MAESTRO: add file drop e2e coverage

Auto Run Docs/SpecKit-web-header-analyzer-Phase-10-Playwright-E2E.md

@@ -70,7 +70,7 @@ All tasks in this phase are parallelizable [P] since they are independent E2E sp
 
 - [x] T054 Create Page Object Model in `frontend/e2e/pages/analyzer-page.ts` — encapsulates all page interactions: `pasteHeaders(text)`, `dropFile(path)`, `clickAnalyse()`, `pressCtrlEnter()`, `selectTests(ids)`, `deselectAll()`, `selectAll()`, `toggleDns()`, `toggleDecodeAll()`, `waitForResults()`, `getResultCards()`, `expandCard(index)`, `collapseCard(index)`, `searchReport(query)`, `exportJson()`, `exportHtml()`, `clearCache()`, `getCaptchaModal()`. Copy test fixture files to `frontend/e2e/fixtures/sample-headers.txt` and `frontend/e2e/fixtures/sample.eml`
 - [x] T055 [P] Create `frontend/e2e/paste-and-analyse.spec.ts` — test US1+US3+US4 primary flow: paste sample headers → click Analyse → verify progress indicator appears with test names → verify report renders with severity-coloured cards → expand/collapse a card → verify hop chain visualisation rendered. Also test Ctrl+Enter keyboard shortcut triggers analysis. Assert on UI effects of SSE progress (progress bar increments, test name updates)
-- [ ] T056 [P] Create `frontend/e2e/file-drop.spec.ts` — test US1 file drop flow: dispatch synthetic DataTransfer+drop events on drop zone with `.eml` fixture → verify textarea auto-populates with header content → click Analyse → verify report renders. Test rejection of unsupported file types (e.g., `.pdf`)
+- [x] T056 [P] Create `frontend/e2e/file-drop.spec.ts` — test US1 file drop flow: dispatch synthetic DataTransfer+drop events on drop zone with `.eml` fixture → verify textarea auto-populates with header content → click Analyse → verify report renders. Test rejection of unsupported file types (e.g., `.pdf`)
 - [ ] T057 [P] Create `frontend/e2e/test-selection.spec.ts` — test US2: open test selector → verify 106+ tests listed → click Deselect All → select 3 specific tests → analyse → verify only 3 results in report. Test search/filter narrows visible tests. Test DNS and decode-all toggle states persist through analysis
 - [ ] T058 [P] Create `frontend/e2e/report-interaction.spec.ts` — test US4 report features: expand all cards → collapse all → search for a term → verify filtered results → clear search → export JSON → verify downloaded file is valid JSON. Export HTML → verify downloaded file contains styled content
 - [ ] T059 [P] Create `frontend/e2e/browser-cache.spec.ts` — test US5: complete analysis → reload page → verify headers and results restored from cache → click Clear Cache → verify input and report cleared → reload → verify empty state

frontend/e2e/file-drop.spec.ts

@@ -0,0 +1,60 @@
+import { test, expect } from "@playwright/test";
+import fs from "fs/promises";
+import path from "path";
+
+import { AnalyzerPage } from "./pages/analyzer-page";
+
+const emlPath = path.resolve(__dirname, "fixtures/sample.eml");
+
+const extractHeaderBlock = (content: string): string => {
+  const normalized = content.replace(/\r\n/g, "\n").replace(/\r/g, "\n");
+  const lines = normalized.split("\n");
+  const headerLines: string[] = [];
+
+  for (const line of lines) {
+    if (line.trim() === "") {
+      break;
+    }
+    headerLines.push(line);
+  }
+
+  if (headerLines.length === 0) {
+    return normalized.trim();
+  }
+
+  return headerLines.join("\n").trimEnd();
+};
+
+test("drop eml file populates headers and renders report", async ({ page }) => {
+  const analyzer = new AnalyzerPage(page);
+  const emlContents = await fs.readFile(emlPath, "utf8");
+  const expectedHeaders = extractHeaderBlock(emlContents);
+
+  await analyzer.goto();
+  await analyzer.dropFile(emlPath);
+
+  const headerInput = page.getByRole("textbox", { name: "Header Input" });
+  await expect(headerInput).toHaveValue(expectedHeaders);
+
+  await analyzer.clickAnalyse();
+  await analyzer.waitForResults();
+
+  await expect(analyzer.getResultCards().first()).toBeVisible();
+});
+
+test("rejects unsupported file types", async ({ page }, testInfo) => {
+  const analyzer = new AnalyzerPage(page);
+  const invalidPath = testInfo.outputPath("unsupported.pdf");
+  await fs.writeFile(invalidPath, "%PDF-1.4 fake pdf content");
+
+  await analyzer.goto();
+  await analyzer.dropFile(invalidPath, "application/pdf");
+
+  const alert = page
+    .locator('p[role="alert"]')
+    .filter({ hasText: "Only .eml or .txt files are supported." });
+  await expect(alert).toBeVisible();
+
+  const headerInput = page.getByRole("textbox", { name: "Header Input" });
+  await expect(headerInput).toHaveValue("");
+});

frontend/e2e/pages/analyzer-page.ts

@@ -2,12 +2,18 @@ import type { Download, Locator, Page } from "@playwright/test";
 import fs from "fs/promises";
 import path from "path";
 
-const resolveMimeType = (fileName: string): string => {
+const resolveMimeType = (fileName: string, override?: string): string => {
+  if (override) {
+    return override;
+  }
   const extension = path.extname(fileName).toLowerCase();
   if (extension === ".eml") {
     return "message/rfc822";
   }
-  return "text/plain";
+  if (extension === ".txt") {
+    return "text/plain";
+  }
+  return "application/octet-stream";
 };
 
 export class AnalyzerPage {
@@ -25,10 +31,10 @@ export class AnalyzerPage {
     await this.headerInput().fill(text);
   }
 
-  async dropFile(filePath: string): Promise<void> {
+  async dropFile(filePath: string, mimeTypeOverride?: string): Promise<void> {
     const resolvedPath = path.resolve(filePath);
     const fileName = path.basename(resolvedPath);
-    const mimeType = resolveMimeType(fileName);
+    const mimeType = resolveMimeType(fileName, mimeTypeOverride);
     const fileBuffer = await fs.readFile(resolvedPath);
     const base64 = fileBuffer.toString("base64");