add chat function

.env.example

@@ -0,0 +1,3 @@
+# Optional: set when frontend and backend are on different origins.
+# local dev with Vite proxy can leave this unset.
+# VITE_CHAT_API_BASE_URL=https://your-backend.example.com

.gitignore

@@ -11,6 +11,7 @@ node_modules
 dist
 dist-ssr
 *.local
+backend/.env
 
 # Editor directories and files
 .vscode/*

README.md

@@ -13,6 +13,7 @@ A modern, responsive portfolio website built with React and TypeScript. This pro
 - **Routing**: Client-side navigation with react-router-dom
 - **Data Visualization**: Charts and graphs with recharts
 - **Accessibility**: Built with accessibility in mind
+- **Portfolio Chat**: RAG-style chat backed by a dedicated backend and Cerebras API
 
 ## 🛠️ Tech Stack
 
@@ -33,51 +34,64 @@ cd portfolio_site
 
 # Install dependencies
 pnpm install
+
+# Install backend dependencies
+cd backend
+pnpm install
+cd ..
 ```
 
 ## 🧰 Available Scripts
 
 ```bash
 # Start development server
 bun run dev
-pnpm dev
+pnpm run dev
 
 # Build for production
 bun run build
-pnpm build
+pnpm run build
 
 # Build for development
 bun run build:dev
-pnpm build:dev
+pnpm run build:dev
 
 # Lint code
 bun run lint
-pnpm lint
+pnpm run lint
 
 # Preview production build
 bun run preview
-pnpm preview
+pnpm run preview
 ```
 
 ## 🚧 Development
 
 1. Start the development server:
    ```bash
    bun run dev
-   pnpm dev
+   pnpm run dev
+   ```
+
+2. Start the chat backend in another terminal:
+   ```bash
+   cd backend
+   cp .env.example .env.local
+   # set CEREBRAS_API_KEY in backend/.env.local
+   bun run dev
    ```
 
-2. Open your browser and visit [http://localhost:5173/](http://localhost:5173/)
+4. Open your browser and visit [http://localhost:8080/](http://localhost:8080/)
 
-3. Make changes to files in the `src` directory to see live updates
+5. Make changes to files in the `src` directory to see live updates
 
 ## 🌐 Deployment
 
 Build the project for production:
 
