diff --git a/bundled-addons/pdf-editor/addon.json b/bundled-addons/pdf-editor/addon.json
index af2dbb9..8b88ad5 100644
--- a/bundled-addons/pdf-editor/addon.json
+++ b/bundled-addons/pdf-editor/addon.json
@@ -1,8 +1,8 @@
 {
   "id": "pdf-editor",
   "name": "PDF Editor",
-  "version": "0.3.1",
-  "description": "Open a PDF in a full tab: read it, mark it up with highlight, underline, strike-through, pen, shapes, arrows, text and a drawn signature, then move, resize, restyle or delete anything you placed. Reorder, rotate or drop pages, fill in form fields, redact for real, and save a new copy. Marks are written into the saved file as real PDF content. The original is never touched.",
+  "version": "0.4.0",
+  "description": "Open a PDF in a full tab: read it, mark it up with highlight, underline, strike-through, pen, shapes, arrows, text and a drawn signature, then move, resize, restyle or delete anything you placed. Reorder, rotate or drop pages, fill in form fields, redact for real, and save a new copy. Build a PDF from pictures, one page each, or join several PDFs into one. Marks are written into the saved file as real PDF content. The original is never touched.",
   "author": "Silent Mode",
   "icon": "data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNCAyNCI+PHBhdGggZD0iTTYgMmg4bDYgNnYxMmEyIDIgMCAwIDEtMiAySDZhMiAyIDAgMCAxLTItMlY0YTIgMiAwIDAgMSAyLTJ6IiBmaWxsPSIjZGMyNjI2Ii8+PHBhdGggZD0iTTE0IDJ2Nmg2eiIgZmlsbD0iIzk5MWIxYiIvPjx0ZXh0IHg9IjEyIiB5PSIxNyIgdGV4dC1hbmNob3I9Im1pZGRsZSIgZm9udC1mYW1pbHk9InN5c3RlbS11aSwtYXBwbGUtc3lzdGVtLHNhbnMtc2VyaWYiIGZvbnQtc2l6ZT0iNS41IiBmb250LXdlaWdodD0iODAwIiBmaWxsPSIjZmZmIj5QREY8L3RleHQ+PC9zdmc+",
   "main": "index.js",
@@ -11,7 +11,7 @@
     "title": "PDF Editor",
     "icon": "data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNCAyNCI+PHBhdGggZD0iTTYgMmg4bDYgNnYxMmEyIDIgMCAwIDEtMiAySDZhMiAyIDAgMCAxLTItMlY0YTIgMiAwIDAgMSAyLTJ6IiBmaWxsPSIjZGMyNjI2Ii8+PHBhdGggZD0iTTE0IDJ2Nmg2eiIgZmlsbD0iIzk5MWIxYiIvPjx0ZXh0IHg9IjEyIiB5PSIxNyIgdGV4dC1hbmNob3I9Im1pZGRsZSIgZm9udC1mYW1pbHk9InN5c3RlbS11aSwtYXBwbGUtc3lzdGVtLHNhbnMtc2VyaWYiIGZvbnQtc2l6ZT0iNS41IiBmb250LXdlaWdodD0iODAwIiBmaWxsPSIjZmZmIj5QREY8L3RleHQ+PC9zdmc+",
     "items": [
-      { "id": "open", "label": "Open a PDF…" }
+      { "id": "open", "label": "Open the editor" }
     ]
   },
   "context-menu-items": [
diff --git a/bundled-addons/pdf-editor/editor.css b/bundled-addons/pdf-editor/editor.css
index 79e1e57..aee789a 100644
--- a/bundled-addons/pdf-editor/editor.css
+++ b/bundled-addons/pdf-editor/editor.css
@@ -139,7 +139,24 @@ body[data-dragover="1"] .dropzone { display: flex; pointer-events: none;
 body[data-dragover="1"] .dz-inner { border-color: rgb(from var(--acid) r g b / .8); color: var(--ink); }
 .dz-inner svg { width: 48px; height: 48px; margin-bottom: 10px; }
 .dz-title { font-size: 15px; color: var(--ink); font-weight: 600; }
-.dz-sub { margin-top: 5px; }
+.dz-sub { margin-top: 5px; max-width: 42ch; margin-left: auto; margin-right: auto; }
+
+/* Start-screen tiles. Hidden while a drag is in flight: during a drop the
+   drop zone is the whole target, and a row of buttons under the cursor
+   reads as somewhere to aim, which it is not. */
+.dz-actions { display: flex; gap: 10px; margin-top: 22px; justify-content: center;
+              flex-wrap: wrap; }
+body[data-dragover="1"] .dz-actions { visibility: hidden; }
+.tile { display: flex; flex-direction: column; align-items: flex-start; gap: 3px;
+        width: 176px; padding: 13px 14px; text-align: left; cursor: pointer;
+        background: var(--bg); color: var(--ink); border: 1px solid var(--line);
+        border-radius: 10px; font: inherit; }
+.tile:hover { border-color: rgb(from var(--acid) r g b / .55);
+              background: rgb(from var(--acid) r g b / .06); }
+.tile:focus-visible { outline: 2px solid var(--acid); outline-offset: 2px; }
+.tile svg { width: 22px; height: 22px; margin: 0 0 5px; color: var(--acid); }
+.tile-t { font-weight: 600; font-size: 13px; }
+.tile-s { font-size: 11.5px; color: var(--dim); line-height: 1.35; }
 .linkish { background: none; border: none; padding: 0; font: inherit; cursor: pointer;
            color: var(--acid); text-decoration: underline; }
 
