feat: troncature annoncee et lecture par fenetres des tableurs #153

- BUG-090 (#153 A8) : render_sheets() expose total_rows/total_cols,
  max_rows/max_cols et truncated ; la visionneuse affiche un bandeau
  « Feuille tronquée » (i18n FR/EN) au lieu de couper en silence, et la
  ligne d'en-têtes devient sticky (top:auto sur les numéros de ligne).
- #153 A9 : GET /api/file/{vault}/xlsx/sheet?sheet&offset&limit sert une
  fenêtre de 1 à 1000 lignes avec les vraies coordonnées A1, has_more de
  pagination et valeurs calculées A12 ; 404 feuille inconnue, 415 non-xlsx.
- Tests : TestXlsxTruncationNotice (4) + TestXlsxSheetWindow (11) avec
  contre-preuves, xlsx-viewer.test.mjs 14/14, E2E 7/7 (fixture
  sample-xlsx-large.xlsx 520 lignes), suite 1417 passed / 6 skipped,
  ruff/mypy 0, i18n parity.

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <[email protected]>

tests/frontend/xlsx-viewer.test.mjs

@@ -7,6 +7,7 @@
  *         workbook gets 409 `xlsx_lossy_content`, asks for confirmation and
  *         retries with `force: true` (or gives up when refused);
  *  - A4 : the f(x) toggle flips `allow_formula` in the save payload.
+ *  - A8 : a sheet bigger than the render caps shows the truncation notice.
  *
  * Usage: node tests/frontend/xlsx-viewer.test.mjs
  */
@@ -116,14 +117,14 @@ const sheetHtml = (value) =>
   `<tr><th class="xlsx-rownum">1</th><td data-cell="A1">${value}</td></tr>` +
   "</tbody></table></div>";
 
-function mount({ lossy = [] } = {}) {
+function mount({ lossy = [], sheet = {} } = {}) {
   const area = document.getElementById("content-area");
   area.innerHTML = "";
   renderXlsxViewer(area, {
     vault: "V",
     path: "data.xlsx",
     is_xlsx: true,
-    xlsx_sheets: [{ name: "Feuille1", html: sheetHtml("100") }],
+    xlsx_sheets: [{ name: "Feuille1", html: sheetHtml("100"), ...sheet }],
     xlsx_lossy_features: lossy,
   });
   return area;
@@ -268,6 +269,49 @@ await test("a non-409 failure is not retried", async () => {
   assert.equal(area.querySelectorAll("td.xlsx-dirty").length, 1);
 });
 
+// ── A8 — truncation notice ───────────────────────────────────────────────────
+
+await test("no notice when the sheet fits within the render caps", () => {
+  const area = mount({
+    sheet: { rows: 500, cols: 40, total_rows: 500, total_cols: 40, max_rows: 500, max_cols: 40, truncated: false },
+  });
+  assert.equal(area.querySelector(".xlsx-truncated"), null);
+});
+
+await test("notice states the cap and the real size of a truncated sheet", () => {
+  const area = mount({
+    sheet: { rows: 500, cols: 12, total_rows: 1200, total_cols: 12, max_rows: 500, max_cols: 40, truncated: true },
+  });
+  const note = area.querySelector(".xlsx-truncated");
+  assert.ok(note, "notice absent");
+  const txt = note.textContent;
+  assert.ok(txt.includes(FR["xlsx.truncated_title"]), txt);
+  // {shown} is the CAP (500), not the post-trim row count: a sparse sheet
+  // renders 1 row but the view still reaches 500 of them.
+  const expected = FR["xlsx.truncated_rows"].replace("{shown}", "500").replace("{total}", "1200");
+  assert.ok(txt.includes(expected), `${txt} !includes ${expected}`);
+  // Nothing to say about the columns here (12 < 40).
+  assert.ok(!txt.includes(FR["xlsx.truncated_cols"]), txt);
+});
+
+await test("notice mentions both axes when rows AND columns overflow", () => {
+  const area = mount({
+    sheet: { rows: 1, cols: 40, total_rows: 501, total_cols: 45, max_rows: 500, max_cols: 40, truncated: true },
+  });
+  const txt = area.querySelector(".xlsx-truncated").textContent;
+  assert.ok(
+    txt.includes(FR["xlsx.truncated_cols"].replace("{shown}", "40").replace("{total}", "45")),
+    txt
+  );
+});
+
+await test("a payload without the dimensions shows no notice", () => {
+  // Backward compatibility: an older cached response must not produce "NaN".
+  const area = mount({ sheet: { name: "Feuille1" } });
+  assert.equal(area.querySelector(".xlsx-truncated"), null);
+  assert.ok(!area.textContent.includes("NaN"));
+});
+
 // ── Report ──────────────────────────────────────────────────────────────────
 console.log(`\n${passCount}/${testCount} tests passed\n`);
 process.exit(passCount === testCount ? 0 : 1);