 ```bash
 bun run build
-pnpm build
+pnpm run build
 ```
 
 The build artifacts will be stored in the `dist/` directory, ready to be deployed to your hosting provider of choice.

backend/.env.example

@@ -0,0 +1,4 @@
+PORT=8787
+FRONTEND_ORIGIN=http://localhost:8080,http://localhost:5173
+CEREBRAS_API_KEY=
+CEREBRAS_MODEL=llama-3.3-70b

backend/README.md

@@ -0,0 +1,25 @@
+# Portfolio Chat Backend
+
+Express + TypeScript backend for portfolio chat.
+
+## Features
+
+- `/api/chat` endpoint for frontend chat UI
+- Retrieval from:
+  - `public/llm.txt`
+  - `src/data/**/*`
+  - `backend/knowledge/cv/**/*`
+  - `backend/knowledge/about/**/*`
+- Cerebras chat completion integration
+
+## Setup
+
+```bash
+cd backend
+bun install
+cp .env.example .env
+# set CEREBRAS_API_KEY in .env
+bun run dev
+```
+
+Server runs at `http://localhost:8787` by default.

backend/knowledge/about/README.md

@@ -0,0 +1,4 @@
+# About Knowledge
+
+Put additional markdown files here.
+These files are included in RAG context automatically.

backend/knowledge/cv/README.md

@@ -0,0 +1,4 @@
+# CV Knowledge
+
+Put CV text/markdown files here.
+For PDF, convert to text/markdown before ingest for now.

backend/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "portfolio-chat-backend",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "tsx watch src/server.ts",
+    "build": "tsc -p tsconfig.json",
+    "start": "node dist/server.js"
+  },
+  "dependencies": {
+    "cors": "^2.8.5",
+    "dotenv": "^16.4.5",
+    "express": "^4.21.0",
+    "zod": "^3.23.8"
+  },
+  "devDependencies": {
+    "@types/cors": "^2.8.17",
+    "@types/express": "^5.0.0",
+    "@types/node": "^22.5.5",
+    "tsx": "^4.19.2",
+    "typescript": "^5.5.3"
+  }
+}

backend/src/ingest/loadDocuments.ts

@@ -0,0 +1,86 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+import { SourceDocument } from '../types/chat.js';
+
+const SUPPORTED_EXTENSIONS = new Set(['.md', '.markdown', '.txt', '.json', '.ts', '.tsx']);
+
+type SourceConfig = {
+  type: SourceDocument['sourceType'];
+  path: string;
+};
+
+const readDirRecursive = async (dir: string): Promise<string[]> => {
+  const entries = await fs.readdir(dir, { withFileTypes: true });
+  const files: string[] = [];
+
+  for (const entry of entries) {
+    const fullPath = path.join(dir, entry.name);
+    if (entry.isDirectory()) {
+      files.push(...(await readDirRecursive(fullPath)));
+      continue;
+    }
+
+    if (entry.isFile() && SUPPORTED_EXTENSIONS.has(path.extname(entry.name).toLowerCase())) {
+      files.push(fullPath);
+    }
+  }
+
+  return files;
+};
+
+const readSourcePath = async (source: SourceConfig): Promise<SourceDocument[]> => {
+  try {
+    const stat = await fs.stat(source.path);
+
+    if (stat.isFile()) {
+      const content = await fs.readFile(source.path, 'utf8');
+      return [
+        {
+          id: source.path,
+          title: path.basename(source.path),
+          path: source.path,
+          content,
+          sourceType: source.type,
+        },
+      ];
+    }
+
+    if (stat.isDirectory()) {
+      const files = await readDirRecursive(source.path);
+      const docs: SourceDocument[] = [];
+
+      for (const file of files) {
+        const content = await fs.readFile(file, 'utf8');
+        docs.push({
+          id: file,
+          title: path.basename(file),
+          path: file,
+          content,
+          sourceType: source.type,
+        });
+      }
+
+      return docs;
+    }
+  } catch (error) {
+    console.error(`Failed to read source path "${source.path}":`, error);
+    return [];
+  }
+
+  return [];
+};
+
+export const loadPortfolioDocuments = async (): Promise<SourceDocument[]> => {
+  const backendRoot = process.cwd();
+  const projectRoot = path.resolve(backendRoot, '..');
+
+  const sources: SourceConfig[] = [
+    { type: 'site', path: path.join(projectRoot, 'public', 'llm.txt') },
+    { type: 'site', path: path.join(projectRoot, 'src', 'data') },
+    { type: 'cv', path: path.join(backendRoot, 'knowledge', 'cv') },
+    { type: 'about', path: path.join(backendRoot, 'knowledge', 'about') },
+  ];
+
+  const all = await Promise.all(sources.map((source) => readSourcePath(source)));
+  return all.flat().filter((doc) => doc.content.trim().length > 0);
+};

backend/src/routes/chat.ts

@@ -0,0 +1,43 @@
+import { Router } from 'express';
+import { z } from 'zod';
+import { ChatService } from '../services/chatService.js';
+
+const schema = z.object({
+  message: z.string().min(1),
+  history: z
+    .array(
+      z.object({
+        role: z.enum(['user', 'assistant']),
+        content: z.string().min(1),
+      }),
+    )
+    .default([]),
+});
+
+export const createChatRouter = (chatService: ChatService) => {
+  const router = Router();
+
+  router.post('/chat', async (req, res) => {
+    console.log('[api] POST /api/chat');
+    const parsed = schema.safeParse(req.body);
+
+    if (!parsed.success) {
+      console.warn('[api] invalid request body');
+      return res.status(400).json({
+        error: 'Invalid request body',
+        details: parsed.error.flatten(),
+      });
+    }
+
+    try {
+      const result = await chatService.ask(parsed.data.message, parsed.data.history);
+      return res.status(200).json(result);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : 'Unexpected server error';
+      console.error(`[api] chat failed: ${message}`);
+      return res.status(500).json({ error: message });
+    }
+  });
+
+  return router;
+};

backend/src/server.ts

@@ -0,0 +1,53 @@
+import cors from "cors";
+import dotenv from "dotenv";
+import express from "express";
+import { createChatRouter } from "./routes/chat.js";
+import { CerebrasClient } from "./services/cerebras.js";
+import { ChatService } from "./services/chatService.js";
+
+dotenv.config();
+const BASE_MODEL = "llama-3.3-70b";
+const port = Number(process.env.PORT ?? 8787);
+const cerebrasApiKey = process.env.CEREBRAS_API_KEY;
+const cerebrasModel = process.env.CEREBRAS_MODEL ?? BASE_MODEL;
+const frontendOrigins = (
+  process.env.FRONTEND_ORIGIN ?? "http://localhost:8080,http://localhost:5173"
+)
+  .split(",")
+  .map((origin) => origin.trim())
+  .filter(Boolean);
+
+if (!cerebrasApiKey) {
+  throw new Error("CEREBRAS_API_KEY is required. Add it to backend/.env");
+}
+
+const app = express();
+app.use(
+  cors({
+    origin: (origin, callback) => {
+      if (!origin || frontendOrigins.includes(origin)) {
+        callback(null, true);
+        return;
+      }
+      callback(new Error(`Origin not allowed by CORS: ${origin}`));
+    },
+  }),
+);
+app.use(express.json({ limit: "1mb" }));
+
+const chatService = new ChatService(
+  new CerebrasClient({
+    apiKey: cerebrasApiKey,
+    model: cerebrasModel,
+  }),
+);
+
+app.get("/health", (_req, res) => {
+  res.status(200).json({ ok: true });
+});
+
+app.use("/api", createChatRouter(chatService));
+
+app.listen(port, () => {
+  console.log(`Portfolio chat backend listening on http://localhost:${port}`);
+});