diff --git a/tests/restart-chaos/board-ui.test.ts b/tests/restart-chaos/board-ui.test.ts
index 6d0f994c7e8..2a5ba83b88a 100644
--- a/tests/restart-chaos/board-ui.test.ts
+++ b/tests/restart-chaos/board-ui.test.ts
@@ -1,4 +1,7 @@
 import { createServer, type Server } from "node:http";
+import { mkdtemp, readFile, readdir, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import path from "node:path";
 import { once } from "node:events";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { BoardUi, UI_RETRY_BUTTON_MISSING, UI_RETRY_NO_REQUEST, isRetryRequestFor } from "./board-ui.js";
@@ -7,6 +10,7 @@ const retry = (issue: string) => `fetch('/api/issues/${issue}/retry',{method:'PO
 const pages: Record<string, string> = {
   "/issues/CHA-1": `<div role="status">Couldn’t finish this attempt. <button onclick="${retry("i1")}">Retry</button></div>`,
   "/issues/CHA-2": `<div role="status">Saving files from the previous attempt</div>`,
+  "/issues/CHA-7": `<div role="status">Couldn’t finish this attempt. <button style="display:none">Retry</button></div>`,
   "/issues/CHA-3": `<div role="status">Automatic recovery stopped. <button>Retry</button></div>`,
   "/issues/CHA-4": `<section><p>Couldn’t load the subtasks.</p><button onclick="window.reloaded=true">Retry</button></section>
     <div role="status">Couldn’t finish this attempt. <button onclick="${retry("i4")}">Retry</button></div>`,
@@ -54,6 +58,37 @@ describe("BoardUi.clickRetry", () => {
     });
   }, 60_000);
 
+  it("saves a screenshot and the banner's HTML when no visible Retry appears", async () => {
+    const directory = await mkdtemp(path.join(tmpdir(), "chaos-retry-diagnostics-"));
+    const board = new BoardUi(baseUrl, undefined, directory);
+    try {
+      const result = await board.clickRetry("CHA-2", "i2", 1_500);
+      expect(result).toMatchObject({ clicked: false, error: UI_RETRY_BUTTON_MISSING,
+        diagnostics: { screenshot: expect.stringMatching(/\.png$/), dom: expect.stringMatching(/\.json$/) } });
+      expect((await readdir(directory)).sort()).toHaveLength(2);
+      const dom = JSON.parse(await readFile(result.diagnostics!.dom!, "utf8"));
+      expect(dom).toMatchObject({ url: expect.stringContaining("/issues/CHA-2"), retryButtons: [],
+        banners: [expect.stringContaining("Saving files from the previous attempt")] });
+    } finally {
+      await board.close();
+      await rm(directory, { recursive: true, force: true });
+    }
+  }, 60_000);
+
+  it("records a hidden Retry with its visibility and box", async () => {
+    const directory = await mkdtemp(path.join(tmpdir(), "chaos-retry-hidden-"));
+    const board = new BoardUi(baseUrl, undefined, directory);
+    try {
+      const result = await board.clickRetry("CHA-7", "i7", 1_500);
+      expect(result).toMatchObject({ clicked: false, error: UI_RETRY_BUTTON_MISSING });
+      const dom = JSON.parse(await readFile(result.diagnostics!.dom!, "utf8"));
+      expect(dom.retryButtons).toEqual([expect.objectContaining({ visible: false, box: null, inBanner: true })]);
+    } finally {
+      await board.close();
+      await rm(directory, { recursive: true, force: true });
+    }
+  }, 60_000);
+
   it("reports a Retry button whose click sends no retry request", async () => {
     await withBoard(async board => {
       expect(await board.clickRetry("CHA-3", "i3", 1_500, 500)).toMatchObject({ clicked: true, httpStatus: null, error: UI_RETRY_NO_REQUEST });
diff --git a/tests/restart-chaos/board-ui.ts b/tests/restart-chaos/board-ui.ts
index 96343025eb7..90390b45288 100644
--- a/tests/restart-chaos/board-ui.ts
+++ b/tests/restart-chaos/board-ui.ts
@@ -1,3 +1,5 @@
+import { mkdir, writeFile } from "node:fs/promises";
+import path from "node:path";
 import { chromium, type Browser, type ElementHandle, type Page } from "@playwright/test";
 import { UI_RETRY_BUTTON_MISSING, UI_RETRY_NO_REQUEST } from "./types.js";
 
