Fix duplicate ledger fees: explicit idempotency + auto-dedupe

The unique expense index can silently fail to build over pre-existing
duplicate data, so re-syncs were re-adding ledger fees every run.

- syncLedgerEntries now explicitly checks existing references (and
  de-dupes within the batch) instead of trusting the unique index
- dedupeLedgerExpenses keeps one row per etsy-ledger-<entry_id> and
  deletes the rest; runs automatically at the start of each sync so
  existing duplicates self-heal. Distinct entries sharing a date/amount
  are untouched (each has its own reference).
- Sync response/toast report deduped and already-imported counts

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/src/pages/Settings.tsx

@@ -127,10 +127,13 @@ const Settings = () => {
     setUnknownDebits([]);
     try {
       const res = await api.post('/etsy/sync');
-      const { created, updated, unmatchedItems: unmatched, receiptsSeen, ledger, legacyEtsyExpenses: legacy } = res.data;
+      const { created, updated, unmatchedItems: unmatched, receiptsSeen, ledger, legacyEtsyExpenses: legacy, dedupedFees } = res.data;
       toast.success(`Synced ${receiptsSeen} Etsy orders: ${created} new, ${updated} updated`);
+      if (dedupedFees > 0) {
+        toast.success(`Cleaned up ${dedupedFees} duplicate fee expense(s) from earlier syncs`);
+      }
       if (ledger) {
-        toast.success(`Fees from Etsy ledger: ${ledger.feesCreated} new expense(s) imported`);
+        toast.success(`Fees from Etsy ledger: ${ledger.feesCreated} new, ${ledger.feesDuplicate} already imported`);
         setUnknownDebits(ledger.unknownDebits || []);
       }
       setLegacyEtsyExpenses(legacy || 0);

server/src/routes/etsy.ts

@@ -11,6 +11,7 @@ import {
   generatePkce,
   syncReceipts,
   syncLedgerEntries,
+  dedupeLedgerExpenses,
 } from '../services/etsyApi';
 
 const router = Router();
@@ -218,7 +219,9 @@ router.post('/sync', authenticate, async (req: AuthRequest, res: Response) => {
     const creds = toCredentials(config);
     const result = await syncReceipts(creds, connection);
 
-    // Also pull the payment-account ledger into expenses (exact fees from Etsy)
+    // Clean up any duplicate ledger expenses from earlier syncs, then pull the
+    // payment-account ledger into expenses (exact fees from Etsy)
+    const deduped = await dedupeLedgerExpenses(req.userId);
     const ledger = await syncLedgerEntries(creds, connection);
 
     // Warn if pre-ledger CSV-imported Etsy fees still exist (would double-count)
@@ -228,7 +231,7 @@ router.post('/sync', authenticate, async (req: AuthRequest, res: Response) => {
       reference: { $not: /^etsy-ledger-/ },
     });
 
-    res.json({ ...result, ledger, legacyEtsyExpenses });
+    res.json({ ...result, ledger, legacyEtsyExpenses, dedupedFees: deduped });
   } catch (err: any) {
     console.error('Etsy sync failed:', err);
     res.status(500).json({ message: err.message || 'Etsy sync failed' });

server/src/services/etsyApi.ts

@@ -430,8 +430,8 @@ export const syncLedgerEntries = async (
           date: when,
           taxDeductible: true,
           vendor: 'Etsy',
-          // Stable per-entry reference makes re-syncs idempotent via the unique
-          // {reference, vendor, amount, date} index
+          // Stable per-entry reference (one per Etsy ledger entry) is what makes
+          // re-syncs idempotent — checked explicitly below before inserting
           reference: `etsy-ledger-${entry.entry_id}`,
           notes: entry.reference_id ? `Etsy ${entry.reference_type || 'ref'} ${entry.reference_id}` : undefined,
           userId: connection.userId,
@@ -446,22 +446,51 @@ export const syncLedgerEntries = async (
     windowStart = windowEnd;
   }
 
-  // Idempotent insert: the unique index rejects entries already imported
+  // Idempotent insert: explicitly skip ledger entries already imported, rather
+  // than relying on a unique index (which may not be enforced if it failed to
+  // build over pre-existing duplicate data). Also de-dupes within this batch.
   if (toCreate.length > 0) {
-    try {
-      const inserted = await Expense.insertMany(toCreate, { ordered: false, rawResult: true } as any);
-      result.feesCreated = (inserted as any).insertedCount ?? toCreate.length;
-    } catch (bulkError: any) {
-      if (bulkError.writeErrors) {
-        for (const e of bulkError.writeErrors) {
-          if (e.code === 11000) result.feesDuplicate++;
-        }
-        result.feesCreated = bulkError.result?.insertedCount ?? (toCreate.length - bulkError.writeErrors.length);
-      } else {
-        throw bulkError;
-      }
+    const refs = toCreate.map(t => t.reference);
+    const existing = await Expense.find(
+      { userId: connection.userId, reference: { $in: refs } },
+      'reference'
+    ).lean();
+    const seen = new Set(existing.map((e: any) => e.reference));
+
+    const fresh = toCreate.filter(t => {
+      if (seen.has(t.reference)) return false;
+      seen.add(t.reference);
+      return true;
+    });
+    result.feesDuplicate = toCreate.length - fresh.length;
+
+    if (fresh.length > 0) {
+      const inserted = await Expense.insertMany(fresh, { ordered: false });
+      result.feesCreated = inserted.length;
     }
   }
 
   return result;
 };
+
+// Remove duplicate ledger expenses: keep one row per Etsy ledger entry
+// (same reference) and delete the rest. Distinct entries that merely share a
+// date/amount are NOT touched, since each has its own reference.
+export const dedupeLedgerExpenses = async (userId: any): Promise<number> => {
+  const ledgerExpenses = await Expense.find({
+    userId,
+    vendor: 'Etsy',
+    reference: { $regex: /^etsy-ledger-/ },
+  }).select('_id reference').sort({ dateCreated: 1 }).lean();
+
+  const seen = new Set<string>();
+  const toDelete: any[] = [];
+  for (const exp of ledgerExpenses as any[]) {
+    if (seen.has(exp.reference)) toDelete.push(exp._id);
+    else seen.add(exp.reference);
+  }
+
+  if (toDelete.length === 0) return 0;
+  const res = await Expense.deleteMany({ _id: { $in: toDelete }, userId });
+  return res.deletedCount || 0;
+};