fix builds

Co-authored-by: Chris Tate <chris@ctate.dev>

.github/workflows/ci.yml

@@ -155,3 +155,34 @@ jobs:
             exit 1
           }
         shell: pwsh
+
+  serverless-chromium:
+    name: Serverless Chromium (@sparticuz/chromium)
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Install @sparticuz/chromium
+        run: pnpm add -D @sparticuz/chromium
+
+      - name: Build TypeScript
+        run: pnpm build
+
+      - name: Run serverless integration test
+        run: pnpm exec vitest run test/serverless.test.ts

README.md

@@ -18,6 +18,8 @@ git clone https://github.com/vercel-labs/agent-browser
 cd agent-browser
 pnpm install
 pnpm build
+pnpm build:native   # Requires Rust (https://rustup.rs)
+pnpm link --global  # Makes agent-browser available globally
 agent-browser install
 ```
 
@@ -293,11 +295,14 @@ agent-browser snapshot -i -c -d 5         # Combine options
 | Option | Description |
 |--------|-------------|
 | `--session <name>` | Use isolated session (or `AGENT_BROWSER_SESSION` env) |
+| `--headers <json>` | Set HTTP headers scoped to the URL's origin |
+| `--executable-path <path>` | Custom browser executable (or `AGENT_BROWSER_EXECUTABLE_PATH` env) |
 | `--json` | JSON output (for agents) |
 | `--full, -f` | Full page screenshot |
 | `--name, -n` | Locator name filter |
 | `--exact` | Exact text match |
 | `--headed` | Show browser window (not headless) |
+| `--cdp <port>` | Connect via Chrome DevTools Protocol |
 | `--debug` | Debug output |
 
 ## Selectors
@@ -387,6 +392,93 @@ agent-browser open example.com --headed
 
 This opens a visible browser window instead of running headless.
 
+## Authenticated Sessions
+
+Use `--headers` to set HTTP headers for a specific origin, enabling authentication without login flows:
+
+```bash
+# Headers are scoped to api.example.com only
+agent-browser open api.example.com --headers '{"Authorization": "Bearer <token>"}'
+
+# Requests to api.example.com include the auth header
+agent-browser snapshot -i --json
+agent-browser click @e2
+
+# Navigate to another domain - headers are NOT sent (safe!)
+agent-browser open other-site.com
+```
+
+This is useful for:
+- **Skipping login flows** - Authenticate via headers instead of UI
+- **Switching users** - Start new sessions with different auth tokens
+- **API testing** - Access protected endpoints directly
+- **Security** - Headers are scoped to the origin, not leaked to other domains
+
+To set headers for multiple origins, use `--headers` with each `open` command:
+
+```bash
+agent-browser open api.example.com --headers '{"Authorization": "Bearer token1"}'
+agent-browser open api.acme.com --headers '{"Authorization": "Bearer token2"}'
+```
+
+For global headers (all domains), use `set headers`:
+
+```bash
+agent-browser set headers '{"X-Custom-Header": "value"}'
+```
+
+## Custom Browser Executable
+
+Use a custom browser executable instead of the bundled Chromium. This is useful for:
+- **Serverless deployment**: Use lightweight Chromium builds like `@sparticuz/chromium` (~50MB vs ~684MB)
+- **System browsers**: Use an existing Chrome/Chromium installation
+- **Custom builds**: Use modified browser builds
+
+### CLI Usage
+
+```bash
+# Via flag
+agent-browser --executable-path /path/to/chromium open example.com
+
+# Via environment variable
+AGENT_BROWSER_EXECUTABLE_PATH=/path/to/chromium agent-browser open example.com
+```
+
+### Serverless Example (Vercel/AWS Lambda)
+
+```typescript
+import chromium from '@sparticuz/chromium';
+import { BrowserManager } from 'agent-browser';
+
+export async function handler() {
+  const browser = new BrowserManager();
+  await browser.launch({
+    executablePath: await chromium.executablePath(),
+    headless: true,
+  });
+  // ... use browser
+}
+```
+
+## CDP Mode
+
+Connect to an existing browser via Chrome DevTools Protocol:
+
+```bash
+# Connect to Electron app
+agent-browser --cdp 9222 snapshot
+
+# Connect to Chrome with remote debugging
+# (Start Chrome with: google-chrome --remote-debugging-port=9222)
+agent-browser --cdp 9222 open about:blank
+```
+
+This enables control of:
+- Electron apps
+- Chrome/Chromium instances with remote debugging
+- WebView2 applications
+- Any browser exposing a CDP endpoint
+
 ## Architecture
 
 agent-browser uses a client-daemon architecture:

cli/Cargo.lock

@@ -4,7 +4,7 @@ version = 4
 
 [[package]]
 name = "agent-browser"
-version = "0.4.3"
+version = "0.4.4"
 dependencies = [
  "libc",
  "serde",

cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "agent-browser"
-version = "0.4.3"
+version = "0.4.4"
 edition = "2021"
 description = "Fast browser automation CLI for AI agents"
 license = "Apache-2.0"

cli/src/commands.rs

@@ -80,7 +80,14 @@ pub fn parse_command(args: &[String], flags: &Flags) -> Result<Value, ParseError
             } else {
                 format!("https://{}", url)
             };
-            Ok(json!({ "id": id, "action": "navigate", "url": url }))
+            let mut nav_cmd = json!({ "id": id, "action": "navigate", "url": url });
+            // If --headers flag is set, include headers (scoped to this origin)
+            if let Some(ref headers_json) = flags.headers {
