diff --git a/tools/lib/harness.mjs b/tools/lib/harness.mjs
index 81086f5d..1cc45e9a 100644
--- a/tools/lib/harness.mjs
+++ b/tools/lib/harness.mjs
@@ -192,8 +192,20 @@ function makeTools({ cdp, projectId, baseUrl, consoleLog, check, shotPrefix }) {
     await sleep(ms);
     await keyEvent('keyUp', name);
   };
+  /**
+   * Typed per character to exercise the per-keystroke paths (live preview, search filters), then
+   * verified: a partial type is otherwise indistinguishable from a wrong value – a run once
+   * committed x=3 for "300" and the check blamed the value, not the lost characters.
+   */
   const typeText = async (text) => {
     for (const ch of text) await cdp.send('Input.insertText', { text: ch });
+    const typed = await json(
+      '({ tag: document.activeElement?.tagName, value: document.activeElement?.value })',
+    );
+    if (typed.tag !== 'INPUT' || !String(typed.value ?? '').includes(text))
+      throw new Error(
+        `typing "${text}" did not arrive: focus is ${typed.tag}, it holds ${JSON.stringify(typed.value)}`,
+      );
   };
   const undo = async () => {
     await press('z', { ctrl: true });