support external browsers

Author: hotzen

docs/docker.md

@@ -149,6 +149,139 @@ volumes:
 
 The `shm_size` and `seccomp` settings are needed for Chromium to run properly in a container.
 
+### External Browser
+
+Run `chromedp/headless-shell` as a separate container and point Spacebot at it via
+`connect_url`. This decouples the browser lifecycle from the main process and avoids
+bundling Chromium into the Spacebot image.
+
+Workers spawned by the same agent share one Chrome process (each gets its own tab). A
+Chrome crash kills all tabs for that agent.
+
+#### Spacebot on host, browser in Docker
+
+When Spacebot runs as a binary directly on the host, expose port 9222 so the host process
+can reach the container:
+
+```yaml
+# docker-compose.yml
+services:
+  browser:
+    image: chromedp/headless-shell:latest
+    container_name: browser
+    ports:
+      - "127.0.0.1:9222:9222"
+    shm_size: 1gb
+    restart: unless-stopped
+```
+
+Test whether the browser is reachable from the host:
+
+```bash
+curl http://localhost:9222/json/version
+```
+
+Then configure Spacebot via config:
+
+```toml
+[defaults.browser]
+connect_url = "http://localhost:9222"
+```
+
+#### Both in Docker
+
+When both Spacebot and the browser run in containers, use a Docker network instead of
+exposing ports:
+
+```yaml
+services:
+  spacebot:
+    image: ghcr.io/spacedriveapp/spacebot:slim
+    ports:
+      - "19898:19898"
+    volumes:
+      - spacebot-data:/data
+    environment:
+      - ANTHROPIC_API_KEY=${ANTHROPIC_API_KEY}
+    volumes:
+      - spacebot-data:/data
+      - ./config.toml:/data/config.toml:ro
+    networks:
+      - spacebot-net
+    restart: unless-stopped
+    
+  browser:
+    image: chromedp/headless-shell:latest
+    networks:
+      - spacebot-net
+    shm_size: 1gb
+    restart: unless-stopped
+
+networks:
+  spacebot-net:
+
+volumes:
+  spacebot-data:
+```
+
+#### Per-agent dedicated sandboxes
+
+Use a `config.toml` to route each agent to its own container:
+
+```toml
+[defaults.browser]
+connect_url = "http://browser-main:9222"
+
+[[agents]]
+id = "research"
+[agents.browser]
+connect_url = "http://browser-research:9222"
+
+[[agents]]
+id = "internal"
+[agents.browser]
+enabled = false
+```
+
+```yaml
+services:
+  spacebot:
+    image: ghcr.io/spacedriveapp/spacebot:slim
+    volumes:
+      - spacebot-data:/data
+      - ./config.toml:/data/config.toml:ro
+    networks:
+      - spacebot-net
+
+  browser-main:
+    image: chromedp/headless-shell:latest
+    networks:
+      - spacebot-net
+    shm_size: 512mb
+    restart: unless-stopped
+
+  browser-research:
+    image: chromedp/headless-shell:latest
+    networks:
+      - spacebot-net
+    shm_size: 1gb
+    restart: unless-stopped
+
+networks:
+  spacebot-net:
+
+volumes:
+  spacebot-data:
+```
+
+#### `connect_url`
+
+Accepted formats:
+- `http://host:9222` — auto-discovers the WebSocket URL via `/json/version` (preferred)
+- `ws://host:9222/devtools/browser/<id>` — direct WebSocket URL
+
+An empty string is treated as unset and falls back to the embedded launch path.
+
 ## Building the Image
 
 From the spacebot repo root:

src/config.rs

@@ -522,6 +522,8 @@ pub struct BrowserConfig {
     pub executable_path: Option<String>,
     /// Directory for storing screenshots and other browser artifacts.
     pub screenshot_dir: Option<PathBuf>,
+    /// CDP URL of an external browser to connect to instead of launching one locally.
+    pub connect_url: Option<String>,
 }
 
 impl Default for BrowserConfig {
@@ -532,6 +534,7 @@ impl Default for BrowserConfig {
             evaluate_enabled: false,
             executable_path: None,
             screenshot_dir: None,
+            connect_url: None,
         }
     }
 }
@@ -1801,6 +1804,7 @@ struct TomlBrowserConfig {
     evaluate_enabled: Option<bool>,
     executable_path: Option<String>,
     screenshot_dir: Option<String>,
+    connect_url: Option<String>,
 }
 
 #[derive(Deserialize)]
@@ -3109,6 +3113,7 @@ impl Config {
                             .screenshot_dir
                             .map(PathBuf::from)
                             .or_else(|| base.screenshot_dir.clone()),
+                        connect_url: b.connect_url.or_else(|| base.connect_url.clone()),
                     }
                 })
                 .unwrap_or_else(|| base_defaults.browser.clone()),
@@ -3295,6 +3300,9 @@ impl Config {
                             .screenshot_dir
                             .map(PathBuf::from)
                             .or_else(|| defaults.browser.screenshot_dir.clone()),
+                        connect_url: b
+                            .connect_url
+                            .or_else(|| defaults.browser.connect_url.clone()),
                     }),
                     mcp: match a.mcp {
                         Some(mcp_servers) => Some(
@@ -3546,6 +3554,13 @@ impl Config {
             });
         }
 
+        warn_browser_config("defaults", &defaults.browser);
+        for agent in &agents {
+            if let Some(browser) = &agent.browser {
+                warn_browser_config(&agent.id, browser);
+            }
+        }
+
         Ok(Config {
             instance_dir,
             llm,
@@ -3787,6 +3802,28 @@ impl std::fmt::Debug for RuntimeConfig {
     }
 }
 