diff --git a/bundled-addons/pdf-editor/editor.html b/bundled-addons/pdf-editor/editor.html
index 3ca06fc..dafbde7 100644
--- a/bundled-addons/pdf-editor/editor.html
+++ b/bundled-addons/pdf-editor/editor.html
@@ -141,7 +141,31 @@
           <path d="M12 6h16l8 8v28H12z"/><path d="M28 6v8h8"/><path d="M24 22v12M19 29l5 5 5-5"/>
         </svg>
         <div class="dz-title">Drop a PDF here</div>
-        <div class="dz-sub">or <button class="linkish" id="open2">choose a file</button></div>
+        <div class="dz-sub">Drop pictures instead and they become the pages. Drop several PDFs and they join up.</div>
+        <div class="dz-actions">
+          <button class="tile" id="start-open" type="button">
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+              <path d="M6 3h8l4 4v14H6z"/><path d="M14 3v4h4"/><path d="M9 12h6M9 16h6"/>
+            </svg>
+            <span class="tile-t">Open a PDF</span>
+            <span class="tile-s">Read it, mark it up, fill it in, sign it</span>
+          </button>
+          <button class="tile" id="start-images" type="button">
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+              <rect x="3" y="5" width="14" height="11" rx="1.5"/><circle cx="7.5" cy="9" r="1.3"/>
+              <path d="M3.5 14l3.5-3 3 2.5 2.5-2 4 4.5"/><path d="M19 9v10H8"/>
+            </svg>
+            <span class="tile-t">Pictures to PDF</span>
+            <span class="tile-s">One page per picture, in the order you pick</span>
+          </button>
+          <button class="tile" id="start-merge" type="button">
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+              <path d="M4 4h7v7H4z"/><path d="M13 13h7v7h-7z"/><path d="M11 7.5h4a2 2 0 0 1 2 2V13"/><path d="M15 11l2 2 2-2"/>
+            </svg>
+            <span class="tile-t">Join PDFs</span>
+            <span class="tile-s">Several files, end to end, as one document</span>
+          </button>
+        </div>
       </div>
     </div>
   </div>
@@ -232,6 +256,33 @@
     </div>
   </div>
 
