fix(browser): stability enhancements + MCP frontend client

S7 Browser Hand:
- Remove dead code: browser/actions.rs (314 lines of unused BrowserAction/ActionResult types)
- Fix browser_scrape_page: log failed selector matches instead of silently swallowing errors
- Fix element_to_info: document known limitation for always-None location/size fields
- Fix browserHandStore: reuse activeSessionId in executeScript/takeScreenshot/executeTemplate
  instead of creating orphan Browser sessions
- Add Browser.connect(sessionId) method for session reuse

MCP Frontend:
- Add desktop/src/lib/mcp-client.ts (77 lines) — typed client for MCP Tauri commands
  (startMcpService, stopMcpService, listMcpServices, callMcpTool)

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

desktop/src-tauri/src/browser/actions.rs

@@ -1,313 +1,5 @@
-// Browser action definitions for Hands system
-// Note: These types are reserved for future Browser Hand automation features
-
-#![allow(dead_code)]
-
-use serde::{Deserialize, Serialize};
-
-/// Browser action types
-#[derive(Debug, Clone, Serialize, Deserialize)]
-#[serde(tag = "type", rename_all = "snake_case")]
-pub enum BrowserAction {
-    /// Create a new browser session
-    CreateSession {
-        webdriver_url: Option<String>,
-        headless: Option<bool>,
-        browser_type: Option<String>,
-        window_size: Option<(u32, u32)>,
-    },
-
-    /// Close browser session
-    CloseSession {
-        session_id: String,
-    },
-
-    /// Navigate to URL
-    Navigate {
-        session_id: String,
-        url: String,
-    },
-
-    /// Go back
-    Back {
-        session_id: String,
-    },
-
-    /// Go forward
-    Forward {
-        session_id: String,
-    },
-
-    /// Refresh page
-    Refresh {
-        session_id: String,
-    },
-
-    /// Click element
-    Click {
-        session_id: String,
-        selector: String,
-    },
-
-    /// Type text
-    Type {
-        session_id: String,
-        selector: String,
-        text: String,
-        clear_first: Option<bool>,
-    },
-
-    /// Get element text
-    GetText {
-        session_id: String,
-        selector: String,
-    },
-
-    /// Get element attribute
-    GetAttribute {
-        session_id: String,
-        selector: String,
-        attribute: String,
-    },
-
-    /// Find element
-    FindElement {
-        session_id: String,
-        selector: String,
-    },
-
-    /// Find multiple elements
-    FindElements {
-        session_id: String,
-        selector: String,
-    },
-
-    /// Execute JavaScript
-    ExecuteScript {
-        session_id: String,
-        script: String,
-        args: Option<Vec<serde_json::Value>>,
-    },
-
-    /// Take screenshot
-    Screenshot {
-        session_id: String,
-    },
-
-    /// Take element screenshot
-    ElementScreenshot {
-        session_id: String,
-        selector: String,
-    },
-
-    /// Wait for element
-    WaitForElement {
-        session_id: String,
-        selector: String,
-        timeout_ms: Option<u64>,
-    },
-
-    /// Get page source
-    GetSource {
-        session_id: String,
-    },
-
-    /// Get current URL
-    GetCurrentUrl {
-        session_id: String,
-    },
-
-    /// Get page title
-    GetTitle {
-        session_id: String,
-    },
-
-    /// List all sessions
-    ListSessions,
-
-    /// Get session info
-    GetSession {
-        session_id: String,
-    },
-}
-
-/// Action execution result
-#[derive(Debug, Clone, Serialize, Deserialize)]
-#[serde(tag = "type", rename_all = "snake_case")]
-pub enum ActionResult {
-    /// Session created
-    SessionCreated {
-        session_id: String,
-    },
-
-    /// Session closed
-    SessionClosed {
-        session_id: String,
-    },
-
-    /// Navigation result
-    Navigated {
-        url: Option<String>,
-        title: Option<String>,
-    },
-
-    /// Element clicked
-    Clicked {
-        selector: String,
-    },
-
-    /// Text typed
-    Typed {
-        selector: String,
-        text: String,
-    },
-
-    /// Text retrieved
-    TextRetrieved {
-        selector: String,
-        text: String,
-    },
-
-    /// Attribute retrieved
-    AttributeRetrieved {
-        selector: String,
-        attribute: String,
-        value: Option<String>,
-    },
-
-    /// Element found
-    ElementFound {
-        element: ElementInfo,
-    },
-
-    /// Elements found
-    ElementsFound {
-        elements: Vec<ElementInfo>,
-    },
-
-    /// Script executed
-    ScriptExecuted {
-        result: serde_json::Value,
-    },
-
-    /// Screenshot taken
-    ScreenshotTaken {
-        base64: String,
-        format: String,
-    },
-
-    /// Page source retrieved
-    SourceRetrieved {
-        source: String,
-    },
-
-    /// URL retrieved
-    UrlRetrieved {
-        url: String,
-    },
-
-    /// Title retrieved
-    TitleRetrieved {
-        title: String,
-    },
-
-    /// Sessions listed
-    SessionsListed {
-        sessions: Vec<SessionInfo>,
-    },
-
-    /// Session info retrieved
-    SessionInfo {
-        session: SessionInfo,
-    },
-
-    /// Operation completed (no specific data)
-    Completed,
-
-    /// Error occurred
-    Error {
-        message: String,
-        code: String,
-    },
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ElementInfo {
-    pub selector: String,
-    pub tag_name: Option<String>,
-    pub text: Option<String>,
-    pub is_displayed: bool,
-    pub is_enabled: bool,
-    pub is_selected: bool,
-    pub location: Option<ElementLocation>,
-    pub size: Option<ElementSize>,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ElementLocation {
-    pub x: i32,
-    pub y: i32,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ElementSize {
-    pub width: u64,
-    pub height: u64,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct SessionInfo {
-    pub id: String,
-    pub name: String,
-    pub current_url: Option<String>,
-    pub title: Option<String>,
-    pub status: String,
-    pub created_at: String,
-    pub last_activity: String,
-}
-
-/// High-level browser task (for Hand integration)
-#[derive(Debug, Clone, Serialize, Deserialize)]
-#[serde(tag = "task", rename_all = "snake_case")]
-pub enum BrowserTask {
-    /// Scrape page content
-    ScrapePage {
-        url: String,
-        selectors: Vec<String>,
-        wait_for: Option<String>,
-    },
-
-    /// Fill form
-    FillForm {
-        url: String,
-        fields: Vec<FormField>,
-        submit_selector: Option<String>,
-    },
-
-    /// Take page snapshot
-    PageSnapshot {
-        url: String,
-        include_screenshot: bool,
-    },
-
-    /// Navigate and extract
-    NavigateAndExtract {
-        url: String,
-        extraction_script: String,
-    },
-
-    /// Multi-page scraping
-    MultiPageScrape {
-        start_url: String,
-        next_page_selector: String,
-        item_selector: String,
-        max_pages: Option<u32>,
-    },
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct FormField {
-    pub selector: String,
-    pub value: String,
-    pub field_type: Option<String>,
-}
+// Removed dead code (was 314 lines of unused BrowserAction/ActionResult/ElementInfo
+// types guarded by #![allow(dead_code)]). The types defined here duplicated structs
+// already present in client.rs and were never consumed by any other module.
+// If browser action types are needed in the future, use the types from client.rs
+// and session.rs directly.

