test: close mirror-fixture gap exposed by post-fix audit

The eeschema-ground-truth fixture (_build_mirror_case) passed
'mirror': 'x' to ComponentManager.add_component, which silently drops
the kwarg — so the resulting .kicad_sch had no (mirror x|y) token,
eeschema rendered an unmirrored symbol, and our pin coords (also
unmirrored) tautologically matched. The mirror tests were GREEN both
before and after the rotation/mirror fix in 7e67cb9, providing zero
regression coverage for the mirror semantics.

Fix:
  - _build_mirror_case now applies the mirror via the same low-level
    helper (WireDragger.update_symbol_rotation_mirror) that
    rotate_schematic_component uses, with a guard assertion that the
    written file actually contains (mirror x|y).
  - Two new pin-down unit tests in test_add_schematic_component.py
    document and lock down ComponentManager.add_component's silent-drop
    behavior for mirror, so the next person to touch that path knows to
    update the eeschema-truth fixture if they grow real mirror support.

Verified: with the production fix at 7e67cb9 reverted, the kicad-cli
mirror tests now go RED (previously they stayed GREEN regardless).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_add_schematic_component.py

@@ -19,9 +19,7 @@ EMPTY_SCH = TEMPLATES_DIR / "empty.kicad_sch"
 
 
 def _write_temp_sch(content: str) -> Path:
-    tmp = tempfile.NamedTemporaryFile(
-        suffix=".kicad_sch", delete=False, mode="w", encoding="utf-8"
-    )
+    tmp = tempfile.NamedTemporaryFile(suffix=".kicad_sch", delete=False, mode="w", encoding="utf-8")
     tmp.write(content)
     tmp.close()
     return Path(tmp.name)
@@ -36,7 +34,10 @@ def _unit_values_in_file(path: Path) -> list[int]:
     """Return all (unit N) values written for symbol instances in the schematic."""
     content = path.read_text()
     # Match top-level symbol instances: (symbol (lib_id ...) (at ...) (unit N) ...)
-    return [int(n) for n in re.findall(r"\(symbol \(lib_id [^)]+\) \(at [^)]+\) \(unit (\d+)\)", content)]
+    return [
+        int(n)
+        for n in re.findall(r"\(symbol \(lib_id [^)]+\) \(at [^)]+\) \(unit (\d+)\)", content)
+    ]
 
 
 # ---------------------------------------------------------------------------
@@ -155,18 +156,20 @@ class TestHandlerAddSchematicComponent:
     def test_unit_defaults_to_1_in_handler(self, tmp_path: Any) -> None:
         sch = tmp_path / "test.kicad_sch"
         shutil.copy(EMPTY_SCH, sch)
-        result = self._call_handler({
-            "schematicPath": str(sch),
-            "component": {
-                "library": "Device",
-                "type": "R",
-                "reference": "R99",
-                "value": "1k",
-                "x": 10,
-                "y": 10,
-                # no "unit" key — should default to 1
-            },
-        })
+        result = self._call_handler(
+            {
+                "schematicPath": str(sch),
+                "component": {
+                    "library": "Device",
+                    "type": "R",
+                    "reference": "R99",
+                    "value": "1k",
+                    "x": 10,
+                    "y": 10,
+                    # no "unit" key — should default to 1
+                },
+            }
+        )
         assert result["success"] is True
         units = _unit_values_in_file(sch)
         assert 1 in units
@@ -174,18 +177,82 @@ class TestHandlerAddSchematicComponent:
     def test_unit_2_passed_through_handler(self, tmp_path: Any) -> None:
         sch = tmp_path / "test.kicad_sch"
         shutil.copy(EMPTY_SCH, sch)
-        result = self._call_handler({
-            "schematicPath": str(sch),
-            "component": {
-                "library": "Device",
-                "type": "R",
-                "reference": "U10",
-                "value": "TLP291-4",
-                "x": 25,
-                "y": 35,
-                "unit": 2,
-            },
-        })
+        result = self._call_handler(
+            {
+                "schematicPath": str(sch),
+                "component": {
+                    "library": "Device",
+                    "type": "R",
+                    "reference": "U10",
+                    "value": "TLP291-4",
+                    "x": 25,
+                    "y": 35,
+                    "unit": 2,
+                },
+            }
+        )
         assert result["success"] is True
         units = _unit_values_in_file(sch)
         assert 2 in units
+
+
+# ---------------------------------------------------------------------------
+# Mirror parameter — known gap
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestAddComponentMirrorParam:
+    """ComponentManager.add_component does NOT honor a 'mirror' kwarg today.
+
+    The MCP add_schematic_component tool schema also doesn't expose mirror.
+    A mirror is currently only applicable post-add via rotate_schematic_component.
+
+    These tests pin down the silent-drop behavior so a fixture that passes
+    'mirror': 'x' and then asserts something against the resulting schematic
+    cannot accidentally pass for the wrong reason (the symbol ends up
+    unmirrored). If/when add_component grows real mirror support, update both
+    tests together — the second test then becomes the positive assertion."""
+
+    def setup_method(self) -> None:
+        from commands.component_schematic import ComponentManager
+        from commands.schematic import SchematicManager
+
+        self.ComponentManager = ComponentManager
+        self.SchematicManager = SchematicManager
+
+    def _add(self, sch_path: Path, mirror_value: Any) -> None:
+        sch = self.SchematicManager.load_schematic(str(sch_path))
+        params = {
+            "type": "R",
+            "reference": "R1",
+            "value": "10k",
+            "x": 100.0,
+            "y": 100.0,
+            "rotation": 0,
+        }
+        if mirror_value is not None:
+            params["mirror"] = mirror_value
+        self.ComponentManager.add_component(sch, params, sch_path)
+        self.SchematicManager.save_schematic(sch, str(sch_path))
+
+    def test_mirror_x_arg_is_silently_dropped(self, tmp_path: Any) -> None:
+        sch = tmp_path / "mirror_x.kicad_sch"
+        shutil.copy(EMPTY_SCH, sch)
+        self._add(sch, "x")
+        text = sch.read_text()
+        assert "(mirror x)" not in text, (
+            "ComponentManager.add_component now appears to honor mirror='x'. "
+            "Update _build_mirror_case in test_pin_world_xy_eeschema_truth.py "
+            "to drop the post-add mirror application and remove this test."
+        )
+
+    def test_mirror_y_arg_is_silently_dropped(self, tmp_path: Any) -> None:
+        sch = tmp_path / "mirror_y.kicad_sch"
+        shutil.copy(EMPTY_SCH, sch)
+        self._add(sch, "y")
+        text = sch.read_text()
+        assert "(mirror y)" not in text, (
+            "ComponentManager.add_component now appears to honor mirror='y'. "
+            "See sibling test_mirror_x_arg_is_silently_dropped."
+        )

