What's Changed
- Simplify effects further by @nikswamy in #4515
- Fix local let-rec SMT encoding to capture free variables by @mtzguido in #4556
- Custard: support [@@PpxDerivingYoJson] by @gebner in #4564
- Custard: an over-declared rule arity is an error when provably wrong by @gebner in #4566
- Rel: keep RHS uvars abstracted over pattern vars in quasi-pattern solutions (fixes #4587) by @gebner in #4590
- Rel: decide equations by lazy whnf instead of full normalization (fixes #4558) by @gebner in #4595
- Custard: propagate a let-bound copy before deciding a tuple's fate by @gebner in #4588
- Custard: do not spell every OCaml integer literal as a string parse by @gebner in #4596
- tests/custard: make RelocApp message check robust to line wrapping by @gebner in #4599
- Custard: expose the current declaration to plugins by @gebner in #4603
- Custard: features and bug fixes, without the compiler bootstrap by @gebner in #4604
- Regression tests for #4485 and #4487 (fixed by #4515) by @nikswamy in #4606
- Bump version to 2026.09.27 by @dzomo in #4607
Full Changelog: v2026.09.20...v2026.09.27