test(resource): add coverage for remove_resource exception rollback path

Add Behave scenario to cover the except Exception rollback path in
ResourceInstanceMixin.remove_resource() in _resource_registry_ops.py.
This uncovered branch was causing the CI coverage gate to fail below
the 97% threshold.

ISSUES CLOSED: #6329

features/resource_registry_service_coverage_boost.feature

@@ -29,6 +29,14 @@ Feature: Resource registry service coverage boost
     Then the unlink_child session should have been rolled back
     And the generic exception from unlink_child should propagate
 
+  # ── remove_resource generic exception rollback ───────────────────
+
+  Scenario: remove_resource rolls back on unexpected generic exception
+    Given a resource registry service prepared for remove_resource with a faulty session
+    When I attempt remove_resource and a generic exception occurs
+    Then the remove_resource session should have been rolled back
+    And the generic exception from remove_resource should propagate
+
   # ── _build_tree_node type_filter filtering ───────────────────────
 
   Scenario: get_resource_tree with type_filter excludes non-matching children

features/steps/resource_registry_service_coverage_boost_steps.py

@@ -5,6 +5,9 @@ Covers the remaining uncovered lines in resource_registry_service.py:
 - Lines 646-648: link_child generic exception rollback
 - Lines 686-688: unlink_child generic exception rollback
 - Line 785: _build_tree_node type_filter skips non-matching children
+
+Also covers _resource_registry_ops.py:
+- remove_resource generic exception rollback path
 """
 
 from __future__ import annotations
@@ -51,6 +54,9 @@ _TREE_PARENT = "01JK00000000000000000000KK"
 _TREE_CHILD1 = "01JM00000000000000000000MM"
 _TREE_CHILD2 = "01JN00000000000000000000NN"
 
+# Scenario 5: remove_resource generic error
+_REMOVE_RES_5 = "01JP00000000000000000000PP"
+
 # ---------------------------------------------------------------------------
 # Helpers
 # ---------------------------------------------------------------------------
@@ -400,6 +406,66 @@ def step_verify_unlink_child_error_propagates(context: Any) -> None:
     assert "disk I/O error in unlink_child" in str(context.boost_unlink_generic_error)
 
 
+# ---------------------------------------------------------------------------
+# Scenario: remove_resource rolls back on unexpected generic exception
+# (targets _resource_registry_ops.py except Exception path)
+# ---------------------------------------------------------------------------
+
+
+@given("a resource registry service prepared for remove_resource with a faulty session")
+def step_setup_faulty_remove_resource(context: Any) -> None:
+    """Set up a service whose session blows up during remove_resource DB ops."""
+    resource = Resource(
+        resource_id=_REMOVE_RES_5,
+        name="test/remove-me",
+        resource_type_name="git-checkout",
+        classification=PhysVirt.PHYSICAL,
+        description=None,
+        properties={},
+        location="/tmp/rm",
+        content_hash=None,
+        sandbox_strategy=None,
+    )
+
+    # Mock session: count() returns 0 (no links/edges), but delete() on the
+    # resource row blows up with a generic exception.
+    mock_session = MagicMock()
+    mock_session.query.return_value.filter.return_value.count.return_value = 0
+    mock_session.query.return_value.filter_by.return_value.first.return_value = (
+        MagicMock()  # non-None row so delete() is called
+    )
+    mock_session.delete.side_effect = OSError("disk I/O error in remove_resource")
+
+    context.boost_remove_mock_session = mock_session
+
+    svc = ResourceRegistryService.__new__(ResourceRegistryService)
+    svc._session_factory = lambda: mock_session
+    svc.show_resource = lambda name_or_id: resource  # type: ignore[assignment]
+    context.boost_remove_svc = svc
+
+
+@when("I attempt remove_resource and a generic exception occurs")
+def step_attempt_remove_resource_generic_error(context: Any) -> None:
+    context.boost_remove_generic_error = None
+    try:
+        context.boost_remove_svc.remove_resource("test/remove-me")
+    except OSError as exc:
+        context.boost_remove_generic_error = exc
+
+
+@then("the remove_resource session should have been rolled back")
+def step_verify_remove_resource_rollback(context: Any) -> None:
+    context.boost_remove_mock_session.rollback.assert_called()
+
+
+@then("the generic exception from remove_resource should propagate")
+def step_verify_remove_resource_error_propagates(context: Any) -> None:
+    assert context.boost_remove_generic_error is not None
+    assert "disk I/O error in remove_resource" in str(
+        context.boost_remove_generic_error
+    )
+
+
 # ---------------------------------------------------------------------------
 # Scenario: get_resource_tree with type_filter excludes non-matching children
 # (targets line 785)