feat: extract in-process MCP action layer, concurrent task dispatch, and spawn/reconcile hardening

- Extract device action execution into artemis/mcp action layer:
  typed ActionResult, capability manifest with startup validation,
  AdbActuator as the single physical implementation, in-memory
  ActionSession (replaces stdio subprocess MCP in validator), and
  McpActionExecutor preserving the legacy executor contract.
  adb_server keeps its external stdio/SSE surface unchanged and now
  reuses the actuator implementation; import-time side effects moved
  into configure_stdio_mode().
- Capability-gated prompt assembly (prompt_assembly.py): tool enums and
  teaching segments render per available backend tools; full-set output
  is byte-identical to the previous static text (locked by tests).
- Admin console task queue: serial worker replaced by a per-device
  concurrent dispatcher (ARTEMIS_CONCURRENCY_MODE=global restores
  serial semantics), per-session cancellation, strict device binding on
  enqueue, unified stdio piping with tee to trace stdout.log, and
  shutdown cleanup of all active runs. Fix _pid_exists exception order
  so PermissionError is treated as alive.
- mcp_server reliability: spawn watchdog kills runners stuck before
  interpreter startup and releases device reservations; task state
  reconcile uses psutil liveness, prefers runner-reported pids, and
  adds a 45s startup grace to stop false failure reports on Windows;
  conversation_id is now optional end-to-end; explicit device_serial is
  validated at submission.
- CLI install now writes ~/.claude/rules/artemis.md for Claude Code and
  migrates/removes the legacy CLAUDE.md injection block; ~/.claude.json
  is never rewritten when it fails to parse.
- Tests: Windows-portable stdio lifecycle and path assertions; new
  suites for action layer, prompt assembly, spawn watchdog, and task
  reconcile (895 passed, 3 skipped).

artemis/mcp/actuators/mock.py

@@ -0,0 +1,70 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Mock actuator for tests: real actuator code paths over an in-memory device.
+
+Subclasses :class:`AdbActuator` deliberately, so tests exercise the same coordinate
+conversion and controller dispatch as production -- only the driver is in-memory.
+``capabilities``/``extensions`` are overridable to model partial and extended
+backends.
+"""
+
+from artemis.context import ArtemisContext, DeviceContext, DevicePlatform
+from artemis.drivers.mock.mock_driver import MockDeviceDriver
+from artemis.mcp.action_manifest import DEVICE_ACTIONS, ExtensionTool
+from artemis.mcp.actuators.adb import AdbActuator
+from artemis.platform import platform
+
+__all__ = ["MockActuator"]
+
+
+class MockActuator(AdbActuator):
+    """An :class:`AdbActuator` bound to a :class:`MockDeviceDriver`."""
+
+    def __init__(
+        self,
+        width: int = 1080,
+        height: int = 2400,
+        capabilities: frozenset[str] | None = None,
+        extensions: list[ExtensionTool] | None = None,
+    ):
+        driver = MockDeviceDriver(width=width, height=height)
+        ctx = ArtemisContext(
+            trace_id="mock-actuator",
+            device=DeviceContext(
+                host_platform=platform.os_type.name,
+                mobile_platform=DevicePlatform.ANDROID,
+                device_id=driver.device_id,
+                device_width=width,
+                device_height=height,
+            ),
+        )
+        # get_driver(ctx) returns a cached `_active_driver` when present
+        # (artemis/drivers/factory.py), the established test seam.
+        ctx._active_driver = driver
+        super().__init__(ctx)
+        self.driver = driver
+        self._capabilities = capabilities if capabilities is not None else DEVICE_ACTIONS
+        self._extensions = list(extensions or [])
+
+    def capabilities(self) -> frozenset[str]:
+        return self._capabilities
+
+    def extensions(self) -> list[ExtensionTool]:
+        return self._extensions
+
+    @property
+    def action_history(self) -> list[dict]:
+        """The mock driver's recorded actions, for assertions."""
+        return self.driver.action_history