js-on-sx: rational handling in typeof/to-string/strict-eq/loose-eq

plans/js-on-sx.md

@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-09 — **Rational handling in `js-typeof` / `js-to-string` / `js-strict-eq` / `js-loose-eq` / `Object.prototype.toString`.** Followup to the `js-to-number` fix. SX rationals were leaking into other paths: `typeof 1/2` returned `"object"` (should be `"number"`), `String(1/2)` fell into the dict branch and returned `"[object Object]"`, and `1/2 === 0.5` was false because strict-eq compared types and `"rational"` ≠ `"number"`. Added rational arms to `js-typeof` and `js-object-tostring-class`, normalised rationals via `(exact->inexact)` in `js-to-string`'s number branch, and introduced a `js-numeric-type?` / `js-numeric-norm` pair that lets strict-eq and loose-eq treat both numeric kinds uniformly. Result: language/expressions/strict-equals 16/22 → 19/22; Math 30/30 confirmed (no regression — but it never had one). Object/Array/Map unchanged. conformance.sh: 148/148.
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 - 2026-05-09 — **`js-to-number` now coerces SX rationals via `exact->inexact`.** SX `(/ 59 16)` returns the rational `59/16` with `(type-of)` `"rational"` — not `"number"` — so `js-to-number` was falling through to the dict branch and ultimately returning `0`. That broke any path that did integer-divide intermediate math (e.g. `js-hex-2` for percent-encoding: `(js-math-trunc (/ 59 16))` was returning 0, so `encodeURIComponent(";")` produced `"%0B"` instead of `"%3B"`). Added a `((= (type-of v) "rational") (exact->inexact v))` clause in `js-to-number` between the existing `"number"` and `"string"` branches. Result: built-ins/encodeURIComponent 9/30 → 15/30, built-ins/encodeURI 22/60 → 28/60, built-ins/decodeURI 11/60 → 20/60. Object/Array unchanged. conformance.sh: 148/148.
 
 - 2026-05-09 — **`parseFloat("+")` / `parseFloat("-")` / `parseFloat(".")` return NaN (were returning 0).** `js-float-prefix-end` happily consumed leading `+`/`-` and dot characters even with no digits — and `js-parse-num-safe` of those characters returned 0. Per spec, the prefix must contain at least one digit. Added a `js-str-has-digit?` walker called between `js-float-prefix-end` and `js-parse-num-safe`; if no digit is present in the consumed slice, return NaN. Result: built-ins/parseFloat 20/30 → 23/30, built-ins/parseInt 22/30 → 24/30. Number unchanged. conformance.sh: 148/148.