feat(connect): make auto-connect to user's Chrome the default behavior

- Auto-connect is now ON by default (was opt-in via --auto-connect)
- Added --launch/--new flags to explicitly start a fresh browser
- CI environments (CI env var) automatically use --launch mode
- Friendly error message with platform-specific Chrome relaunch guide
- Mentions Chrome 144+ runtime CDP toggle (chrome://inspect)
- --cdp and --provider flags implicitly disable auto-connect
- AGENT_BROWSER_NO_AUTO_CONNECT=1 to disable, AGENT_BROWSER_FORCE_LAUNCH=1 to force

Track 3 of native-stealth migration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/connection.rs

@@ -410,6 +410,7 @@ pub struct DaemonOptions<'a> {
     pub confirm_actions: Option<&'a str>,
     pub engine: Option<&'a str>,
     pub auto_connect: bool,
+    pub force_launch: bool,
     pub idle_timeout: Option<&'a str>,
     pub default_timeout: Option<u64>,
     pub cdp: Option<&'a str>,
@@ -495,6 +496,9 @@ fn apply_daemon_env(cmd: &mut Command, session: &str, opts: &DaemonOptions) {
     if opts.auto_connect {
         cmd.env("AGENT_BROWSER_AUTO_CONNECT", "1");
     }
+    if opts.force_launch {
+        cmd.env("AGENT_BROWSER_FORCE_LAUNCH", "1");
+    }
     if let Some(idle) = opts.idle_timeout {
         cmd.env("AGENT_BROWSER_IDLE_TIMEOUT_MS", idle);
     }

cli/src/flags.rs

@@ -308,6 +308,7 @@ pub struct Flags {
     pub allow_file_access: bool,
     pub device: Option<String>,
     pub auto_connect: bool,
+    pub force_launch: bool,
     pub session_name: Option<String>,
     pub annotate: bool,
     pub color_scheme: Option<String>,
@@ -443,8 +444,11 @@ pub fn parse_flags(args: &[String]) -> Flags {
         allow_file_access: env_var_is_truthy("AGENT_BROWSER_ALLOW_FILE_ACCESS")
             || config.allow_file_access.unwrap_or(false),
         device: env::var("AGENT_BROWSER_IOS_DEVICE").ok().or(config.device),
-        auto_connect: env_var_is_truthy("AGENT_BROWSER_AUTO_CONNECT")
-            || config.auto_connect.unwrap_or(false),
+        auto_connect: !env_var_is_truthy("AGENT_BROWSER_NO_AUTO_CONNECT")
+            && (env_var_is_truthy("AGENT_BROWSER_AUTO_CONNECT")
+                || config.auto_connect.unwrap_or(true)),
+        force_launch: env_var_is_truthy("AGENT_BROWSER_FORCE_LAUNCH")
+            || env::var("CI").is_ok(),
         session_name: env::var("AGENT_BROWSER_SESSION_NAME")
             .ok()
             .or(config.session_name),
@@ -682,10 +686,17 @@ pub fn parse_flags(args: &[String]) -> Flags {
             "--auto-connect" => {
                 let (val, consumed) = parse_bool_arg(args, i);
                 flags.auto_connect = val;
+                if !val {
+                    flags.force_launch = true;
+                }
                 if consumed {
                     i += 1;
                 }
             }
+            "--launch" | "--new" => {
+                flags.force_launch = true;
+                flags.auto_connect = false;
+            }
             "--session-name" => {
                 if let Some(s) = args.get(i + 1) {
                     flags.session_name = Some(s.clone());
@@ -842,6 +853,8 @@ pub fn clean_args(args: &[String]) -> Vec<String> {
         "--ignore-https-errors",
         "--allow-file-access",
         "--auto-connect",
+        "--launch",
+        "--new",
         "--annotate",
         "--content-boundaries",
         "--confirm-interactive",

cli/src/main.rs

@@ -511,7 +511,7 @@ fn main() {
     }
 
     let args: Vec<String> = env::args().skip(1).collect();
-    let flags = parse_flags(&args);
+    let mut flags = parse_flags(&args);
     let clean = clean_args(&args);
 
