fix: rotate_schematic_component mirror parameter no longer crashes

Previously passing mirror='x' or mirror='y' to rotate_schematic_component
always raised:
  'NoneType' object has no attribute 'value'

Root cause: kicad-skip has no API for setting (mirror x/y) on a placed
symbol instance. The handler tried to use a non-existent kicad-skip
attribute, returning None, then calling .value on it.

Fix: add _apply_mirror_to_symbol_sexp() which directly patches the
(mirror x/y) S-expression token in the .kicad_sch file. The rotate
handler now applies rotation via kicad-skip (which works fine) and
delegates mirror to this helper.

The helper:
- Inserts (mirror x/y) immediately after the (at x y rot) token
- Removes any existing mirror token before inserting the new one
  (prevents duplicate tokens when toggling axis)
- Returns False gracefully when the reference is not found

Tests: 6 unit tests in tests/test_rotate_schematic_mirror.py
covering: add x, add y, remove, replace, unknown ref, no-mirror smoke test.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_rotate_schematic_mirror.py

@@ -0,0 +1,171 @@
+"""
+Unit tests for rotate_schematic_component mirror fix.
+
+Verifies that _apply_mirror_to_symbol_sexp correctly adds, removes
+and toggles (mirror x/y) in .kicad_sch S-expression files.
+"""
+
+import os
+import sys
+import importlib.util
+import tempfile
+import textwrap
+from unittest.mock import patch, MagicMock
+
+# Stub KiCad-only and server-only modules so kicad_interface can be
+# imported in a plain Python environment.
+_pcbnew_mock = MagicMock()
+_pcbnew_mock.__file__ = "/fake/pcbnew.so"       # prevents AttributeError at module level
+_pcbnew_mock.GetBuildVersion.return_value = "9.0.0"
+sys.modules.setdefault("pcbnew", _pcbnew_mock)
+
+for _modname in ("skip", "resources", "schemas",
+                 "resources.resource_definitions", "schemas.tool_schemas"):
+    sys.modules.setdefault(_modname, MagicMock())
+
+sys.modules["resources.resource_definitions"].RESOURCE_DEFINITIONS = {}
+sys.modules["resources.resource_definitions"].handle_resource_read = MagicMock()
+sys.modules["schemas.tool_schemas"].TOOL_SCHEMAS = []
+
+# Import KiCADInterface directly, bypassing package __init__ chains
+_spec = importlib.util.spec_from_file_location(
+    "kicad_interface",
+    os.path.join(os.path.dirname(__file__), "..", "python", "kicad_interface.py"),
+)
+_mod = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(_mod)
+KiCADInterface = _mod.KiCADInterface
+SchematicManager = _mod.SchematicManager
+
+# ---------------------------------------------------------------------------
+# Minimal .kicad_sch snippets
+# ---------------------------------------------------------------------------
+
+SCHEMATIC_TEMPLATE = textwrap.dedent("""\
+    (kicad_sch (version 20250114) (generator "test")
+      (symbol (lib_id "Transistor_BJT:MMBT3904")
+              (at 75 105 0)
+              (unit 1)
+              (property "Reference" "Q1" (at 0 0 0))
+              (property "Value" "MMBT3904" (at 0 0 0))
+      )
+    )
+""")
+
+SCHEMATIC_TEMPLATE_MIRRORED_X = textwrap.dedent("""\
+    (kicad_sch (version 20250114) (generator "test")
+      (symbol (lib_id "Transistor_BJT:MMBT3904")
+              (at 75 105 0) (mirror x)
+              (unit 1)
+              (property "Reference" "Q1" (at 0 0 0))
+              (property "Value" "MMBT3904" (at 0 0 0))
+      )
+    )
+""")
+
+
+def _write_temp_sch(content: str) -> str:
+    fd, path = tempfile.mkstemp(suffix=".kicad_sch")
+    os.close(fd)
