fix(k1): allow explicit reset after terminal start fault

src/k1link/device_plugins/xgrids_k1/facade.py

@@ -8477,6 +8477,7 @@ class XgridsK1CompatibilityService:
                         acquisition_id=(
                             acquisition.acquisition_id if acquisition is not None else None
                         ),
+                        allow_terminal_failure_retirement=True,
                     )
                 )
                 self._supersede_control_bootstrap_continuation()
@@ -27415,6 +27416,7 @@ class XgridsK1CompatibilityService:
         self,
         *,
         acquisition_id: str | None,
+        allow_terminal_failure_retirement: bool = False,
     ) -> tuple[_LocalStopRetirementDisposition, str | None]:
         """Cancel the local worker under the exact publish fence.
 
@@ -27450,6 +27452,24 @@ class XgridsK1CompatibilityService:
             )
             self._application_control_session.close()
             retired_control = dict(self._application_control_session.snapshot())
+            if (
+                allow_terminal_failure_retirement
+                and retired_control.get("state") == "failed"
+            ):
+                # ``can_open`` deliberately remains false after an ambiguous
+                # START/STOP failure even when the socket worker has already
+                # exited. That is the correct admission policy for an
+                # ordinary retry, but an explicit scenario reset is a
+                # different operation: retire only the dead local owner while
+                # the durable physical ledger below preserves the ambiguous
+                # device outcome. ``retire_for_network_change`` still checks
+                # that the thread and transport are actually gone, so a live
+                # publisher cannot be detached by this path.
+                with suppress(AttributeError, RuntimeError):
+                    self._retire_application_control_for_network_change(
+                        allow_terminal_failure=True,
+                    )
+                retired_control = dict(self._application_control_session.snapshot())
             if (
                 retired_control.get("state")
                 not in {"idle", "completed", "closed", "failed"}

tests/test_xgrids_connection_scenario_reset.py

@@ -1722,6 +1722,72 @@ def test_terminal_cleanup_pending_is_locally_sealed_by_mode_reset(
     assert reset["connection_scenario_reset"]["network_write_performed"] is False
 
 
+def test_terminal_ambiguous_start_failure_can_be_locally_reset_after_worker_exit(
+    monkeypatch: pytest.MonkeyPatch,
+    tmp_path: Path,
+) -> None:
+    service = _service(monkeypatch, tmp_path)
+    _seed_resettable_physical_record(service)
+    acquisition = AcquisitionRecord(
+        acquisition_id="reset-preflight-acquisition-0001",
+        device_id="device-reset-terminal-start-fault",
+        device_session_id="device-session-reset-terminal-start-fault",
+        compatibility_profile_id=("xgrids.lixelkity-k1.fw-3.0.2.local-network.v2"),
+        control_mode="plugin-commanded",
+        requested_streams=("points",),
+        target_host="192.168.68.51",
+        duration_seconds=None,
+        evidence_policy="required",
+    )
+    acquisition.transition(
+        "failed",
+        message_code="acquisition.start.device_outcome_unknown",
+        result={
+            "receiver_stopped": False,
+            "device_start": "outcome-unknown",
+        },
+    )
+    control = service._application_control_session  # noqa: SLF001
+    with control._lock:  # noqa: SLF001
+        control._set_phase_locked("failed")  # noqa: SLF001
+        control._failure = {  # noqa: SLF001
+            "reason_code": "device_status_fault",
+            "safe_to_retry": False,
+            "modeling_command_attempted": True,
+            "outcome_unknown": True,
+        }
+        control._thread = None  # noqa: SLF001
+        control._transport = None  # noqa: SLF001
+    with service._lock:  # noqa: SLF001
+        service._acquisition = acquisition  # noqa: SLF001
+
+    before = control.snapshot()
+    assert before["state"] == "failed"
+    assert before["can_open"] is False
+
+    reset = service.select_connection_mode(
+        _reset(
+            mode="bridge",
+            revision=0,
+            reset_id="op-reset-terminal-ambiguous-start-01",
+        )
+    )
+
+    assert reset["desired_connection_mode_revision"] == 1
+    assert reset["connection_scenario_reset"]["local_session_closed"] is True
+    assert reset["connection_scenario_reset"]["physical_disposition"] == (
+        "operator-retired-outcome-unknown"
+    )
+    assert reset["connection_scenario_reset"]["device_command_performed"] is False
+    assert reset["connection_scenario_reset"]["network_write_performed"] is False
+    assert reset["application_control_session"]["state"] == "idle"
+    assert reset["acquisition"]["state"] == "failed"
+    assert reset["acquisition"]["cleanup_pending"] is False
+    physical = service._physical_command_ledger.snapshot().record  # noqa: SLF001
+    assert physical is not None
+    assert physical.resolution == "operator-retired-outcome-unknown"
+
+
 def test_terminal_cleanup_failure_stays_visible_and_exact_reset_can_retry(
     monkeypatch: pytest.MonkeyPatch,
     tmp_path: Path,