feat(backup): pre-migration snapshot gated on pending migrations; checkpoint WAL on shutdown

packages/server/src/db/index.ts

@@ -5,7 +5,9 @@ import { config } from '../config.js';
 import * as schema from './schema.js';
 import { ensureDefaults } from './migrate.js';
 import { setWorkerId } from '../utils/snowflake.js';
-import { mkdirSync } from 'fs';
+import { createSnapshot } from '../utils/backup.js';
+import { hasPendingMigrations } from './pendingMigrations.js';
+import { mkdirSync, existsSync } from 'fs';
 import { dirname, resolve } from 'path';
 import { fileURLToPath } from 'url';
 
@@ -20,12 +22,29 @@ function ensureDirectory(filePath: string): void {
 
 export function initDatabase() {
   ensureDirectory(config.dbPath);
+  // Capture existence BEFORE opening — new Database() creates the file, so a
+  // post-open check would always report "exists" and snapshot a 0-row DB on first boot.
+  const dbExisted = existsSync(config.dbPath);
+
   sqlite = new Database(config.dbPath);
   sqlite.pragma('journal_mode = WAL');
   sqlite.pragma('foreign_keys = ON');
 
-  // Apply any pending Drizzle migrations
   const migrationsFolder = resolve(__dirname, '../../drizzle');
+
+  // Snapshot before migrating — but only when there is a real DB AND a migration
+  // is actually pending. History is stable across most boots, so this avoids
+  // churning the pre-migration retention with identical copies on every restart.
+  if (!config.backup.disabled && dbExisted && hasPendingMigrations(sqlite, migrationsFolder)) {
+    try {
+      const snap = createSnapshot(sqlite, 'pre-migration');
+      console.log(`[backup] pre-migration snapshot written: ${snap}`);
+    } catch (err) {
+      console.error(`[backup] pre-migration snapshot FAILED — aborting migration to protect data: ${(err as Error).message}`);
+      throw err;
+    }
+  }
+
   const db = drizzle(sqlite, { schema });
   migrate(db, { migrationsFolder });
 

packages/server/src/db/pendingMigrations.test.ts

@@ -0,0 +1,31 @@
+import { describe, it, expect } from 'vitest';
+import Database from 'better-sqlite3';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { hasPendingMigrations } from './pendingMigrations.js';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const migrationsFolder = path.resolve(__dirname, '../../drizzle');
+
+describe('hasPendingMigrations', () => {
+  it('returns true when __drizzle_migrations is missing', () => {
+    const db = new Database(':memory:');
+    expect(hasPendingMigrations(db, migrationsFolder)).toBe(true);
+  });
+
+  it('returns true when fewer rows than journal entries are applied', () => {
+    const db = new Database(':memory:');
+    db.exec('CREATE TABLE __drizzle_migrations (id INTEGER PRIMARY KEY, hash TEXT, created_at NUMERIC)');
+    db.prepare('INSERT INTO __drizzle_migrations (hash, created_at) VALUES (?, ?)').run('x', 1);
+    expect(hasPendingMigrations(db, migrationsFolder)).toBe(true);
+  });
+
+  it('returns false when applied count >= journal entries', () => {
+    const db = new Database(':memory:');
+    db.exec('CREATE TABLE __drizzle_migrations (id INTEGER PRIMARY KEY, hash TEXT, created_at NUMERIC)');
+    const journal = require(path.join(migrationsFolder, 'meta/_journal.json'));
+    const insert = db.prepare('INSERT INTO __drizzle_migrations (hash, created_at) VALUES (?, ?)');
+    for (let i = 0; i < journal.entries.length; i++) insert.run(`h${i}`, i);
+    expect(hasPendingMigrations(db, migrationsFolder)).toBe(false);
+  });
+});

packages/server/src/db/pendingMigrations.ts

@@ -0,0 +1,25 @@
+import Database from 'better-sqlite3';
+import fs from 'node:fs';
+import path from 'node:path';
+
+interface DrizzleJournal { entries: Array<{ idx: number; tag: string; when: number }>; }
+
+/**
+ * True when migrations are pending. Drizzle's better-sqlite3 migrator appends one
+ * row per applied migration to `__drizzle_migrations`, in journal order. Comparing
+ * the applied row count to the journal entry count is sufficient to know whether
+ * `migrate()` will apply anything — without running it. A missing table means a
+ * pre-drizzle or empty DB: treat as pending.
+ */
+export function hasPendingMigrations(db: Database.Database, migrationsFolder: string): boolean {
+  const journalPath = path.join(migrationsFolder, 'meta', '_journal.json');
+  const journal = JSON.parse(fs.readFileSync(journalPath, 'utf8')) as DrizzleJournal;
+
+  const tableExists = db
+    .prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = '__drizzle_migrations'")
+    .get();
+  if (!tableExists) return true;
+
+  const applied = db.prepare('SELECT COUNT(*) AS n FROM __drizzle_migrations').get() as { n: number };
+  return applied.n < journal.entries.length;
+}