Add screenshot server

og-screenshot/src/cache.ts

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+import { createHash } from 'crypto';
+import { existsSync, mkdirSync, statSync, createReadStream, writeFileSync } from 'fs';
+import { join } from 'path';
+import type { Readable } from 'stream';
+
+const MAX_AGE_MS = 24 * 60 * 60 * 1000; // 24 hours
+
+export class ScreenshotCache {
+  private dir: string;
+
+  constructor(dir: string) {
+    this.dir = dir;
+    if (!existsSync(dir)) {
+      mkdirSync(dir, { recursive: true });
+    }
+  }
+
+  /**
+   * Build a cache key by quantizing view params and hashing.
+   * - lat/lng quantized to 2 decimal places
+   * - zoom quantized to integer
+   * - filters sorted alphabetically
+   */
+  buildKey(params: Record<string, string>): string {
+    const normalized: Record<string, string> = {};
+
+    // Parse and quantize the view param (lat,lng,zoom)
+    if (params.v) {
+      const parts = params.v.split(',');
+      if (parts.length === 3) {
+        const lat = parseFloat(parts[0]).toFixed(2);
+        const lng = parseFloat(parts[1]).toFixed(2);
+        const zoom = Math.round(parseFloat(parts[2])).toString();
+        normalized.v = `${lat},${lng},${zoom}`;
+      } else {
+        normalized.v = params.v;
+      }
+    }
+
+    // Sort filters
+    if (params.f) {
+      const segments = params.f.split(',').sort();
+      normalized.f = segments.join(',');
+    }
+
+    if (params.poi) {
+      const cats = params.poi.split(',').sort();
+      normalized.poi = cats.join(',');
+    }
+
+    if (params.tab) {
+      normalized.tab = params.tab;
+    }
+
+    const input = JSON.stringify(normalized);
+    const hash = createHash('sha256').update(input).digest('hex').substring(0, 16);
+    return hash;
+  }
+
+  getPath(key: string): string {
+    return join(this.dir, `${key}.png`);
+  }
+
+  /**
+   * Returns a readable stream if a fresh cached file exists, null otherwise.
+   */
+  get(key: string): Readable | null {
+    const path = this.getPath(key);
+    if (!existsSync(path)) return null;
+
+    try {
+      const stat = statSync(path);
+      const age = Date.now() - stat.mtimeMs;
+      if (age > MAX_AGE_MS) return null;
+      return createReadStream(path);
+    } catch {
+      return null;
+    }
+  }
+
+  /**
+   * Write screenshot bytes to cache.
+   */
+  set(key: string, data: Buffer): void {
+    const path = this.getPath(key);
+    writeFileSync(path, data);
+  }
+}