+  <div class="modal" id="modal-images" hidden>
+    <h2>Pictures to PDF</h2>
+    <p id="images-count"></p>
+    <div class="mrow">
+      <label class="mfield">Page
+        <select id="images-page">
+          <option value="fit" selected>Shaped like the picture</option>
+          <option value="a4">A4</option>
+          <option value="letter">Letter</option>
+        </select>
+      </label>
+      <label class="mfield" id="images-margin-field">Border
+        <select id="images-margin">
+          <option value="0">None</option>
+          <option value="18" selected>Narrow</option>
+          <option value="48">Wide</option>
+        </select>
+      </label>
+    </div>
+    <p class="mhint" id="images-note"></p>
+    <div class="mrow">
+      <span class="spacer"></span>
+      <button class="btn wide" id="images-cancel">Cancel</button>
+      <button class="btn wide primary" id="images-go">Make the PDF</button>
+    </div>
+  </div>
+
   <div class="modal" id="modal-save" hidden>
     <h2>Save a copy</h2>
     <label class="mfield block">File name
@@ -276,6 +327,8 @@
 
 <div class="toast" id="toast"></div>
 <input type="file" id="file-input" accept="application/pdf,.pdf" hidden>
+<input type="file" id="img-input" accept="image/*" multiple hidden>
+<input type="file" id="merge-input" accept="application/pdf,.pdf" multiple hidden>
 <a id="download-link" style="display:none"></a>
 
 <script type="module" src="editor.js"></script>
diff --git a/bundled-addons/pdf-editor/editor.js b/bundled-addons/pdf-editor/editor.js
index 2e2818a..a7d5b03 100644
--- a/bundled-addons/pdf-editor/editor.js
+++ b/bundled-addons/pdf-editor/editor.js
@@ -23,6 +23,7 @@ import { buildPdf, unencodableStamps, replacedRuns } from "./lib/save.js";
 import { boundsOf, clampFont } from "./lib/shape.js";
 import { reflow } from "./lib/reflow.js";
 import { buildDocx } from "./lib/docx.js";
+import { imagesToPdf, mergePdfs } from "./lib/create.js";
 
 const $ = (id) => document.getElementById(id);
 const sm = window.silentmode || null;
@@ -60,7 +61,7 @@ const session = {
   rail: null,
   tools: null,
   scratchId: null,    // set when the document came from the add-on's scratch dir
-  name: "document.pdf",
+  name: null,         // null until something is loaded; the chrome says so
 };
 
 // ---- chrome -----------------------------------------------------------
@@ -264,10 +265,15 @@ async function teardown() {
 }
 
 // ---- open paths -------------------------------------------------------
+// A tab that can be given files three ways — the dock, a button, a drop — has
+// to decide what a handful of files MEANS before it can act. One PDF is a
+// document to edit. Several are a document to build. Pictures are pages.
+const isPdfFile = (f) => /\.pdf$/i.test(f.name) || f.type === "application/pdf";
+const isImageFile = (f) => /^image\//.test(f.type) || /\.(png|jpe?g|webp|gif|bmp|avif|tiff?)$/i.test(f.name);
+
 async function openFile(file) {
   if (!file) return;
-  const looksPdf = /\.pdf$/i.test(file.name) || file.type === "application/pdf";
-  if (!looksPdf) { toast(`${file.name} is not a PDF`, true); return; }
+  if (!isPdfFile(file)) { toast(`${file.name} is not a PDF`, true); return; }
   if (!(await confirmDiscard())) return;
   const buf = new Uint8Array(await file.arrayBuffer());
   if (buf.subarray(0, 5).every((b, i) => b === "%PDF-".charCodeAt(i)) === false) {
@@ -277,14 +283,114 @@ async function openFile(file) {
   await loadBytes(buf, file.name);
 }
 