@@ -9,6 +11,29 @@ export interface UiRetryClick {
   accepted: boolean | null;
   error: string | null;
   bannerText: string | null;
+  diagnostics?: { screenshot: string | null; dom: string | null } | null;
+}
+
+export async function saveRetryMissingDiagnostics(page: Page, directory: string, label: string) {
+  const stem = path.join(directory, `ui-retry-missing-${label.replace(/[^A-Za-z0-9_-]+/g, "_")}-${Date.now()}`);
+  await mkdir(directory, { recursive: true });
+  const screenshot = await page.screenshot({ path: `${stem}.png`, fullPage: true, timeout: 10_000 })
+    .then(() => `${stem}.png`).catch(() => null);
+  const banners = await page.locator("[role=status], [role=alert]")
+    .evaluateAll(nodes => nodes.map(node => (node as Element).outerHTML.slice(0, 20_000))).catch(() => []);
+  const buttons = [];
+  for (const button of await page.getByRole("button", { name: "Retry", exact: true, includeHidden: true })
+    .elementHandles().catch(() => [])) {
+    buttons.push({
+      visible: await button.isVisible().catch(() => null),
+      box: await button.boundingBox().catch(() => null),
+      inBanner: await button.evaluate(node => Boolean((node as Element).closest("[role=status], [role=alert]"))).catch(() => null),
+      html: await button.evaluate(node => (node as Element).outerHTML.slice(0, 2_000)).catch(() => null),
+    });
+  }
+  const dom = await writeFile(`${stem}.json`, JSON.stringify({ url: page.url(), savedAt: new Date().toISOString(),
+    banners, retryButtons: buttons }, null, 2)).then(() => `${stem}.json`).catch(() => null);
+  return { screenshot, dom };
 }
 
 const PER_BUTTON_REQUEST_MS = 5_000;
@@ -30,7 +55,7 @@ async function retryButtonsBannerFirst(page: Page): Promise<ElementHandle[]> {
 }
 
 export async function clickRetryOnPage(page: Page, url: string, issueRefs: readonly string[], timeoutMs: number,
-  perButtonMs = PER_BUTTON_REQUEST_MS): Promise<UiRetryClick> {
+  perButtonMs = PER_BUTTON_REQUEST_MS, diagnosticsDirectory: string | null = null): Promise<UiRetryClick> {
   await page.goto(url, { waitUntil: "domcontentloaded", timeout: timeoutMs });
   const banner = async () => {
     const texts = await page.locator("[role=status], [role=alert]").allInnerTexts().catch(() => []);
@@ -40,7 +65,11 @@ export async function clickRetryOnPage(page: Page, url: string, issueRefs: reado
     await page.getByRole("button", { name: "Retry", exact: true }).filter({ visible: true }).first()
       .waitFor({ state: "visible", timeout: timeoutMs });
   } catch {
-    return { clicked: false, httpStatus: null, accepted: null, error: UI_RETRY_BUTTON_MISSING, bannerText: await banner() };
+    const bannerText = await banner();
+    const diagnostics = diagnosticsDirectory
+      ? await saveRetryMissingDiagnostics(page, diagnosticsDirectory, issueRefs[0] ?? "issue").catch(() => null) : undefined;
+    return { clicked: false, httpStatus: null, accepted: null, error: UI_RETRY_BUTTON_MISSING, bannerText,
+      ...(diagnostics !== undefined ? { diagnostics } : {}) };
   }
   const bannerText = await banner();
   for (const button of await retryButtonsBannerFirst(page)) {
@@ -59,7 +88,8 @@ export async function clickRetryOnPage(page: Page, url: string, issueRefs: reado
 export class BoardUi {
   private browser: Promise<Browser> | null = null;
 
