fix(probe): include login failure diagnostics

scripts/web-live-dom-probe.mjs

@@ -217,6 +217,7 @@ export async function runProbe(args) {
   const { width, height } = parseViewport(args.viewport);
   const actions = [];
   let browser;
+  let page;
   let result;
   if (args.credentialError) {
     result = {
@@ -247,7 +248,7 @@ export async function runProbe(args) {
     const { chromium } = await importPlaywright();
     browser = await launchChromium(chromium);
     const context = await browser.newContext({ viewport: { width, height } });
-    const page = await context.newPage();
+    page = await context.newPage();
     const bootstrapRoutes = observeBootstrapRoutes(page);
     await page.goto(args.url, { waitUntil: "domcontentloaded", timeout: args.timeoutMs });
     await waitForAuthBootstrap(page, args, actions);
@@ -300,6 +301,8 @@ export async function runProbe(args) {
       actions,
       credentials: args.credentials,
       error: error instanceof Error ? error.message : String(error),
+      finalUrl: page ? page.url() : null,
+      failureDom: page ? await collectFailureDomEvidence(page).catch((domError) => ({ error: domError instanceof Error ? domError.message : String(domError) })) : null,
       artifacts: { reportPath, screenshotPath }
     };
   } finally {
@@ -317,6 +320,30 @@ export async function runProbe(args) {
   return result;
 }
 
+async function collectFailureDomEvidence(page) {
+  return page.evaluate(() => {
+    const text = (selector) => document.querySelector(selector)?.textContent?.trim() ?? null;
+    const bodyText = document.body?.innerText?.replace(/\s+/gu, " ").trim() ?? "";
+    return {
+      authState: document.body?.getAttribute("data-auth-state") ?? null,
+      title: document.title || null,
+      locationPath: window.location.pathname,
+      login: {
+        cardVisible: Boolean(document.querySelector(".login-card")),
+        usernameVisible: Boolean(document.querySelector('#login-username, input[autocomplete="username"]')),
+        passwordVisible: Boolean(document.querySelector('#login-password, input[autocomplete="current-password"], input[type="password"]')),
+        errorText: text(".login-error, [role='alert'], .error, .text-red-500, .text-destructive")
+      },
+      requiredSelectors: {
+        workspace: Boolean(document.querySelector("#workspace")),
+        commandInput: Boolean(document.querySelector("#command-input")),
+        conversationList: Boolean(document.querySelector("#conversation-list"))
+      },
+      bodyTextPreview: bodyText.slice(0, 500)
+    };
+  });
+}
+
 function validatePromptFinalResponse(dom, args) {
   if (!args.message) return { ok: true, applicable: false, reason: "no-prompt-submitted" };
   const messages = Array.isArray(dom.messages) ? dom.messages : [];