+async function openFiles(list) {
+  const files = [...(list || [])];
+  if (!files.length) return;
+  if (files.length === 1 && isPdfFile(files[0])) return openFile(files[0]);
+  if (files.every(isImageFile)) return fromImages(files);
+  if (files.every(isPdfFile)) return joinPdfs(files);
+  const odd = files.find((f) => !isPdfFile(f) && !isImageFile(f));
+  toast(odd ? `${odd.name} is neither a PDF nor a picture` : "Drop PDFs or pictures, not both at once", true);
+}
+
+/**
+ * Pictures in, one page each.
+ *
+ * The result is a document that exists only here until it is saved, so it is
+ * marked unsaved the moment it opens — otherwise closing the tab would throw
+ * away work that never touched a disk, without asking.
+ */
+async function fromImages(files) {
+  if (!(await confirmDiscard())) return;
+  $("images-count").textContent =
+    `${files.length} picture${files.length === 1 ? "" : "s"}, one per page, in the order your file browser listed them.`;
+  syncImagesDialog();
+  if (!(await openModal("modal-images"))) return;
+  const page = $("images-page").value;
+  const margin = Number($("images-margin").value) || 0;
+  setBusy(true, "Building…");
+  let out;
+  try {
+    out = await imagesToPdf(files, {
+      page, margin,
+      onProgress: (i, n) => setBusy(true, `Adding picture ${i} of ${n}…`),
+    });
+  } catch (e) {
+    setBusy(false);
+    status(`Could not build a PDF: ${e?.message || e}`, true);
+    toast(`Could not build a PDF: ${e?.message || e}`, true);
+    return;
+  }
+  if (!(await loadBytes(new Uint8Array(out.bytes), "pictures.pdf"))) return;
+  afterBuild(`${out.pages} page${out.pages === 1 ? "" : "s"} from your pictures`, out.failed);
+}
+
+/**
+ * Several PDFs, end to end. Order is the order they were handed over; the
+ * page rail is where it gets fixed, which is the honest answer to "can I
+ * reorder them" — yes, once they are one document.
+ */
+async function joinPdfs(files) {
+  if (!(await confirmDiscard())) return;
+  setBusy(true, "Joining…");
+  let out;
+  try {
+    out = await mergePdfs(files, { onProgress: (i, n) => setBusy(true, `Reading file ${i} of ${n}…`) });
+  } catch (e) {
+    setBusy(false);
+    status(`Could not join those files: ${e?.message || e}`, true);
+    toast(`Could not join those files: ${e?.message || e}`, true);
+    return;
+  }
+  if (!(await loadBytes(new Uint8Array(out.bytes), "joined.pdf"))) return;
+  const from = out.parts.map((p) => `${p.name} (${p.pages})`).join(", ");
+  afterBuild(`${out.pages} pages from ${out.parts.length} files · ${from}`, out.failed);
+  if (out.hadForms) {
+    toast("Form fields do not survive joining — the pages kept their look, not their fields", true);
+  }
+}
+
+// Shared tail for the two build paths: say where the document came from, say
+// that it is not on disk yet, and name anything that had to be skipped.
+function afterBuild(what, failed) {
+  session.model.markUnsaved();
+  paintChrome();
+  status(`${what} · not saved yet — use Save a copy`);
+  if (failed && failed.length) {
+    toast(`Skipped ${failed.length} file${failed.length === 1 ? "" : "s"}: ${failed.map((f) => f.name).join(", ")}`, true);
+  }
+}
+
+// A page shaped like its picture has no border to set, so the field goes away
+// rather than sitting there doing nothing.
+function syncImagesDialog() {
+  const fit = $("images-page").value === "fit";
+  $("images-margin-field").hidden = fit;
+  $("images-note").textContent = fit
+    ? "Each page takes the shape of its picture, edge to edge, sized so the long side matches A4."
+    : "Each picture is centred on the page, scaled to fit inside the border. Wide pictures turn the page on its side.";
+}
+$("images-page").addEventListener("change", syncImagesDialog);
+$("images-go").addEventListener("click", () => closeModal(true));
+$("images-cancel").addEventListener("click", () => closeModal(null));
+
 $("file-input").addEventListener("change", (e) => {
   const f = e.target.files?.[0];
   e.target.value = "";
   openFile(f);
 });
+for (const [inputId, handler] of [["img-input", fromImages], ["merge-input", joinPdfs]]) {
+  $(inputId).addEventListener("change", (e) => {
+    const files = [...(e.target.files || [])];
+    e.target.value = "";
+    if (files.length) handler(files);
+  });
+}
 const pick = () => $("file-input").click();
 $("open").addEventListener("click", pick);
-$("open2").addEventListener("click", pick);
+$("start-open").addEventListener("click", pick);
+$("start-images").addEventListener("click", () => $("img-input").click());
+$("start-merge").addEventListener("click", () => $("merge-input").click());
 