-  constructor(private readonly baseUrl: string, private readonly launch: () => Promise<Browser> = () => chromium.launch({ headless: true })) {}
+  constructor(private readonly baseUrl: string, private readonly launch: () => Promise<Browser> = () => chromium.launch({ headless: true }),
+    private readonly diagnosticsDirectory: string | null = null) {}
 
   async clickRetry(identifier: string, issueId: string = identifier, timeoutMs = 60_000, perButtonMs = PER_BUTTON_REQUEST_MS): Promise<UiRetryClick> {
     let context: Awaited<ReturnType<Browser["newContext"]>> | null = null;
@@ -67,7 +97,7 @@ export class BoardUi {
       this.browser ??= this.launch();
       context = await (await this.browser).newContext({ viewport: { width: 1440, height: 1000 } });
       return await clickRetryOnPage(await context.newPage(), `${this.baseUrl}/issues/${encodeURIComponent(identifier)}`,
-        [identifier, issueId], timeoutMs, perButtonMs);
+        [identifier, issueId], timeoutMs, perButtonMs, this.diagnosticsDirectory);
     } catch (error) {
       return { clicked: false, httpStatus: null, accepted: null, error: error instanceof Error ? error.message : String(error), bannerText: null };
     } finally {
diff --git a/tests/restart-chaos/main.ts b/tests/restart-chaos/main.ts
index 7bf78e0fe9e..d31cdd29190 100644
--- a/tests/restart-chaos/main.ts
+++ b/tests/restart-chaos/main.ts
@@ -348,7 +348,8 @@ async function main(): Promise<number> {
     }
     // The instance root holds the secrets master key and the database: oracle code may not read it.
     const protectedRoots = [os.homedir(), supervisor.paths.temporaryRoot, resultsRoot];
-    board = serverEnvironment.SERVE_UI === "false" ? null : new BoardUi(supervisor.baseUrl);
+    board = serverEnvironment.SERVE_UI === "false" ? null
+      : new BoardUi(supervisor.baseUrl, undefined, path.join(waveDir, "ui-retry-diagnostics"));
     const observers = plan.tasks.map(task => new TaskObserver(task, api, lab, timeline, supervisor, protectedRoots, board));
     const pending = [...observers];
     const launched: TaskObserver[] = [];
diff --git a/tests/restart-chaos/observer.ts b/tests/restart-chaos/observer.ts
index 0bbcdc4fabd..7ba82e01fda 100644
--- a/tests/restart-chaos/observer.ts
+++ b/tests/restart-chaos/observer.ts
@@ -717,7 +717,8 @@ export class TaskObserver {
     const attempt: RetryAttempt = { at: now, observedRunId, httpStatus: null, accepted: null, error: null };
     if (this.board) {
       const click = await this.board.clickRetry(issueRef, issueId);
-      Object.assign(attempt, { via: "ui", httpStatus: click.httpStatus, accepted: click.accepted, error: click.error, bannerText: click.bannerText });
+      Object.assign(attempt, { via: "ui", httpStatus: click.httpStatus, accepted: click.accepted, error: click.error, bannerText: click.bannerText,
+        ...(click.diagnostics !== undefined ? { diagnostics: click.diagnostics } : {}) });
       if (click.accepted) attempt.acceptedAt = Math.max(now, Date.now());
       return attempt;
     }
diff --git a/tests/restart-chaos/types.ts b/tests/restart-chaos/types.ts
index 34286455798..58d82c4fd65 100644
--- a/tests/restart-chaos/types.ts
+++ b/tests/restart-chaos/types.ts
@@ -252,6 +252,7 @@ export interface RetryAttempt {
   error: string | null;
   via?: "ui" | "api";
   bannerText?: string | null;
+  diagnostics?: { screenshot: string | null; dom: string | null } | null;
 }
 
 export const UI_RETRY_BUTTON_MISSING = "ui_retry_button_missing";