Ask before opening a shared item in a message

The share address takes a plain form POST, which any website can make,
and the app opened whatever arrived straight into a composer. It now
shows what was shared -- the title, the start of the text and link, and
the file names -- and opens a message only when the reader chooses to.
Discarding drops it.

Confirm dialogs now put a message that is not plain text in a div, since
the summary has blocks of its own.

Three new strings, translated in all nine catalogs.

web/src/lib/__tests__/shareTarget.test.ts

@@ -1,5 +1,5 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
-import { collectShare, shareBody, SHARE_MAX_AGE_MS } from "@/lib/shareTarget";
+import { shareSummary, collectShare, shareBody, SHARE_MAX_AGE_MS } from "@/lib/shareTarget";
 import { SW_CACHE_NAME } from "@/lib/sw/swCache";
 
 /**
@@ -112,3 +112,19 @@ describe("the body a share turns into", () => {
     expect(shareBody({ text: "a thought", url: "" })).toBe("a thought");
   });
 });
+
+describe("shareSummary", () => {
+  const file = (name: string) => new File(["x"], name);
+  it("gives the title, the text and link together, and the file names", () => {
+    expect(shareSummary({ title: " Trip ", text: "See this", url: "https://example.com", files: [file("a.jpg")] })).toEqual({
+      title: "Trip",
+      preview: "See this https://example.com",
+      files: ["a.jpg"],
+    });
+  });
+  it("shortens a long text rather than showing all of it", () => {
+    const { preview } = shareSummary({ title: "", text: "word ".repeat(100), url: "", files: [] });
+    expect(preview.length).toBeLessThanOrEqual(160);
+    expect(preview.endsWith("…")).toBe(true);
+  });
+});

web/src/lib/shareTarget.ts

@@ -117,3 +117,17 @@ export function shareBody(share: Pick<SharedContent, "text" | "url">): string {
   if (!url || text.includes(url)) return text;
   return text ? `${text}\n\n${url}` : url;
 }
+
+/**
+ * What a share holds, in the few words the confirmation shows.
+ *
+ * Only what the reader needs to recognize it as theirs: the title, the start
+ * of the text or link, and the names of the files. It is shown before any of
+ * it goes near a message, because the page cannot tell a share the reader
+ * made from one a website posted at the same address (#375 review).
+ */
+export function shareSummary(share: SharedContent): { title: string; preview: string; files: string[] } {
+  const body = [share.text, share.url].map((s) => s.trim()).filter(Boolean).join(" ");
+  const preview = body.length > 160 ? `${body.slice(0, 157).trimEnd()}…` : body;
+  return { title: share.title.trim(), preview, files: share.files.map((f) => f.name) };
+}

web/src/locales/de.ts

@@ -1190,6 +1190,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Neue Nachricht",
+    "Start a new message with what was shared?": "Neue Nachricht mit dem geteilten Inhalt beginnen?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "Es wurde etwas mit ihasmail geteilt. Gesendet wird erst, wenn Sie „Senden“ wählen. Wenn Sie dies nicht gerade selbst geteilt haben, verwerfen Sie es.",
+    "Start a message": "Nachricht beginnen",
     "New mail": "Neue E-Mail",
     "Could not do that — open ihasmail and try again": "Nicht möglich – öffnen Sie ihasmail und versuchen Sie es erneut",
     "Sending…": "Wird gesendet…",

web/src/locales/es.ts

@@ -1163,6 +1163,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Mensaje nuevo",
+    "Start a new message with what was shared?": "¿Empezar un mensaje nuevo con lo que se ha compartido?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "Se ha compartido algo con ihasmail. No se envía nada hasta que elija Enviar. Si no acaba de compartirlo usted, descártelo.",
+    "Start a message": "Empezar mensaje",
     "New mail": "Correo nuevo",
     "Could not do that — open ihasmail and try again": "No se pudo hacer eso: abra ihasmail e inténtelo de nuevo",
     "Sending…": "Enviando…",

web/src/locales/fr.ts

@@ -1168,6 +1168,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Nouveau message",
+    "Start a new message with what was shared?": "Commencer un nouveau message avec le contenu partagé ?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "Un contenu a été partagé avec ihasmail. Rien n'est envoyé tant que vous n'avez pas choisi Envoyer. Si vous ne venez pas de le partager, abandonnez-le.",
+    "Start a message": "Commencer un message",
     "New mail": "Nouveau courrier",
     "Could not do that — open ihasmail and try again": "Impossible : ouvrez ihasmail et réessayez",
     "Sending…": "Envoi…",

web/src/locales/ja.ts

@@ -1171,6 +1171,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "新規メール",
+    "Start a new message with what was shared?": "共有された内容で新規メールを作成しますか？",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "ihasmail に何かが共有されました。「送信」を選ぶまで何も送信されません。共有した覚えがない場合は破棄してください。",
+    "Start a message": "メールを作成",
     "New mail": "新着メール",
     "Could not do that — open ihasmail and try again": "実行できませんでした - ihasmail を開いてやり直してください",
     "Sending…": "送信中…",

