feat: automate verified SQLite backups and safe recovery

src/ops/backups.ts

@@ -0,0 +1,96 @@
+import { Database } from "bun:sqlite";
+import { chmodSync, closeSync, constants, copyFileSync, existsSync, fsyncSync, linkSync, mkdirSync, openSync, readdirSync, renameSync, rmSync, statSync, unlinkSync } from "node:fs";
+import { dirname, join, resolve } from "node:path";
+
+export type BackupConfig = { directory: string; replica?: string; retain: number; intervalMs: number; enabled: boolean };
+const filenamePattern = /^minabot-\d{4}-\d{2}-\d{2}T[\d-]+Z-[a-f0-9-]+\.sqlite$/;
+export function backupConfig(database: string, env = process.env): BackupConfig {
+  const retain = Number(env.BACKUP_RETAIN ?? 7);
+  const hours = Number(env.BACKUP_INTERVAL_HOURS ?? 24);
+  if (!Number.isInteger(retain) || retain < 2 || retain > 365 || !Number.isFinite(hours) || hours < 1 || hours > 168)
+    throw new Error("BACKUP_RETAIN must be 2–365 and BACKUP_INTERVAL_HOURS must be 1–168");
+  const base = dirname(database);
+  const directory = resolve(base, env.BACKUP_DIR ?? "backups");
+  const replica = env.BACKUP_REPLICA_DIR ? resolve(base, env.BACKUP_REPLICA_DIR) : undefined;
+  if (replica === directory) throw new Error("The backup replica must use a separate directory");
+  return { directory, replica, retain, intervalMs: hours * 3600000, enabled: env.BACKUP_ENABLED !== "false" };
+}
+function durable(path: string) {
+  chmodSync(path, 0o600);
+  const fd = openSync(path, "r"); try { fsyncSync(fd); } finally { closeSync(fd); }
+}
+export function verifyBackup(path: string) {
+  const db = new Database(path, { readonly: true, strict: true });
+  try {
+    const integrity = db.query("PRAGMA integrity_check").all() as { integrity_check: string }[];
+    if (integrity.length !== 1 || integrity[0]?.integrity_check !== "ok" || db.query("PRAGMA foreign_key_check").all().length)
+      throw new Error("Backup integrity check failed");
+    db.query("SELECT id FROM users LIMIT 1").all();
+    db.query("SELECT id FROM habits LIMIT 1").all();
+    db.query("SELECT hash FROM __drizzle_migrations LIMIT 1").all();
+  } finally { db.close(); }
+}
+function snapshots(directory: string) {
+  if (!existsSync(directory)) return [];
+  return readdirSync(directory).filter(name => filenamePattern.test(name)).sort().reverse();
+}
+export function latestBackupTime(config: BackupConfig) {
+  const latest = snapshots(config.directory)[0];
+  if (!latest || (config.replica && !existsSync(join(config.replica, latest)))) return 0;
+  return statSync(join(config.directory, latest)).mtimeMs;
+}
+export function createBackup(database: Database, config: BackupConfig) {
+  const name = `minabot-${new Date().toISOString().replace(/[:.]/g, "-")}-${crypto.randomUUID()}.sqlite`;
+  mkdirSync(config.directory, { recursive: true, mode: 0o700 });
+  const path = join(config.directory, name);
+  const staging = `${path}.partial`;
+  mkdirSync(staging, { mode: 0o700 });
+  const temporary = join(staging, "snapshot.sqlite");
+  try {
+    // VACUUM INTO includes committed WAL transactions in one consistent snapshot.
+    // SQLite creates the output inside a private staging directory.
+    database.query("VACUUM INTO ?").run(temporary);
+    verifyBackup(temporary); durable(temporary); renameSync(temporary, path);
+    if (config.replica) {
+      // Require the configured mount to exist; never silently create an absent mount.
+      if (!statSync(config.replica).isDirectory()) throw new Error("Backup replica directory unavailable");
+      const replica = join(config.replica, name);
+      copyFileSync(path, `${replica}.partial`, constants.COPYFILE_EXCL);
+      durable(`${replica}.partial`); verifyBackup(`${replica}.partial`); renameSync(`${replica}.partial`, replica);
+    }
+    for (const directory of [config.directory, ...(config.replica ? [config.replica] : [])])
+      for (const old of snapshots(directory).slice(config.retain)) unlinkSync(join(directory, old));
+    return path;
+  } finally { rmSync(staging, { recursive: true, force: true }); }
+}
+export function restoreBackup(source: string, destination: string) {
+  if (existsSync(destination) || existsSync(`${destination}-wal`) || existsSync(`${destination}-shm`))
+    throw new Error("Restore destination must be a new path with no SQLite sidecars");
+  verifyBackup(source);
+  mkdirSync(dirname(destination), { recursive: true, mode: 0o700 });
+  const temporary = `${destination}.${crypto.randomUUID()}.partial`;
+  try {
+    copyFileSync(source, temporary, constants.COPYFILE_EXCL); chmodSync(temporary, 0o600);
+    const restored = new Database(temporary);
+    try { restored.exec("PRAGMA journal_mode=DELETE; DELETE FROM sessions;"); } finally { restored.close(); }
+    verifyBackup(temporary); durable(temporary);
+    // Link is exclusive: a concurrently-created destination is never overwritten.
+    linkSync(temporary, destination);
+  } finally { if (existsSync(temporary)) unlinkSync(temporary); }
+  return destination;
+}
+export function startBackups(database: Database, config: BackupConfig) {
+  const state = { enabled: config.enabled, lastSuccess: 0, failed: false };
+  if (!config.enabled) return { state, stop() {} };
+  const tick = () => {
+    try {
+      const latest = latestBackupTime(config);
+      if (latest && Date.now() - latest < config.intervalMs) { state.lastSuccess = latest; state.failed = false; return; }
+      createBackup(database, config); state.lastSuccess = Date.now(); state.failed = false;
+      console.log(JSON.stringify({ event: "backup_completed", timestamp: new Date().toISOString() }));
+    } catch { state.failed = true; console.error(JSON.stringify({ event: "backup_failed", timestamp: new Date().toISOString() })); }
+  };
+  tick();
+  const timer = setInterval(tick, 60000); timer.unref();
+  return { state, stop: () => clearInterval(timer) };
+}