forth: LSHIFT/RSHIFT + 32-bit arith truncation + early binding (Hayes 174→268)

lib/forth/scoreboard.md

@@ -3,15 +3,15 @@
 | metric            | value |
 | ----------------- | ----: |
 | chunks available  | 638 |
-| chunks fed        | 590 |
-| total             | 590 |
-| pass              | 174 |
-| fail              | 0 |
-| error             | 416 |
-| percent           | 29% |
+| chunks fed        | 638 |
+| total             | 638 |
+| pass              | 268 |
+| fail              | 2 |
+| error             | 368 |
+| percent           | 42% |
 
 - **Source**: `gerryjackson/forth2012-test-suite` `src/core.fr`
-- **Generated**: 2026-04-24T21:06:54Z
+- **Generated**: 2026-04-24T22:26:31Z
 - **Note**: completed
 
 A "chunk" is any preprocessed segment ending at a `}T` (every Hayes test
@@ -23,8 +23,6 @@ covers tests whose `->` / `}T` comparison mismatched.
 ### Chunk cap
 
 `conformance.sh` processes the first `$MAX_CHUNKS` chunks (default
-**590**). Past that, `core.fr` ships tests that rely on unsigned
-integer wrap-around (e.g. `COUNT-BITS` using `BEGIN DUP WHILE … 2*
-REPEAT`), which never terminates on our bignum-based interpreter. The
-cap should rise as those tests unblock — run with `MAX_CHUNKS=639
-./conformance.sh` once they do.
+**638**, i.e. the whole Hayes Core file). Lower the cap temporarily
+while iterating on primitives if a regression re-opens an infinite
+loop in later tests.