diff --git a/__tests__/unit/wallets/wallet-column-grant-drift.test.ts b/__tests__/unit/wallets/wallet-column-grant-drift.test.ts
new file mode 100644
index 000000000..58e02a9e7
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+++ b/__tests__/unit/wallets/wallet-column-grant-drift.test.ts
@@ -0,0 +1,160 @@
+/**
+ * Wallet column-grant drift guard — the TS column list and the SQL GRANT that
+ * makes it readable are two sources of truth for one fact.
+ *
+ * Migration 20260802120000 revoked table-level SELECT on `wallets` and replaced
+ * it with an explicit COLUMN list, so that `nwc_connection_uri` (an encrypted
+ * wallet-spending credential) is write-only for client roles. Every non-service
+ * client therefore selects `WALLET_CLIENT_COLUMNS` — the code-side mirror of
+ * that GRANT.
+ *
+ * The two must agree, and nothing enforced it.
+ *
+ * WHY IT MATTERS MORE THAN IT LOOKS
+ *
+ * **Postgres does not auto-grant a column added later.** Add a column to
+ * wallets, add it to WALLET_CLIENT_COLUMNS because your query needs it, and the
+ * SELECT starts failing with 42501 permission-denied for anon/authenticated —
+ * for every wallet read on the site, not just the new feature. It presents as a
+ * broken page, not as a missing grant, which is how #561 was spent finding it
+ * once already. bitbaum/orangecat#563 finding 5.
+ *
+ * If this test fails you have exactly two valid moves:
+ *   1. You added a column to WALLET_CLIENT_COLUMNS → write a NEW forward
+ *      migration granting SELECT on it (never edit the baseline).
+ *   2. You granted a new column in SQL → add it to WALLET_CLIENT_COLUMNS, or
+ *      list it in SECRET_COLUMNS below if clients must never read it.
+ *
+ * Verified against production 2026-08-28: anon holds SELECT on exactly the 25
+ * columns below; the table has 26; the one withheld is nwc_connection_uri.
+ */
+
+import { readFileSync, readdirSync } from 'fs';
+import { join } from 'path';
+import { WALLET_CLIENT_COLUMNS } from '@/config/database-tables';
+
+const MIGRATIONS_DIR = join(process.cwd(), 'supabase', 'migrations');
+const LOCKDOWN = '20260802120000_wallets_select_lockdown.sql';
+
+/** Columns clients must NEVER be able to read, whatever the code asks for. */
+const SECRET_COLUMNS = ['nwc_connection_uri'];
+
+/** Split a comma-separated SQL/TS column list into a comparable set. */
+function toColumnSet(list: string): Set<string> {
+  return new Set(
+    list
+      .split(',')
+      .map((c) => c.trim())
+      .filter(Boolean)
+  );
+}
+
+/**
+ * The column list from a `GRANT SELECT (...) ON public.wallets` statement.
+ * Exported shape kept simple on purpose: a regex over SQL is only trustworthy
+ * if you can see exactly what it matches, and the test below proves it does.
+ */
+export function grantedColumns(sql: string): Set<string> {
+  const match = sql.match(/GRANT\s+SELECT\s*\(([^)]*)\)\s*ON\s+public\.wallets/i);
+  return match ? toColumnSet(match[1]!) : new Set<string>();
+}
+
+/** Columns any migration ADDs to wallets, in file order. */
+export function addedColumns(sql: string): string[] {
+  const found: string[] = [];
+  const re = /ALTER\s+TABLE\s+(?:IF\s+EXISTS\s+)?(?:public\.)?wallets\b([\s\S]*?);/gi;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(sql)) !== null) {
+    const body = m[1]!;
+    const add = /ADD\s+COLUMN\s+(?:IF\s+NOT\s+EXISTS\s+)?"?([a-z0-9_]+)"?/gi;
+    let a: RegExpExecArray | null;
+    while ((a = add.exec(body)) !== null) found.push(a[1]!);
+  }
+  return found;
+}
+
+const migrationFiles = readdirSync(MIGRATIONS_DIR).filter((f) => f.endsWith('.sql'));
+const readMigration = (f: string) => readFileSync(join(MIGRATIONS_DIR, f), 'utf8');
+
+describe('wallet column grants', () => {
+  it('the SQL GRANT and WALLET_CLIENT_COLUMNS list the same columns', () => {
+    const granted = grantedColumns(readMigration(LOCKDOWN));
+    const inCode = toColumnSet(WALLET_CLIENT_COLUMNS);
+
+    // Non-empty guards the regex itself: a parser that silently matches nothing
+    // would make this whole test a green light over an unchecked invariant.
