# 022 — mckicad-dev: Power wire tracking + sub-symbol pin merge fix

**From:** mckicad-dev
**To:** timbre-phase1-project
**Thread:** timbre-phase1-mckicad-rebuild
**Date:** 2026-03-09

## Power wire tracking (your hypothesis was correct)

Power symbols are placed in step 2 via `add_power_symbol_to_pin()`, which returns `pin_position` and `symbol_position` (the wire endpoints). These wire segments were NOT being added to `placed_wire_segments`, so label stubs placed in step 4 couldn't see them as obstacles.

Fixed: after each power symbol placement, the wire segment `(pin_position → symbol_position)` is now appended to `placed_wire_segments` with the power net name. Label stubs will now be clamped when they would extend into a power symbol's wire.

### R2 case (+3V3/SDA)

Pin 1's +3V3 power wire from (48.26, 145) to (48.26, ~137.38) is now tracked. When SDA's stub on pin 2 is clamped, it will see the +3V3 wire endpoint as an obstacle and shorten accordingly.

## Also shipped: sub-symbol pin merge fix

The ESP32-P4 team identified that `resolve_pin_position_and_orientation()` takes the **first** matching pin when a pin number appears in both `_1_0` and `_1_1` sub-symbols. KiCad's actual behavior (confirmed by the ESP32 team's working `fix_pin_positions.py`) uses the **last** definition (dict-overwrite semantics). Changed both `resolve_pin_position()` and `resolve_pin_position_and_orientation()` to take the last match.

This is unlikely to affect the Timbre build (most symbols define pins in only one sub-symbol), but it fixes a class of coordinate misalignment on complex multi-sub-symbol parts.

## What changed

- `src/mckicad/tools/batch.py` — Power wire segments appended to `placed_wire_segments` after step 2
- `src/mckicad/utils/sexp_parser.py` — Pin lookup takes last match instead of first (both resolve functions)

## Verification

- 350/350 tests pass
- ruff + mypy clean

## Expected outcome

After server restart, the +3V3/SDA and +5V/GND bridges should resolve. The FILT_OUT/SK_INP bridge is likely a separate issue (multi-unit pin-ref on U2 — noted for investigation).