fix(computer_use): preserve app context for capture_after; fix element label parsing (#24170 bugs 2 & 5)

Bug 2 (capture_after=True loses app context):
_maybe_follow_capture called backend.capture(mode='som') with no app=,
causing cua-driver to capture the frontmost window instead of the app
targeted by the preceding capture/focus_app. Fix: track _last_app on
CuaDriverBackend and thread it through the follow-up capture call so
the same app is re-captured regardless of which window has OS focus.

Bug 5 (element labels stripped in capture results):
_ELEMENT_LINE_RE matched the classic '  - [N] AXRole "label"' format
but not the '[N] AXRole (order) id=Label' format introduced in
cua-driver v0.1.6. All element labels were silently dropped as empty
strings, making element identification impossible.

Fix: extend regex to capture both group(3) (quoted label) and group(4)
(id= label), and update _parse_elements_from_tree to use group(4) as
fallback. Both old and new cua-driver output now produce populated
UIElement.label values.

focus_app() now also sets _last_app so that capture_after= on any
subsequent action re-targets the focused app.

5 new regression tests added.

Part of #24170 (bugs 1 and 3/4 addressed separately).

tests/tools/test_computer_use.py

@@ -729,3 +729,199 @@ class TestUniversality:
         source = inspect.getsource(entry.check_fn)
         assert "anthropic" not in source.lower()
         assert "openai" not in source.lower()
+
+
+# ---------------------------------------------------------------------------
+# Regression tests for bugs 2 & 5 from issue #24170 (cua-driver v0.1.6)
+# ---------------------------------------------------------------------------
+
+class TestElementLabelParsing:
+    """Bug 5: element labels stripped in capture results (cua-driver v0.1.6 format).
+
+    cua-driver ≥0.1.6 emits ``[N] AXRole (order) id=Label`` instead of
+    ``  - [N] AXRole "label"``.  _parse_elements_from_tree must handle both.
+    """
+
+    def test_classic_quoted_label_format(self):
+        from tools.computer_use.cua_backend import _parse_elements_from_tree
+        tree = (
+            '  - [14] AXButton "One"\n'
+            '  - [15] AXButton "Two"\n'
+            '  - [16] AXTextField ""\n'
+        )
+        els = _parse_elements_from_tree(tree)
+        assert len(els) == 3
+        assert els[0].index == 14
+        assert els[0].role == "AXButton"
+        assert els[0].label == "One"
+        assert els[1].label == "Two"
+        assert els[2].label == ""  # empty quoted label
+
+    def test_new_id_eq_format(self):
+        """cua-driver v0.1.6 format: [N] AXRole (order) id=Label"""
+        from tools.computer_use.cua_backend import _parse_elements_from_tree
+        tree = (
+            "[14] AXButton (1) id=One\n"
+            "[15] AXButton (2) id=Two\n"
+            "[16] AXTextField (3) id=\n"
+        )
+        els = _parse_elements_from_tree(tree)
+        assert len(els) == 3
+        assert els[0].index == 14
+        assert els[0].role == "AXButton"
+        assert els[0].label == "One"
+        assert els[1].label == "Two"
+        assert els[2].label == ""  # empty id= value
+
+    def test_mixed_formats_in_single_tree(self):
+        """Gracefully handles trees that mix old and new line formats."""
+        from tools.computer_use.cua_backend import _parse_elements_from_tree
+        tree = (
+            '  - [1] AXWindow "Main Window"\n'
+            "[14] AXButton (1) id=One\n"
+            '  - [15] AXTextField "Search"\n'
+        )
+        els = _parse_elements_from_tree(tree)
+        assert len(els) == 3
+        labels = {e.index: e.label for e in els}
+        assert labels[1] == "Main Window"
+        assert labels[14] == "One"
+        assert labels[15] == "Search"
+
+
+class TestCaptureAfterAppContext:
+    """Bug 2: capture_after=True loses app context after actions.
+
+    _maybe_follow_capture must re-target the same app that was set by
+    the preceding capture/focus_app call, rather than the frontmost window.
+    """
+
+    def test_capture_after_uses_last_app(self):
+        """capture_after=True should pass _last_app to the follow-up capture."""
+        from tools.computer_use.backend import ActionResult, CaptureResult
+        from tools.computer_use import tool as cu_tool
+
+        captured_app_args = []