og-screenshot/src/screenshot.ts

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+import { chromium, type Browser, type BrowserContext } from 'playwright';
+
+const VIEWPORT = { width: 1200, height: 630 };
+const NAVIGATION_TIMEOUT = 15_000;
+const TILE_BUFFER_MS = 500;
+const MAX_CONCURRENT = 2;
+
+let browser: Browser | null = null;
+let concurrency = 0;
+const queue: Array<{ resolve: () => void }> = [];
+
+async function ensureBrowser(): Promise<Browser> {
+  if (!browser || !browser.isConnected()) {
+    browser = await chromium.launch({
+      args: [
+        '--no-sandbox',
+        '--disable-dev-shm-usage',
+        '--use-gl=angle',
+        '--use-angle=swiftshader',
+      ],
+    });
+  }
+  return browser;
+}
+
+async function acquireSlot(): Promise<void> {
+  if (concurrency < MAX_CONCURRENT) {
+    concurrency++;
+    return;
+  }
+  return new Promise<void>((resolve) => {
+    queue.push({ resolve });
+  });
+}
+
+function releaseSlot(): void {
+  concurrency--;
+  const next = queue.shift();
+  if (next) {
+    concurrency++;
+    next.resolve();
+  }
+}
+
+export async function takeScreenshot(url: string): Promise<Buffer> {
+  await acquireSlot();
+  let context: BrowserContext | null = null;
+
+  try {
+    const instance = await ensureBrowser();
+    context = await instance.newContext({
+      viewport: VIEWPORT,
+      deviceScaleFactor: 1,
+    });
+    const page = await context.newPage();
+
+    await page.goto(url, { waitUntil: 'networkidle', timeout: NAVIGATION_TIMEOUT });
+
+    // Wait for the frontend to signal readiness
+    try {
+      await page.waitForFunction('window.__og_ready === true', {
+        timeout: NAVIGATION_TIMEOUT,
+      });
+    } catch {
+      // Proceed anyway — partial screenshot is better than nothing
+    }
+
+    // Extra buffer for map tiles to finish rendering
+    await page.waitForTimeout(TILE_BUFFER_MS);
+
+    const screenshot = await page.screenshot({ type: 'png' });
+    return Buffer.from(screenshot);
+  } finally {
+    if (context) {
+      await context.close().catch(() => {});
+    }
+    releaseSlot();
+  }
+}
+
+export async function closeBrowser(): Promise<void> {
+  if (browser) {
+    await browser.close().catch(() => {});
+    browser = null;
+  }
+}

og-screenshot/src/server.ts

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+import express from 'express';
+import { ScreenshotCache } from './cache.js';
+import { takeScreenshot, closeBrowser } from './screenshot.js';
+
+const PORT = parseInt(process.env.PORT || '8002', 10);
+const NARROWIT_URL = process.env.NARROWIT_URL || 'http://localhost:8001';
+const CACHE_DIR = process.env.CACHE_DIR || '/cache';
+
+const cache = new ScreenshotCache(CACHE_DIR);
+const app = express();
+
+app.get('/health', (_req, res) => {
+  res.status(200).send('ok');
+});
+
+app.get('/screenshot', async (req, res) => {
+  try {
+    const params: Record<string, string> = {};
+    for (const key of ['v', 'f', 'poi', 'tab']) {
+      const val = req.query[key];
+      if (typeof val === 'string' && val) {
+        params[key] = val;
+      }
+    }
+
+    const cacheKey = cache.buildKey(params);
+
+    // Check cache first
+    const cached = cache.get(cacheKey);
+    if (cached) {
+      res.setHeader('Content-Type', 'image/png');
+      res.setHeader('Cache-Control', 'public, max-age=86400');
+      res.setHeader('X-Cache', 'HIT');
+      cached.pipe(res);
+      return;
+    }
+
+    // Build the URL for the frontend in screenshot mode
+    const qs = new URLSearchParams(params);
+    qs.set('screenshot', '1');
+    const url = `${NARROWIT_URL}/?${qs}`;
+
+    console.log(`Taking screenshot: ${url}`);
+    const png = await takeScreenshot(url);
+
+    // Cache it
+    cache.set(cacheKey, png);
+
+    res.setHeader('Content-Type', 'image/png');
+    res.setHeader('Cache-Control', 'public, max-age=86400');
+    res.setHeader('X-Cache', 'MISS');
+    res.send(png);
+  } catch (err) {
+    console.error('Screenshot failed:', err);
+    res.status(500).json({ error: 'Screenshot failed' });
+  }
+});
+
+const server = app.listen(PORT, () => {
+  console.log(`OG screenshot service listening on port ${PORT}`);
+  console.log(`  NARROWIT_URL: ${NARROWIT_URL}`);
+  console.log(`  CACHE_DIR: ${CACHE_DIR}`);
+});
+
+// Graceful shutdown
+for (const signal of ['SIGTERM', 'SIGINT']) {
+  process.on(signal, async () => {
+    console.log(`Received ${signal}, shutting down...`);
+    server.close();
+    await closeBrowser();
+    process.exit(0);
+  });
+}