fix: bound task failures and release stalled workers

artemis/agents/validator/tool_declarations.py

@@ -136,9 +136,14 @@ async def capture_screenshot_and_parse_ui(
     Thin adapter over :func:`artemis.mcp.observation.observe` that adds the LangGraph
     ``State`` write-back (indexed points/elements) the agents rely on.
     """
-    obs, screenshot_bytes = await observe(ctx, controller, settle_ms=0 if skip_settling else 400)
-    if not obs.ok:
-        return None, None, None
+    from artemis.mcp.observation import require_observation
+
+    state.indexed_points = []
+    state.indexed_elements = []
+    state.latest_screenshot = None
+    obs, screenshot_bytes = await require_observation(
+        ctx, controller, settle_ms=0 if skip_settling else 400
+    )
 
     if obs.hierarchy_ok:
         state.indexed_points = [el["center"] for el in obs.elements]