 // Drag and drop anywhere in the tab.
 for (const type of ["dragenter", "dragover"]) {
@@ -303,7 +409,7 @@ window.addEventListener("drop", (e) => {
   if (![...(e.dataTransfer?.types || [])].includes("Files")) return;
   e.preventDefault();
   document.body.dataset.dragover = "";
-  openFile(e.dataTransfer.files?.[0]);
+  openFiles(e.dataTransfer.files);
 });
 
 // ---- page operations --------------------------------------------------
@@ -1101,7 +1207,7 @@ window.addEventListener("keydown", (e) => {
   } catch {}
 
   const id = new URLSearchParams(location.search).get("doc");
-  if (!id) { status("Drop a PDF here, or use Open."); paintChrome(); return; }
+  if (!id) { status("Drop a PDF or some pictures here, or pick one of the options."); paintChrome(); return; }
   if (!sm?.invoke) { status("This page has to be opened from the PDF Editor add-on.", true); return; }
   setBusy(true, "Fetching…");
   try {
diff --git a/bundled-addons/pdf-editor/index.js b/bundled-addons/pdf-editor/index.js
index 8902f0d..815f3e2 100644
--- a/bundled-addons/pdf-editor/index.js
+++ b/bundled-addons/pdf-editor/index.js
@@ -97,55 +97,21 @@ module.exports = {
     // ---- launch paths -------------------------------------------------
     // Dock → the file picker, straight away.
     //
-    // This used to open an empty editor whose own drop zone then asked for a
-    // file, which meant three clicks and two screens before the user reached
-    // their own documents: dock, menu item, Open, and only then the file
-    // browser. Asking here collapses it — the dock click IS the "open a file"
-    // gesture, so answer it with a file browser.
+    // The dock click opens the editor, and stops there.
     //
-    // The dialog is native, raised from the add-on's Node side, because a
-    // file:// page cannot open one without a user gesture of its own and a
-    // freshly-opened tab has no gesture to spend.
-    //
-    // Cancelling still lands you in the editor, empty. Someone who changed
-    // their mind about which file probably still wants the editor, and it is
-    // where drag-and-drop works.
+    // It briefly raised a native file browser instead, to save the clicks
+    // between the dock and a document. That was right while the editor had
+    // exactly one thing to offer an empty tab. It stopped being right once
+    // the start screen grew: a file browser can only answer "which PDF",
+    // and the answer is now sometimes "none of them — build one from these
+    // photos" or "weld these four together".
     api.onMessage("menu-select", async (payload) => {
       const item = String(payload && payload.id || "");
       if (item !== "open") throw new Error(`unknown menu item: ${item}`);
-      const entry = await pickPdf();
-      if (!entry) { api.openTab("editor.html"); api.log("picker cancelled — opened an empty editor"); return { ok: true, cancelled: true }; }
-      api.openTab("editor.html", { query: { doc: entry.id } });
-      api.log(`picked ${entry.name} (${entry.size} bytes) → ${entry.id}`);
-      return { ok: true, id: entry.id };
+      api.openTab("editor.html");
+      return { ok: true };
     });
 