web/src/locales/nl.ts

@@ -1161,6 +1161,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Nieuw bericht",
+    "Start a new message with what was shared?": "Een nieuw bericht beginnen met wat is gedeeld?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "Er is iets met ihasmail gedeeld. Er wordt niets verzonden totdat u Verzenden kiest. Hebt u dit niet zelf zojuist gedeeld, gooi het dan weg.",
+    "Start a message": "Bericht beginnen",
     "New mail": "Nieuwe e-mail",
     "Could not do that — open ihasmail and try again": "Dat lukte niet — open ihasmail en probeer het opnieuw",
     "Sending…": "Bezig met verzenden…",

web/src/locales/pt-BR.ts

@@ -1166,6 +1166,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Nova mensagem",
+    "Start a new message with what was shared?": "Iniciar uma nova mensagem com o que foi compartilhado?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "Algo foi compartilhado com o ihasmail. Nada é enviado até você escolher Enviar. Se não foi você que acabou de compartilhar, descarte.",
+    "Start a message": "Iniciar mensagem",
     "New mail": "Novo e-mail",
     "Could not do that — open ihasmail and try again": "Não foi possível fazer isso — abra o ihasmail e tente novamente",
     "Sending…": "Enviando…",

web/src/locales/ru.ts

@@ -1165,6 +1165,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Новое письмо",
+    "Start a new message with what was shared?": "Начать новое письмо с полученным содержимым?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "В ihasmail что-то передали через «Поделиться». Ничего не отправится, пока вы не нажмёте «Отправить». Если вы только что ничего не передавали, нажмите «Не сохранять».",
+    "Start a message": "Начать письмо",
     "New mail": "Новое письмо",
     "Could not do that — open ihasmail and try again": "Не удалось — откройте ihasmail и повторите попытку",
     "Sending…": "Отправка…",

web/src/locales/uk.ts

@@ -1159,6 +1159,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "Новий лист",
+    "Start a new message with what was shared?": "Почати новий лист з отриманим вмістом?",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "До ihasmail щось передали через «Поділитися». Нічого не буде надіслано, доки ви не натиснете «Надіслати». Якщо ви щойно нічого не передавали, натисніть «Не зберігати».",
+    "Start a message": "Почати лист",
     "New mail": "Новий лист",
     "Could not do that — open ihasmail and try again": "Не вдалося — відкрийте ihasmail і повторіть спробу",
     "Sending…": "Надсилання…",

web/src/locales/zh-Hans.ts

@@ -1170,6 +1170,9 @@ export const catalog: Catalog = {
 
     // ── Composer status, calendar title ────────────────────────────────
     "New message": "新邮件",
+    "Start a new message with what was shared?": "用共享的内容新建邮件吗？",
+    "Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.": "有内容被共享到 ihasmail。在您选择“发送”之前不会发送任何内容。如果不是您刚才共享的，请放弃。",
+    "Start a message": "新建邮件",
     "New mail": "新邮件",
     "Could not do that — open ihasmail and try again": "无法执行 — 请打开 ihasmail 后重试",
     "Sending…": "正在发送…",

web/src/styles/app.css

@@ -2418,3 +2418,7 @@ button.dp-open:disabled { cursor: default; opacity: .5; }
 .ev-resize { position: absolute; left: 0; right: 0; bottom: 0; height: 8px; cursor: ns-resize; touch-action: none; }
 .ev-resize::after { content: ""; position: absolute; left: 50%; bottom: 2px; width: 18px; height: 2px; margin-left: -9px; border-radius: 2px; background: currentColor; opacity: 0; }
 .ev-block:hover .ev-resize::after { opacity: .5; }
+
+/* What arrived from the operating system's share sheet, shown before it is opened. */
+.share-summary { margin: 0 0 8px; padding-left: 1ex; border-left: 2px solid var(--border-strong); color: var(--fg-muted); overflow-wrap: anywhere; }
+.share-summary-files { margin: 0 0 8px; padding-left: 1.2em; color: var(--fg-muted); overflow-wrap: anywhere; }

web/src/ui/dialog.tsx

@@ -185,7 +185,8 @@ export function ConfirmHost() {
         )
       }
     >
-      {req.message && <p style={{ marginTop: 0 }}>{req.message}</p>}
+      {/* A paragraph for text; a block for anything with blocks of its own in it. */}
+      {req.message && (typeof req.message === "string" ? <p style={{ marginTop: 0 }}>{req.message}</p> : <div style={{ marginTop: 0 }}>{req.message}</div>)}
       {req.kind === "choice" && (
         <div className="dialog-choices">
           {req.choices?.map((c) => (

