[ronaldtse]

Summary

Contextual (before/after-constrained) rules were silently inert whenever they referenced an imported charset alias — alalc-ell-Grek-Latn-2010's medial γκ rules never fired, so TS rendered "gk" where the map's embedded tests and the RS runtime render "nk" (5 golden-capture divergences).

Root cause

compileItem had a single alias-expansion context. An imported charset alias resolving to a plain string (dependency map unicode's greek, ~400 codepoints) compiled via the string case to regexpEscape(<whole charset>) — a literal sequence. In a constraint position that sequence became the lookbehind (?<=(?:<400 chars…>)), which no input can ever satisfy, so rules like

sub { from "γ" to "n"
      before any(greek)
      not_before boundary
      after any("κΚ") + any(greek)
      not_after any("κΚ") + boundary }

never matched and the unconstrained parallel γ → g won.

Ruby/RS resolve aliases in two contexts (RS builder.rs: materialize_class vs materialize; convert_class_alias): constraints and any() arguments are CLASS context, where an imported Item::Str charset expands one entry per character; from/to stay sequence context; a local string alias stays a sequence even in class context. The fix mirrors exactly that with a classCtx parameter on compileItem; the executor's constraint compile sites pass class context, any() class-resolves its alias arguments, capture innards and group parts stay sequence-resolved.

Fix

• src/runtime/compile-item.ts: compileItem(item, ctx, classCtx = false); imported charset alias in class position → per-character set (stringCharset); any() arguments class-resolve alias entries; capture innards forced to sequence context (RS parity).
• src/runtime/executor.ts: executeSubRule and the parallel megaregexp path compile before/not_before/after/not_after with classCtx = true.

Verification

• Golden delta (pre-fix, measured on a worktree at ff173b0): exactly 5 divergent rows, all on alalc-ell-Grek-Latn-2010 — γκέγκε gkegke→gkenke, Λαγκαδάς Lagkadas→Lankadas, Παγκράτι Pagkrati→Pankrati, Κονγκό Kongko→Konnko, Νταγκεστάν Ḏagkestan→Ḏankestan.
• Golden re-run (post-fix): 11,048 / 11,048 rows byte-identical — no other map's output changes (the bug sweep is the sweep itself: zero deltas elsewhere).
• RS side untouched: cargo test --release --test golden_capture passes; the rs crate and maps corpus were only read.
• Full suite: vitest run — 310 passed / 4 skipped (pre-existing), 0 failed. npm run lint, npm run format:check, npm run build all clean.

New specs (9 tests)

• test/golden-isc-wf0.test.ts — TS mirror of the RS golden_capture additivity gate: replays all 11,048 rows, requires byte-identical output (skips without the sibling interscript-rs/maps checkouts).
• test/isc/constraints.test.ts — per-shape regression units, each verified to fail pre-fix: imported charset in class position (root-cause shape), from any(charset) per-char, to any(charset) nth_string, sum constraint with charset part, boundary-sum word-final protection, before+after combined with capital-vs-small variants, local-alias sequence preservation, plus the five ell rows (and Χονγκ Κονγκ / Γκαμπόν guards) through the full path.

Test plan

• npx vitest run — full suite green (310 passed / 4 skipped)
• npx vitest run test/golden-isc-wf0.test.ts test/isc/constraints.test.ts — 9/9 with sibling checkouts present
• Pre-fix baseline via worktree: golden sweep fails on exactly the 5 ell rows; constraint units fail 6/8
• cd ../interscript-rs && cargo test --release --test golden_capture — rust additivity gate green
• npm run lint && npm run format:check && npm run build