+    with open(path, "w", encoding="utf-8") as f:
+        f.write(content)
+    return path
+
+
+def _read(path: str) -> str:
+    with open(path, encoding="utf-8") as f:
+        return f.read()
+
+
+# ---------------------------------------------------------------------------
+# Tests for _apply_mirror_to_symbol_sexp
+# ---------------------------------------------------------------------------
+
+def test_apply_mirror_x_adds_token():
+    """mirror='x' should insert (mirror x) after the (at ...) token."""
+    path = _write_temp_sch(SCHEMATIC_TEMPLATE)
+    try:
+        result = KiCADInterface._apply_mirror_to_symbol_sexp(path, "Q1", "x")
+        assert result is True
+        content = _read(path)
+        assert "(mirror x)" in content
+        assert "(mirror y)" not in content
+    finally:
+        os.unlink(path)
+
+
+def test_apply_mirror_y_adds_token():
+    """mirror='y' should insert (mirror y) after the (at ...) token."""
+    path = _write_temp_sch(SCHEMATIC_TEMPLATE)
+    try:
+        result = KiCADInterface._apply_mirror_to_symbol_sexp(path, "Q1", "y")
+        assert result is True
+        content = _read(path)
+        assert "(mirror y)" in content
+        assert "(mirror x)" not in content
+    finally:
+        os.unlink(path)
+
+
+def test_apply_mirror_none_removes_existing():
+    """mirror=None should remove an existing (mirror x) token."""
+    path = _write_temp_sch(SCHEMATIC_TEMPLATE_MIRRORED_X)
+    try:
+        result = KiCADInterface._apply_mirror_to_symbol_sexp(path, "Q1", None)
+        assert result is True
+        content = _read(path)
+        assert "(mirror x)" not in content
+        assert "(mirror y)" not in content
+    finally:
+        os.unlink(path)
+
+
+def test_apply_mirror_x_replaces_existing_y():
+    """mirror='x' should replace an existing (mirror y) without duplication."""
+    path = _write_temp_sch(SCHEMATIC_TEMPLATE_MIRRORED_X.replace("mirror x", "mirror y"))
+    try:
+        result = KiCADInterface._apply_mirror_to_symbol_sexp(path, "Q1", "x")
+        assert result is True
+        content = _read(path)
+        assert content.count("(mirror x)") == 1
+        assert "(mirror y)" not in content
+    finally:
+        os.unlink(path)
+
+
+def test_apply_mirror_returns_false_for_unknown_reference():
+    """Should return False gracefully when reference not found."""
+    path = _write_temp_sch(SCHEMATIC_TEMPLATE)
+    try:
+        result = KiCADInterface._apply_mirror_to_symbol_sexp(path, "U99", "x")
+        assert result is False
+        assert "(mirror x)" not in _read(path)
+    finally:
+        os.unlink(path)
+
+
+def test_rotate_handler_no_mirror_still_works(tmp_path):
+    """rotate_schematic_component without mirror param should not crash."""
+    sch_path = str(tmp_path / "test.kicad_sch")
+    with open(sch_path, "w") as f:
+        f.write(SCHEMATIC_TEMPLATE)
+
+    iface = KiCADInterface.__new__(KiCADInterface)
+
+    with patch.object(_mod.SchematicManager, "load_schematic") as mock_load, \
+         patch.object(_mod.SchematicManager, "save_schematic"):
+        mock_sym = MagicMock()
+        mock_sym.property.Reference.value = "Q1"
+        mock_sym.at.value = [75, 105, 0]
+        mock_sch = MagicMock()
+        mock_sch.symbol = [mock_sym]
+        mock_load.return_value = mock_sch
+
+        result = iface._handle_rotate_schematic_component({
+            "schematicPath": sch_path,
+            "reference": "Q1",
+            "angle": 90,
+        })
+
+    assert result["success"] is True
+    assert result["angle"] == 90