plans: tick dict-passing elaborator + progress log

plans/haskell-on-sx.md

@@ -100,7 +100,7 @@ Key mappings:
 
 ### Phase 5 — typeclasses (dictionary passing)
 - [x] `class` / `instance` declarations
-- [ ] Dictionary-passing elaborator: inserts dict args at call sites
+- [x] Dictionary-passing elaborator: inserts dict args at call sites
 - [ ] Standard classes: `Eq`, `Ord`, `Show`, `Num`, `Functor`, `Monad`, `Applicative`
 - [ ] `deriving (Eq, Show)` for ADTs
 
@@ -114,6 +114,13 @@ Key mappings:
 
 _Newest first._
 
+- **2026-05-06** — Phase 5 dict-passing elaborator. `hk-bind-decls!` class-decl
+  arm now wraps dispatch functions as `hk-mk-lazy-builtin` (arity 1) so
+  `hk-apply` can call them; instance methods called via `hk-apply` not native SX
+  apply; thunk-forcing uses `hk-force` not `type-of == "thunk"` (Haskell thunks
+  are dicts, not SX native thunks). `tests/class.sx` gains 3 dispatch tests
+  (Int instance, Bool instance, error on unknown). 506/506 green.
+
 - **2026-05-06** — Phase 5 class/instance declarations. Parser: `hk-parse-class`
   and `hk-parse-instance` added to the parser closure; `hk-parse-decl` gains
   arms for `"class"` and `"instance"` reserved words (tokenizer already marks