@@ -0,0 +1,160 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#21163] An autonumber prefix carrying a `LIKE` metacharacter seeds its
+ * counter from the data table's MAX — cold, and on the #5495 re-seed — on every
+ * dialect, SQLite included.
+ *
+ * # The defect
+ *
+ * `scanMaxNumericTail` is the one read of "the highest counter already stored
+ * under this prefix". It anchors the scan with `escapeLikePrefix(prefix) + '%'`,
+ * which escapes `\`, `%` and `_` with a backslash — and then compiled the
+ * predicate through Knex's `where(col, 'like', …)`, which declares NO `ESCAPE`
+ * clause on any dialect. Postgres and MySQL read a backslash as the default
+ * `LIKE` escape, so they were right by default. SQLite has no escape character
+ * unless one is declared, so `SO\_%` asked for the literal three characters
+ * `S`,`O`,`\` followed by any one character — and matched nothing. Measured on
+ * better-sqlite3 at `cb45469e` (this file's fixtures, before the fix):
+ *
+ * | format | stored | cold create issued | re-seed after rows 2..30 land |
+ * |:---|:---|:---|:---|
+ * | `SO_{0000}` | `SO_0007` | `SO_0001` | refused: UNIQUE constraint failed |
+ * | `SO%{0000}` | `SO%0007` | `SO%0001` | refused: UNIQUE constraint failed |
+ * | `SO\{0000}` | `SO\0007` | `SO\0001` | refused: UNIQUE constraint failed |
+ * | `{region}-{0000}`, region `north_east` | `north_east-0007` | `north_east-0001` | — |
+ * | `SO-{0000}` (control) | `SO-0007` | `SO-0008` | `SO-0031` |
+ *
+ * The `{region}` row is why this is not an exotic-format problem: the prefix is
+ * RENDERED, so a `_` arrives from data as readily as from the format — and
+ * snake_case is this platform's spelling for machine names.
+ *
+ * Cold, the counter starts under numbers already stored, so a later issue
+ * collides with them. On the re-seed path the scan answers 0, the forward-only
+ * re-seed cannot move the counter, and every retry collides again until the
+ * retry budget is spent: the #5495 storm, back for that format.
+ *
+ * # What is asserted
+ *
+ * The issued value — the caller-visible answer — on a cold bootstrap over a
+ * stored row, and on the create that follows a bypass write landing ABOVE a
+ * warm counter. Per dialect cell: SQLite always runs; live Postgres and MySQL
+ * run where provisioned (the `Temporal Conformance (live PG + MySQL)` job runs
+ * this whole package against both) and are declared un-run otherwise. On those
+ * two the backslash was already the default escape, so their cells pin that
+ * DECLARING it changed nothing there — they passed before the fix and must
+ * pass after it.
+ *
+ * The plain prefix is the control on every cell: it has nothing to escape, so
+ * it was right before and after, and a fix that broke the scan wholesale would
+ * redden it too.
