From bf09055c4ef9f9e61fd4be16b3fd0a17f7191298 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 24 Apr 2026 11:59:47 +0000
Subject: [PATCH] js-on-sx: new Number/String/Array link to ctor.prototype (+5
 Number)
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js-get-ctor-proto used to always synthesise a per-ctor-id empty dict in
__js_proto_table__, ignoring the :prototype slot that every built-in
constructor dict (Number, String, Array, Boolean, Object, Function)
already carries. So `new Number()` got `{__proto__: {}}` instead of
`{__proto__: Number.prototype}`, breaking every prototype-chain-method
lookup:

  (new Number()).toLocaleString            // undefined → function
  (new Number()).toLocaleString === Number.prototype.toLocaleString

Fix: when the receiver is a dict with a "prototype" key, return that
directly; otherwise fall through to the existing proto-table path.
Declared classes from JS still go through the table because they emit
js-set-ctor-proto! at definition.

Unit 521/522, slice 148/148 unchanged.
Number scoreboard: 53/100 → 58/100 (+5). Sample: S15.7.5_A1_T03..T07
(toLocaleString/toString/toFixed/toExponential prototype identity).
---
 lib/js/runtime.sx | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/lib/js/runtime.sx b/lib/js/runtime.sx
index 080f937a..b8bbf7b8 100644
--- a/lib/js/runtime.sx
+++ b/lib/js/runtime.sx
@@ -739,12 +739,18 @@
   js-get-ctor-proto
   (fn
     (ctor)
-    (let
-      ((id (js-ctor-id ctor)))
-      (cond
-        ((dict-has? __js_proto_table__ id) (get __js_proto_table__ id))
-        (else
-          (let ((p (dict))) (begin (dict-set! __js_proto_table__ id p) p)))))))
+    (cond
+      ((and (= (type-of ctor) "dict") (contains? (keys ctor) "prototype"))
+        (get ctor "prototype"))
+      (else
+        (let
+          ((id (js-ctor-id ctor)))
+          (cond
+            ((dict-has? __js_proto_table__ id) (get __js_proto_table__ id))
+            (else
+              (let
+                ((p (dict)))
+                (begin (dict-set! __js_proto_table__ id p) p)))))))))
 (define
   js-reset-ctor-proto!
   (fn