fix: Major browser connection fixes for external Chrome

1. Use existing tab instead of creating new one when connecting to Chrome
   - Check for existing pages and use the first/active one
   - Only create new tab if no tabs exist

2. Prevent cleanup/closing of externally connected Chrome instances
   - Do not close browser when disconnecting from external Chrome
   - Skip idle monitor for external connections
   - Only cleanup profiles we created, not external ones

3. Fix dual browser instance issue
   - Use global browser manager singleton in both TUI and core
   - Prevents creation of separate browser instances
   - Ensures /browser local and browser tools use same instance

This prevents Chrome from being killed when connected via CDP and ensures
the existing tab is used for navigation instead of creating new ones.

codex-rs/browser/src/manager.rs

@@ -262,10 +262,19 @@ impl BrowserManager {
         let mut page_guard = self.page.lock().await;
         *page_guard = None;
         
+        let config = self.config.read().await;
+        let is_external_chrome = config.connect_port.is_some() || config.connect_ws.is_some();
+        drop(config);
+        
         let mut browser_guard = self.browser.lock().await;
         if let Some(mut browser) = browser_guard.take() {
-            info!("Stopping browser");
-            browser.close().await?;
+            if is_external_chrome {
+                info!("Disconnecting from external Chrome (not closing it)");
+                // Just drop the connection, don't close the browser
+            } else {
+                info!("Stopping browser we launched");
+                browser.close().await?;
+            }
         }
         
         // Only cleanup user data directory if we should
@@ -308,12 +317,31 @@ impl BrowserManager {
             .as_ref()
             .ok_or(BrowserError::NotInitialized)?;
 
-        let cdp_page = browser.new_page("about:blank").await?;
+        let config = self.config.read().await;
+        
+        // If we're connected to an existing Chrome (via connect_port or connect_ws),
+        // try to use the current active tab instead of creating a new one
+        let cdp_page = if config.connect_port.is_some() || config.connect_ws.is_some() {
+            // Try to get existing pages
+            let pages = browser.pages().await?;
+            
+            if !pages.is_empty() {
+                // Use the first page (or the active one if we can determine it)
+                info!("Using existing Chrome tab instead of creating new one");
+                pages.into_iter().next().unwrap()
+            } else {
+                // No existing pages, create a new one
+                info!("No existing tabs found, creating new tab");
+                browser.new_page("about:blank").await?
+            }
+        } else {
+            // We launched Chrome ourselves, create a new page
+            browser.new_page("about:blank").await?
+        };
         
         // Apply page overrides (UA, locale, timezone, viewport, etc.)
         self.apply_page_overrides(&cdp_page).await?;
         
-        let config = self.config.read().await;
         let page = Arc::new(Page::new(cdp_page, config.clone()));
         *page_guard = Some(Arc::clone(&page));
 
@@ -533,7 +561,14 @@ impl BrowserManager {
     async fn start_idle_monitor(&self) {
         let config = self.config.read().await;
         let idle_timeout = Duration::from_millis(config.idle_timeout_ms);
+        let is_external_chrome = config.connect_port.is_some() || config.connect_ws.is_some();
         drop(config);
+        
+        // Don't start idle monitor for external Chrome connections
+        if is_external_chrome {
+            info!("Skipping idle monitor for external Chrome connection");
+            return;
+        }
 
         let browser = Arc::clone(&self.browser);
         let last_activity = Arc::clone(&self.last_activity);

codex-rs/tui/src/chatwidget.rs

@@ -60,7 +60,7 @@ use crate::history_cell::PatchEventType;
 use crate::live_wrap::RowBuilder;
 use crate::text_block::TextBlock;
 use crate::user_approval_widget::ApprovalRequest;
-use codex_browser::{BrowserManager, config::BrowserConfig};
+use codex_browser::BrowserManager;
 use codex_file_search::FileMatch;
 use ratatui::style::Stylize;
 
@@ -374,10 +374,10 @@ impl ChatWidget<'_> {
             }
         });
 
-        // Browser manager will be initialized lazily when needed
-        // For now, create a placeholder that will be replaced on first use
-        let browser_config = BrowserConfig::default();
-        let browser_manager = Arc::new(BrowserManager::new(browser_config));
+        // Use the global browser manager singleton to ensure consistency
+        // between TUI and core session
+        let browser_manager = tokio::runtime::Handle::current()
+            .block_on(codex_browser::global::get_or_create_browser_manager());
         
         // Add initial animated welcome message to history
         let mut history_cells = Vec::new();