Seed batches: insert files and binaries in chunks of 2,000 rows

A batch of a dense range (over ~5,400 files) exceeded Postgres' 65,535
bind parameters per statement, so its post failed with a 500 until the
range was given up.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/services/FileStore.ts

@@ -36,6 +36,9 @@ export function loadedSegments(stored: Buffer | null): Segment[] {
   return stored ? unpackSegments(stored) : []
 }
 
+/** Rows per INSERT, well below Postgres' 65,535 bind parameters. */
+export const INSERT_ROWS = 2000
+
 class FileStore {
   /**
    * Inserts files, skipping those whose `file_key` exists. Returns the rows
@@ -66,8 +69,13 @@ class FileStore {
         return { ...file, segments: packSegments(sorted), first_message_id: sorted[0]?.id ?? null }
       })
     if (rows.length === 0) return []
-    const inserted = await client.knexQuery().table('files').insert(rows).onConflict().ignore().returning(['id', 'filename'])
-    return inserted.map((row: any) => ({ id: Number(row.id), filename: row.filename }))
+    // A statement takes at most 65,535 parameters: ~5,400 rows of 12 columns.
+    const inserted: { id: number; filename: string }[] = []
+    for (let i = 0; i < rows.length; i += INSERT_ROWS) {
+      const chunk = await client.knexQuery().table('files').insert(rows.slice(i, i + INSERT_ROWS)).onConflict().ignore().returning(['id', 'filename'])
+      for (const row of chunk) inserted.push({ id: Number(row.id), filename: row.filename })
+    }
+    return inserted
   }
 }