fix: correct task scheduling and simplify agent internals

Fix queue cancellation, concurrency limits and worker status updates.

Use direct Explorer imports, split the Diagnoser loop into helpers and remove unused tool registration and prompt-builder code.

Correct model caching, endpoint selection and retry handling.

tests/unit/agents/test_explorer_tiers.py

@@ -28,7 +28,9 @@ from artemis.config import settings
 from artemis.context import ArtemisContext
 from artemis.graph.state import State
 
-FACADE = "artemis.agents.explorer.explorer"
+EXPLORER = "artemis.agents.explorer.explorer"
+RUN_SETUP = "artemis.agents.explorer.run_setup"
+UNIVERSAL_RUNNER = "artemis.agents.explorer.universal_runner"
 
 
 def _context(model: str = "gemini-3.8-flash", denylist: list[str] | None = None) -> MagicMock:
@@ -108,7 +110,7 @@ def _isolated_env(monkeypatch):
 
 
 def test_construction_creates_no_genai_client():
-    with patch(f"{FACADE}.genai.Client") as client_cls:
+    with patch(f"{EXPLORER}.genai.Client") as client_cls:
         explorer = Explorer(_context())
     client_cls.assert_not_called()
     assert explorer.client is None
@@ -124,7 +126,7 @@ def test_construction_creates_no_genai_client():
 )
 def test_tier_sets_turn_budget_and_exposed_tools(version, max_turns, expected_tools):
     explorer = Explorer(_context())
-    with patch(f"{FACADE}.is_ocr_configured", return_value=True):
+    with patch(f"{EXPLORER}.is_ocr_configured", return_value=True):
         explorer._apply_tier(get_tier(version))
         native_names = {t.name for t in explorer.get_exposed_tools()}
         universal_names = {t["function"]["name"] for t in explorer._universal_exposed_tools()}
@@ -137,7 +139,7 @@ def test_tier_sets_turn_budget_and_exposed_tools(version, max_turns, expected_to
 
 def test_unconfigured_ocr_and_user_denylist_hide_tools_on_ultra():
     explorer = Explorer(_context(denylist=["inspect_region"]))
-    with patch(f"{FACADE}.is_ocr_configured", return_value=False):
+    with patch(f"{EXPLORER}.is_ocr_configured", return_value=False):
         explorer._apply_tier(get_tier("ultra"))
     names = {t.name for t in explorer.get_exposed_tools()}
     assert "get_ocr_list" not in names
@@ -190,9 +192,9 @@ async def test_universal_run_without_google_key_never_touches_genai(screenshot):
 
     with (
         patch.object(settings, "GOOGLE_API_KEY", None),
-        patch(f"{FACADE}.genai.Client") as client_cls,
-        patch(f"{FACADE}.get_llm", return_value=llm),
-        patch(f"{FACADE}.StorageManager", return_value=storage),
+        patch(f"{EXPLORER}.genai.Client") as client_cls,
+        patch(f"{UNIVERSAL_RUNNER}.get_llm", return_value=llm),
+        patch(f"{RUN_SETUP}.StorageManager", return_value=storage),
     ):
         explorer = Explorer(ctx)
         raw = await explorer.run("find it", "", screenshot, _state(screenshot), version="pro")
@@ -342,7 +344,7 @@ def test_pro_prompt_only_describes_exposed_tools():
 
 def test_ultra_prompt_describes_all_tools():
     explorer = Explorer(_context())
-    with patch(f"{FACADE}.is_ocr_configured", return_value=True):
+    with patch(f"{EXPLORER}.is_ocr_configured", return_value=True):
         explorer._apply_tier(get_tier("ultra"))
         prompt, error = explorer._build_prompt_template(get_tier("ultra"))
     assert error is None
@@ -355,7 +357,7 @@ def test_ultra_prompt_describes_all_tools():
 