+                if let Ok(headers) = serde_json::from_str::<serde_json::Value>(headers_json) {
+                    nav_cmd["headers"] = headers;
+                }
+            }
+            Ok(nav_cmd)
         }
         "back" => Ok(json!({ "id": id, "action": "back" })),
         "forward" => Ok(json!({ "id": id, "action": "forward" })),
@@ -766,7 +773,13 @@ fn parse_set(rest: &[&str], id: &str) -> Result<Value, ParseError> {
                 context: "set headers".to_string(),
                 usage: "set headers <json>",
             })?;
-            Ok(json!({ "id": id, "action": "headers", "headers": headers_json }))
+            // Parse the JSON string into an object
+            let headers: serde_json::Value = serde_json::from_str(headers_json)
+                .map_err(|_| ParseError::MissingArguments {
+                    context: "set headers".to_string(),
+                    usage: "set headers <json> (must be valid JSON object)",
+                })?;
+            Ok(json!({ "id": id, "action": "headers", "headers": headers }))
         }
         Some("credentials") | Some("auth") => {
             let user = rest.get(1).ok_or_else(|| ParseError::MissingArguments {
@@ -886,6 +899,9 @@ mod tests {
             full: false,
             headed: false,
             debug: false,
+            headers: None,
+            executable_path: None,
+            cdp: None,
         }
     }
 
@@ -1012,6 +1028,81 @@ mod tests {
         assert_eq!(cmd["url"], "https://example.com");
     }
 
+    #[test]
+    fn test_navigate_with_headers() {
+        let mut flags = default_flags();
+        flags.headers = Some(r#"{"Authorization": "Bearer token"}"#.to_string());
+        let cmd = parse_command(&args("open api.example.com"), &flags).unwrap();
+        assert_eq!(cmd["action"], "navigate");
+        assert_eq!(cmd["url"], "https://api.example.com");
+        assert_eq!(cmd["headers"]["Authorization"], "Bearer token");
+    }
+
+    #[test]
+    fn test_navigate_with_multiple_headers() {
+        let mut flags = default_flags();
+        flags.headers = Some(r#"{"Authorization": "Bearer token", "X-Custom": "value"}"#.to_string());
+        let cmd = parse_command(&args("open api.example.com"), &flags).unwrap();
+        assert_eq!(cmd["headers"]["Authorization"], "Bearer token");
+        assert_eq!(cmd["headers"]["X-Custom"], "value");
+    }
+
+    #[test]
+    fn test_navigate_without_headers_flag() {
+        let cmd = parse_command(&args("open example.com"), &default_flags()).unwrap();
+        assert_eq!(cmd["action"], "navigate");
+        // headers should not be present when flag is not set
+        assert!(cmd.get("headers").is_none());
+    }
+
+    #[test]
+    fn test_navigate_with_invalid_headers_json() {
+        let mut flags = default_flags();
+        flags.headers = Some("not valid json".to_string());
+        let cmd = parse_command(&args("open api.example.com"), &flags).unwrap();
+        // Invalid JSON should result in no headers field (graceful handling)
+        assert!(cmd.get("headers").is_none());
+    }
+
+    // === Set Headers Tests ===
+
+    #[test]
+    fn test_set_headers_parses_json() {
+        let input: Vec<String> = vec![
+            "set".to_string(),
+            "headers".to_string(),
+            r#"{"Authorization":"Bearer token"}"#.to_string(),
+        ];
+        let cmd = parse_command(&input, &default_flags()).unwrap();
+        assert_eq!(cmd["action"], "headers");
+        // Headers should be an object, not a string
+        assert!(cmd["headers"].is_object());
+        assert_eq!(cmd["headers"]["Authorization"], "Bearer token");
+    }
+
+    #[test]
+    fn test_set_headers_with_multiple_values() {
+        let input: Vec<String> = vec![
+            "set".to_string(),
+            "headers".to_string(),
+            r#"{"Authorization": "Bearer token", "X-Custom": "value"}"#.to_string(),
+        ];
+        let cmd = parse_command(&input, &default_flags()).unwrap();
+        assert_eq!(cmd["headers"]["Authorization"], "Bearer token");
+        assert_eq!(cmd["headers"]["X-Custom"], "value");
+    }
+
+    #[test]
+    fn test_set_headers_invalid_json_error() {
+        let input: Vec<String> = vec![
+            "set".to_string(),
+            "headers".to_string(),
+            "not-valid-json".to_string(),
+        ];
+        let result = parse_command(&input, &default_flags());
+        assert!(result.is_err());
+    }
+
     #[test]
     fn test_back() {
         let cmd = parse_command(&args("back"), &default_flags()).unwrap();

cli/src/connection.rs

@@ -153,9 +153,15 @@ fn daemon_ready(session: &str) -> bool {
     }
 }
 
-pub fn ensure_daemon(session: &str, headed: bool) -> Result<(), String> {
+/// Result of ensure_daemon indicating whether a new daemon was started
+pub struct DaemonResult {
+    /// True if we connected to an existing daemon, false if we started a new one
+    pub already_running: bool,
+}
+
+pub fn ensure_daemon(session: &str, headed: bool, executable_path: Option<&str>) -> Result<DaemonResult, String> {
     if is_daemon_running(session) && daemon_ready(session) {
-        return Ok(());
+        return Ok(DaemonResult { already_running: true });
     }
 
     let exe_path = env::current_exe().map_err(|e| e.to_string())?;
@@ -186,6 +192,10 @@ pub fn ensure_daemon(session: &str, headed: bool) -> Result<(), String> {
             cmd.env("AGENT_BROWSER_HEADED", "1");
         }
 
+        if let Some(path) = executable_path {
+            cmd.env("AGENT_BROWSER_EXECUTABLE_PATH", path);
+        }
+
         // Create new process group and session to fully detach
         unsafe {
             cmd.pre_exec(|| {
@@ -220,6 +230,10 @@ pub fn ensure_daemon(session: &str, headed: bool) -> Result<(), String> {
             cmd.env("AGENT_BROWSER_HEADED", "1");
         }
 
+        if let Some(path) = executable_path {
+            cmd.env("AGENT_BROWSER_EXECUTABLE_PATH", path);
+        }
+
         // CREATE_NEW_PROCESS_GROUP | DETACHED_PROCESS
         const CREATE_NEW_PROCESS_GROUP: u32 = 0x00000200;
         const DETACHED_PROCESS: u32 = 0x00000008;
@@ -234,7 +248,7 @@ pub fn ensure_daemon(session: &str, headed: bool) -> Result<(), String> {
 
     for _ in 0..50 {
         if daemon_ready(session) {
-            return Ok(());
+            return Ok(DaemonResult { already_running: false });
         }
         thread::sleep(Duration::from_millis(100));
     }

cli/src/flags.rs

@@ -6,6 +6,9 @@ pub struct Flags {
     pub headed: bool,
     pub debug: bool,
     pub session: String,
+    pub headers: Option<String>,
+    pub executable_path: Option<String>,
+    pub cdp: Option<String>,
 }
 
 pub fn parse_flags(args: &[String]) -> Flags {
@@ -15,6 +18,9 @@ pub fn parse_flags(args: &[String]) -> Flags {
         headed: false,
         debug: false,
         session: env::var("AGENT_BROWSER_SESSION").unwrap_or_else(|_| "default".to_string()),
+        headers: None,
+        executable_path: env::var("AGENT_BROWSER_EXECUTABLE_PATH").ok(),
+        cdp: None,
     };
 
     let mut i = 0;
@@ -30,6 +36,24 @@ pub fn parse_flags(args: &[String]) -> Flags {
                     i += 1;
                 }
             }
+            "--headers" => {
+                if let Some(h) = args.get(i + 1) {
+                    flags.headers = Some(h.clone());
+                    i += 1;
+                }
+            }
+            "--executable-path" => {
+                if let Some(s) = args.get(i + 1) {
+                    flags.executable_path = Some(s.clone());
+                    i += 1;
+                }
+            }
+            "--cdp" => {
+                if let Some(s) = args.get(i + 1) {
+                    flags.cdp = Some(s.clone());
+                    i += 1;
+                }
+            }
             _ => {}
         }
         i += 1;
@@ -43,13 +67,15 @@ pub fn clean_args(args: &[String]) -> Vec<String> {
 
     // Global flags that should be stripped from command args
     const GLOBAL_FLAGS: &[&str] = &["--json", "--full", "--headed", "--debug"];
+    // Global flags that take a value (need to skip the next arg too)
+    const GLOBAL_FLAGS_WITH_VALUE: &[&str] = &["--session", "--headers", "--executable-path", "--cdp"];
 
     for arg in args.iter() {
         if skip_next {
             skip_next = false;
             continue;
         }
-        if arg == "--session" {
+        if GLOBAL_FLAGS_WITH_VALUE.contains(&arg.as_str()) {
             skip_next = true;
             continue;
         }
@@ -61,3 +87,111 @@ pub fn clean_args(args: &[String]) -> Vec<String> {
     }
     result
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn args(s: &str) -> Vec<String> {
+        s.split_whitespace().map(String::from).collect()
+    }
+
+    #[test]
+    fn test_parse_headers_flag() {
+        let flags = parse_flags(&args(r#"open example.com --headers {"Auth":"token"}"#));
+        assert_eq!(flags.headers, Some(r#"{"Auth":"token"}"#.to_string()));
+    }
+
+    #[test]
+    fn test_parse_headers_flag_with_spaces() {
+        // Headers JSON is passed as a single quoted argument in shell
+        let input: Vec<String> = vec![
+            "open".to_string(),
+            "example.com".to_string(),
+            "--headers".to_string(),
+            r#"{"Authorization": "Bearer token"}"#.to_string(),
+        ];
+        let flags = parse_flags(&input);
+        assert_eq!(flags.headers, Some(r#"{"Authorization": "Bearer token"}"#.to_string()));
+    }
+
+    #[test]
+    fn test_parse_no_headers_flag() {
+        let flags = parse_flags(&args("open example.com"));
+        assert!(flags.headers.is_none());
+    }
+
+    #[test]
+    fn test_clean_args_removes_headers() {
+        let input: Vec<String> = vec![
+            "open".to_string(),
+            "example.com".to_string(),
+            "--headers".to_string(),
+            r#"{"Auth":"token"}"#.to_string(),
+        ];
+        let clean = clean_args(&input);
+        assert_eq!(clean, vec!["open", "example.com"]);
+    }
+
+    #[test]
+    fn test_clean_args_removes_headers_at_start() {
+        let input: Vec<String> = vec![
+            "--headers".to_string(),
+            r#"{"Auth":"token"}"#.to_string(),
+            "open".to_string(),
+            "example.com".to_string(),
+        ];
+        let clean = clean_args(&input);
+        assert_eq!(clean, vec!["open", "example.com"]);
+    }
+
+    #[test]
+    fn test_headers_with_other_flags() {
+        let input: Vec<String> = vec![
+            "open".to_string(),
+            "example.com".to_string(),
+            "--headers".to_string(),
+            r#"{"Auth":"token"}"#.to_string(),
+            "--json".to_string(),
+            "--headed".to_string(),
+        ];
+        let flags = parse_flags(&input);
+        assert_eq!(flags.headers, Some(r#"{"Auth":"token"}"#.to_string()));
+        assert!(flags.json);
+        assert!(flags.headed);
+        
+        let clean = clean_args(&input);
+        assert_eq!(clean, vec!["open", "example.com"]);
+    }
+
+    #[test]
+    fn test_parse_executable_path_flag() {
+        let flags = parse_flags(&args("--executable-path /path/to/chromium open example.com"));
+        assert_eq!(flags.executable_path, Some("/path/to/chromium".to_string()));
+    }
+
+    #[test]
+    fn test_parse_executable_path_flag_no_value() {
+        let flags = parse_flags(&args("--executable-path"));
+        assert_eq!(flags.executable_path, None);
+    }
+
+    #[test]
+    fn test_clean_args_removes_executable_path() {
+        let cleaned = clean_args(&args("--executable-path /path/to/chromium open example.com"));
+        assert_eq!(cleaned, vec!["open", "example.com"]);
+    }
+
+    #[test]
+    fn test_clean_args_removes_executable_path_with_other_flags() {
+        let cleaned = clean_args(&args("--json --executable-path /path/to/chromium --headed open example.com"));
+        assert_eq!(cleaned, vec!["open", "example.com"]);
+    }
+
+    #[test]
+    fn test_parse_flags_with_session_and_executable_path() {
+        let flags = parse_flags(&args("--session test --executable-path /custom/chrome open example.com"));
+        assert_eq!(flags.session, "test");
+        assert_eq!(flags.executable_path, Some("/custom/chrome".to_string()));
+    }
+}

cli/src/main.rs

@@ -149,21 +149,91 @@ fn main() {
         }
     };
 
-    if let Err(e) = ensure_daemon(&flags.session, flags.headed) {
-        if flags.json {
-            println!(r#"{{"success":false,"error":"{}"}}"#, e);
-        } else {
-            eprintln!("\x1b[31m✗\x1b[0m {}", e);
+    let daemon_result = match ensure_daemon(&flags.session, flags.headed, flags.executable_path.as_deref()) {
+        Ok(result) => result,
+        Err(e) => {
+            if flags.json {
+                println!(r#"{{"success":false,"error":"{}"}}"#, e);
+            } else {
+                eprintln!("\x1b[31m✗\x1b[0m {}", e);
+            }
+            exit(1);
+        }
+    };
+
+    // Warn if executable_path was specified but daemon was already running
+    if daemon_result.already_running && flags.executable_path.is_some() {
+        if !flags.json {
+            eprintln!("\x1b[33m⚠\x1b[0m --executable-path ignored: daemon already running. Use 'agent-browser close' first to restart with new path.");
         }
-        exit(1);
     }
 
-    // If --headed flag is set, send launch command first to switch to headed mode
-    if flags.headed {
-        let launch_cmd = json!({ "id": gen_id(), "action": "launch", "headless": false });
+    // Connect via CDP if --cdp flag is set
+    if let Some(ref port) = flags.cdp {
+        let cdp_port: u16 = match port.parse::<u32>() {
+            Ok(p) if p == 0 => {
+                let msg = "Invalid CDP port: port must be greater than 0".to_string();
+                if flags.json {
+                    println!(r#"{{"success":false,"error":"{}"}}"#, msg);
+                } else {
+                    eprintln!("\x1b[31m✗\x1b[0m {}", msg);
+                }
+                exit(1);
+            }
+            Ok(p) if p > 65535 => {
+                let msg = format!("Invalid CDP port: {} is out of range (valid range: 1-65535)", p);
+                if flags.json {
+                    println!(r#"{{"success":false,"error":"{}"}}"#, msg);
+                } else {
+                    eprintln!("\x1b[31m✗\x1b[0m {}", msg);
+                }
+                exit(1);
+            }
+            Ok(p) => p as u16,
+            Err(_) => {
+                let msg = format!("Invalid CDP port: '{}' is not a valid number. Port must be a number between 1 and 65535", port);
+                if flags.json {
+                    println!(r#"{{"success":false,"error":"{}"}}"#, msg);
+                } else {
+                    eprintln!("\x1b[31m✗\x1b[0m {}", msg);
+                }
+                exit(1);
+            }
+        };
+
+        let launch_cmd = json!({
+            "id": gen_id(),
+            "action": "launch",
+            "cdpPort": cdp_port
+        });
+
+        let err = match send_command(launch_cmd, &flags.session) {
+            Ok(resp) if resp.success => None,
+            Ok(resp) => Some(resp.error.unwrap_or_else(|| "CDP connection failed".to_string())),
+            Err(e) => Some(e.to_string()),
+        };
+
+        if let Some(msg) = err {
+            if flags.json {
+                println!(r#"{{"success":false,"error":"{}"}}"#, msg);
+            } else {
+                eprintln!("\x1b[31m✗\x1b[0m {}", msg);
+            }
+            exit(1);
+        }
+    }
+