     let has_help = args.iter().any(|a| a == "--help" || a == "-h");
@@ -752,6 +752,7 @@ fn main() {
         confirm_actions: flags.confirm_actions.as_deref(),
         engine: flags.engine.as_deref(),
         auto_connect: flags.auto_connect,
+        force_launch: flags.force_launch,
         idle_timeout: flags.idle_timeout.as_deref(),
         default_timeout: flags.default_timeout,
         cdp: flags.cdp.as_deref(),
@@ -840,24 +841,9 @@ fn main() {
         exit(1);
     }
 
-    if flags.auto_connect && flags.cdp.is_some() {
-        let msg = "Cannot use --auto-connect and --cdp together";
-        if flags.json {
-            print_json_error(msg);
-        } else {
-            eprintln!("{} {}", color::error_indicator(), msg);
-        }
-        exit(1);
-    }
-
-    if flags.auto_connect && flags.provider.is_some() {
-        let msg = "Cannot use --auto-connect and -p/--provider together";
-        if flags.json {
-            print_json_error(msg);
-        } else {
-            eprintln!("{} {}", color::error_indicator(), msg);
-        }
-        exit(1);
+    // Explicit --cdp or --provider disables auto-connect (they specify the connection)
+    if flags.cdp.is_some() || flags.provider.is_some() {
+        flags.auto_connect = false;
     }
 
     if flags.provider.is_some() && !flags.extensions.is_empty() {
@@ -1069,7 +1055,7 @@ fn main() {
         || !flags.extensions.is_empty())
         && flags.cdp.is_none()
         && flags.provider.is_none()
-        && !flags.auto_connect
+        && (flags.force_launch || !flags.auto_connect)
     {
         let mut launch_cmd = json!({
             "id": gen_id(),

cli/src/native/actions.rs

@@ -1555,18 +1555,40 @@ async fn auto_launch(state: &mut DaemonState) -> Result<(), String> {
         return Ok(());
     }
 
-    if env::var("AGENT_BROWSER_AUTO_CONNECT").is_ok() {
-        state.reset_input_state();
-        state.browser = Some(connect_auto_with_fresh_tab().await?);
-        state.subscribe_to_browser_events();
-        state.start_fetch_handler();
-        state.start_dialog_handler();
-        state.update_stream_client().await;
-        apply_launch_init_scripts(state).await;
-        try_auto_restore_state(state).await;
-        try_load_storage_state(state, &storage_state_path).await;
-        apply_stealth_to_browser(state).await;
-        return Ok(());
+    let force_launch = env::var("AGENT_BROWSER_FORCE_LAUNCH").is_ok();
+
+    // Default behavior: try to connect to the user's existing Chrome first.
+    // This shares cookies/sessions so the agent can reuse logged-in state.
+    // Skip if --launch/--new was passed or running in CI.
+    if env::var("AGENT_BROWSER_AUTO_CONNECT").is_ok() && !force_launch {
+        match connect_auto_with_fresh_tab().await {
+            Ok(mgr) => {
+                state.reset_input_state();
+                state.browser = Some(mgr);
+                state.subscribe_to_browser_events();
+                state.start_fetch_handler();
+                state.start_dialog_handler();
+                state.update_stream_client().await;
+                apply_launch_init_scripts(state).await;
+                try_auto_restore_state(state).await;
+                try_load_storage_state(state, &storage_state_path).await;
+                apply_stealth_to_browser(state).await;
+                return Ok(());
+            }
+            Err(_e) => {
+                // Could not find a running Chrome with CDP enabled.
+                // Return a helpful error guiding the user to enable it.
+                return Err(format!(
+                    "Could not connect to your Chrome browser.\n\n\
+                     To let agent-browser work with your existing Chrome (recommended):\n\
+                     {}\n\n\
+                     Or start a standalone browser with: agent-browser --launch open <url>\n\n\
+                     Tip: On Chrome 144+, you can enable CDP without restarting:\n\
+                     Open chrome://inspect/#remote-debugging and toggle it on.",
+                    chrome_relaunch_hint(),
+                ));
+            }
+        }
     }
 
