Fix coordinate precision and per-schematic sidecar isolation

Reduce _rc() and transform_pin_to_schematic() rounding from 3 to 2
decimal places to match KiCad's 0.01mm coordinate quantum — prevents
union-find misses when wire endpoints and sexp-parsed pin positions
differ at the sub-quantum level.

Use schematic stem as subdirectory inside .mckicad/ so multi-sheet
analysis outputs (connectivity.json, etc.) don't collide.

src/mckicad/tools/schematic_analysis.py

@@ -92,9 +92,11 @@ def _require_kicad_cli() -> tuple[str, None] | tuple[None, dict[str, Any]]:
 
 
 def _sidecar_dir(schematic_path: str) -> str:
-    """Return the .mckicad/ directory next to a schematic, creating it if needed."""
-    parent = os.path.dirname(os.path.abspath(schematic_path))
-    sidecar = os.path.join(parent, ".mckicad")
+    """Return the .mckicad/{stem}/ directory next to a schematic, creating it if needed."""
+    abs_sch = os.path.abspath(schematic_path)
+    parent = os.path.dirname(abs_sch)
+    stem = os.path.splitext(os.path.basename(abs_sch))[0]
+    sidecar = os.path.join(parent, ".mckicad", stem)
     os.makedirs(sidecar, exist_ok=True)
     return sidecar
 
@@ -150,7 +152,7 @@ def _build_connectivity(
 
     def _rc(x: float, y: float) -> tuple[float, float]:
         """Round coordinates for stable floating-point comparison."""
-        return (round(x, 3), round(y, 3))
+        return (round(x, 2), round(y, 2))
 
     def _coord_from_point(pt: Any) -> tuple[float, float]:
         """Extract (x, y) from a Point-like object or sequence."""

src/mckicad/utils/file_utils.py

@@ -18,7 +18,12 @@ def write_detail_file(schematic_path: str | None, filename: str, data: Any) -> s
     """Write large result data to a .mckicad/ sidecar directory.
 
     When ``schematic_path`` is provided, the sidecar directory is created
-    next to the schematic file.  When ``None``, falls back to CWD.
+    next to the schematic file, inside a subdirectory named after the
+    schematic's stem (e.g. ``.mckicad/power/connectivity.json``).  This
+    prevents multi-sheet designs from overwriting each other's output.
+
+    When ``None``, falls back to a flat ``.mckicad/`` in CWD (used for
+    search results that have no schematic context).
 
     Args:
         schematic_path: Path to a .kicad_sch file (sidecar dir created next to it),
@@ -29,8 +34,13 @@ def write_detail_file(schematic_path: str | None, filename: str, data: Any) -> s
     Returns:
         Absolute path to the written file.
     """
-    parent_dir = os.path.dirname(os.path.abspath(schematic_path)) if schematic_path else os.getcwd()
-    sidecar_dir = os.path.join(parent_dir, ".mckicad")
+    if schematic_path:
+        abs_sch = os.path.abspath(schematic_path)
+        parent_dir = os.path.dirname(abs_sch)
+        stem = os.path.splitext(os.path.basename(abs_sch))[0]
+        sidecar_dir = os.path.join(parent_dir, ".mckicad", stem)
+    else:
+        sidecar_dir = os.path.join(os.getcwd(), ".mckicad")
     os.makedirs(sidecar_dir, exist_ok=True)
 
     out_path = os.path.join(sidecar_dir, filename)

src/mckicad/utils/sexp_parser.py

@@ -162,7 +162,7 @@ def transform_pin_to_schematic(
     ry = px * sin_r + py * cos_r
 
     # Apply position offset
-    return (round(comp_x + rx, 3), round(comp_y + ry, 3))
+    return (round(comp_x + rx, 2), round(comp_y + ry, 2))
 
 
 # ---------------------------------------------------------------------------

tests/test_schematic.py

@@ -3,6 +3,7 @@
 import os
 
 import pytest
+
 from tests.conftest import requires_sch_api
 
 
@@ -120,7 +121,7 @@ def test_get_schematic_hierarchy(populated_schematic):
 
 @pytest.mark.unit
 def test_file_output_infrastructure(tmp_output_dir):
-    """write_detail_file should create .mckicad sidecar directory and file."""
+    """write_detail_file should create .mckicad/{stem}/ sidecar directory and file."""
     from mckicad.utils.file_utils import write_detail_file
 
     fake_sch = os.path.join(tmp_output_dir, "test.kicad_sch")
@@ -132,12 +133,12 @@ def test_file_output_infrastructure(tmp_output_dir):
 
     assert os.path.isfile(path)
     assert ".mckicad" in path
-    assert path.endswith("test_output.json")
+    assert os.path.join(".mckicad", "test", "test_output.json") in path
 
 
 @pytest.mark.unit
 def test_file_output_cwd_fallback(tmp_output_dir, monkeypatch):
-    """write_detail_file with None path should use CWD."""
+    """write_detail_file with None path should use flat CWD/.mckicad/."""
     from mckicad.utils.file_utils import write_detail_file
 
     monkeypatch.chdir(tmp_output_dir)
@@ -145,3 +146,25 @@ def test_file_output_cwd_fallback(tmp_output_dir, monkeypatch):
 
     assert os.path.isfile(path)
     assert ".mckicad" in path
+    # None path stays flat — no stem subdirectory
+    assert path.endswith(os.path.join(".mckicad", "test_cwd.json"))
+
+
+@pytest.mark.unit
+def test_sidecar_per_schematic_isolation(tmp_output_dir):
+    """Detail files for different schematics land in separate subdirectories."""
+    from mckicad.utils.file_utils import write_detail_file
+
+    sch_a = os.path.join(tmp_output_dir, "power.kicad_sch")
+    sch_b = os.path.join(tmp_output_dir, "esp32_p4_core.kicad_sch")
+    open(sch_a, "w").close()
+    open(sch_b, "w").close()
+
+    path_a = write_detail_file(sch_a, "connectivity.json", {"nets": {}})
+    path_b = write_detail_file(sch_b, "connectivity.json", {"nets": {}})
+
+    assert os.path.isfile(path_a)
+    assert os.path.isfile(path_b)
+    assert path_a != path_b
+    assert os.path.join(".mckicad", "power", "connectivity.json") in path_a
+    assert os.path.join(".mckicad", "esp32_p4_core", "connectivity.json") in path_b