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { SqlDriver } from '../src/index.js';
+import { DIALECT_CELLS, declareDialectCell, type DialectCell } from './live-dialect-matrix.testkit.js';
+
+const TABLE = 'os21163_like_escape';
+const SEQUENCES_TABLE = '_objectstack_sequences';
+
+interface PrefixCase {
+  /** Suite label. */
+  label: string;
+  /** The declared format. */
+  format: string;
+  /** The stored value for counter `n` under this format. */
+  render: (n: number) => string;
+  /** True when the rendered prefix carries a character `escapeLikePrefix` escapes. */
+  escaped: boolean;
+}
+
+const pad4 = (n: number) => String(n).padStart(4, '0');
+
+const STATIC_PREFIX_CASES: readonly PrefixCase[] = [
+  { label: '`_` in the prefix', format: 'SO_{0000}', render: (n) => `SO_${pad4(n)}`, escaped: true },
+  { label: '`%` in the prefix', format: 'SO%{0000}', render: (n) => `SO%${pad4(n)}`, escaped: true },
+  { label: '`\\` in the prefix', format: 'SO\\{0000}', render: (n) => `SO\\${pad4(n)}`, escaped: true },
+  { label: 'a plain prefix (control)', format: 'SO-{0000}', render: (n) => `SO-${pad4(n)}`, escaped: false },
+];
+
+const objectWith = (format: string) =>
+  ({
+    name: TABLE,
+    fields: {
+      region: { type: 'string' },
+      so_no: { type: 'autonumber', format, unique: true },
+      title: { type: 'string' },
+    },
+  }) as any;
+
+function suite(cell: DialectCell) {
+  describe(`sql-driver — autonumber prefix LIKE escape (${cell.label}) [#21163]`, () => {
+    let driver: SqlDriver;
+
+    const knex = () => (driver as any).knex;
+
+    /** Drop the data table and this object's counter rows, so every test starts COLD. */
+    const reset = async () => {
+      await knex().schema.dropTableIfExists(TABLE);
+      await knex()(SEQUENCES_TABLE)
+        .where('object', TABLE)
+        .del()
+        .catch(() => {});
+    };
+
+    /** Land rows by a path that bypasses `fillAutoNumberFields`, as a seed replay does. */
+    const bypassInsert = async (values: string[], region: string | null = null) => {
+      await knex()(TABLE).insert(
+        values.map((v) => ({ id: `bypass-${v}`, region, so_no: v, title: 'seed replay' })),
+      );
+    };
+
+    beforeEach(async () => {
+      driver = new SqlDriver(cell.config());
+      await reset();
+    });
+
+    afterEach(async () => {
+      await reset();
+      await driver.disconnect();
+    });
+
+    for (const c of STATIC_PREFIX_CASES) {
+      const role = c.escaped ? 'red before the fix on SQLite' : 'control';
+
+      it(`${c.label}: a COLD bootstrap seeds from the stored MAX (${role})`, async () => {
+        await driver.initObjects([objectWith(c.format)]);
+        await bypassInsert([c.render(7)]);
+
+        const created = await driver.create(TABLE, { title: 'first issued' });
+        expect(created.so_no).toBe(c.render(8));
+      });
+
+      it(`${c.label}: the #5495 re-seed moves a warm counter past rows a bypass write landed (${role})`, async () => {
+        await driver.initObjects([objectWith(c.format)]);
+
+        // Warm the counter on an EMPTY table, so this test does not depend on
+        // the cold scan above: there is nothing for the bootstrap to find.
+        expect((await driver.create(TABLE, { title: 'warm' })).so_no).toBe(c.render(1));
+
+        // Rows 2..30 land above the counter. Nothing tells the sequence.
+        await bypassInsert(Array.from({ length: 29 }, (_, i) => c.render(i + 2)));
+
+        const created = await driver.create(TABLE, { title: 'after the seeds' });
+        expect(created.so_no).toBe(c.render(31));
+      });
+    }
+
+    it('a `_` that arrives from DATA through `{field}` interpolation seeds from the stored MAX (red before the fix on SQLite)', async () => {
+      await driver.initObjects([objectWith('{region}-{0000}')]);
+      await bypassInsert(['north_east-0007'], 'north_east');
+
+      const created = await driver.create(TABLE, { region: 'north_east', title: 'first issued' });
+      expect(created.so_no).toBe('north_east-0008');
+    });
+  });
+}
+
+for (const cell of DIALECT_CELLS) {
+  declareDialectCell(cell, 'autonumber prefix LIKE escape (#21163)', suite);
+}
@@ -7527,6 +7527,28 @@ export class SqlDriver implements IDataDriver {
    * duplicate-record-number harm, self-inflicted. The predicate therefore stays
    * `prefix%` and the suffix is applied per row, where a non-match simply means
    * "different suffix, same counter".
