diff --git a/lib/hyperscript/compiler.sx b/lib/hyperscript/compiler.sx
index 9e7eaac7..73d8ce50 100644
--- a/lib/hyperscript/compiler.sx
+++ b/lib/hyperscript/compiler.sx
@@ -653,6 +653,14 @@
                   (quote dom-add-class)
                   (hs-to-sx (nth ast 2))
                   (nth ast 1)))
+              ((= head (quote multi-add-class))
+                (let ((target (hs-to-sx (nth ast 1)))
+                      (classes (rest (rest ast))))
+                  (cons (quote do) (map (fn (cls) (list (quote dom-add-class) target cls)) classes))))
+              ((= head (quote multi-remove-class))
+                (let ((target (hs-to-sx (nth ast 1)))
+                      (classes (rest (rest ast))))
+                  (cons (quote do) (map (fn (cls) (list (quote dom-remove-class) target cls)) classes))))
               ((= head (quote remove-class))
                 (list
                   (quote dom-remove-class)
diff --git a/lib/hyperscript/parser.sx b/lib/hyperscript/parser.sx
index 1346f1e6..84ee38e1 100644
--- a/lib/hyperscript/parser.sx
+++ b/lib/hyperscript/parser.sx
@@ -666,10 +666,20 @@
           (if
             (= (tp-type) "class")
             (let
-              ((cls (get (adv!) "value")))
+              ((cls (get (adv!) "value"))
+               (extra-classes (list)))
+              ;; Collect additional class refs
+              (define collect-classes!
+                (fn ()
+                  (when (= (tp-type) "class")
+                    (set! extra-classes (append extra-classes (list (get (adv!) "value"))))
+                    (collect-classes!))))
+              (collect-classes!)
               (let
                 ((tgt (parse-tgt-kw "to" (list (quote me)))))
-                (list (quote add-class) cls tgt)))
+                (if (empty? extra-classes)
+                  (list (quote add-class) cls tgt)
+                  (cons (quote multi-add-class) (cons tgt (cons cls extra-classes))))))
             nil)))
       (define
         parse-remove-cmd
@@ -678,10 +688,19 @@
           (if
             (= (tp-type) "class")
             (let
-              ((cls (get (adv!) "value")))
+              ((cls (get (adv!) "value"))
+               (extra-classes (list)))
+              (define collect-classes!
+                (fn ()
+                  (when (= (tp-type) "class")
+                    (set! extra-classes (append extra-classes (list (get (adv!) "value"))))
+                    (collect-classes!))))
+              (collect-classes!)
               (let
                 ((tgt (parse-tgt-kw "from" (list (quote me)))))
-                (list (quote remove-class) cls tgt)))
+                (if (empty? extra-classes)
+                  (list (quote remove-class) cls tgt)
+                  (cons (quote multi-remove-class) (cons tgt (cons cls extra-classes))))))
             nil)))
       (define
         parse-toggle-cmd
diff --git a/shared/static/wasm/sx/hs-compiler.sx b/shared/static/wasm/sx/hs-compiler.sx
index 9e7eaac7..73d8ce50 100644
--- a/shared/static/wasm/sx/hs-compiler.sx
+++ b/shared/static/wasm/sx/hs-compiler.sx
@@ -653,6 +653,14 @@
                   (quote dom-add-class)
                   (hs-to-sx (nth ast 2))
                   (nth ast 1)))
+              ((= head (quote multi-add-class))
+                (let ((target (hs-to-sx (nth ast 1)))
+                      (classes (rest (rest ast))))
+                  (cons (quote do) (map (fn (cls) (list (quote dom-add-class) target cls)) classes))))
+              ((= head (quote multi-remove-class))
+                (let ((target (hs-to-sx (nth ast 1)))
+                      (classes (rest (rest ast))))
+                  (cons (quote do) (map (fn (cls) (list (quote dom-remove-class) target cls)) classes))))
               ((= head (quote remove-class))
                 (list
                   (quote dom-remove-class)
diff --git a/shared/static/wasm/sx/hs-parser.sx b/shared/static/wasm/sx/hs-parser.sx
index 1346f1e6..84ee38e1 100644
--- a/shared/static/wasm/sx/hs-parser.sx
+++ b/shared/static/wasm/sx/hs-parser.sx
@@ -666,10 +666,20 @@
           (if
             (= (tp-type) "class")
             (let
-              ((cls (get (adv!) "value")))
+              ((cls (get (adv!) "value"))
+               (extra-classes (list)))
+              ;; Collect additional class refs
+              (define collect-classes!
+                (fn ()
+                  (when (= (tp-type) "class")
+                    (set! extra-classes (append extra-classes (list (get (adv!) "value"))))
+                    (collect-classes!))))
+              (collect-classes!)