-    /**
-     * Native open dialog, then the bytes in scratch. Returns null when the
-     * user cancels or picks something that is not a PDF.
-     */
-    async function pickPdf() {
-      const { dialog, BrowserWindow } = api.require("electron");
-      // Parent it to Theseus so the dialog is attached to the window rather
-      // than floating loose behind it.
-      const parent = BrowserWindow.getFocusedWindow() || BrowserWindow.getAllWindows()[0] || null;
-      const opts = {
-        title: "Open a PDF",
-        properties: ["openFile"],
-        filters: [{ name: "PDF documents", extensions: ["pdf"] }, { name: "All files", extensions: ["*"] }],
-      };
-      const res = parent ? await dialog.showOpenDialog(parent, opts) : await dialog.showOpenDialog(opts);
-      const file = !res.canceled && res.filePaths && res.filePaths[0];
-      if (!file) return null;
-      const stat = await fs.promises.stat(file);
-      if (stat.size > MAX_BYTES) throw new Error(`${path.basename(file)} is ${(stat.size / 1048576).toFixed(0)} MB — over the ${MAX_BYTES / 1048576} MB cap`);
-      const buf = await fs.promises.readFile(file);
-      if (buf.subarray(0, 5).toString("latin1") !== "%PDF-") {
-        throw new Error(`${path.basename(file)} does not start with a PDF header`);
-      }
-      return writeScratch(buf, safeName(path.basename(file)));
-    }
-
     // Right-click a link → fetch it here, hand the editor an id.
     api.onMessage("context-menu", async (payload) => {
       if (String(payload && payload.itemId || "") !== "open-link") return;
diff --git a/bundled-addons/pdf-editor/lib/create.js b/bundled-addons/pdf-editor/lib/create.js
new file mode 100644
index 0000000..a52bfe8
--- /dev/null
+++ b/bundled-addons/pdf-editor/lib/create.js
@@ -0,0 +1,133 @@
+// Making a PDF where there wasn't one: photos in, or several files welded
+// into one. Both paths hand back plain bytes, which the editor then opens as
+// if they had come off disk — so everything downstream (marks, page rail,
+// save, convert) works on them without knowing where they came from.
+
+import { PDFDocument } from "../vendor/pdf-lib/pdf-lib.esm.min.js";
+
+// Points, the PDF's own unit. A4 is the world's paper; Letter is North
+// America's. "fit" below means neither: the page takes the image's shape.
+export const PAGE_SIZES = {
+  a4: [595.28, 841.89],
+  letter: [612, 792],
+};
+// The long edge of a fitted page. A phone photo is 4000 px on its longest
+// side; read as points that would be a 55-inch page, technically valid and
+// useless to anyone who prints it. Mapping the long edge to A4's long edge
+// keeps the image's proportions and gives a page a printer understands.
+const FIT_LONG_EDGE = 841.89;
+
+const JPEG = [0xff, 0xd8, 0xff];
+const PNG = [0x89, 0x50, 0x4e, 0x47];
+const starts = (bytes, sig) => sig.every((b, i) => bytes[i] === b);
+
+/**
+ * pdf-lib embeds JPEG and PNG, and nothing else. Rather than refuse a WebP or
+ * a HEIC-turned-WebP screenshot, hand it to the browser — which can decode far
+ * more than pdf-lib can embed — and re-encode as PNG. Lossless, so a screenshot
+ * survives intact; a photo re-encoded this way grows, which is why anything
+ * already JPEG is passed through untouched.
+ */
+async function toEmbeddable(file) {
+  const bytes = new Uint8Array(await file.arrayBuffer());
+  if (starts(bytes, JPEG)) return { bytes, kind: "jpg" };
+  if (starts(bytes, PNG)) return { bytes, kind: "png" };
+  let bitmap;
+  try { bitmap = await createImageBitmap(file); }
+  catch { throw new Error(`${file.name} is not an image this browser can read`); }
+  const canvas = new OffscreenCanvas(bitmap.width, bitmap.height);
+  canvas.getContext("2d").drawImage(bitmap, 0, 0);
+  bitmap.close();
+  const blob = await canvas.convertToBlob({ type: "image/png" });
+  return { bytes: new Uint8Array(await blob.arrayBuffer()), kind: "png" };
+}
+
+/**
+ * One image per page, in the order given.
+ *
+ * `page` is "fit" (the page takes each image's shape), "a4" or "letter". For
+ * the two paper sizes the sheet turns landscape when the image is wider than
+ * it is tall, because a landscape photo on a portrait page is mostly margin.
+ * `margin` is in points and ignored by "fit" — the whole point of fitting the
+ * page to the image is that there is no border.
+ */
