Crease-segment referencing — bundle model, `at`, `pinch` #50

New issue

Open

opened 2026-07-03 18:33:20 +00:00 by toph · 0 comments

toph commented

2026-07-03 18:33:20 +00:00

Owner

Problem: a crease name is a bundle of segments (one crease_id, one edge per crossed face; collinear only in the folded moment, scattered across the CP). We need to reference a single segment, and to create just one.

Design — converged, unimplemented:

Decision: ADR 0014 — a crease is a bundle of segments
Detail:
- notes/2026-07-03-crease-segment-at-operator.md
- notes/2026-07-03-crease-layer-selection.md

Supersedes #28's --( --d #(...) ) / #(...) restrict escape hatch (folded into the at operator).

Slices (fan out at spec/plan time; each writes its spec section + code together and lands them):

at operator + bundle model — incidence selection, singleton-target rule
pinch creation primitive — one segment, short-render edge flag
debug/tooling — ambiguity enumeration + selector reachability + renderer highlight

Refs #28

**Problem:** a crease name is a *bundle* of segments (one `crease_id`, one edge per crossed face; collinear only in the folded moment, scattered across the CP). We need to reference a single segment, and to create just one. **Design — converged, unimplemented:** - Decision: [ADR 0014 — a crease is a bundle of segments](https://git.toph.so/toph/beloch/src/branch/main/decisions/0014-crease-is-a-bundle-of-segments.md) - Detail: - `notes/2026-07-03-crease-segment-at-operator.md` - `notes/2026-07-03-crease-layer-selection.md` Supersedes #28's `--( --d #(...) )` / `#(...)` restrict escape hatch (folded into the `at` operator). **Slices** (fan out at spec/plan time; each writes its spec section + code together and lands them): - [ ] `at` operator + bundle model — incidence selection, singleton-target rule - [ ] `pinch` creation primitive — one segment, short-render edge flag - [ ] debug/tooling — ambiguity enumeration + selector reachability + renderer highlight Refs #28

toph referenced this issue

2026-07-04 19:06:41 +00:00

design: first-class topology in Fold_state (pocket-slice prerequisite) #26

toph referenced this issue

2026-07-04 19:06:42 +00:00

design: crease reference semantics after later folds and flips #28

toph referenced this issue from a commit

2026-07-04 20:49:02 +00:00

docs(plan): at operator — crease-segment selection (#50)

toph referenced this issue from a commit

2026-07-04 20:49:02 +00:00

feat(fold-state): enumerate a crease bundle's segments (#50)