               (let
                 ((tgt (parse-tgt-kw "to" (list (quote me)))))
-                (list (quote add-class) cls tgt)))
+                (if (empty? extra-classes)
+                  (list (quote add-class) cls tgt)
+                  (cons (quote multi-add-class) (cons tgt (cons cls extra-classes))))))
             nil)))
       (define
         parse-remove-cmd
@@ -678,10 +688,19 @@
           (if
             (= (tp-type) "class")
             (let
-              ((cls (get (adv!) "value")))
+              ((cls (get (adv!) "value"))
+               (extra-classes (list)))
+              (define collect-classes!
+                (fn ()
+                  (when (= (tp-type) "class")
+                    (set! extra-classes (append extra-classes (list (get (adv!) "value"))))
+                    (collect-classes!))))
+              (collect-classes!)
               (let
                 ((tgt (parse-tgt-kw "from" (list (quote me)))))
-                (list (quote remove-class) cls tgt)))
+                (if (empty? extra-classes)
+                  (list (quote remove-class) cls tgt)
+                  (cons (quote multi-remove-class) (cons tgt (cons cls extra-classes))))))
             nil)))
       (define
         parse-toggle-cmd
diff --git a/tests/playwright/hs-behavioral.spec.js b/tests/playwright/hs-behavioral.spec.js
index ed3bd74d..7760dc65 100644
--- a/tests/playwright/hs-behavioral.spec.js
+++ b/tests/playwright/hs-behavioral.spec.js
@@ -198,16 +198,14 @@ test.describe('Hyperscript behavioral tests', () => {
       let result;
       try {
         result = await Promise.race([
-          page.evaluate(idx => {
+          page.evaluate(async (idx) => {
             const K = window.SxKernel;
-            // Thorough cleanup: replace body to kill all event listeners
             const newBody = document.createElement('body');
             document.documentElement.replaceChild(newBody, document.body);
 
             const thunk = K.eval(`(get (nth _test-registry ${idx}) "thunk")`);
             if (!thunk) return { p: false, e: 'no thunk' };
 
-            // Capture errors — only from THIS test's execution
             let lastErr = null;
             const orig = console.error;
             console.error = function() {
@@ -215,12 +213,52 @@ test.describe('Hyperscript behavioral tests', () => {
               if (m.startsWith('[sx]')) lastErr = m;
               orig.apply(console, arguments);
             };
+
+            // Drive async suspension chains (wait, fetch, etc.)
+            let pending = 0;
+            const oldDrive = window._driveAsync;
+            window._driveAsync = function driveAsync(result) {
+              if (!result || !result.suspended) return;
+              pending++;
+              const req = result.request;
+              const items = req && (req.items || req);
+              const op = items && items[0];
+              const opName = typeof op === 'string' ? op : (op && op.name) || String(op);
+              const arg = items && items[1];
+              function doResume(val, delay) {
+                setTimeout(() => {
+                  try { const r = result.resume(val); pending--; driveAsync(r); }
+                  catch(e) { pending--; }
+                }, delay);
+              }
+              if (opName === 'io-sleep' || opName === 'wait') doResume(null, Math.min(typeof arg === 'number' ? arg : 0, 10));
+              else if (opName === 'io-fetch') doResume({ok: true, text: ''}, 1);
+              else if (opName === 'io-settle') doResume(null, 5);
+              else if (opName === 'io-wait-event') doResume(null, 5);
+              else pending--;
+            };
+
             try {
-              K.callFn(thunk, []);
+              const r = K.callFn(thunk, []);
+              // If thunk itself suspended, drive it
+              if (r && r.suspended) window._driveAsync(r);
+              // Wait for all pending async chains to settle
+              if (pending > 0) {
+                await new Promise(resolve => {
+                  let waited = 0;
+                  const check = () => {
+                    if (pending <= 0 || waited > 2000) resolve();
+                    else { waited += 10; setTimeout(check, 10); }
+                  };
+                  setTimeout(check, 10);
+                });
+              }
               console.error = orig;
+              window._driveAsync = oldDrive;
               return lastErr ? { p: false, e: lastErr.replace(/[\\"]/g, ' ').slice(0, 150) } : { p: true, e: null };
             } catch(e) {
               console.error = orig;
+              window._driveAsync = oldDrive;
               return { p: false, e: (e.message || '').replace(/[\\"]/g, ' ').slice(0, 150) };
             }
           }, i),
@@ -285,9 +323,9 @@ test.describe('Hyperscript behavioral tests', () => {
       console.log(`    [${info.count}x] ${e}`);
     }
     // Show samples of "bar" error specifically
-    const barSamples = results.filter(r => !r.p && (r.e||'').match(/exception:  \w+ *$/)).slice(0, 10);
+    const barSamples = results.filter(r => !r.p && (r.e||'').includes('Assertion failed')).slice(0, 20);
     if (barSamples.length > 0) {
-      console.log(`  "bar" error samples (${barSamples.length}):`);
+      console.log(`  Assertion failures (${barSamples.length}):`);
       for (const s of barSamples) console.log(`    ${s.s}/${s.n}`);
     }