+   *
+   * ## The escape the prefix is escaped FOR is declared, on every dialect (#21163)
+   *
+   * {@link escapeLikePrefix} writes a backslash before each `\`, `%` and `_`,
+   * which only means "literally" under a `LIKE` whose escape character IS that
+   * backslash. SQLite's `LIKE` has no escape character unless one is declared,
+   * and Knex's `where(col, 'like', …)` declares none on any dialect. Measured on
+   * better-sqlite3 before this change: the pattern `SO\_%` without `ESCAPE`
+   * matched nothing against a stored `SO_0007`, so on every SQLite face a
+   * format whose rendered prefix carries `_`, `%` or `\` — from the format's
+   * literal text OR from a `{field}` value such as `north_east` — scanned an
+   * empty partition: the cold bootstrap seeded the counter from 0 and the
+   * #5495 re-seed could not move it. Postgres and MySQL read a backslash as the
+   * default `LIKE` escape, so they were right by default rather than by
+   * declaration.
+   *
+   * The character is BOUND, never written as a literal — the same
+   * {@link LIKE_ESCAPE_CHARACTER} the filter compiler binds, for the reason
+   * given there: MySQL applies C escape syntax inside string literals, so a
+   * literal backslash is spelled differently per dialect while a bound value
+   * has one spelling everywhere. Turso's remote face sends its own statement
+   * to a SQLite engine only, and declares the same backslash there.
    */
   protected async scanMaxNumericTail(
     queryRunner: Knex | Knex.Transaction,
@@ -7537,7 +7559,10 @@ export class SqlDriver implements IDataDriver {
     tenantId: string | null,
     suffix = '',
   ): Promise<number> {
-    let builder = queryRunner(tableName).select(field).where(field, 'like', `${this.escapeLikePrefix(prefix)}%`).whereNotNull(field);
+    let builder = queryRunner(tableName)
+      .select(field)
+      .whereRaw('?? like ? escape ?', [field, `${this.escapeLikePrefix(prefix)}%`, LIKE_ESCAPE_CHARACTER])
+      .whereNotNull(field);
     if (tenantField && tenantId !== null) {
       builder = builder.where(tenantField, tenantId);
     }
@@ -7547,8 +7572,11 @@ export class SqlDriver implements IDataDriver {
 
   /**
    * The rendered prefix as a `LIKE` anchor: `\`, `%` and `_` escaped with a
-   * backslash, so a prefix is matched literally. The predicate's pre-filter
-   * only — {@link maxAutonumberCounter} re-checks the prefix per row.
+   * backslash, so a prefix is matched literally — under a `LIKE` that declares
+   * that backslash as its `ESCAPE`, which every statement using this anchor
+   * must do (see {@link scanMaxNumericTail}; SQLite has no escape character
+   * otherwise). The predicate's pre-filter only — {@link maxAutonumberCounter}
+   * re-checks the prefix per row.
    */
   protected escapeLikePrefix(prefix: string): string {
     return prefix.replace(/([\\%_])/g, '\\$1');
 
@@ -0,0 +1,122 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#21163] The Turso faces, held to one answer for an autonumber prefix that
+ * carries a `LIKE` metacharacter.
+ *
+ * The data table's MAX is read by two statements built from ONE escape helper
+ * (`SqlDriver.escapeLikePrefix`, which writes a backslash before `\`, `%` and
+ * `_`), and a backslash only escapes under a `LIKE` that declares it:
+ *
+ *  - **LOCAL (and embedded replica, same local engine)** inherits
+ *    `SqlDriver.scanMaxNumericTail`, compiled through Knex. Knex declared no
+ *    `ESCAPE`, and SQLite has no escape character otherwise, so `SO\_%` matched
+ *    nothing against a stored `SO_0007` (measured on this face at `cb45469e`:
+ *    the cold create issued `SO_0001`, and the re-seed after a bypass write
+ *    could not move the counter, so the create was refused). Fixed in
+ *    `driver-sql`, where the scan now binds the escape on every dialect.
+ *  - **REMOTE** sends its own statement through the transport, and that one
+ *    already declared `ESCAPE '\'` — so its legs below passed before the fix.
+ *    They are here as the other half of the same claim: both faces read the
+ *    one helper's output under a declared backslash, and answer the same
+ *    number. Change the helper's escape character without moving both
+ *    declarations and one half of this file reddens.
