Fix browser URL intent routing

Limit the Browser URL-intent handler to web URL schemes so custom Agent Zero schemes fall through to their owning surfaces.

Document the scheme-ownership contract and cover the a0-editor misroute regression in the desktop/editor routing test.

plugins/_browser/AGENTS.md

@@ -20,6 +20,7 @@
 - Keep the WebUI Browser inside its own modal/canvas affordance; do not replace it with page-level navigation.
 - Default the visible WebUI Browser to live CDP screencast for responsiveness. Keep lightweight CDP/DOM state snapshots as the fallback transport.
 - Keep narrow WebUI Browser controls usable by grouping navigation with Annotate/settings above a full-width address bar.
+- Browser URL-intent handling must only claim web URL schemes and leave custom Agent Zero schemes to their owning surfaces.
 - Prefer DOM/CDP browser actions with refs, selectors, frame-chain refs, and screenshots over viewport coordinate input. Coordinates remain a visual fallback.
 - Do not hardcode user-specific browser paths or secrets.
 

plugins/_browser/webui/browser-store.js

@@ -2846,8 +2846,21 @@ const model = {
 
 export const store = createStore("browserPage", model);
 
+const WEB_INTENT_SCHEMES = new Set(["http", "https", "file", "about"]);
+
+function isWebUrlIntent(url = "") {
+  const value = String(url || "").trim();
+  if (!value) return true;
+  const scheme = /^([a-z][a-z0-9+.-]*):/i.exec(value);
+  if (!scheme) return true;
+  return WEB_INTENT_SCHEMES.has(scheme[1].toLowerCase());
+}
+
 registerUrlHandler(async (intent = {}) => {
   const url = String(intent.url || "").trim();
+  // Custom schemes such as a0-editor: belong to other surfaces; claiming them
+  // here would navigate the browser to an unloadable URL.
+  if (!isWebUrlIntent(url)) return false;
   const payload = { url, source: intent.source || "surface-url-intent" };
   await openLatestSurface("browser", payload);
   return await store.openUrlIntent(url, { source: payload.source });

tests/test_office_canvas_setup.py

@@ -592,6 +592,7 @@ def test_desktop_text_open_with_routes_to_editor_surface():
     desktop_session = read("plugins", "_desktop", "helpers", "desktop_session.py")
     desktop_store = read("plugins", "_desktop", "webui", "desktop-store.js")
     editor_store = read("plugins", "_editor", "webui", "editor-store.js")
+    browser_store = read("plugins", "_browser", "webui", "browser-store.js")
 
     assert 'EDITOR_HANDLER_DESKTOP_ID = "agent-zero-editor.desktop"' in desktop_session
     assert "def _write_editor_bridge_script" in desktop_session
@@ -607,6 +608,11 @@ def test_desktop_text_open_with_routes_to_editor_surface():
     assert "handleEditorUrlIntent" in editor_store
     assert 'openLatestSurface("editor"' in editor_store
 
+    # The browser surface must not claim a0-editor: intents, otherwise the
+    # editor "Open With" handler lands on an unloadable about:blank page.
+    assert "function isWebUrlIntent" in browser_store
+    assert "if (!isWebUrlIntent(url)) return false;" in browser_store
+
 
 def test_office_and_desktop_skills_are_rehomed_and_renamed():
     office_skills = PROJECT_ROOT / "plugins" / "_office" / "skills"