mark filter
+ * can miss tickets whose lastActivityDate never advances after a status change.
+ * This job bounds local staleness at 7 days by re-fetching each stale-open
+ * ticket from Autotask and either re-upserting or soft-deleting.
+ *
+ * NOTE: This is a stopgap. The underlying incremental-filter issue is tracked
+ * separately and should fix the root cause.
+ */
+
+import { postgresClient } from './postgres-client';
+import { AutotaskClient } from './autotask-client';
+import { autotaskRateLimiter } from './rate-limiter';
+import { mapAutotaskToDatabase } from '../utils/entity-mapper';
+import { getTableName } from '../utils/sync-helpers';
+import { EntityType } from '../types/sync';
+import { createSyncLogger } from '../utils/sync-logger';
+
+export interface ReconcileResult {
+  scanned: number;
+  updated: number;
+  statusFlippedToComplete: number;
+  softDeleted: number;
+  errors: number;
+}
+
+const STALE_DAYS = 7;
+const SCAN_LIMIT = 500;
+const COMPLETE_STATUS = 5; // Autotask status id for Complete
+
+let _client: AutotaskClient | null = null;
+function getClient(): AutotaskClient {
+  if (!_client) {
+    _client = new AutotaskClient({
+      apiUrl: process.env.AUTOTASK_API_URL || '',
+      username: process.env.AUTOTASK_USERNAME || '',
+      password: process.env.AUTOTASK_SECRET || '',
+      apiIntegrationCode: process.env.AUTOTASK_API_INTEGRATION_CODE || '',
+    });
+  }
+  return _client;
+}
+
+/**
+ * Re-fetch up to SCAN_LIMIT stale-open tickets from Autotask and reconcile
+ * the local mirror. Idempotent and safe to run alongside the regular sync.
+ */
+export async function reconcileStaleTickets(): Promise<ReconcileResult> {
+  const logger = createSyncLogger({ component: 'TicketReconciliation' });
+  const startedAt = Date.now();
+  const result: ReconcileResult = {
+    scanned: 0,
+    updated: 0,
+    statusFlippedToComplete: 0,
+    softDeleted: 0,
+    errors: 0,
+  };
+
+  // 1. Find stale-open tickets in the postgres mirror.
+  const staleQuery = `
+    SELECT id, status
+    FROM tickets
+    WHERE is_deleted = false
+      AND status <> $1
+      AND synced_at < NOW() - INTERVAL '${STALE_DAYS} days'
+    ORDER BY synced_at ASC
+    LIMIT $2
+  `;
+  const stale = await postgresClient.query<{ id: string; status: number | null }>(
+    staleQuery,
+    [COMPLETE_STATUS, SCAN_LIMIT]
+  );
+  result.scanned = stale.rows.length;
+
+  logger.info(`Scanning ${result.scanned} stale-open tickets (>${STALE_DAYS}d, limit=${SCAN_LIMIT})`);
+
+  if (result.scanned === 0) {
+    logger.info('No stale tickets found', { duration: Date.now() - startedAt });
+    return result;
+  }
+
+  const client = getClient();
+  const tableName = getTableName(EntityType.TICKETS); // 'tickets'
+
+  // 2. Walk each id. Use the singleton rate limiter as an extra guard on top of
+  //    AutotaskClient's internal limiter (defense in depth for parallel callers).
+  for (const row of stale.rows) {
+    const ticketId = Number(row.id);
+    const priorStatus = row.status;
+    try {
+      const entity = await autotaskRateLimiter.throttle(() =>
+        client.getEntityById<Record<string, any>>('Tickets', ticketId)
+      );
+
+      if (!entity) {
+        // Not in Autotask anymore -> soft-delete locally.
+        await postgresClient.query(
+          `UPDATE ${tableName}
+             SET is_deleted = true, deleted_at = NOW(), updated_at = NOW()
+           WHERE id = $1`,
+          [ticketId]
+        );
+        result.softDeleted += 1;
+        continue;
+      }
+
+      // 3. Upsert using the same SQL shape the webhook handler uses.
+      const mapped = mapAutotaskToDatabase(EntityType.TICKETS, entity);
+      if (!mapped) {
+        throw new Error(`mapAutotaskToDatabase returned null for ticket ${ticketId}`);
+      }
+      const keys = Object.keys(mapped);
+      const values = Object.values(mapped);
+      const placeholders = keys.map((_, i) => `$${i + 1}`).join(', ');
+      const updateClause = keys
+        .filter(k => k !== 'id')
+        .map(k => `${k} = EXCLUDED.${k}`)
+        .join(', ');
+      const upsertSql = `
+        INSERT INTO ${tableName} (${keys.join(', ')})
+        VALUES (${placeholders})
+        ON CONFLICT (id)
+        DO UPDATE SET ${updateClause}, updated_at = NOW()
+      `;
+      await postgresClient.query(upsertSql, values);
+      result.updated += 1;
+
+      const newStatus = (mapped.status ?? null) as number | null;
+      if (priorStatus !== COMPLETE_STATUS && newStatus === COMPLETE_STATUS) {
+        result.statusFlippedToComplete += 1;
+      }
+    } catch (err) {
+      result.errors += 1;
+      logger.warn(
+        `Reconcile failed for ticket ${ticketId}`,
+        { ticketId },
+        err instanceof Error ? err : new Error(String(err))
+      );
+    }
+  }
+
+  logger.info(
+    `Reconciliation complete: scanned=${result.scanned} updated=${result.updated} flippedComplete=${result.statusFlippedToComplete} softDeleted=${result.softDeleted} errors=${result.errors}`,
+    { duration: Date.now() - startedAt }
+  );
+
+  return result;
+}