desktop/src-tauri/src/browser/client.rs

@@ -407,8 +407,15 @@ impl BrowserClient {
         let is_displayed = element.is_displayed().await.unwrap_or(false);
         let is_enabled = element.is_enabled().await.unwrap_or(false);
         let is_selected = element.is_selected().await.unwrap_or(false);
-        // Note: location() and size() may not be available in all fantoccini versions
-        // Using placeholder values if not available
+        // KNOWN LIMITATION: location and size are always None.
+        // The fantoccini Element type does not expose a synchronous bounding-box
+        // helper; retrieving geometry requires a separate execute_script call
+        // (e.g. element.getBoundingClientRect()). Since no current caller relies
+        // on these fields, they are intentionally left as None rather than adding
+        // an extra round-trip. If bounding-box data is needed in the future,
+        // add a dedicated browser_element_rect command that calls
+        // execute_script("return arguments[0].getBoundingClientRect()") and
+        // deprecate the location/size fields on ElementInfo entirely.
         let location = None;
         let size = None;
 

desktop/src-tauri/src/browser/commands.rs

@@ -1,9 +1,5 @@
 // Tauri commands for browser automation
-// Note: Some imports are reserved for future Browser Hand features
 
-#![allow(unused_imports)]
-
-use crate::browser::actions::BrowserAction;
 use crate::browser::client::BrowserClient;
 use crate::browser::session::{BrowserType, SessionConfig};
 use serde::{Deserialize, Serialize};
@@ -454,9 +450,18 @@ pub async fn browser_scrape_page(
     let mut results = serde_json::Map::new();
 
     for selector in selectors {
-        if let Ok(elements) = client.find_elements(&session_id, &selector).await {
-            let texts: Vec<String> = elements.iter().filter_map(|e| e.text.clone()).collect();
-            results.insert(selector, serde_json::json!(texts));
+        match client.find_elements(&session_id, &selector).await {
+            Ok(elements) => {
+                let texts: Vec<String> = elements.iter().filter_map(|e| e.text.clone()).collect();
+                results.insert(selector, serde_json::json!(texts));
+            }
+            Err(e) => {
+                tracing::warn!(
+                    selector = %selector,
+                    error = %e,
+                    "browser_scrape_page: find_elements failed, skipping selector"
+                );
+            }
         }
     }
 

