Infrastructure build to support third-party app integrations

backend/db/seed.ts

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+import 'dotenv/config';
+import split2 from 'split2';
+import { from as copyFrom } from 'pg-copy-streams';
+import { createReadStream } from 'node:fs';
+import { Transform, type TransformCallback } from 'node:stream';
+import { pipeline } from 'node:stream/promises';
+import { fileURLToPath } from 'node:url';
+import { getPool, close } from './index.js';
+
+const FIXTURE = fileURLToPath(new URL('./fixtures/notes.jsonl', import.meta.url));
+
+const COLUMNS = ['id', 'text', 'x', 'y', 'author', 'color'] as const;
+
+type Column = typeof COLUMNS[number];
+
+const DEFAULTS: Partial<Record<Column, unknown>> = { x: 0, y: 0, color: 'yellow' };
+
+const csvField = (value: unknown): string => {
+  if (value === null || value === undefined) return '';
+  return `"${String(value).replaceAll('"', '""')}"`;
+};
+
+const toCsvRows = (): Transform => new Transform({
+  writableObjectMode: true,
+  transform(line: string, _encoding: BufferEncoding, callback: TransformCallback) {
+    if (line.trim().length === 0) {
+      callback();
+      return;
+    }
+
+    let note: Record<string, unknown>;
+    try {
+      note = JSON.parse(line) as Record<string, unknown>;
+    } catch {
+      callback(new Error(`Fixture contains a malformed JSON line: ${line.slice(0, 80)}`));
+      return;
+    }
+
+    const row = COLUMNS.map((col) => csvField(note[col] ?? DEFAULTS[col]));
+    callback(null, `${row.join(',')}\n`);
+  },
+});
+
+const run = async (): Promise<void> => {
+  const client = await getPool().connect();
+
+  try {
+    await client.query('BEGIN');
+
+    // COPY has no ON CONFLICT, so land the fixture in a temp table first and
+    // let a single INSERT ... SELECT apply the existing idempotency.
+    await client.query(
+      'CREATE TEMP TABLE notes_import (LIKE notes INCLUDING DEFAULTS) ON COMMIT DROP'
+    );
+
+    const copy = client.query(
+      copyFrom(`COPY notes_import (${COLUMNS.join(', ')}) FROM STDIN WITH (FORMAT csv)`)
+    );
+
+    await pipeline(createReadStream(FIXTURE), split2(), toCsvRows(), copy);
+
+    const { rowCount: staged } = await client.query('SELECT 1 FROM notes_import');
+    const { rowCount: inserted } = await client.query(
+      `INSERT INTO notes (${COLUMNS.join(', ')})
+       SELECT ${COLUMNS.join(', ')} FROM notes_import
+       ON CONFLICT (id) DO NOTHING`
+    );
+
+    await client.query('COMMIT');
+
+    console.log(`Seed complete — ${inserted} notes inserted (${(staged ?? 0) - (inserted ?? 0)} already existed).`);
+  } catch (err) {
+    await client.query('ROLLBACK').catch(() => {});
+    console.error('Seed failed:', err instanceof Error ? err.message : err);
+    process.exitCode = 1;
+  } finally {
+    client.release();
+    await close();
+  }
+};
+
+run();