A library drawing can say how individual contours must be cut. A
`ContourCutPin` holds the entry point in the drawing's source frame plus
the lead-in, lead-out and optional tab used there; `Drawing.CutPins`
lists them. Nothing plans with pins yet (Slice 5).
- Pins accept only the exact built-in lead and tab types, copied through
the same owned copiers the planner uses, so a pin cannot carry a type
the emitter would not certify. Properties return copies: the pin is
immutable.
- A tab requires no lead-out, because the planner refuses a lead-out
after an open contour.
- The source frame is the frame of the source entities. It does not move
when BuildDrawing re-origins the program at its first rapid, so pins
survive converter edits that change Source.Offset.
`CutPinResolver` maps pins to (contour ordinal, entity ordinal, local
point) for a placement rotation, using the same `PreparedContours`
ordinals Plan Cutting will use. It never guesses: a pin must lie within
the contour closure tolerance of exactly one contour that no other pin
claims, otherwise it is reported unresolved with a typed reason. A
drawing program rotated in place (a canonical copy) is not the source
frame and resolves nothing; canonical copies and split pieces carry no
pins.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>