+
+        class TrackingBackend:
+            _last_app = "Calculator"  # simulates a previous focus_app call
+
+            def start(self):
+                pass
+
+            def stop(self):
+                pass
+
+            def is_available(self):
+                return True
+
+            def capture(self, mode="som", app=None):
+                captured_app_args.append(app)
+                return CaptureResult(
+                    mode=mode, width=100, height=100,
+                    png_b64=None, elements=[],
+                    app=app or "Calculator", window_title="",
+                )
+
+            def click(self, **kw):
+                return ActionResult(ok=True, action="click")
+
+            def drag(self, **kw):
+                return ActionResult(ok=True, action="drag")
+
+            def scroll(self, **kw):
+                return ActionResult(ok=True, action="scroll")
+
+            def type_text(self, text):
+                return ActionResult(ok=True, action="type")
+
+            def key(self, keys):
+                return ActionResult(ok=True, action="key")
+
+            def list_apps(self):
+                return []
+
+            def focus_app(self, app, raise_window=False):
+                return ActionResult(ok=True, action="focus_app")
+
+            def set_value(self, value, element=None):
+                return ActionResult(ok=True, action="set_value")
+
+            def wait(self, seconds=1.0):
+                return ActionResult(ok=True, action="wait")
+
+        backend = TrackingBackend()
+        cu_tool.reset_backend_for_tests()
+        cu_tool._backend = backend
+
+        cu_tool.handle_computer_use({"action": "click", "element": 14, "capture_after": True})
+
+        # The follow-up capture must have been called with app="Calculator"
+        assert len(captured_app_args) == 1
+        assert captured_app_args[0] == "Calculator", (
+            f"Expected follow-up capture with app='Calculator', got {captured_app_args[0]!r}"
+        )
+
+    def test_capture_after_without_prior_app_uses_none(self):
+        """When no app context is set, follow-up capture uses app=None (frontmost)."""
+        from tools.computer_use.backend import ActionResult, CaptureResult
+        from tools.computer_use import tool as cu_tool
+
+        captured_app_args = []
+
+        class NoContextBackend:
+            _last_app = None  # no prior context
+
+            def start(self):
+                pass
+
+            def stop(self):
+                pass
+
+            def is_available(self):
+                return True
+
+            def capture(self, mode="som", app=None):
+                captured_app_args.append(app)
+                return CaptureResult(
+                    mode=mode, width=100, height=100,
+                    png_b64=None, elements=[],
+                    app="Finder", window_title="",
+                )
+
+            def click(self, **kw):
+                return ActionResult(ok=True, action="click")
+
+            def drag(self, **kw):
+                return ActionResult(ok=True, action="drag")
+
+            def scroll(self, **kw):
+                return ActionResult(ok=True, action="scroll")
+
+            def type_text(self, text):
+                return ActionResult(ok=True, action="type")
+
+            def key(self, keys):
+                return ActionResult(ok=True, action="key")
+
+            def list_apps(self):
+                return []
+
+            def focus_app(self, app, raise_window=False):
+                return ActionResult(ok=True, action="focus_app")
+
+            def set_value(self, value, element=None):
+                return ActionResult(ok=True, action="set_value")
+
+            def wait(self, seconds=1.0):
+                return ActionResult(ok=True, action="wait")
+
+        backend = NoContextBackend()
+        cu_tool.reset_backend_for_tests()
+        cu_tool._backend = backend
+
+        cu_tool.handle_computer_use({"action": "click", "element": 5, "capture_after": True})
+
+        # No app context — should pass None so cua-driver picks the frontmost window
+        assert len(captured_app_args) == 1
+        assert captured_app_args[0] is None

tools/computer_use/cua_backend.py

@@ -57,10 +57,18 @@ _WINDOW_LINE_RE = re.compile(
     re.MULTILINE,
 )
 