+ *
+ * Remote legs run over `makeLibsqlSqliteStub` — a real SQLite behind the
+ * `@libsql/client` interface — so the `LIKE` is evaluated by SQLite, not
+ * asserted as a string.
+ */
+
+import { describe, it, expect, afterEach } from 'vitest';
+import { TursoDriver } from './index.js';
+import { makeLibsqlSqliteStub } from './libsql-sqlite-stub.testkit.js';
+
+const TABLE = 'so_order';
+
+const pad4 = (n: number) => String(n).padStart(4, '0');
+
+const CASES = [
+  { label: '`_` in the prefix', format: 'SO_{0000}', render: (n: number) => `SO_${pad4(n)}`, role: 'red before the fix on LOCAL' },
+  { label: '`%` in the prefix', format: 'SO%{0000}', render: (n: number) => `SO%${pad4(n)}`, role: 'red before the fix on LOCAL' },
+  { label: 'a plain prefix', format: 'SO-{0000}', render: (n: number) => `SO-${pad4(n)}`, role: 'control' },
+] as const;
+
+const objectWith = (format: string) =>
+  ({
+    name: TABLE,
+    fields: {
+      so_no: { type: 'autonumber', format, unique: true },
+      title: { type: 'string' },
+    },
+  }) as any;
+
+interface Face {
+  driver: TursoDriver;
+  /** Land rows by a path that never enters `fillAutoNumberFields`. */
+  bypassInsert(values: string[]): Promise<void>;
+}
+
+async function localFace(format: string): Promise<Face> {
+  const driver = new TursoDriver({ url: ':memory:' });
+  expect(driver.transportMode).toBe('local');
+  await driver.initObjects([objectWith(format)]);
+  return {
+    driver,
+    bypassInsert: async (values) => {
+      await (driver as any).knex(TABLE).insert(values.map((v) => ({ id: `bypass-${v}`, so_no: v, title: 'seed replay' })));
+    },
+  };
+}
+
+async function remoteFace(format: string): Promise<Face> {
+  const stub = makeLibsqlSqliteStub();
+  const driver = new TursoDriver({ url: 'libsql://example.turso.io', client: stub as never });
+  expect(driver.transportMode).toBe('remote');
+  await driver.connect();
+  await driver.initObjects([objectWith(format)]);
+  const insert = stub.raw.prepare(`insert into "${TABLE}" ("id", "so_no", "title") values (?, ?, ?)`);
+  return {
+    driver,
+    bypassInsert: async (values) => {
+      for (const v of values) insert.run(`bypass-${v}`, v, 'seed replay');
+    },
+  };
+}
+
+for (const [faceName, open] of [
+  ['LOCAL', localFace],
+  ['REMOTE', remoteFace],
+] as const) {
+  describe(`[#21163] TursoDriver ${faceName}: an autonumber prefix carrying a LIKE metacharacter`, () => {
+    let face: Face | undefined;
+
+    afterEach(async () => {
+      await face?.driver.disconnect();
+      face = undefined;
+    });
+
+    for (const c of CASES) {
+      const role = faceName === 'REMOTE' ? 'passed before the fix' : c.role;
+
+      it(`${c.label}: a COLD bootstrap seeds from the stored MAX (${role})`, async () => {
+        face = await open(c.format);
+        await face.bypassInsert([c.render(7)]);
+
+        const created = await face.driver.create(TABLE, { title: 'first issued' });
+        expect(created.so_no).toBe(c.render(8));
+      });
+
+      it(`${c.label}: the #5495 re-seed moves a warm counter past rows a bypass write landed (${role})`, async () => {
+        face = await open(c.format);
+
+        // Warmed on an EMPTY table, so this leg does not lean on the cold scan.
+        expect((await face.driver.create(TABLE, { title: 'warm' })).so_no).toBe(c.render(1));
+
+        await face.bypassInsert(Array.from({ length: 29 }, (_, i) => c.render(i + 2)));
+
+        const created = await face.driver.create(TABLE, { title: 'after the seeds' });
+        expect(created.so_no).toBe(c.render(31));
+      });
+    }
+  });
+}