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/tools/test_command_tool.py

@@ -373,9 +373,9 @@ async def test_analyze_task_output_tool(mock_get_llm, mock_ctx):
         del _FINISHED_TASKS_LOGS[task_id]
 
 
-def test_run_adb_command_tool_subclass_and_registry():
-    """Verify RunAdbCommandTool is a subclass of ArtemisTool and properly registered."""
-    from artemis.tools.base import ArtemisTool, ToolRegistry
+def test_run_adb_command_tool_subclass():
+    """Verify RunAdbCommandTool is a subclass of ArtemisTool."""
+    from artemis.tools.base import ArtemisTool
     from artemis.tools.command_tool import (
         RunAdbCommand,
         RunAdbCommandArgs,
@@ -392,11 +392,6 @@ def test_run_adb_command_tool_subclass_and_registry():
     assert run_adb_command.category == "system"
     assert run_adb_command.args_schema == RunAdbCommandArgs
 
-    # Registry lookup
-    reg_tool = ToolRegistry.get("run_adb_command")
-    assert reg_tool is not None
-    assert isinstance(reg_tool, RunAdbCommandTool)
-
     # GenAI FunctionDeclaration export
     declaration = run_adb_command.to_genai_declaration()
     assert declaration.name == "run_adb_command"
@@ -421,9 +416,9 @@ async def test_run_adb_command_tool_mock_driver_execute():
     assert "pm list packages" in driver.action_history[-1]["command"]
 
 
-def test_manage_task_tool_subclass_and_registry():
-    """Verify ManageTaskTool is a subclass of ArtemisTool and properly registered."""
-    from artemis.tools.base import ArtemisTool, ToolRegistry
+def test_manage_task_tool_subclass():
+    """Verify ManageTaskTool is a subclass of ArtemisTool."""
+    from artemis.tools.base import ArtemisTool
     from artemis.tools.command_tool import (
         ManageTask,
         ManageTaskArgs,
@@ -440,11 +435,6 @@ def test_manage_task_tool_subclass_and_registry():
     assert manage_task.category == "system"
     assert manage_task.args_schema == ManageTaskArgs
 
-    # Registry lookup
-    reg_tool = ToolRegistry.get("manage_task")
-    assert reg_tool is not None
-    assert isinstance(reg_tool, ManageTaskTool)
-
     # GenAI FunctionDeclaration export
     declaration = manage_task.to_genai_declaration()
     assert declaration.name == "manage_task"
@@ -488,9 +478,9 @@ async def test_manage_task_tool_direct_execute(mock_ctx):
     registry.background.clear()
 
 
-def test_analyze_task_output_tool_subclass_and_registry():
-    """Verify AnalyzeTaskOutputTool is a subclass of ArtemisTool and properly registered."""
-    from artemis.tools.base import ArtemisTool, ToolRegistry
+def test_analyze_task_output_tool_subclass():
+    """Verify AnalyzeTaskOutputTool is a subclass of ArtemisTool."""
+    from artemis.tools.base import ArtemisTool
     from artemis.tools.command_tool import (
         AnalyzeTaskOutput,
         AnalyzeTaskOutputArgs,
@@ -507,11 +497,6 @@ def test_analyze_task_output_tool_subclass_and_registry():
     assert analyze_task_output.category == "system"
     assert analyze_task_output.args_schema == AnalyzeTaskOutputArgs
 
-    # Registry lookup
-    reg_tool = ToolRegistry.get("analyze_task_output")
-    assert reg_tool is not None
-    assert isinstance(reg_tool, AnalyzeTaskOutputTool)
-
     # GenAI FunctionDeclaration export
     declaration = analyze_task_output.to_genai_declaration()
     assert declaration.name == "analyze_task_output"
@@ -558,9 +543,9 @@ async def test_analyze_task_output_tool_direct_execute(mock_get_llm, mock_ctx):
         del _FINISHED_TASKS_LOGS[task_id]
 
 
-def test_run_short_adb_command_tool_subclass_and_registry():
-    """Verify RunShortAdbCommandTool is a subclass of ArtemisTool and properly registered."""
-    from artemis.tools.base import ArtemisTool, ToolRegistry
+def test_run_short_adb_command_tool_subclass():
+    """Verify RunShortAdbCommandTool is a subclass of ArtemisTool."""
+    from artemis.tools.base import ArtemisTool
     from artemis.tools.command_tool import (
         RunShortAdbCommand,
         RunShortAdbCommandArgs,
@@ -577,11 +562,6 @@ def test_run_short_adb_command_tool_subclass_and_registry():
     assert run_short_adb_command.category == "system"
     assert run_short_adb_command.args_schema == RunShortAdbCommandArgs
 
-    # Registry lookup
-    reg_tool = ToolRegistry.get("run_short_adb_command")
-    assert reg_tool is not None
-    assert isinstance(reg_tool, RunShortAdbCommandTool)
-
     # GenAI FunctionDeclaration export
     declaration = run_short_adb_command.to_genai_declaration()
     assert declaration.name == "run_short_adb_command"