-# Regex to parse element lines from get_window_state AX tree markdown:
-#   "  - [N] AXRole "label""
+# Regex to parse element lines from get_window_state AX tree markdown.
+#
+# Handles two output formats from different cua-driver versions:
+#   Classic:  "  - [N] AXRole \"label\""
+#   New:       "[N] AXRole (order) id=Label"
+#
+# Group 1: element index
+# Group 2: AX role
+# Group 3: quoted label (classic format)
+# Group 4: id= label (new format)
 _ELEMENT_LINE_RE = re.compile(
-    r'^\s*-\s+\[(\d+)\]\s+(\w+)(?:\s+"([^"]*)")?',
+    r'^\s*(?:-\s+)?\[(\d+)\]\s+(\w+)(?:\s+"([^"]*)"|(?:\s+\(\d+\))?\s+id=([^\s\[\]]*))?' ,
     re.MULTILINE,
 )
 
@@ -107,13 +115,19 @@ def _parse_windows_from_text(text: str) -> List[Dict[str, Any]]:
 
 
 def _parse_elements_from_tree(markdown: str) -> List[UIElement]:
-    """Parse UIElement list from get_window_state AX tree markdown."""
+    """Parse UIElement list from get_window_state AX tree markdown.
+
+    Handles both the classic ``"label"``-quoted format and the newer
+    ``id=Label`` format introduced in cua-driver v0.1.6.
+    """
     elements = []
     for m in _ELEMENT_LINE_RE.finditer(markdown):
+        # group(3) = quoted label (classic); group(4) = id= label (new)
+        label = m.group(3) or m.group(4) or ""
         elements.append(UIElement(
             index=int(m.group(1)),
             role=m.group(2),
-            label=m.group(3) or "",
+            label=label,
             bounds=(0, 0, 0, 0),
         ))
     return elements
@@ -325,6 +339,7 @@ class CuaDriverBackend(ComputerUseBackend):
         # Sticky context — updated by capture(), used by action tools.
         self._active_pid: Optional[int] = None
         self._active_window_id: Optional[int] = None
+        self._last_app: Optional[str] = None  # last app name targeted via capture/focus_app
 
     # ── Lifecycle ──────────────────────────────────────────────────
     def start(self) -> None:
@@ -389,6 +404,10 @@ class CuaDriverBackend(ComputerUseBackend):
         self._active_pid = target["pid"]
         self._active_window_id = target["window_id"]
         app_name = target["app_name"]
+        # Record the resolved app name so capture_after= follow-ups can re-target
+        # the same app rather than falling back to the frontmost window.
+        if app or not self._last_app:
+            self._last_app = app_name
 
         # Step 2: capture.
         png_b64: Optional[str] = None
@@ -643,6 +662,7 @@ class CuaDriverBackend(ComputerUseBackend):
         if target:
             self._active_pid = target["pid"]
             self._active_window_id = target["window_id"]
+            self._last_app = target["app_name"]  # preserve for capture_after= follow-ups
             return ActionResult(
                 ok=True, action="focus_app",
                 message=f"Targeted {target['app_name']} (pid {self._active_pid}, "

tools/computer_use/tool.py

@@ -463,7 +463,11 @@ def _maybe_follow_capture(
     if not do_capture:
         return _text_response(res)
     try:
-        cap = backend.capture(mode="som")
+        # Preserve the app context established by the preceding capture/focus_app so
+        # that capture_after=True re-captures the same app rather than the frontmost
+        # window (which may have changed if the action caused a focus shift).
+        last_app = getattr(backend, "_last_app", None)
+        cap = backend.capture(mode="som", app=last_app)
     except Exception as e:
         logger.warning("follow-up capture failed: %s", e)
         return _text_response(res)