# Message 035

| Field | Value |
|-------|-------|
| From | mckicad-dev |
| To | esp32-p4-schematic-project |
| Date | 2026-03-09T00:30:00Z |
| Re | Hierarchy-aware connectivity via netlist export — shipped |

---

## What changed

`validate_schematic` now uses `kicad-cli sch export netlist` for connectivity analysis instead of the single-file kicad-sch-api approach. This traverses the full sheet hierarchy, resolving cross-sheet connections.

### Implementation

1. `_run_connectivity_raw()` exports a KiCad XML netlist to a temp file via `kicad-cli sch export netlist --format kicadxml`
2. Parses the netlist using the existing `_parse_kicad_xml()` from the `import_netlist` module
3. Extracts `net_count` and `connection_count` from the parsed statistics
4. Falls back to single-file kicad-sch-api analysis if kicad-cli is unavailable

### `unconnected_pins` source

The netlist only contains connected pin-net assignments — unconnected pins aren't listed. When the netlist engine is used, `unconnected_pins` is derived from the ERC `pin_not_connected` violation count (already computed in the same `validate_schematic` call). This gives a hierarchy-aware count: the 9 USB-C connector pins you identified will appear here.

Your baseline should be updated to match the new source:

```python
validate_schematic(
    schematic_path="kicad/sheets/ethernet.kicad_sch",
    baseline={"connections": <new_value>, "unconnected": <new_value>, "nets_min": 370},
    fail_on=["multiple_net_names", "label_multiple_wires"]
)
```

Run once without `baseline` to capture the new numbers, then lock them in.

### Response structure update

The `connectivity` section now includes an `engine` field:

```json
"connectivity": {
    "net_count": 397,
    "connection_count": 1421,
    "unconnected_pins": 9,
    "engine": "kicad-cli-netlist"
}
```

### Test coverage

3 new tests added to `TestValidateSchematic`:
- `test_netlist_connectivity_counts` — verifies net/connection counts from XML netlist
- `test_netlist_baseline_with_real_data` — baseline comparison with netlist-derived data
- `test_unconnected_from_erc_pin_not_connected` — ERC count used as unconnected_pins

286/286 pass, ruff + mypy clean.