Add --profile flag for persistent browser profiles

Adds support for persistent browser profiles that preserve cookies,
localStorage, and login sessions across browser restarts.

Changes:
- Add --profile <path> CLI flag (flags.rs)
- Add AGENT_BROWSER_PROFILE environment variable support
- Add profile field to LaunchCommand type (types.ts)
- Use launchPersistentContext when profile is specified (browser.ts)
- Update help text and README with documentation

Usage:
  agent-browser --profile ~/.myapp-profile open myapp.com

This enables AI agents to maintain authenticated sessions across
browser restarts without re-authenticating each time.

cli/src/flags.rs

@@ -10,6 +10,7 @@ pub struct Flags {
     pub executable_path: Option<String>,
     pub cdp: Option<String>,
     pub extensions: Vec<String>,
+    pub profile: Option<String>,
 }
 
 pub fn parse_flags(args: &[String]) -> Flags {
@@ -28,6 +29,7 @@ pub fn parse_flags(args: &[String]) -> Flags {
         executable_path: env::var("AGENT_BROWSER_EXECUTABLE_PATH").ok(),
         cdp: None,
         extensions: extensions_env,
+        profile: env::var("AGENT_BROWSER_PROFILE").ok(),
     };
 
     let mut i = 0;
@@ -67,6 +69,12 @@ pub fn parse_flags(args: &[String]) -> Flags {
                     i += 1;
                 }
             }
+            "--profile" => {
+                if let Some(s) = args.get(i + 1) {
+                    flags.profile = Some(s.clone());
+                    i += 1;
+                }
+            }
             _ => {}
         }
         i += 1;
@@ -81,7 +89,7 @@ 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", "--extension"];
+    const GLOBAL_FLAGS_WITH_VALUE: &[&str] = &["--session", "--headers", "--executable-path", "--cdp", "--extension", "--profile"];
 
     for arg in args.iter() {
         if skip_next {

cli/src/main.rs

@@ -161,8 +161,8 @@ fn main() {
         }
     };
 
-    // Warn if executable_path was specified but daemon was already running
-    if daemon_result.already_running && (flags.executable_path.is_some() || !flags.extensions.is_empty()) {
+    // Warn if executable_path, profile, or extensions were specified but daemon was already running
+    if daemon_result.already_running && (flags.executable_path.is_some() || !flags.extensions.is_empty() || flags.profile.is_some()) {
         if !flags.json {
             if flags.executable_path.is_some() {
                 eprintln!("\x1b[33m⚠\x1b[0m --executable-path ignored: daemon already running. Use 'agent-browser close' first to restart with new path.");
@@ -170,6 +170,9 @@ fn main() {
             if !flags.extensions.is_empty() {
                 eprintln!("\x1b[33m⚠\x1b[0m --extension ignored: daemon already running. Use 'agent-browser close' first to restart with extensions.");
             }
+            if flags.profile.is_some() {
+                eprintln!("\x1b[33m⚠\x1b[0m --profile ignored: daemon already running. Use 'agent-browser close' first to restart with profile.");
+            }
         }
     }
 
@@ -229,16 +232,22 @@ fn main() {
     }
 
     // Launch headed browser if --headed flag is set (without CDP)
-    if flags.headed && flags.cdp.is_none() {
-        let launch_cmd = json!({
+    // Also launch with profile if --profile is set
+    if (flags.headed || flags.profile.is_some()) && flags.cdp.is_none() {
+        let mut launch_cmd = json!({
             "id": gen_id(),
             "action": "launch",
-            "headless": false
+            "headless": !flags.headed
         });
 
+        // Add profile path if specified
+        if let Some(ref profile_path) = flags.profile {
+            launch_cmd["profile"] = json!(profile_path);
+        }
+
         if let Err(e) = send_command(launch_cmd, &flags.session) {
             if !flags.json {
-                eprintln!("\x1b[33m⚠\x1b[0m Could not launch headed browser: {}", e);
+                eprintln!("\x1b[33m⚠\x1b[0m Could not launch browser: {}", e);
             }
         }
     }

cli/src/output.rs

@@ -1189,6 +1189,7 @@ Snapshot Options:
 
 Options:
   --session <name>           Isolated session (or AGENT_BROWSER_SESSION env)
+  --profile <path>           Persistent browser profile (or AGENT_BROWSER_PROFILE env)
   --headers <json>           HTTP headers scoped to URL's origin (for auth)
   --executable-path <path>   Custom browser executable (or AGENT_BROWSER_EXECUTABLE_PATH)
   --extension <path>         Load browser extensions (repeatable).
@@ -1207,6 +1208,7 @@ Examples:
   agent-browser get text @e1
   agent-browser screenshot --full
   agent-browser --cdp 9222 snapshot      # Connect via CDP port
+  agent-browser --profile ~/.myapp open example.com  # Persistent profile
 "#
     );
 }