+    // Launch headed browser if --headed flag is set (without CDP)
+    if flags.headed && flags.cdp.is_none() {
+        let launch_cmd = json!({
+            "id": gen_id(),
+            "action": "launch",
+            "headless": false
+        });
+
         if let Err(e) = send_command(launch_cmd, &flags.session) {
             if !flags.json {
-                eprintln!("\x1b[33m⚠\x1b[0m Could not switch to headed mode: {}", e);
+                eprintln!("\x1b[33m⚠\x1b[0m Could not launch headed browser: {}", e);
             }
         }
     }

cli/src/output.rs

@@ -162,12 +162,15 @@ Aliases: goto, navigate
 Global Options:
   --json               Output as JSON
   --session <name>     Use specific session
+  --headers <json>     Set HTTP headers (scoped to this origin)
   --headed             Show browser window
 
 Examples:
   agent-browser open example.com
   agent-browser open https://github.com
   agent-browser open localhost:3000
+  agent-browser open api.example.com --headers '{"Authorization": "Bearer token"}'
+    # ^ Headers only sent to api.example.com, not other domains
 "##,
         "back" => r##"
 agent-browser back - Navigate back in history
@@ -1186,9 +1189,12 @@ Snapshot Options:
 
 Options:
   --session <name>           Isolated session (or AGENT_BROWSER_SESSION env)
+  --headers <json>           HTTP headers scoped to URL's origin (for auth)
+  --executable-path <path>   Custom browser executable (or AGENT_BROWSER_EXECUTABLE_PATH)
   --json                     JSON output
   --full, -f                 Full page screenshot
   --headed                   Show browser window (not headless)
+  --cdp <port>               Connect via CDP (Chrome DevTools Protocol)
   --debug                    Debug output
 
 Examples:
@@ -1199,6 +1205,7 @@ Examples:
   agent-browser find role button click --name Submit
   agent-browser get text @e1
   agent-browser screenshot --full
+  agent-browser --cdp 9222 snapshot      # Connect via CDP port
 "#
     );
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "agent-browser",
-  "version": "0.4.3",
+  "version": "0.4.4",
   "description": "Headless browser automation CLI for AI agents",
   "type": "module",
   "main": "dist/daemon.js",

src/actions.ts

@@ -411,6 +411,12 @@ async function handleNavigate(
   browser: BrowserManager
 ): Promise<Response<NavigateData>> {
   const page = browser.getPage();
+
+  // If headers are provided, set up scoped headers for this origin
+  if (command.headers && Object.keys(command.headers).length > 0) {
+    await browser.setScopedHeaders(command.url, command.headers);
+  }
+
   await page.goto(command.url, {
     waitUntil: command.waitUntil ?? 'load',
   });

src/browser.test.ts

@@ -22,6 +22,35 @@ describe('BrowserManager', () => {
       const page = browser.getPage();
       expect(page).toBeDefined();
     });
+
+    it('should reject invalid executablePath', async () => {
+      const testBrowser = new BrowserManager();
+      await expect(
+        testBrowser.launch({
+          headless: true,
+          executablePath: '/nonexistent/path/to/chromium',
+        })
+      ).rejects.toThrow();
+    });
+
+    it('should be no-op when relaunching with same options', async () => {
+      const browserInstance = browser.getBrowser();
+      await browser.launch({ id: 'test', action: 'launch', headless: true });
+      expect(browser.getBrowser()).toBe(browserInstance);
+    });
+
+    it('should reconnect when CDP port changes', async () => {
+      const newBrowser = new BrowserManager();
+      await newBrowser.launch({ id: 'test', action: 'launch', headless: true });
+      expect(newBrowser.getBrowser()).not.toBeNull();
+
+      await expect(
+        newBrowser.launch({ id: 'test', action: 'launch', cdpPort: 59999 })
+      ).rejects.toThrow();
+
+      expect(newBrowser.getBrowser()).toBeNull();
+      await newBrowser.close();
+    });
   });
 
   describe('navigation', () => {
@@ -294,4 +323,59 @@ describe('BrowserManager', () => {
       expect(h1).toBe('Example Domain');
     });
   });
+
+  describe('scoped headers', () => {
+    it('should register route for scoped headers', async () => {
+      // Test that setScopedHeaders doesn't throw and completes successfully
+      await browser.clearScopedHeaders();
+      await expect(
+        browser.setScopedHeaders('https://example.com', { 'X-Test': 'value' })
+      ).resolves.not.toThrow();
+      await browser.clearScopedHeaders();
+    });
+
+    it('should handle full URL origin', async () => {
+      await browser.clearScopedHeaders();
+      await expect(
+        browser.setScopedHeaders('https://api.example.com/path', { Authorization: 'Bearer token' })
+      ).resolves.not.toThrow();
+      await browser.clearScopedHeaders();
+    });
+
+    it('should handle hostname-only origin', async () => {
+      await browser.clearScopedHeaders();
+      await expect(
+        browser.setScopedHeaders('example.com', { 'X-Custom': 'value' })
+      ).resolves.not.toThrow();
+      await browser.clearScopedHeaders();
+    });
+
+    it('should clear scoped headers for specific origin', async () => {
+      await browser.clearScopedHeaders();
+      await browser.setScopedHeaders('https://example.com', { 'X-Test': 'value' });
