fix(db): export every MySQL table and restore with foreign keys off

Bug: `void db export` in an app with "database": "mysql" fails on
MySQL 8 with "Table 'app.undefined' doesn't exist" (with or without
--output, --no-schema, --no-data). Once the table names are read
correctly, the dump still cannot be restored when a child table's
name sorts before its parent's: a full dump fails with "Failed to
open the referenced table", and a --no-schema dump fails with
"Cannot add or update a child row: a foreign key constraint fails".

Repro: on MySQL 8, create posts(id PK) and comments(post_id FK ->
posts.id) with one row each, then run `void db export --output
dump.sql`. It throws. With the name read fixed, load the dump into an
empty database: comments is created (or filled) before posts and the
foreign key check rejects it.

Cause: runExport in packages/void/src/cli/db.ts lists tables with an
unaliased `SELECT table_name FROM information_schema.tables`. MySQL 8
labels that column `TABLE_NAME`, so `row.table_name` is undefined and
every table becomes "undefined". The loop then writes tables in name
order, SHOW CREATE TABLE keeps foreign keys inline, and the dump never
turns FOREIGN_KEY_CHECKS off, so restore order breaks on parent/child
pairs.

Fix: alias the column (`table_name AS table_name`), the same fix
`void db reset` already uses, and wrap the MySQL dump in
`SET FOREIGN_KEY_CHECKS = 0;` ... `SET FOREIGN_KEY_CHECKS = 1;`. The
wrapper is smaller than sorting tables by dependency and also covers
foreign key cycles. Only the MySQL branch of runExport changes.

Test: packages/void/test/unit/db-commands.test.ts, "void db export >
MySQL: exports every table with foreign key checks off". Without the
fix the export queries `undefined` and has no SET lines.

Note: every MySQL export (full, --table, --no-schema, --no-data) now
starts with FOREIGN_KEY_CHECKS = 0 and ends with = 1, the MySQL
default. A restore into a session that already had the checks off
ends with them on.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0123r5HnanmW2VUrZ7VWDufH

Author: Brooooooklyn

packages/void/src/cli/db.ts

@@ -1832,12 +1832,16 @@ async function runExport(
         }
         tables = [args.table];
       } else {
+        // MySQL 8 returns an unaliased information_schema column as `TABLE_NAME`.
         const rows = await client.query<Array<{ table_name: string }>>(
-          "SELECT table_name FROM information_schema.tables WHERE table_schema = DATABASE() AND table_type = 'BASE TABLE' AND table_name NOT LIKE '\\_%' ORDER BY table_name",
+          "SELECT table_name AS table_name FROM information_schema.tables WHERE table_schema = DATABASE() AND table_type = 'BASE TABLE' AND table_name NOT LIKE '\\_%' ORDER BY table_name",
         );
         tables = rows.map((row) => String(row.table_name));
       }
 
+      // Tables come out in name order with inline foreign keys, so a child
+      // table can precede its parent; restore with the checks off.
+      parts.push('SET FOREIGN_KEY_CHECKS = 0;');
       for (const table of tables) {
         const escapedTable = table.replaceAll('`', '``');
         if (!args.noSchema) {
@@ -1863,6 +1867,7 @@ async function runExport(
         }
         parts.push('');
       }
+      parts.push('SET FOREIGN_KEY_CHECKS = 1;', '');
     });
 
     const output = parts.join('\n');

packages/void/test/unit/db-commands.test.ts

@@ -451,6 +451,47 @@ describe('void db reset', () => {
   });
 });
 
+describe('void db export', () => {
+  let runDbCommand: typeof import('../../src/cli/db.ts').runDbCommand;
+
+  beforeEach(async () => {
+    vi.clearAllMocks();
+    vi.spyOn(process, 'exit').mockImplementation(((code?: number) => {
+      throw new Error(`process.exit:${code ?? 0}`);
+    }) as never);
+    runDbCommand = (await import('../../src/cli/db.ts')).runDbCommand;
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    for (const root of rootsToClean.splice(0, rootsToClean.length)) {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+
+  it('MySQL: exports every table with foreign key checks off', async () => {
+    const root = mkdtempSync(join(tmpdir(), 'void-export-mysql-'));
+    rootsToClean.push(root);
+    writeFileSync(join(root, 'void.json'), JSON.stringify({ database: 'mysql' }));
+    writeFileSync(join(root, '.env'), 'DATABASE_URL="mysql://root@127.0.0.1:3306/app"\n');
+    mysqlQueries.length = 0;
+    let stdout = '';
+    vi.spyOn(process.stdout, 'write').mockImplementation((chunk: string | Uint8Array) => {
+      stdout += chunk.toString();
+      return true;
+    });
+
+    await runDbCommand(root, { action: 'export' });
+
+    expect(mysqlQueries).toContain('SHOW CREATE TABLE `users`');
+    expect(mysqlQueries).toContain('SELECT * FROM `users`');
+    expect(mysqlQueries.join('\n')).not.toContain('`undefined`');
+    const lines = stdout.trim().split('\n');
+    expect(lines[0]).toBe('SET FOREIGN_KEY_CHECKS = 0;');
+    expect(lines.at(-1)).toBe('SET FOREIGN_KEY_CHECKS = 1;');
+  });
+});
+
 describe('void db status', () => {
   let runDbCommand: typeof import('../../src/cli/db.ts').runDbCommand;