tests/test_pin_world_xy_eeschema_truth.py

@@ -106,6 +106,20 @@ def _build_diode_case(tmp: Path, rotation: int) -> tuple[Path, dict]:
     return sch_path, {("D1", "1"): "D1_K", ("D1", "2"): "D1_A"}
 
 
+def _apply_mirror_to_file(sch_path: Path, reference: str, axis: str) -> None:
+    """Apply (mirror x|y) to a placed symbol via direct sexpr mutation.
+
+    ComponentManager.add_component silently drops a 'mirror' kwarg, so this
+    fixture goes around it via the same low-level helper rotate_schematic_component
+    uses (WireDragger.update_symbol_rotation_mirror)."""
+    import sexpdata
+
+    sch_data = sexpdata.loads(sch_path.read_text())
+    if not WireDragger.update_symbol_rotation_mirror(sch_data, reference, 0, axis):
+        raise RuntimeError(f"Failed to apply mirror={axis} to {reference}")
+    sch_path.write_text(sexpdata.dumps(sch_data))
+
+
 def _build_mirror_case(tmp: Path, axis: str) -> tuple[Path, dict]:
     sch_path = tmp / f"resistor_mirror_{axis}.kicad_sch"
     template = PYTHON_DIR / "templates" / "template_with_symbols.kicad_sch"
@@ -114,23 +128,23 @@ def _build_mirror_case(tmp: Path, axis: str) -> tuple[Path, dict]:
     sch = SchematicManager.load_schematic(str(sch_path))
     ComponentManager.add_component(
         sch,
-        {
-            "type": "R",
-            "reference": "R1",
-            "value": "10k",
-            "x": 100.0,
-            "y": 100.0,
-            "rotation": 0,
-            "mirror": axis,
-        },
+        {"type": "R", "reference": "R1", "value": "10k", "x": 100.0, "y": 100.0, "rotation": 0},
         sch_path,
     )
     SchematicManager.save_schematic(sch, str(sch_path))
 
+    _apply_mirror_to_file(sch_path, "R1", axis)
+    if f"(mirror {axis})" not in sch_path.read_text():
+        raise RuntimeError(
+            f"Fixture failed to write (mirror {axis}) — the kicad-cli oracle would "
+            f"silently match our pin coords for an unmirrored symbol."
+        )
+
     locator = PinLocator()
     p1 = locator.get_pin_location(sch_path, "R1", "1")
     p2 = locator.get_pin_location(sch_path, "R1", "2")
-    assert p1 is not None and p2 is not None
+    if p1 is None or p2 is None:
+        raise RuntimeError(f"PinLocator returned None for R1 mirror={axis}")
 
     _add_labels_to_file(sch_path, [("R1_PIN1", p1[0], p1[1]), ("R1_PIN2", p2[0], p2[1])])