+      await expect(browser.clearScopedHeaders('https://example.com')).resolves.not.toThrow();
+    });
+
+    it('should clear all scoped headers', async () => {
+      await browser.setScopedHeaders('https://example.com', { 'X-Test-1': 'value1' });
+      await browser.setScopedHeaders('https://example.org', { 'X-Test-2': 'value2' });
+      await expect(browser.clearScopedHeaders()).resolves.not.toThrow();
+    });
+
+    it('should replace headers when called twice for same origin', async () => {
+      await browser.clearScopedHeaders();
+      await browser.setScopedHeaders('https://example.com', { 'X-First': 'first' });
+      // Second call should replace, not add
+      await expect(
+        browser.setScopedHeaders('https://example.com', { 'X-Second': 'second' })
+      ).resolves.not.toThrow();
+      await browser.clearScopedHeaders();
+    });
+
+    it('should handle clearing non-existent origin gracefully', async () => {
+      await browser.clearScopedHeaders();
+      // Should not throw when clearing headers that were never set
+      await expect(browser.clearScopedHeaders('https://never-set.com')).resolves.not.toThrow();
+    });
+  });
 });

src/browser.ts

@@ -39,6 +39,7 @@ interface PageError {
  */
 export class BrowserManager {
   private browser: Browser | null = null;
+  private cdpPort: number | null = null;
   private contexts: BrowserContext[] = [];
   private pages: Page[] = [];
   private activePageIndex: number = 0;
@@ -51,6 +52,7 @@ export class BrowserManager {
   private isRecordingHar: boolean = false;
   private refMap: RefMap = {};
   private lastSnapshot: string = '';
+  private scopedHeaderRoutes: Map<string, (route: Route) => Promise<void>> = new Map();
 
   /**
    * Check if browser is launched
@@ -439,7 +441,7 @@ export class BrowserManager {
   }
 
   /**
-   * Set extra HTTP headers
+   * Set extra HTTP headers (global - all requests)
    */
   async setExtraHeaders(headers: Record<string, string>): Promise<void> {
     const context = this.contexts[0];
@@ -448,6 +450,76 @@ export class BrowserManager {
     }
   }
 
+  /**
+   * Set scoped HTTP headers (only for requests matching the origin)
+   * Uses route interception to add headers only to matching requests
+   */
+  async setScopedHeaders(origin: string, headers: Record<string, string>): Promise<void> {
+    const page = this.getPage();
+
+    // Build URL pattern from origin (e.g., "api.example.com" -> "**://api.example.com/**")
+    // Handle both full URLs and just hostnames
+    let urlPattern: string;
+    try {
+      const url = new URL(origin.startsWith('http') ? origin : `https://${origin}`);
+      // Match any protocol, the host, and any path
+      urlPattern = `**://${url.host}/**`;
+    } catch {
+      // If parsing fails, treat as hostname pattern
+      urlPattern = `**://${origin}/**`;
+    }
+
+    // Remove existing route for this origin if any
+    const existingHandler = this.scopedHeaderRoutes.get(urlPattern);
+    if (existingHandler) {
+      await page.unroute(urlPattern, existingHandler);
+    }
+
+    // Create handler that adds headers to matching requests
+    const handler = async (route: Route) => {
+      const requestHeaders = route.request().headers();
+      await route.continue({
+        headers: {
+          ...requestHeaders,
+          ...headers,
+        },
+      });
+    };
+
+    // Store and register the route
+    this.scopedHeaderRoutes.set(urlPattern, handler);
+    await page.route(urlPattern, handler);
+  }
+
+  /**
+   * Clear scoped headers for an origin (or all if no origin specified)
+   */
+  async clearScopedHeaders(origin?: string): Promise<void> {
+    const page = this.getPage();
+
+    if (origin) {
+      let urlPattern: string;
+      try {
+        const url = new URL(origin.startsWith('http') ? origin : `https://${origin}`);
+        urlPattern = `**://${url.host}/**`;
+      } catch {
+        urlPattern = `**://${origin}/**`;
+      }
+
+      const handler = this.scopedHeaderRoutes.get(urlPattern);
+      if (handler) {
+        await page.unroute(urlPattern, handler);
+        this.scopedHeaderRoutes.delete(urlPattern);
+      }
+    } else {
+      // Clear all scoped header routes
+      for (const [pattern, handler] of this.scopedHeaderRoutes) {
+        await page.unroute(pattern, handler);
+      }
+      this.scopedHeaderRoutes.clear();
+    }
+  }
+
   /**
    * Start tracing
    */
@@ -502,13 +574,51 @@ export class BrowserManager {
     return this.browser;
   }
 
+  /**
+   * Check if an existing CDP connection is still alive
+   * by verifying we can access browser contexts and that at least one has pages
+   */
+  private isCdpConnectionAlive(): boolean {
+    if (!this.browser) return false;
+    try {
+      const contexts = this.browser.contexts();
+      if (contexts.length === 0) return false;
+      return contexts.some((context) => context.pages().length > 0);
+    } catch {
+      return false;
+    }
+  }
+
+  /**
+   * Check if CDP connection needs to be re-established
+   */
+  private needsCdpReconnect(cdpPort: number): boolean {
+    if (!this.browser?.isConnected()) return true;