+/// Warn at config load time about `BrowserConfig` fields that have no effect when
+/// `connect_url` is set.
+fn warn_browser_config(context: &str, config: &BrowserConfig) {
+    let Some(url) = config.connect_url.as_deref().filter(|u| !u.is_empty()) else {
+        return;
+    };
+    if config.executable_path.is_some() {
+        tracing::warn!(
+            context,
+            connect_url = url,
+            "connect_url is set; executable_path has no effect"
+        );
+    }
+    if !config.headless {
+        tracing::warn!(
+            context,
+            connect_url = url,
+            "connect_url is set; headless flag has no effect"
+        );
+    }
+}
+
 /// Watches config, prompt, identity, and skill files for changes and triggers
 /// hot reload on the corresponding RuntimeConfig.
 ///

src/tools/browser.rs

@@ -145,12 +145,15 @@ struct BrowserState {
     element_refs: HashMap<String, ElementRef>,
     /// Counter for generating element refs.
     next_ref: usize,
+    /// True when connected to an external browser process rather than a locally launched one.
+    connected: bool,
 }
 
 impl std::fmt::Debug for BrowserState {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("BrowserState")
             .field("has_browser", &self.browser.is_some())
+            .field("connected", &self.connected)
             .field("pages", &self.pages.len())
             .field("active_target", &self.active_target)
             .field("element_refs", &self.element_refs.len())
@@ -180,6 +183,7 @@ impl BrowserTool {
                 active_target: None,
                 element_refs: HashMap::new(),
                 next_ref: 0,
+                connected: false,
             })),
             config,
             screenshot_dir,
@@ -472,12 +476,48 @@ impl BrowserTool {
             return Ok(BrowserOutput::success("Browser already running"));
         }
 
+        let is_connect = self
+            .config
+            .connect_url
+            .as_deref()
+            .is_some_and(|url| !url.is_empty());
+
+        if is_connect {
+            self.connect(&mut state).await
+        } else {
+            self.launch(&mut state).await
+        }
+    }
+
+    async fn connect(&self, state: &mut BrowserState) -> Result<BrowserOutput, BrowserError> {
+        let connect_url = self.config.connect_url.as_deref().unwrap();
+
+        tracing::info!(connect_url, "connecting to external browser");
+
+        let (browser, mut handler) = Browser::connect(connect_url).await.map_err(|error| {
+            BrowserError::new(format!(
+                "failed to connect to browser at {connect_url}: {error}"
+            ))
+        })?;
+
+        let handler_task = tokio::spawn(async move { while handler.next().await.is_some() {} });
+
+        state.browser = Some(browser);
+        state._handler_task = Some(handler_task);
+        state.connected = true;
+
+        tracing::info!(connect_url, "connected to external browser");
+        Ok(BrowserOutput::success(format!(
+            "Connected to external browser at {connect_url}"
+        )))
+    }
+
+    async fn launch(&self, state: &mut BrowserState) -> Result<BrowserOutput, BrowserError> {
         let mut builder = ChromeConfig::builder().no_sandbox();
 
         if !self.config.headless {
             builder = builder.with_head().window_size(1280, 900);
         }
-
         if let Some(path) = &self.config.executable_path {
             builder = builder.chrome_executable(path);
         }
@@ -489,7 +529,7 @@ impl BrowserTool {
         tracing::info!(
             headless = self.config.headless,
             executable = ?self.config.executable_path,
-            "launching chrome"
+            "launching browser"
         );
 
         let (browser, mut handler) = Browser::launch(chrome_config)
@@ -500,6 +540,7 @@ impl BrowserTool {
 
         state.browser = Some(browser);
         state._handler_task = Some(handler_task);
+        state.connected = false;
 
         tracing::info!("browser launched");
         Ok(BrowserOutput::success("Browser launched successfully"))
@@ -955,20 +996,39 @@ impl BrowserTool {
     async fn handle_close(&self) -> Result<BrowserOutput, BrowserError> {
         let mut state = self.state.lock().await;
 
+        if state.connected {
+            self.disconnect(&mut state).await
+        } else {
+            self.close(&mut state).await
+        }
+    }
+
+    async fn disconnect(&self, state: &mut BrowserState) -> Result<BrowserOutput, BrowserError> {
+        // Drop without Browser.close — that CDP command would terminate the external process.
+        state.browser.take();
+        self.reset_state(state);
+        tracing::info!("external browser disconnected");
+        Ok(BrowserOutput::success("Browser disconnected"))
+    }
+
+    async fn close(&self, state: &mut BrowserState) -> Result<BrowserOutput, BrowserError> {
         if let Some(mut browser) = state.browser.take()
             && let Err(error) = browser.close().await
         {
-            tracing::warn!(%error, "browser close returned error");
+            tracing::warn!(%error, "embedded browser close returned error");
         }
+        self.reset_state(state);
+        tracing::info!("embedded browser closed");
+        Ok(BrowserOutput::success("Browser closed"))
+    }
 
+    fn reset_state(&self, state: &mut BrowserState) {
         state.pages.clear();
         state.active_target = None;
         state.element_refs.clear();
         state.next_ref = 0;
         state._handler_task = None;
-
-        tracing::info!("browser closed");
-        Ok(BrowserOutput::success("Browser closed"))
+        state.connected = false;
     }
 
     /// Get the active page, or create a first one if the browser has no pages yet.