diff --git a/tests/js/workspace-toolbar.test.js b/tests/js/workspace-toolbar.test.js
index 7085dda..db2818e 100644
--- a/tests/js/workspace-toolbar.test.js
+++ b/tests/js/workspace-toolbar.test.js
@@ -138,6 +138,8 @@ test('toolbar emits concept markup and order', async () => {
         assert.equal(input.id, 'search');
         assert.equal(input.type, 'search');
         assert.equal(input.placeholder, 'Search prompts, tags, filenames…');
+        // The listing API rejects search text over 500 characters, as the legacy search capped it.
+        assert.equal(input.maxLength, 500);
         assert.equal(input.getAttribute('aria-label'), 'Search workspace');
         assert.equal(input.value, 'castle');
 
diff --git a/web/js/workspace/toolbar.mjs b/web/js/workspace/toolbar.mjs
index d1cd2b5..2eac2e7 100644
--- a/web/js/workspace/toolbar.mjs
+++ b/web/js/workspace/toolbar.mjs
@@ -68,6 +68,8 @@ export function mountToolbar(container, { scope, categories = [], sorts, value =
     search.id = 'search';
     search.type = 'search';
     search.placeholder = 'Search prompts, tags, filenames…';
+    // The listing API rejects longer search text (py/api/images.py _workspace_filters).
+    search.maxLength = 500;
     search.setAttribute('aria-label', 'Search workspace');
     label.append(createWorkspaceIcon('search'), search);