HS: DOM ref-eq + compound selector + DOM tree fixes

- hs-id= uses JS === for DOM elements (hs-ref-eq), = for scalars
- != operator now uses hs-id= for structural correctness
- compound tag[attr=val] selector matching in test runner
- dom-query-all replaces host-call querySelectorAll
- DOM tree structure corrected in 4 generated tests (elements were
  appended to wrong parents)

tests/hs-run-filtered.js

@@ -297,6 +297,15 @@ function mt(e,s) {
     const m = base.match(/^\[([^\]=]+)(?:="([^"]*)")?\]$/);
     if(m) return m[2] !== undefined ? e.getAttribute(m[1]) === m[2] : e.hasAttribute(m[1]);
   }
+  // Compound tag[attr=val] e.g. input[type=checkbox] or input[type="checkbox"]
+  if(base.includes('[')) {
+    const cm = base.match(/^([\w-]+)(\[.+\])$/);
+    if(cm) {
+      if(e.tagName.toLowerCase() !== cm[1]) return false;
+      const attrParts = cm[2].match(/^\[([^\]=]+)(?:=["']?([^"'\]]+)["']?)?\]$/);
+      if(attrParts) return attrParts[2] !== undefined ? e.getAttribute(attrParts[1]) === attrParts[2] : e.hasAttribute(attrParts[1]);
+    }
+  }
   if(base.includes('.')) { const [tag, cls] = base.split('.'); return e.tagName.toLowerCase() === tag && e.classList.contains(cls); }
   if(base.includes('#')) { const [tag, id] = base.split('#'); return e.tagName.toLowerCase() === tag && e.id === id; }
   return e.tagName.toLowerCase() === base.toLowerCase();
@@ -536,6 +545,9 @@ globalThis.console = { log: () => {}, error: () => {}, warn: () => {}, info: ()
 const _log = _origLog; // keep reference for our own output
 
 // ─── FFI ────────────────────────────────────────────────────────
+// JS-level reference equality for host objects (works around OCaml boxing).
+// The SX `=` primitive doesn't do JS === for host objects in the WASM kernel.
+K.registerNative('hs-ref-eq',a=>a[0]===a[1]);
 K.registerNative('host-global',a=>{const n=a[0];return(n in globalThis)?globalThis[n]:null;});
 K.registerNative('host-get',a=>{
   if(a[0]==null)return null;

tests/playwright/generate-sx-tests.py

@@ -210,11 +210,18 @@ def parse_html(html):
     # button HTML in `properly processes hyperscript X` tests). HTMLParser handles
     # backslashes in attribute values as literal characters, so we leave them.
 
+    # HTML5 void elements — never have children, auto-pop from stack immediately.
+    VOID_TAGS = {'area','base','br','col','embed','hr','img','input','link',
+                 'meta','param','source','track','wbr'}
+
     elements = []
     stack = []
 
     class Parser(HTMLParser):
         def handle_starttag(self, tag, attrs):
+            # Pop any void elements left on the stack (they have no close tag).
+            while stack and stack[-1]['tag'] in VOID_TAGS:
+                stack.pop()
             el = {
                 'tag': tag, 'id': None, 'classes': [], 'hs': None,
                 'attrs': {}, 'inner': '', 'depth': len(stack),
@@ -244,6 +251,9 @@ def parse_html(html):
             elements.append(el)
 
         def handle_endtag(self, tag):
+            # Pop void elements first (they don't have close tags but may linger).
+            while stack and stack[-1]['tag'] in VOID_TAGS:
+                stack.pop()
             if stack and stack[-1]['tag'] == tag:
                 stack.pop()