feat: add PostgreSQL document persistence

- Configure a shared PostgreSQL connection pool with connection and idle timeouts
- Add repository functions to create documents and store embedded chunks
- Persist chunks and mark documents as completed within a transaction
- Roll back failed chunk storage operations while preserving the original error
- Load environment variables from .env in development and production commands

package.json

@@ -5,9 +5,9 @@
   "main": "index.js",
   "scripts": {
     "test": "tsx --test src/**/*.test.ts",
-    "dev": "tsx watch src/server.ts",
+    "dev": "node --env-file=.env --import tsx/esm --watch src/server.ts",
     "build": "tsc -p tsconfig.json",
-    "start": "node dist/server.js"
+    "start": "node --env-file=.env dist/server.js"
   },
   "keywords": [],
   "author": "",

src/db.ts

@@ -0,0 +1,14 @@
+import pg from "pg";
+
+const { Pool } = pg;
+
+export const pool = new Pool({
+  connectionString: process.env.DATABASE_URL,
+  connectionTimeoutMillis: 5_000,
+  idleTimeoutMillis: 30_000,
+  max: 10,
+});
+
+pool.on("error", (error) => {
+  console.error("Unexpected PostgreSQL pool error:", error);
+});

src/document-repository.ts

@@ -0,0 +1,74 @@
+import { pool } from "./db.js";
+import type { TextChunk } from "./chunking.js";
+
+export interface NewDocument {
+  title: string;
+  source?: string;
+}
+
+export interface StoredChunk extends TextChunk {
+  embedding: number[];
+}
+
+export const createDocument = async (
+  document: NewDocument,
+): Promise<string> => {
+  const result = await pool.query<{ id: string }>(
+    `INSERT INTO documents (title, source, status)
+    VALUES ($1, $2, 'processing')
+    RETURNING id`,
+    [document.title, document.source ?? null],
+  );
+
+  const id = result.rows[0]?.id;
+
+  if (!id) {
+    throw new Error("Failed to create document");
+  }
+
+  return id;
+};
+
+export const storeDocumentChunks = async (
+  documentId: string,
+  chunks: StoredChunk[],
+): Promise<void> => {
+  const client = await pool.connect();
+
+  try {
+    await client.query("BEGIN");
+
+    for (const chunk of chunks) {
+      await client.query(
+        `INSERT INTO document_chunks
+          (document_id, chunk_index, content, embedding)
+        VALUES ($1, $2, $3, $4::vector)`,
+        [
+          documentId,
+          chunk.chunkIndex,
+          chunk.content,
+          `[${chunk.embedding.join(",")}]`,
+        ],
+      );
+    }
+
+    await client.query(
+      `UPDATE documents
+      SET status = 'completed'
+      WHERE id = $1`,
+      [documentId],
+    );
+
+    await client.query("COMMIT");
+  } catch (error) {
+    try {
+      await client.query("ROLLBACK");
+    } catch {
+      // Preserve the original error.
+    }
+
+    throw error;
+  } finally {
+    client.release();
+  }
+};