diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..e0c8eff
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,54 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project
+
+http2pic - PHP website renderer that takes screenshots of URLs and returns them as images. Live at https://http2pic.haschek.at/
+
+## Architecture
+
+**Entry point:** `web/index.php` - PSR-4 router with two paths:
+- `/api` - Chrome/Chromium screenshot via Selenium WebDriver (php-webdriver). Takes `url`, `viewport` (WIDTHxHEIGHT), `js` (true/false) params. Connects to `localhost:4444` ChromeDriver, sets window size, disables scrollbars, takes screenshot as PNG.
+- default - renders `src/templates/index.html.php` (landing page).
+
+**Legacy class:** `src/http2pic.class.php` - Old `wkhtmltoimage`-based renderer (deprecated, not used in production). Supports PNG/JPG, viewport, resize, URL reachability check, file caching.
+
+**Helpers:** `src/helpers.php` - `renderTemplate()`, `addToLog()`, `getUserIP()`.
+
+**Config:** `src/config.inc.php` - set at build time by `start.sh` from `URL` env var.
+
+## Running
+
+**Docker (production):**
+```
+docker compose up -d
+```
+Services: Caddy (:80), PHP-FPM, ChromeDriver (:4444). Volumes: `./cache` and `./logs`. Configured via `URL` env var.
+
+**Dev container:** `.devcontainer/` - same stack, run `./devcontainer/start.sh`. Forward port 8080.
+
+**Quick test:**
+```
+php -S localhost:8080 -t web/
+# Then visit http://localhost:8080/api?url=<target>
+```
+
+## Key files
+
+| File | Purpose |
+|------|---------|
+| `web/index.php` | API + template router |
+| `src/http2pic.class.php` | Legacy wkhtmltoimage renderer |
+| `src/helpers.php` | Template render, logging, IP helper |
+| `src/config.inc.php` | Runtime config (URL) |
+| `docker/Caddyfile` | Reverse proxy, PHP-FPM, file server |
+| `docker/start.sh` | Boots PHP-FPM, ChromeDriver, writes config |
+| `docker-compose.yml` | Production compose |
+
+## Caveats
+
+- `web/index.php` has a `var_dump($cmd)` debug statement left in `http2pic.class.php:181` - remove before shipping.
+- Legacy `http2pic.class.php` has a variable scoping bug: line 109 uses `$url` instead of `$this->params['url']`.
+- Cache dir permissions must be `777` (set by `start.sh`).
+- ChromeDriver must be running on `localhost:4444` for the API to work.
diff --git a/docker-compose-dev.yml b/docker-compose-dev.yml
index e4b4eca..d6071a2 100755
--- a/docker-compose-dev.yml
+++ b/docker-compose-dev.yml
@@ -1,4 +1,3 @@
-version: '3.3'
 services:
   http2pic:
     build:
@@ -13,6 +12,6 @@ services:
       - ./logs:/srv/logs
 
     environment:
-      - URL=http://localhostxxx:8080
+      - URL=http://localhost:8080
     ports:
       - 8080:80
diff --git a/src/http2pic.class.php b/src/http2pic.class.php
index 130ea58..c9d357a 100755
--- a/src/http2pic.class.php
+++ b/src/http2pic.class.php
@@ -178,11 +178,14 @@ class http2pic
 
 		$cmd.=' --wait-for-network-idle';
 
-		var_dump($cmd);
-			
 		$cmd = escapeshellcmd($cmd);
-		shell_exec($cmd);
+		$output = [];
+		$rc = 0;
+		exec($cmd . ' 2>&1', $output, $rc);
 		$this->params['cmd'] = $cmd;
+		if ($rc !== 0) {
+			$this->params['render_error'] = implode("\n", $output);
+		}
 		
 		$this->postRender();
 
diff --git a/web/index.php b/web/index.php
index ccb5ea1..2f81bbe 100755
--- a/web/index.php
+++ b/web/index.php
@@ -50,8 +50,9 @@ switch ($url[0]) {
             $capabilities->setCapability('javascriptEnabled', false);
 
 
+        $driver = null;
         try {
-            $driver = RemoteWebDriver::create($serverUrl, $capabilities);
+            $driver = RemoteWebDriver::create($serverUrl, $capabilities, 30000, 60);
             $driver->get($target);
             //hide scroll bars
             $driver->executeScript('document.body.style.overflow = "hidden";');
@@ -68,18 +69,25 @@ switch ($url[0]) {
             }
             $viewportLabel = is_array($viewport) ? implode('x', $viewport) : (string) $viewport;
             addToLog("$ip\tRequested $target with viewport " . $viewportLabel . " and js " . ($js ? 'enabled' : 'disabled'));
+
+            // take screenshot and send to user
+            header('Content-Type: image/png');
+            echo $driver->takeScreenshot();
         } catch (Exception $e) {
+            // ensure driver is closed to free ChromeDriver memory
+            if ($driver instanceof \Facebook\WebDriver\Remote\RemoteWebDriver) {
+                try { $driver->quit(); } catch (Exception $qe) {}
+            }
             header('HTTP/1.0 500 Internal Server Error');
             addToLog("$ip\tRequested $target but resulted in error:\t" . $e->getMessage());
             echo 'Error: ' . $e->getMessage();
             exit;
+        } finally {
+            if ($driver instanceof \Facebook\WebDriver\Remote\RemoteWebDriver) {
+                try { $driver->quit(); } catch (Exception $q) {}
+            }
         }
 
-        // take screenshot and save to file
-        //header for png
-        header('Content-Type: image/png');
-        echo $driver->takeScreenshot();
-
         break;
     default:
         echo renderTemplate('index.html.php');