fix(backup): incremental backups against S3 + jsonb stats parsing

Three fixes uncovered while bringing the backup-s3 integration suite to
12/12 against MinIO + Postgres:

- backupService.getDatabaseBackupInfo: pg's jsonb driver auto-parses
  `statistics` / `table_checksums` to objects; the old JSON.parse() then
  threw "[object Object]" is not valid JSON and the manifest dropped
  database info silently. Accept both string and object inputs.

- backupService.runBackup: incremental path called
  backupManifest.loadManifest() with an s3:// URI directly, which falls
  through to fs.readFile() and ENOENTs — every "incremental" backup
  silently downgraded to a full one. Added loadManifestFromAnywhere()
  helper that downloads s3:// to a tmp file before delegating.

- backupManifest.generateIncrementalManifest: attached the `incremental`
  section AFTER generateManifest() had already stamped
  verification.total_checksum, so every incremental manifest failed
  validateManifest() on read-back. Recompute the checksum after.

Test side: updated assertions to the current manifest shape
(`incremental.changes.modified_files_count`), Number()-coerce bigint
columns from pg, and gate the logger mock on UNMOCK_LOGGER for
diagnosing similar silent-failure modes in the future.

backend/src/services/backupManifest.js

@@ -323,6 +323,12 @@ class BackupManifestGenerator {
       deleted_files: comparison.deleted_files.map(f => f.path)
     };
 
+    // Recalculate the checksum after attaching the incremental section,
+    // otherwise validateManifest() rejects the loaded manifest because
+    // generateManifest() stamped a checksum that did NOT include this
+    // section.
+    fullManifest.verification.total_checksum = this.calculateManifestChecksum(fullManifest);
+
     return fullManifest;
   }
 

backend/src/services/backupService.js

@@ -268,6 +268,15 @@ async function getDatabaseBackupInfoInternal() {
 
     if (recent && recent.file_path) {
       const hasChanged = await hasDatabaseChanged(recent.completed_at);
+      // Postgres jsonb columns come back already parsed; sqlite TEXT comes
+      // back as a JSON string. Accept both.
+      const parseField = (v) => {
+        if (v == null) return null;
+        if (typeof v === 'object') return v;
+        try { return JSON.parse(v); } catch { return null; }
+      };
+      const stats = parseField(recent.statistics);
+      const checksums = parseField(recent.table_checksums);
       return {
         type: recent.backup_type || 'unknown',
         backupFile: recent.file_path,
@@ -275,8 +284,8 @@ async function getDatabaseBackupInfoInternal() {
         checksum: recent.checksum,
         hasChanged,
         backupTime: recent.completed_at,
-        tables: recent.statistics ? JSON.parse(recent.statistics).tables : {},
-        rowCounts: recent.table_checksums ? JSON.parse(recent.table_checksums) : {}
+        tables: (stats && stats.tables) || {},
+        rowCounts: checksums || {}
       };
     }
 
@@ -826,7 +835,7 @@ async function runBackupInternal(isManual = false) {
       let manifest = await backupManifest.generateManifest(manifestOptions);
       if (previousBackup && previousBackup.manifest_path) {
         try {
-          const parentManifest = await backupManifest.loadManifest(previousBackup.manifest_path);
+          const parentManifest = await loadManifestFromAnywhere(previousBackup.manifest_path, config);
           manifest = await backupManifest.generateIncrementalManifest(manifestOptions, parentManifest);
         } catch (error) {
           logger.warn('Failed to load parent manifest, generating full manifest:', error);
@@ -1097,6 +1106,71 @@ async function cleanupOldBackupRuns(retentionDays = 30) {
   }
 }
 
+/**
+ * Load a backup manifest regardless of whether it lives on the local
+ * filesystem or in S3. Used by both the public getBackupManifest API
+ * and the incremental-manifest path in runBackupInternal — previously
+ * the latter called loadManifest() with an s3:// URI directly, which
+ * tried fs.readFile on the literal string and threw ENOENT, silently
+ * downgrading every incremental backup to a full manifest.
+ */
+async function loadManifestFromAnywhere(manifestPath, config) {
+  if (!manifestPath) {
+    throw new Error('Manifest path is required');
+  }
+  if (!manifestPath.startsWith('s3://')) {
+    return backupManifest.loadManifest(manifestPath);
+  }
+
+  const cfg = config || (await resolveConfigWithFallback());
+  const accessKey = cfg?.backup_s3_access_key
+    ?? (cfg?.__raw && Object.prototype.hasOwnProperty.call(cfg.__raw, 'backup_s3_access_key')
+      ? parseSettingValue(cfg.__raw.backup_s3_access_key)
+      : undefined)
+    ?? process.env.BACKUP_S3_ACCESS_KEY;
+  const secretKey = cfg?.backup_s3_secret_key
+    ?? (cfg?.__raw && Object.prototype.hasOwnProperty.call(cfg.__raw, 'backup_s3_secret_key')
+      ? parseSettingValue(cfg.__raw.backup_s3_secret_key)
+      : undefined)
+    ?? process.env.BACKUP_S3_SECRET_KEY;
+
+  if (!accessKey || !secretKey) {
+    throw new Error('S3 credentials not configured for manifest retrieval');
+  }
+
+  const match = manifestPath.match(/^s3:\/\/([^\/]+)\/(.+)$/);
+  if (!match) {
+    throw new Error('Invalid S3 manifest path');
+  }
+  const [, bucket, key] = match;
+
+  const tempDir = await fs.mkdtemp(path.join(os.tmpdir(), 'backup-manifest-'));
+  // Preserve the original extension so loadManifest's format detection
+  // picks the right parser.
+  const ext = path.extname(key) || '.json';
+  const tempPath = path.join(tempDir, `manifest-${Date.now()}${ext}`);
+
+  const s3Client = new S3StorageAdapter({
+    bucket,
+    region: (cfg && cfg.backup_s3_region) || 'us-east-1',
+    endpoint: cfg && cfg.backup_s3_endpoint,
+    accessKeyId: accessKey,
+    secretAccessKey: secretKey,
+    forcePathStyle: cfg ? normalizeBoolean(cfg.backup_s3_force_path_style) : false,
+    sslEnabled: cfg && cfg.backup_s3_ssl_enabled !== undefined
+      ? normalizeBoolean(cfg.backup_s3_ssl_enabled)
+      : true,
+  });
+
+  try {
+    await s3Client.download(key, tempPath);
+    return await backupManifest.loadManifest(tempPath);
+  } finally {
+    await fs.unlink(tempPath).catch(() => {});
+    await fs.rm(tempDir, { recursive: true, force: true }).catch(() => {});
+  }
+}
+
 async function getBackupManifest(backupRunId) {
   const run = await db('backup_runs')
     .where('id', backupRunId)