feat: align browser callback runtime and export flows

Consolidate the browser task runtime around the callback path, add safer artifact opening for Zhihu exports, and cover the new service/browser flows with focused tests and supporting docs.

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

src/browser/callback_backend.rs

@@ -13,6 +13,9 @@ const TYPE_PROBE_CALLBACK_NAME: &str = "sgclawOnTypeProbe";
 const GET_TEXT_CALLBACK_NAME: &str = "sgclawOnGetText";
 const EVAL_CALLBACK_NAME: &str = "sgclawOnEval";
 const SHOW_AREA: &str = "show";
+const LOCAL_DASHBOARD_EXPECTED_DOMAIN: &str = "__sgclaw_local_dashboard__";
+const LOCAL_DASHBOARD_SOURCE: &str = "compat.workflow_executor";
+const LOCAL_DASHBOARD_KIND_ZHIHU_HOTLIST_SCREEN: &str = "zhihu_hotlist_screen";
 
 pub trait BrowserCallbackHost: Send + Sync {
     fn execute(&self, request: BrowserCallbackRequest) -> Result<BrowserCallbackResponse, PipeError>;
@@ -304,7 +307,21 @@ impl BrowserBackend for BrowserCallbackBackend {
         params: Value,
         expected_domain: &str,
     ) -> Result<CommandOutput, PipeError> {
-        self.mac_policy.validate(&action, expected_domain)?;
+        if let Some(local_dashboard) = approved_local_dashboard_request(&action, &params, expected_domain)
+        {
+            self.mac_policy
+                .validate_local_dashboard_presentation(
+                    &action,
+                    expected_domain,
+                    &local_dashboard.presentation_url,
+                    &local_dashboard.output_path,
+                )
+                .map_err(PipeError::Security)?;
+        } else {
+            self.mac_policy
+                .validate(&action, expected_domain)
+                .map_err(PipeError::Security)?;
+        }
 
         let seq = self.next_seq.fetch_add(1, Ordering::Relaxed);
         let reply = self.host.execute(BrowserCallbackRequest {
@@ -532,6 +549,42 @@ fn escape_js_single_quoted(raw: &str) -> String {
         .replace('\u{2029}', "\\u2029")
 }
 
+struct LocalDashboardRequest {
+    presentation_url: String,
+    output_path: String,
+}
+
+fn approved_local_dashboard_request(
+    action: &Action,
+    params: &Value,
+    expected_domain: &str,
+) -> Option<LocalDashboardRequest> {
+    if action != &Action::Navigate || expected_domain != LOCAL_DASHBOARD_EXPECTED_DOMAIN {
+        return None;
+    }
+
+    let presentation_url = params.get("url")?.as_str()?.trim();
+    let marker = params.get("sgclaw_local_dashboard_open")?.as_object()?;
+    let source = marker.get("source")?.as_str()?.trim();
+    let kind = marker.get("kind")?.as_str()?.trim();
+    let output_path = marker.get("output_path")?.as_str()?.trim();
+    let marker_presentation_url = marker.get("presentation_url")?.as_str()?.trim();
+
+    if source != LOCAL_DASHBOARD_SOURCE
+        || kind != LOCAL_DASHBOARD_KIND_ZHIHU_HOTLIST_SCREEN
+        || output_path.is_empty()
+        || presentation_url.is_empty()
+        || marker_presentation_url != presentation_url
+    {
+        return None;
+    }
+
+    Some(LocalDashboardRequest {
+        presentation_url: presentation_url.to_string(),
+        output_path: output_path.to_string(),
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -818,6 +871,71 @@ mod tests {
         ]));
     }
 
+    #[test]
+    fn callback_backend_accepts_approved_local_dashboard_navigate_request() {
+        let host = Arc::new(FakeCallbackHost::new(vec![success_reply(json!({
+            "navigated": true
+        }))]));
+        let backend = BrowserCallbackBackend::new(
+            host.clone(),
+            test_policy(),
+            "http://127.0.0.1:17888/sgclaw/browser-helper.html",
+        );
+
+        let output = backend
+            .invoke(
+                Action::Navigate,
+                json!({
+                    "url": "file:///C:/tmp/zhihu-hotlist-screen.html",
+                    "sgclaw_local_dashboard_open": {
+                        "source": "compat.workflow_executor",
+                        "kind": "zhihu_hotlist_screen",
+                        "output_path": "C:/tmp/zhihu-hotlist-screen.html",
+                        "presentation_url": "file:///C:/tmp/zhihu-hotlist-screen.html"
+                    }
+                }),
+                "__sgclaw_local_dashboard__",
+            )
+            .expect("approved local dashboard request should be accepted");
+
+        assert!(output.success);
+        let requests = host.requests();
+        assert_eq!(requests.len(), 1);
+        assert_eq!(requests[0].command, json!([
+            "http://127.0.0.1:17888/sgclaw/browser-helper.html",
+            "sgBrowerserOpenPage",
+            "file:///C:/tmp/zhihu-hotlist-screen.html"
+        ]));
+    }
+
+    #[test]
+    fn callback_backend_rejects_local_dashboard_navigate_without_required_marker_fields() {
+        let host = Arc::new(FakeCallbackHost::new(vec![]));
+        let backend = BrowserCallbackBackend::new(
+            host.clone(),
+            test_policy(),
+            "http://127.0.0.1:17888/sgclaw/browser-helper.html",
+        );
+
+        let err = backend
+            .invoke(
+                Action::Navigate,
+                json!({
+                    "url": "file:///C:/tmp/zhihu-hotlist-screen.html",
+                    "sgclaw_local_dashboard_open": {
+                        "source": "compat.workflow_executor",
+                        "kind": "zhihu_hotlist_screen",
+                        "presentation_url": "file:///C:/tmp/zhihu-hotlist-screen.html"
+                    }
+                }),
+                "__sgclaw_local_dashboard__",
+            )
+            .unwrap_err();
+
+        assert!(host.requests().is_empty());
+        assert!(err.to_string().contains("domain is not allowed"));
+    }
+
     #[test]
     fn escape_js_single_quoted_escapes_newlines_and_control_chars() {
         let raw = "第一行\n第二行\r\n第三行";