Add live browser test runner to /specs/testing page

sx-browser.js evaluates test.sx directly in the browser — click
"Run 81 tests" to see SX test itself. Uses the same Sx global that
rendered the page.

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

shared/static/scripts/sx-test-runner.js

@@ -0,0 +1,96 @@
+// sx-test-runner.js — Run test.sx in the browser using sx-browser.js.
+// Loaded on the /specs/testing page. Uses the Sx global.
+(function() {
+  var NIL = Sx.NIL;
+  function isNil(x) { return x === NIL || x === null || x === undefined; }
+  function deepEqual(a, b) {
+    if (a === b) return true;
+    if (isNil(a) && isNil(b)) return true;
+    if (typeof a !== typeof b) return false;
+    if (Array.isArray(a) && Array.isArray(b)) {
+      if (a.length !== b.length) return false;
+      for (var i = 0; i < a.length; i++) if (!deepEqual(a[i], b[i])) return false;
+      return true;
+    }
+    if (a && typeof a === "object" && b && typeof b === "object") {
+      var ka = Object.keys(a), kb = Object.keys(b);
+      if (ka.length !== kb.length) return false;
+      for (var j = 0; j < ka.length; j++) if (!deepEqual(a[ka[j]], b[ka[j]])) return false;
+      return true;
+    }
+    return false;
+  }
+
+  window.sxRunTests = function(srcId, outId, btnId) {
+    var src = document.getElementById(srcId).textContent;
+    var out = document.getElementById(outId);
+    var btn = document.getElementById(btnId);
+
+    var stack = [], passed = 0, failed = 0, num = 0, lines = [];
+
+    var env = {
+      "try-call": function(thunk) {
+        try {
+          Sx.eval([thunk], env);
+          return { ok: true };
+        } catch(e) {
+          return { ok: false, error: e.message || String(e) };
+        }
+      },
+      "report-pass": function(name) {
+        num++; passed++;
+        lines.push("ok " + num + " - " + stack.concat([name]).join(" > "));
+      },
+      "report-fail": function(name, error) {
+        num++; failed++;
+        lines.push("not ok " + num + " - " + stack.concat([name]).join(" > "));
+        lines.push("  # " + error);
+      },
+      "push-suite": function(name) { stack.push(name); },
+      "pop-suite": function() { stack.pop(); },
+
+      "equal?": function(a, b) { return deepEqual(a, b); },
+      "eq?": function(a, b) { return a === b; },
+      "boolean?": function(x) { return typeof x === "boolean"; },
+      "string-length": function(s) { return String(s).length; },
+      "substring": function(s, start, end) { return String(s).slice(start, end); },
+      "string-contains?": function(s, n) { return String(s).indexOf(n) !== -1; },
+      "upcase": function(s) { return String(s).toUpperCase(); },
+      "downcase": function(s) { return String(s).toLowerCase(); },
+      "reverse": function(c) { return c ? c.slice().reverse() : []; },
+      "flatten": function(c) {
+        var r = [];
+        for (var i = 0; i < (c||[]).length; i++) {
+          if (Array.isArray(c[i])) for (var j = 0; j < c[i].length; j++) r.push(c[i][j]);
+          else r.push(c[i]);
+        }
+        return r;
+      },
+      "has-key?": function(d, k) { return d && typeof d === "object" && k in d; },
+      "append": function(c, x) { return Array.isArray(x) ? (c||[]).concat(x) : (c||[]).concat([x]); },
+    };
+
+    try {
+      var t0 = performance.now();
+      var exprs = Sx.parseAll(src);
+      for (var i = 0; i < exprs.length; i++) Sx.eval(exprs[i], env);
+      var elapsed = Math.round(performance.now() - t0);
+      lines.push("");
+      lines.push("1.." + num);
+      lines.push("# tests " + (passed + failed));
+      lines.push("# pass  " + passed);
+      if (failed > 0) lines.push("# fail  " + failed);
+      lines.push("# time  " + elapsed + "ms");
+    } catch(e) {
+      lines.push("");
+      lines.push("FATAL: " + (e.message || String(e)));
+    }
+
+    out.textContent = lines.join("\n");
+    out.style.display = "block";
+    btn.textContent = passed + "/" + (passed + failed) + " passed" + (failed === 0 ? "" : " (" + failed + " failed)");
+    btn.className = failed > 0
+      ? "px-4 py-2 rounded-md bg-red-600 text-white font-medium text-sm cursor-default"
+      : "px-4 py-2 rounded-md bg-green-600 text-white font-medium text-sm cursor-default";
+  };
+})();