+    if (this.cdpPort !== cdpPort) return true;
+    if (!this.isCdpConnectionAlive()) return true;
+    return false;
+  }
+
   /**
    * Launch the browser with the specified options
    * If already launched, this is a no-op (browser stays open)
    */
   async launch(options: LaunchCommand): Promise<void> {
-    // If already launched, don't relaunch
+    const cdpPort = options.cdpPort;
+
     if (this.browser) {
+      const switchingFromCdpToBrowser = !cdpPort && this.cdpPort !== null;
+      const needsCdpReconnect = !!cdpPort && this.needsCdpReconnect(cdpPort);
+
+      if (switchingFromCdpToBrowser || needsCdpReconnect) {
+        await this.close();
+      } else {
+        return;
+      }
+    }
+
+    if (cdpPort) {
+      await this.connectViaCDP(cdpPort);
       return;
     }
 
@@ -520,11 +630,14 @@ export class BrowserManager {
     // Launch browser
     this.browser = await launcher.launch({
       headless: options.headless ?? true,
+      executablePath: options.executablePath,
     });
+    this.cdpPort = null;
 
-    // Create context with viewport
+    // Create context with viewport and optional headers
     const context = await this.browser.newContext({
       viewport: options.viewport ?? { width: 1280, height: 720 },
+      extraHTTPHeaders: options.headers,
     });
 
     // Set default timeout to 10 seconds (Playwright default is 30s)
@@ -542,7 +655,56 @@ export class BrowserManager {
   }
 
   /**
-   * Set up console and error tracking for a page
+   * Connect to a running browser via CDP (Chrome DevTools Protocol)
+   */
+  private async connectViaCDP(cdpPort: number | undefined): Promise<void> {
+    if (!cdpPort) {
+      throw new Error('cdpPort is required for CDP connection');
+    }
+
+    const browser = await chromium.connectOverCDP(`http://localhost:${cdpPort}`).catch(() => {
+      throw new Error(
+        `Failed to connect via CDP on port ${cdpPort}. ` +
+          `Make sure the app is running with --remote-debugging-port=${cdpPort}`
+      );
+    });
+
+    // Validate and set up state, cleaning up browser connection if anything fails
+    try {
+      const contexts = browser.contexts();
+      if (contexts.length === 0) {
+        throw new Error('No browser context found. Make sure the app has an open window.');
+      }
+
+      const allPages = contexts.flatMap((context) => context.pages());
+      if (allPages.length === 0) {
+        throw new Error('No page found. Make sure the app has loaded content.');
+      }
+
+      // All validation passed - commit state
+      this.browser = browser;
+      this.cdpPort = cdpPort;
+
+      for (const context of contexts) {
+        this.contexts.push(context);
+        this.setupContextTracking(context);
+      }
+
+      for (const page of allPages) {
+        this.pages.push(page);
+        this.setupPageTracking(page);
+      }
+
+      this.activePageIndex = 0;
+    } catch (error) {
+      // Clean up browser connection if validation or setup failed
+      await browser.close().catch(() => {});
+      throw error;
+    }
+  }
+
+  /**
+   * Set up console, error, and close tracking for a page
    */
   private setupPageTracking(page: Page): void {
     page.on('console', (msg) => {
@@ -559,6 +721,26 @@ export class BrowserManager {
         timestamp: Date.now(),
       });
     });
+
+    page.on('close', () => {
+      const index = this.pages.indexOf(page);
+      if (index !== -1) {
+        this.pages.splice(index, 1);
+        if (this.activePageIndex >= this.pages.length) {
+          this.activePageIndex = Math.max(0, this.pages.length - 1);
+        }
+      }
+    });
+  }
+
+  /**
+   * Set up tracking for new pages in a context (for CDP connections)
+   */
+  private setupContextTracking(context: BrowserContext): void {
+    context.on('page', (page) => {
+      this.pages.push(page);
+      this.setupPageTracking(page);
+    });
   }
 
   /**
@@ -672,21 +854,29 @@ export class BrowserManager {
    * Close the browser and clean up
    */
   async close(): Promise<void> {
-    for (const page of this.pages) {
-      await page.close().catch(() => {});
+    // CDP: only disconnect, don't close external app's pages
+    if (this.cdpPort !== null) {
+      if (this.browser) {
+        await this.browser.close().catch(() => {});
+        this.browser = null;
+      }
+    } else {
+      // Regular browser: close everything
+      for (const page of this.pages) {
+        await page.close().catch(() => {});
+      }
+      for (const context of this.contexts) {
+        await context.close().catch(() => {});
+      }
+      if (this.browser) {
+        await this.browser.close().catch(() => {});
+        this.browser = null;
+      }
     }
+
     this.pages = [];
-
-    for (const context of this.contexts) {
-      await context.close().catch(() => {});
-    }
     this.contexts = [];
-
-    if (this.browser) {
-      await this.browser.close().catch(() => {});
-      this.browser = null;
-    }
-
+    this.cdpPort = null;
     this.activePageIndex = 0;
     this.refMap = {};
     this.lastSnapshot = '';

src/daemon.ts

@@ -158,7 +158,12 @@ export async function startDaemon(): Promise<void> {
             parseResult.command.action !== 'launch' &&