+    expect(granted.size).toBeGreaterThan(0);
+
+    const grantedOnly = [...granted].filter((c) => !inCode.has(c)).sort();
+    const codeOnly = [...inCode].filter((c) => !granted.has(c)).sort();
+
+    expect({ grantedOnly, codeOnly }).toEqual({ grantedOnly: [], codeOnly: [] });
+  });
+
+  it('never grants a column the database is meant to keep secret', () => {
+    const granted = grantedColumns(readMigration(LOCKDOWN));
+    for (const secret of SECRET_COLUMNS) {
+      expect([...granted]).not.toContain(secret);
+    }
+    expect(toColumnSet(WALLET_CLIENT_COLUMNS).has('nwc_connection_uri')).toBe(false);
+  });
+
+  it('every column later added to wallets is granted, or declared secret', () => {
+    // Postgres does not auto-grant a column added after the lockdown, so an
+    // ADD COLUMN with no matching GRANT is a 42501 waiting for the first read.
+    const allGranted = new Set<string>();
+    const added: Array<{ file: string; column: string }> = [];
+
+    for (const file of migrationFiles.sort()) {
+      const sql = readMigration(file);
+      for (const c of grantedColumns(sql)) allGranted.add(c);
+      for (const c of addedColumns(sql)) added.push({ file, column: c });
+    }
+
+    const ungranted = added.filter(
+      ({ column }) => !allGranted.has(column) && !SECRET_COLUMNS.includes(column)
+    );
+
+    // Say the coverage out loud. Today no migration adds a wallets column, so
+    // this passes with nothing to check — and a silent pass over an empty set
+    // reads exactly like a pass over a checked one.
+    // eslint-disable-next-line no-console
+    console.log(
+      `[wallet-grants] ${migrationFiles.length} migration(s) scanned, ` +
+        `${added.length} wallets ADD COLUMN found, ${ungranted.length} ungranted`
+    );
+
+    expect(ungranted).toEqual([]);
+  });
+});
+
+describe('the parsers actually parse', () => {
+  // Proving detection on fixtures, because all three tests above currently pass
+  // and two of them would pass just as happily against a regex that matches
+  // nothing at all.
+  it('reads a GRANT list', () => {
+    const sql = 'GRANT SELECT (\n  id, label,\n  balance_btc\n) ON public.wallets TO anon;';
+    expect([...grantedColumns(sql)].sort()).toEqual(['balance_btc', 'id', 'label']);
+  });
+
+  it('returns nothing for a GRANT on a different table', () => {
+    expect(grantedColumns('GRANT SELECT (id) ON public.profiles TO anon;').size).toBe(0);
+  });
+
+  it('spots an added column, with or without IF NOT EXISTS', () => {
+    expect(addedColumns('ALTER TABLE public.wallets ADD COLUMN foo text;')).toEqual(['foo']);
+    expect(addedColumns('ALTER TABLE wallets ADD COLUMN IF NOT EXISTS "bar" int;')).toEqual(['bar']);
+  });
+
+  it('ignores a column added to another table', () => {
+    expect(addedColumns('ALTER TABLE public.profiles ADD COLUMN foo text;')).toEqual([]);
+  });
+
+  it('catches the real mistake: added but never granted', () => {
+    const sql = 'ALTER TABLE public.wallets ADD COLUMN sweep_key text;';
+    const added = addedColumns(sql);
+    const granted = grantedColumns(readMigration(LOCKDOWN));
+    expect(added).toEqual(['sweep_key']);
+    expect(granted.has('sweep_key')).toBe(false);
+  });
+});