desktop/src-tauri/src/browser/mod.rs

@@ -7,4 +7,4 @@ pub mod client;
 pub mod commands;
 pub mod error;
 pub mod session;
-pub mod actions;
+// pub mod actions; // Removed: dead code — see actions.rs for details

desktop/src/lib/browser-client.ts

@@ -324,6 +324,14 @@ export class Browser {
     return this.sessionId;
   }
 
+  /**
+   * Attach to an existing session by ID.
+   * Use this to reuse a session created elsewhere without spawning a new one.
+   */
+  connect(sessionId: string): void {
+    this.sessionId = sessionId;
+  }
+
   /**
    * Close browser session
    */

desktop/src/lib/mcp-client.ts

@@ -0,0 +1,77 @@
+/**
+ * MCP (Model Context Protocol) Client for ZCLAW
+ *
+ * Thin typed wrapper around the 4 Tauri MCP commands.
+ * All communication goes through invoke() — no direct HTTP or WebSocket.
+ */
+
+import { invoke } from '@tauri-apps/api/core';
+import { createLogger } from './logger';
+
+const log = createLogger('mcp-client');
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface McpServiceConfig {
+  name: string;
+  command: string;
+  args?: string[];
+  env?: Record<string, string>;
+  cwd?: string;
+}
+
+export interface McpToolInfo {
+  service_name: string;
+  tool_name: string;
+  description: string;
+  input_schema: Record<string, unknown>;
+}
+
+export interface McpServiceStatus {
+  name: string;
+  tool_count: number;
+  tools: McpToolInfo[];
+}
+
+// ============================================================================
+// Functions
+// ============================================================================
+
+/**
+ * Start an MCP service process and discover its tools.
+ */
+export async function startMcpService(
+  config: McpServiceConfig
+): Promise<McpToolInfo[]> {
+  log.info('startMcpService', { name: config.name });
+  return invoke<McpToolInfo[]>('mcp_start_service', { config });
+}
+
+/**
+ * Stop a running MCP service by name.
+ */
+export async function stopMcpService(name: string): Promise<void> {
+  log.info('stopMcpService', { name });
+  return invoke<void>('mcp_stop_service', { name });
+}
+
+/**
+ * List all running MCP services with their discovered tools.
+ */
+export async function listMcpServices(): Promise<McpServiceStatus[]> {
+  return invoke<McpServiceStatus[]>('mcp_list_services');
+}
+
+/**
+ * Call a tool exposed by a running MCP service.
+ */
+export async function callMcpTool(
+  serviceName: string,
+  toolName: string,
+  args: Record<string, unknown>
+): Promise<unknown> {
+  log.info('callMcpTool', { serviceName, toolName });
+  return invoke<unknown>('mcp_call_tool', { serviceName, toolName, args });
+}

desktop/src/store/browserHandStore.ts

@@ -10,6 +10,8 @@ import Browser, {
   createSession,
   closeSession,
   listSessions,
+  screenshot as screenshotFn,
+  executeScript as executeScriptFn,
 } from '../lib/browser-client';
 import {
   BUILTIN_TEMPLATES,
@@ -247,14 +249,21 @@ export const useBrowserHandStore = create<BrowserHandState & BrowserHandActions>
       },
     });
 
-    // Create browser instance
+    // Create browser instance — reuse active session if available
     const browser = new Browser();
+    let createdOwnSession = false;
 
     try {
       store.addLog({ level: 'info', message: `开始执行模板: ${template.name}` });
 
-      // Start browser session
-      await browser.start({ headless: true });
+      // Attach to existing session or start a new one
+      if (store.activeSessionId) {
+        browser.connect(store.activeSessionId);
+        createdOwnSession = false;
+      } else {
+        await browser.start({ headless: true });
+        createdOwnSession = true;
+      }
 
       // Create execution context
       const context = {
@@ -322,7 +331,10 @@ export const useBrowserHandStore = create<BrowserHandState & BrowserHandActions>
 
       throw error;
     } finally {
-      await browser.close();
+      // Only close the session if we created it (no pre-existing active session)
+      if (createdOwnSession) {
+        await browser.close();
+      }
     }
   },
 
@@ -340,10 +352,8 @@ export const useBrowserHandStore = create<BrowserHandState & BrowserHandActions>
     });
 
     try {
-      const browser = new Browser();
-      await browser.start();
-
-      const result = await browser.eval(script, args);
+      // Use the standalone function with the existing session — no new session created
+      const result = await executeScriptFn(store.activeSessionId, script, args);
 
       store.updateExecutionState({
         isRunning: false,
@@ -399,10 +409,8 @@ export const useBrowserHandStore = create<BrowserHandState & BrowserHandActions>
     }
 
     try {
-      const browser = new Browser();
-      await browser.start();
-
-      const result = await browser.screenshot();
+      // Use the standalone function with the existing session — no new session created
+      const result = await screenshotFn(store.activeSessionId);
 
       set((state) => ({
         execution: {