web/src/views/AppShell.tsx

@@ -17,6 +17,7 @@ import { ShortcutsDialog, useGlobalShortcuts } from "./Shortcuts";
 import { MailboxPicker } from "./mail/MailboxPicker";
 import { formatSize } from "@/lib/format";
 import { collectShare } from "@/lib/shareTarget";
+import { offerShare } from "./ShareOffer";
 import { TranslateBoundary } from "@/ui/TranslateBoundary";
 import { t } from "@/lib/i18n";
 import { hasAdministration } from "@/lib/admin/adminAccess";
@@ -119,11 +120,12 @@ export function AppShell({ children }: { children: ReactNode }) {
    * `addFiles` uploads as it goes, and there is nothing to upload to until the
    * session is in place. AppShell only exists once there is one.
    */
+  // Asked about first, not opened straight away: see `offerShare`.
   useEffect(() => {
-    void collectShare().then((share) => {
+    void collectShare().then(async (share) => {
       if (!share) return;
-      openShare(share);
       if (new URLSearchParams(window.location.search).has("share")) navigate("/mail", { replace: true });
+      await offerShare(share, openShare);
     });
   }, [openShare, navigate]);
 

web/src/views/ShareOffer.tsx

@@ -0,0 +1,45 @@
+import { shareSummary, type SharedContent } from "@/lib/shareTarget";
+import { confirmDialog } from "@/ui/dialog";
+import { t } from "@/lib/i18n";
+
+/**
+ * Ask before a share becomes a message.
+ *
+ * The share address takes a plain form POST, so any website can send one, and
+ * the page cannot tell that from a share the reader made. Nothing would be
+ * sent without them pressing Send, but a composer that appears full of
+ * somebody else's text and files is still something to be asked about first.
+ */
+export async function offerShare(share: SharedContent, open: (share: SharedContent) => unknown): Promise<boolean> {
+  const yes = await confirmDialog({
+    title: t("Start a new message with what was shared?"),
+    message: <ShareSummary share={share} />,
+    confirmLabel: t("Start a message"),
+    cancelLabel: t("Discard"),
+  });
+  if (yes) open(share);
+  return yes;
+}
+
+/** What arrived, so the reader can tell whether it is theirs. */
+function ShareSummary({ share }: { share: SharedContent }) {
+  const { title, preview, files } = shareSummary(share);
+  return (
+    <div>
+      {(title || preview) && (
+        <blockquote className="share-summary notranslate" translate="no">
+          {title && <strong>{title}</strong>}
+          {title && preview && <br />}
+          {preview}
+        </blockquote>
+      )}
+      {files.length > 0 && (
+        <ul className="share-summary-files notranslate" translate="no">
+          {files.slice(0, 5).map((name, i) => <li key={`${name}-${i}`}>{name}</li>)}
+          {files.length > 5 && <li>…</li>}
+        </ul>
+      )}
+      <p>{t("Something was shared with ihasmail. Nothing is sent until you choose Send. If you didn't just share this, discard it.")}</p>
+    </div>
+  );
+}

web/src/views/__tests__/share-offer.test.tsx

@@ -0,0 +1,69 @@
+import { act } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { ConfirmHost } from "@/ui/dialog";
+import { offerShare } from "../ShareOffer";
+import type { SharedContent } from "@/lib/shareTarget";
+
+(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+/**
+ * A share becomes a message only when the reader says so. The share address
+ * takes a plain form POST, which any website can make.
+ */
+
+const share: SharedContent = {
+  title: "Quarterly figures",
+  text: "Have a look at these before Friday",
+  url: "https://example.com/q3",
+  files: [new File(["x"], "q3.xlsx"), new File(["y"], "notes.txt")],
+};
+
+let host: HTMLDivElement;
+let root: Root;
+
+beforeEach(() => {
+  host = document.createElement("div");
+  document.body.appendChild(host);
+  root = createRoot(host);
+  act(() => root.render(<ConfirmHost />));
+});
+
+afterEach(() => {
+  act(() => root.unmount());
+  host.remove();
+  document.body.innerHTML = "";
+});
+
+const button = (label: string) => [...document.querySelectorAll("button")].find((b) => b.textContent?.trim() === label);
+
+describe("offering a share", () => {
+  it("shows what arrived before anything is opened", async () => {
+    const open = vi.fn();
+    let pending!: Promise<boolean>;
+    await act(async () => {
+      pending = offerShare(share, open);
+    });
+    const text = document.body.textContent ?? "";
+    expect(text).toContain("Start a new message with what was shared?");
+    expect(text).toContain("Quarterly figures");
+    expect(text).toContain("Have a look at these before Friday https://example.com/q3");
+    expect(text).toContain("q3.xlsx");
+    expect(text).toContain("notes.txt");
+    expect(open).not.toHaveBeenCalled();
+    await act(async () => button("Start a message")!.click());
+    expect(await pending).toBe(true);
+    expect(open).toHaveBeenCalledWith(share);
+  });
+
+  it("opens nothing when discarded", async () => {
+    const open = vi.fn();
+    let pending!: Promise<boolean>;
+    await act(async () => {
+      pending = offerShare(share, open);
+    });
+    await act(async () => button("Discard")!.click());
+    expect(await pending).toBe(false);
+    expect(open).not.toHaveBeenCalled();
+  });
+});