+export async function imagesToPdf(files, { page = "fit", margin = 18, onProgress } = {}) {
+  if (!files.length) throw new Error("no images given");
+  const pdf = await PDFDocument.create();
+  const failed = [];
+  let n = 0;
+  for (const file of files) {
+    onProgress?.(++n, files.length, file.name);
+    let img;
+    try {
+      const { bytes, kind } = await toEmbeddable(file);
+      img = kind === "jpg" ? await pdf.embedJpg(bytes) : await pdf.embedPng(bytes);
+    } catch (e) {
+      failed.push({ name: file.name, why: e?.message || String(e) });
+      continue;
+    }
+    if (page === "fit") {
+      const scale = FIT_LONG_EDGE / Math.max(img.width, img.height);
+      const w = img.width * scale, h = img.height * scale;
+      pdf.addPage([w, h]).drawImage(img, { x: 0, y: 0, width: w, height: h });
+      continue;
+    }
+    const [pw, ph] = PAGE_SIZES[page] || PAGE_SIZES.a4;
+    const landscape = img.width > img.height;
+    const sheet = pdf.addPage(landscape ? [ph, pw] : [pw, ph]);
+    const boxW = sheet.getWidth() - margin * 2;
+    const boxH = sheet.getHeight() - margin * 2;
+    // contain, never crop: the smaller ratio wins, and the leftover becomes
+    // an even border on the two sides that did not bind.
+    const scale = Math.min(boxW / img.width, boxH / img.height);
+    const w = img.width * scale, h = img.height * scale;
+    sheet.drawImage(img, {
+      x: (sheet.getWidth() - w) / 2,
+      y: (sheet.getHeight() - h) / 2,
+      width: w, height: h,
+    });
+  }
+  if (!pdf.getPageCount()) {
+    throw new Error(failed.length ? `none of those files could be read (${failed[0].why})` : "no pages were made");
+  }
+  return { bytes: await pdf.save(), pages: pdf.getPageCount(), failed };
+}
+
+/**
+ * Several PDFs, end to end, in the order given.
+ *
+ * Page content, annotations and links inside each document survive, because
+ * copyPages carries the whole page object across. What does NOT survive is
+ * anything that lives above the page: form fields, the outline, and
+ * attachments. Those belong to the document they came from, and merging four
+ * documents that each define a field called "name" has no correct answer.
+ * The editor says so plainly rather than silently dropping them.
+ */
+export async function mergePdfs(files, { onProgress } = {}) {
+  if (files.length < 2) throw new Error("pick at least two PDFs to merge");
+  const out = await PDFDocument.create();
+  const parts = [];
+  const failed = [];
+  let hadForms = false;
+  let n = 0;
+  for (const file of files) {
+    onProgress?.(++n, files.length, file.name);
+    try {
+      const bytes = new Uint8Array(await file.arrayBuffer());
+      // An encrypted-but-openable PDF is the common case (print/copy flags,
+      // no password). ignoreEncryption lets those through; a real
+      // password-protected file still throws, and lands in `failed`.
+      const src = await PDFDocument.load(bytes, { ignoreEncryption: true });
+      try { if (src.getForm().getFields().length) hadForms = true; } catch {}
+      const copied = await out.copyPages(src, src.getPageIndices());
+      for (const p of copied) out.addPage(p);
+      parts.push({ name: file.name, pages: copied.length });
+    } catch (e) {
+      failed.push({ name: file.name, why: e?.message || String(e) });
+    }
+  }
+  if (!out.getPageCount()) {
+    throw new Error(failed.length ? `nothing could be read (${failed[0].why})` : "no pages were copied");
+  }
+  return { bytes: await out.save(), pages: out.getPageCount(), parts, failed, hadForms };
+}
diff --git a/bundled-addons/pdf-editor/lib/model.js b/bundled-addons/pdf-editor/lib/model.js
index 0f56012..5d3e673 100644
--- a/bundled-addons/pdf-editor/lib/model.js
+++ b/bundled-addons/pdf-editor/lib/model.js
@@ -127,6 +127,10 @@ export class DocModel {
     return step.label;
   }
   markSaved() { this.savedMark = this._key(); this._emit("saved"); }
+  // A document this session BUILT — from pictures, or by joining files — has
+  // never been anywhere. It carries no marks, so the usual comparison calls
+  // it clean and closing the tab would take it away without a word.
+  markUnsaved() { this.savedMark = null; this._emit("dirty"); }
   isDirty() { return this._key() !== this.savedMark; }
 
   // ---- mutations ----------------------------------------------------