 def test_prompt_denylist_section_only_for_user_denied_tier_tools():
     explorer = Explorer(_context(denylist=["inspect_region", "search_xml_ocr"]))
-    with patch(f"{FACADE}.is_ocr_configured", return_value=True):
+    with patch(f"{EXPLORER}.is_ocr_configured", return_value=True):
         explorer._apply_tier(get_tier("ultra"))
         ultra_prompt, _ = explorer._build_prompt_template(get_tier("ultra"))
         explorer._apply_tier(get_tier("pro"))
@@ -399,8 +401,8 @@ async def test_flash_run_returns_detected_candidates(screenshot):
         }
     )
     with (
-        patch(f"{FACADE}._run_object_detection", detection),
-        patch(f"{FACADE}.genai.Client") as client_cls,
+        patch(f"{RUN_SETUP}._run_object_detection", detection),
+        patch(f"{EXPLORER}.genai.Client") as client_cls,
     ):
         explorer = Explorer(_context())
         raw = await explorer.run(
@@ -421,7 +423,7 @@ async def test_flash_run_returns_detected_candidates(screenshot):
 
 @pytest.mark.asyncio
 async def test_flash_run_reports_missing_detection(screenshot):
-    with patch(f"{FACADE}._run_object_detection", AsyncMock(return_value={"detected": []})):
+    with patch(f"{RUN_SETUP}._run_object_detection", AsyncMock(return_value={"detected": []})):
         raw = await Explorer(_context()).run(
             "ghost", "", screenshot, _state(screenshot), version="flash"
         )
@@ -442,8 +444,8 @@ async def test_native_ultra_run_uses_async_cache_api(screenshot):
     storage.get_image.return_value = None
 
     with (
-        patch(f"{FACADE}.genai.Client") as client_cls,
-        patch(f"{FACADE}.StorageManager", return_value=storage),
+        patch(f"{EXPLORER}.genai.Client") as client_cls,
+        patch(f"{RUN_SETUP}.StorageManager", return_value=storage),
         patch.object(settings, "EXPLORER_CACHING", None),
     ):
         explorer = Explorer(ctx)
@@ -466,7 +468,7 @@ async def test_native_pro_run_skips_cache_by_default(screenshot):
     storage.get_image.return_value = None
 
     with (
-        patch(f"{FACADE}.StorageManager", return_value=storage),
+        patch(f"{RUN_SETUP}.StorageManager", return_value=storage),
         patch.object(settings, "EXPLORER_CACHING", None),
     ):
         await Explorer(ctx).run("target", "", screenshot, _state(screenshot), version="pro")
@@ -489,7 +491,7 @@ async def test_native_file_api_uploads_and_deletes_asynchronously(screenshot, mo
     storage = MagicMock()
     storage.get_image.return_value = None
 
-    with patch(f"{FACADE}.StorageManager", return_value=storage):
+    with patch(f"{RUN_SETUP}.StorageManager", return_value=storage):
         await Explorer(ctx).run("target", "", screenshot, _state(screenshot), version="pro")
 
     client.aio.files.upload.assert_awaited_once_with(file=screenshot)
@@ -507,7 +509,7 @@ async def test_run_closes_http_client_on_both_engines(screenshot):
     ctx._genai_client = client
     native = Explorer(ctx)
     native.http_client = SimpleNamespace(aclose=AsyncMock())
-    with patch(f"{FACADE}.StorageManager", return_value=storage):
+    with patch(f"{RUN_SETUP}.StorageManager", return_value=storage):
         await native.run("t", "", screenshot, _state(screenshot), version="pro")
     native_close = native.http_client  # already reset
     assert native_close is None
@@ -519,8 +521,8 @@ async def test_run_closes_http_client_on_both_engines(screenshot):
     http_client = SimpleNamespace(aclose=AsyncMock())
     universal.http_client = http_client
     with (
-        patch(f"{FACADE}.StorageManager", return_value=storage),
-        patch(f"{FACADE}.get_llm", return_value=llm),
+        patch(f"{RUN_SETUP}.StorageManager", return_value=storage),
+        patch(f"{UNIVERSAL_RUNNER}.get_llm", return_value=llm),
         pytest.raises(RuntimeError),
     ):
         await universal.run("t", "", screenshot, _state(screenshot), version="pro")