     // Cloud provider: when AGENT_BROWSER_PROVIDER is set, connect via the
@@ -1689,6 +1711,23 @@ async fn apply_launch_init_scripts(state: &DaemonState) {
 }
 
 /// Inject stealth scripts into the active browser session.
+/// Platform-specific hint for relaunching Chrome with CDP enabled.
+fn chrome_relaunch_hint() -> &'static str {
+    if cfg!(target_os = "macos") {
+        "  1. Quit Chrome completely\n\
+         2. Run:  open -a \"Google Chrome\" --args --remote-debugging-port=9222\n\
+         3. Then retry your agent-browser command"
+    } else if cfg!(target_os = "windows") {
+        "  1. Close Chrome completely\n\
+         2. Run:  start chrome --remote-debugging-port=9222\n\
+         3. Then retry your agent-browser command"
+    } else {
+        "  1. Close Chrome completely\n\
+         2. Run:  google-chrome --remote-debugging-port=9222\n\
+         3. Then retry your agent-browser command"
+    }
+}
+
 /// Called after every successful launch / CDP connect / auto-connect.
 async fn apply_stealth_to_browser(state: &DaemonState) {
     if env::var("AGENT_BROWSER_STEALTH").map(|v| v == "0").unwrap_or(false) {
@@ -1998,15 +2037,31 @@ async fn handle_launch(cmd: &Value, state: &mut DaemonState) -> Result<Value, St
     }
 
     if auto_connect {
-        state.reset_input_state();
-        state.browser = Some(connect_auto_with_fresh_tab().await?);
-        state.subscribe_to_browser_events();
-        state.start_fetch_handler();
-        state.start_dialog_handler();
-        state.update_stream_client().await;
-        load_storage_state_or_rollback(state, &storage_state_owned).await?;
-        apply_launch_init_scripts(state).await;
-        return Ok(json!({ "launched": true }));
+        match connect_auto_with_fresh_tab().await {
+            Ok(mgr) => {
+                state.reset_input_state();
+                state.browser = Some(mgr);
+                state.subscribe_to_browser_events();
+                state.start_fetch_handler();
+                state.start_dialog_handler();
+                state.update_stream_client().await;
+                load_storage_state_or_rollback(state, &storage_state_owned).await?;
+                apply_launch_init_scripts(state).await;
+                apply_stealth_to_browser(state).await;
+                return Ok(json!({ "launched": true }));
+            }
+            Err(_e) => {
+                return Err(format!(
+                    "Could not connect to your Chrome browser.\n\n\
+                     To let agent-browser work with your existing Chrome (recommended):\n\
+                     {}\n\n\
+                     Or start a standalone browser with: agent-browser --launch open <url>\n\n\
+                     Tip: On Chrome 144+, you can enable CDP without restarting:\n\
+                     Open chrome://inspect/#remote-debugging and toggle it on.",
+                    chrome_relaunch_hint(),
+                ));
+            }
+        }
     }
 
     if let Some(provider) = cmd.get("provider").and_then(|v| v.as_str()) {

cli/src/output.rs

@@ -3076,8 +3076,9 @@ Authentication:
                              (or AGENT_BROWSER_SESSION_NAME env)
   --state <path>             Load saved auth state (cookies + storage) from JSON file
                              (or AGENT_BROWSER_STATE env)
-  --auto-connect             Connect to a running Chrome to reuse its auth state
-                             Tip: agent-browser --auto-connect state save ./auth.json
+  --auto-connect             Connect to a running Chrome (DEFAULT - shares cookies/sessions)
+                             Tip: enable CDP via chrome://inspect/#remote-debugging
+  --launch, --new            Launch a fresh browser instead of connecting to existing
   --headers <json>           HTTP headers scoped to URL's origin (e.g., Authorization bearer token)
 
 Options: