diff --git a/packages/fincaps/src/txSync.js b/packages/fincaps/src/txSync.js
new file mode 100644
index 0000000..35321e5
--- /dev/null
+++ b/packages/fincaps/src/txSync.js
@@ -0,0 +1,81 @@
+// @ts-check
+import { E, Far } from '@endo/far';
+
+/** @template T @typedef {import('@endo/far').ERef<T>} ERef */
+
+// I goofed during Sheetsync setup.
+// TODO: make this a parameter.
+const txTitle = 'Transactions (2)';
+
+/**
+ * Match Syncsheets transactions with GnuCash.
+ *
+ * For each row that does not yet have a tx_guid,
+ * look it up in split_detail by date, amount, and account code.
+ * Update tx_guid and online_id in Syncsheets.
+ *
+ * update sheets.Transactions dest
+ * set dest.tx_guid = x.tx_guid
+ *   , dest.online_id = x.online_id
+ * from (
+ *   select dest.rowNum, src.tx_guid, src.online_id
+ *   from sheets.Transactions dest
+ *   join gnucash.split_detail src
+ *   on src.date = dest.date
+ *   and src.amount = dest.amount
+ *   and src.code = dest.code
+ *   where dest.tx_guid is null
+ * ) x where x.rowNum = dest.rowNum
+ *
+ * @param {ERef<import("./sheetsTool").Spreadsheet>} sc Sheetsync "ORM"
+ * @param {ERef<import("./dbTool").DBTool>} gc GnuCash "ORM"
+ * @param {object} pageOptions
+ * @param {number} [pageOptions.offset]
+ * @param {number} [pageOptions.limit]
+ */
+export const pushTxIds = async (sc, gc, { offset, limit = 3000 } = {}) => {
+  const txSheet = E(sc).getSheetByTitle(txTitle);
+  const acctSheet = E(sc).getSheetByTitle('Accounts');
+  const txs = await E(txSheet).getRows(offset, limit);
+
+  //   const sample = {
+  //     first: txs[0]._rawData,
+  //     last: txs.at(-1)?._rawData,
+  //   };
+  console.log('Sheetsync txs:', txs.length);
+  let modified = 0;
+
+  for (const tx of txs) {
+    if (tx.tx_guid >= '') continue;
+    const { ['Account #']: acctNum, ['Account']: acctName } = tx;
+    const acct = await E(acctSheet)
+      .select1({
+        'Account #': acctNum,
+        Account: acctName,
+      })
+      .then(it => E(it).get());
+    const detail = E(
+      E(E(gc).getTable('split_detail')).query({
+        post_date: tx.Date,
+        amount: Number(tx.Amount.replace(/[,$]/g, '')),
+        code: acct.code,
+      }),
+    ).get();
+    if (detail) {
+      //   console.log('found split:', detail);
+      const edits = {
+        tx_guid: detail.tx_guid,
+        ...(detail.online_id ? { online_id: detail.online_id } : {}),
+      };
+      console.log('@@sc.update', ['Transactions', tx.rowIndex - 1, edits]);
+      modified += 1;
+    }
+  }
+  console.log('modified:', modified, { limit, offset });
+  if (modified > 0) {
+    console.log('@@@', `await sc.commit('Transactions')`);
+  }
+  return modified;
+};
+
+export const make = () => Far('SyncTool', { pushTxIds });