             parseResult.command.action !== 'close'
           ) {
-            await browser.launch({ id: 'auto', action: 'launch', headless: true });
+            await browser.launch({
+              id: 'auto',
+              action: 'launch',
+              headless: true,
+              executablePath: process.env.AGENT_BROWSER_EXECUTABLE_PATH,
+            });
           }
 
           // Handle close command specially

src/protocol.test.ts

@@ -461,6 +461,24 @@ describe('parseCommand', () => {
         expect(result.command.headless).toBe(false);
       }
     });
+
+    it('should parse launch with cdpPort', () => {
+      const result = parseCommand(cmd({ id: '1', action: 'launch', cdpPort: 9222 }));
+      expect(result.success).toBe(true);
+      if (result.success) {
+        expect(result.command.cdpPort).toBe(9222);
+      }
+    });
+
+    it('should reject launch with invalid cdpPort', () => {
+      const result = parseCommand(cmd({ id: '1', action: 'launch', cdpPort: -1 }));
+      expect(result.success).toBe(false);
+    });
+
+    it('should reject launch with non-numeric cdpPort', () => {
+      const result = parseCommand(cmd({ id: '1', action: 'launch', cdpPort: 'invalid' }));
+      expect(result.success).toBe(false);
+    });
   });
 
   describe('mouse actions', () => {

src/protocol.ts

@@ -18,6 +18,7 @@ const launchSchema = baseCommandSchema.extend({
     })
     .optional(),
   browser: z.enum(['chromium', 'firefox', 'webkit']).optional(),
+  cdpPort: z.number().positive().optional(),
 });
 
 const navigateSchema = baseCommandSchema.extend({

src/types.ts

@@ -12,12 +12,16 @@ export interface LaunchCommand extends BaseCommand {
   headless?: boolean;
   viewport?: { width: number; height: number };
   browser?: 'chromium' | 'firefox' | 'webkit';
+  headers?: Record<string, string>;
+  executablePath?: string;
+  cdpPort?: number;
 }
 
 export interface NavigateCommand extends BaseCommand {
   action: 'navigate';
   url: string;
   waitUntil?: 'load' | 'domcontentloaded' | 'networkidle';
+  headers?: Record<string, string>;
 }
 
 export interface ClickCommand extends BaseCommand {

test/serverless.test.ts

@@ -0,0 +1,85 @@
+/**
+ * Integration test for @sparticuz/chromium compatibility
+ * This tests the executablePath option with a serverless-optimized Chromium build
+ *
+ * Note: @sparticuz/chromium only works on Linux (designed for AWS Lambda).
+ * This test will skip on non-Linux platforms.
+ */
+import { describe, it, expect, afterAll } from 'vitest';
+import { BrowserManager } from '../src/browser.js';
+import * as os from 'os';
+
+const isLinux = os.platform() === 'linux';
+
+// Only run if @sparticuz/chromium is available AND we're on Linux
+const canRunTest = await (async () => {
+  if (!isLinux) {
+    console.log('Skipping @sparticuz/chromium test: only runs on Linux');
+    return false;
+  }
+  try {
+    await import('@sparticuz/chromium');
+    return true;
+  } catch {
+    console.log('Skipping @sparticuz/chromium test: package not installed');
+    return false;
+  }
+})();
+
+describe.skipIf(!canRunTest)('Serverless Chromium Integration', () => {
+  let browser: BrowserManager;
+  let chromiumPath: string;
+
+  it('should get executable path from @sparticuz/chromium', async () => {
+    const chromium = await import('@sparticuz/chromium');
+    chromiumPath = await chromium.default.executablePath();
+    expect(chromiumPath).toBeTruthy();
+    expect(typeof chromiumPath).toBe('string');
+    console.log('Chromium executable path:', chromiumPath);
+  });
+
+  it('should launch browser with custom executablePath', async () => {
+    const chromium = await import('@sparticuz/chromium');
+    chromiumPath = await chromium.default.executablePath();
+
+    browser = new BrowserManager();
+    await browser.launch({
+      headless: true,
+      executablePath: chromiumPath,
+    });
+
+    expect(browser.isLaunched()).toBe(true);
+  });
+
+  it('should navigate to a page', async () => {
+    const page = browser.getPage();
+    await page.goto('https://example.com');
+    expect(page.url()).toBe('https://example.com/');
+  });
+
+  it('should get page title', async () => {
+    const page = browser.getPage();
+    const title = await page.title();
+    expect(title).toBe('Example Domain');
+  });
+
+  it('should take snapshot with refs', async () => {
+    const { tree, refs } = await browser.getSnapshot();
+    expect(tree).toContain('Example Domain');
+    expect(typeof refs).toBe('object');
+    expect(Object.keys(refs).length).toBeGreaterThan(0);
+  });
+
+  it('should take screenshot', async () => {
+    const page = browser.getPage();
+    const buffer = await page.screenshot();
+    expect(buffer).toBeInstanceOf(Buffer);
+    expect(buffer.length).toBeGreaterThan(0);
+  });
+
+  afterAll(async () => {
+    if (browser?.isLaunched()) {
+      await browser.close();
+    }
+  });
+});

vitest.config.ts

@@ -3,7 +3,7 @@ import { defineConfig } from 'vitest/config';
 export default defineConfig({
   test: {
     globals: true,
-    include: ['src/**/*.test.ts'],
+    include: ['src/**/*.test.ts', 'test/**/*.test.ts'],
     testTimeout: 30000,
   },
 });