HS: test runner — unwrap value handles before native interop

The new kernel ABI wraps atoms (number, string, boolean, nil) in opaque
handles {_type, __sx_handle}. When such handles flow through host-call
into native JS functions, value equality breaks: each integer literal
becomes a unique handle object, so JS Set.add(handle_for_1) does NOT
dedup against a prior set.add(handle_for_1). Same problem for any JS
API that uses identity or value equality on incoming arguments.

Fix: add _unwrapHandle that converts handles back to JS primitives via
K.stringify, and apply it to argument lists in host-call and host-new
(the two natives that pass user values into native JS constructors /
methods). Forward-compatible: no-op when called with already-unwrapped
plain values from the legacy kernel.

Root-cause analysis traced through:
  1. Test 27 'can append a value to a set' failed (Expected 3, got 4)
     on the new WASM only. Set was admitting duplicates.
  2. dbg-set.js minimal repro confirmed each `1` literal arriving at
     set.add as a different {_type, __sx_handle} object.
  3. JS Set.add uses SameValueZero — handle objects with the same
     underlying value are still distinct identity.
  4. Unwrapping in host-call/host-new resolves the equality issue.

This is preparation for the JIT Phase 1 WASM rollout (which still
needs more native-interop unwrap audits before it can replace the
pre-merge WASM that the test tree currently pins).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/hs-run-filtered.js

@@ -36,6 +36,26 @@ if (K && typeof K.eval === 'function' && K.stringify) {
   };
 }
 
+// Value-handle unwrap helper for native interop. The new kernel wraps atoms
+// (number, string, boolean, nil) in {_type, __sx_handle} handles. JS natives
+// receiving these in argument lists would do reference-equality on the handle
+// instead of value-equality on the underlying primitive — breaking things
+// like JS Set dedup (each literal `1` becomes a new handle). Unwrap before
+// handing off to native JS.
+function _unwrapHandle(v) {
+  if (v && typeof v === 'object' && typeof v._type === 'string' && K.stringify) {
+    switch (v._type) {
+      case 'number':  { const s = K.stringify(v); const n = Number(s);
+                        return Number.isInteger(n) || /^-?\d+$/.test(s) ? n : n; }
+      case 'string':  return K.stringify(v);
+      case 'boolean': return K.stringify(v) === 'true';
+      case 'nil':     return null;
+      default:        return v;
+    }
+  }
+  return v;
+}
+
 // Step limit API — exposed from OCaml kernel
 const STEP_LIMIT = parseInt(process.env.HS_STEP_LIMIT || '1000000');
 
@@ -688,9 +708,9 @@ K.registerNative('host-get',a=>{
   return v;
 });
 K.registerNative('host-set!',a=>{if(a[0]!=null){const v=a[2]; if(a[1]==='innerHTML'&&a[0] instanceof El){const s=v===null?'null':v===undefined?'':String(v);a[0]._setInnerHTML(s);a[0][a[1]]=a[0].innerHTML;} else if(a[1]==='textContent'&&a[0] instanceof El){const s=v===null?'null':v===undefined?'':String(v);a[0].textContent=s;a[0].innerHTML=s;for(const c of a[0].children){c.parentElement=null;c.parentNode=null;}a[0].children=[];a[0].childNodes=[];} else{a[0][a[1]]=v;}} return a[2];});
-K.registerNative('host-call',a=>{if(_testDeadline&&Date.now()>_testDeadline)throw new Error('TIMEOUT: wall clock exceeded');const[o,m,...r]=a;if(o==null){const f=globalThis[m];return typeof f==='function'?f.apply(null,r):null;}if(o&&typeof o[m]==='function'){try{const v=o[m].apply(o,r);return v===undefined?null:v;}catch(e){return null;}}return null;});
+K.registerNative('host-call',a=>{if(_testDeadline&&Date.now()>_testDeadline)throw new Error('TIMEOUT: wall clock exceeded');const[o,m,...r]=a;if(o==null){const f=globalThis[m];return typeof f==='function'?f.apply(null,r.map(_unwrapHandle)):null;}if(o&&typeof o[m]==='function'){try{const v=o[m].apply(o,r.map(_unwrapHandle));return v===undefined?null:v;}catch(e){return null;}}return null;});
 K.registerNative('host-call-fn',a=>{const[fn,argList]=a;if(typeof fn!=='function'&&!(fn&&fn.__sx_handle!==undefined))return null;const callArgs=(argList&&argList._type==='list'&&argList.items)?Array.from(argList.items):(Array.isArray(argList)?argList:[]);if(fn&&fn.__sx_handle!==undefined){try{return K.callFn(fn,callArgs);}catch(e){const msg=e&&e.message||'';if(String(msg).includes('TIMEOUT'))throw e;return null;}}function sxToJs(v){if(v&&v._type==='list'&&v.items)return Array.from(v.items).map(sxToJs);return v;}try{const v=fn.apply(null,callArgs.map(sxToJs));return v===undefined?null:v;}catch(e){return null;}});
-K.registerNative('host-new',a=>{const C=typeof a[0]==='string'?globalThis[a[0]]:a[0];return typeof C==='function'?new C(...a.slice(1)):null;});
+K.registerNative('host-new',a=>{const C=typeof a[0]==='string'?globalThis[a[0]]:a[0];return typeof C==='function'?new C(...a.slice(1).map(_unwrapHandle)):null;});
 K.registerNative('host-callback',a=>{const fn=a[0];if(typeof fn==='function'&&fn.__sx_handle===undefined)return fn;if(fn&&fn.__sx_handle!==undefined)return function(){const r=K.callFn(fn,Array.from(arguments));if(globalThis._driveAsync)globalThis._driveAsync(r);return r;};return function(){};});
 K.registerNative('host-make-js-thrower',a=>{const val=a[0];return function(){throw val;};});
 K.registerNative('host-typeof',a=>{const o=a[0];if(o==null)return'nil';if(o instanceof El)return'element';if(o&&o.nodeType===3)return'text';if(o instanceof Ev)return'event';if(o instanceof Promise)return'promise';return typeof o;});