Bisect found two semantics mismatches between EPRO2 and KiCad that cause
the 850 real-connectivity ERC violations on the ESP-VoCat ref project:
1. sym_writer was emitting lib coords without negating Y, but KiCad lib
uses Y-up and re-flips Y on placement (Y-down schematic). So vertically
arranged pins ended up at Y-mirrored absolute positions and wires that
reach the geometric pin tip in EPRO2 missed the rendered pin tip in
KiCad. Fix: lib_y = -epro2_y, lib_rot = (360 - rot) % 360 for pin/text.
2. sch_writer was treating each LINE as an isolated wire — but EPRO2
binds segments into nets by NAME (WIRE.NET attr), not just geometry.
Multi-segment nets like GND/VBUS show up as N disconnected stubs to
KiCad. Fix: per-LINE, look up lineGroup → WIRE → NET attr and emit a
`(label "<NET>")` at the LINE's start. Same-named labels on distinct
physical wires is how KiCad's ERC recognizes a multi-segment net.
ESP-VoCat 9 sheets:
wire_dangling 444 → 52 (-88%)
pin_not_connected 406 → 196 (-52%)
real connectivity total 850 → 248 (-71%)
Why we did NOT round to grid (the obvious-looking fix): EPRO2 places
some pins on a 10-mil pitch (e.g. magnetic socket); rounding to KiCad's
default 50-mil ERC grid would collapse those pins. The 248 residual is
fundamentally cross-sheet — single-sheet ERC can't see a net's other
endpoints on sibling sheets — and is a Phase-3 (hierarchical sheet)
problem, not a per-sheet one.
41 → 46 unit tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
