feat(messaging-ui): mail attachment download + scrollable reader (0.1.1)

- Attachment chips in the mail reader are now clickable: new InboxAdapter
  downloadAttachment() resolves a short-lived URL, opened in a new tab.
- Mail reader scrolls again: convert the .miu-detail/.miu-mail height:100%
  chain to flex fill so a long thread scrolls within the pane instead of
  being clipped. MockInboxAdapter implements download. Bump to 0.1.1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/iios-messaging-ui/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@insignia/iios-messaging-ui",
-  "version": "0.1.0",
+  "version": "0.1.1",
   "type": "module",
   "main": "dist/index.js",
   "module": "dist/index.js",

packages/iios-messaging-ui/src/adapters/mock-inbox.ts

@@ -88,6 +88,11 @@ export class MockInboxAdapter implements InboxAdapter {
     return { contentRef: `mock/${this.seq++}`, mimeType: file.type || 'application/octet-stream', sizeBytes: file.size, filename: file.name };
   }
 
+  async downloadAttachment(attachment: MailAttachment): Promise<string> {
+    // Demo: no real bytes — hand back a data URL so the click resolves without a network call.
+    return `data:${attachment.mimeType};base64,`;
+  }
+
   async directory(): Promise<MailPerson[]> {
     return [...PEOPLE];
   }

packages/iios-messaging-ui/src/inbox/adapter.ts

@@ -22,6 +22,10 @@ export interface InboxAdapter {
   /** Upload a file to storage, returning a reference to send with a reply/compose. */
   uploadAttachment?(file: File): Promise<MailAttachment>;
 
+  /** Resolve a short-lived URL to view/download an attachment. Absent => attachment chips are
+   *  shown but not clickable. */
+  downloadAttachment?(attachment: MailAttachment): Promise<string>;
+
   // ── Compose (optional) — absent hides the "New message" affordance ──
   /** People you can compose an in-app message to. */
   directory?(): Promise<MailPerson[]>;

packages/iios-messaging-ui/src/inbox/hooks.ts

@@ -60,6 +60,8 @@ export interface MailThreadState {
   reply: (content: string, attachment?: MailAttachment) => Promise<void>;
   canAttach: boolean;
   upload: (file: File) => Promise<MailAttachment>;
+  canDownload: boolean;
+  download: (attachment: MailAttachment) => Promise<string>;
   refetch: () => void;
 }
 
@@ -113,8 +115,25 @@ export function useMailThread(threadId: string | null): MailThreadState {
     },
     [adapter],
   );
+  const download = useCallback(
+    async (attachment: MailAttachment) => {
+      if (!adapter.downloadAttachment) throw new Error('attachment download is not supported by this adapter');
+      return adapter.downloadAttachment(attachment);
+    },
+    [adapter],
+  );
 
-  return { messages, loading, error, reply, canAttach: typeof adapter.uploadAttachment === 'function', upload, refetch };
+  return {
+    messages,
+    loading,
+    error,
+    reply,
+    canAttach: typeof adapter.uploadAttachment === 'function',
+    upload,
+    canDownload: typeof adapter.downloadAttachment === 'function',
+    download,
+    refetch,
+  };
 }
 
 export interface ComposeState {

packages/iios-messaging-ui/src/inbox/inbox.tsx

@@ -117,7 +117,7 @@ function Detail({ item, onTransition }: { item: InboxItem; onTransition: (state:
 
 /** Read a mail thread (HTML in a sandboxed iframe) + reply. */
 export function MailReader({ threadId, subject }: { threadId: string; subject: string }) {
-  const { messages, loading, error, reply, canAttach, upload } = useMailThread(threadId);
+  const { messages, loading, error, reply, canAttach, upload, canDownload, download } = useMailThread(threadId);
   const [draft, setDraft] = useState('');
   const [sending, setSending] = useState(false);
   const [pending, setPending] = useState<MailAttachment | null>(null);
@@ -125,6 +125,15 @@ export function MailReader({ threadId, subject }: { threadId: string; subject: s
   const [attachErr, setAttachErr] = useState<string | null>(null);
   const fileRef = useRef<HTMLInputElement>(null);
 
+  async function openAttachment(att: MailAttachment): Promise<void> {
+    try {
+      const url = await download(att);
+      window.open(url, '_blank', 'noopener,noreferrer');
+    } catch (err) {
+      setAttachErr(err instanceof Error ? err.message : String(err));
+    }
+  }
+
   async function pick(e: React.ChangeEvent<HTMLInputElement>): Promise<void> {
     const file = e.target.files?.[0];
     e.target.value = '';
@@ -176,7 +185,13 @@ export function MailReader({ threadId, subject }: { threadId: string; subject: s
               <div className="miu-mail-text">{m.text}</div>
             ) : null}
             {m.attachment ? (
+              canDownload ? (
+                <button type="button" className="miu-attach-chip miu-attach-dl" onClick={() => void openAttachment(m.attachment!)} title="Download">
+                  📎 {m.attachment.filename ?? 'attachment'}{m.attachment.sizeBytes ? ` · ${fmtBytes(m.attachment.sizeBytes)}` : ''} ↓
+                </button>
+              ) : (
                 <span className="miu-attach-chip">📎 {m.attachment.filename ?? 'attachment'}{m.attachment.sizeBytes ? ` · ${fmtBytes(m.attachment.sizeBytes)}` : ''}</span>
+              )
             ) : null}
           </article>
         ))}

packages/iios-messaging-ui/src/styles.css

@@ -353,7 +353,15 @@
   white-space: nowrap;
 }
 .miu-mail-msg .miu-attach-chip {
-  margin-top: 6px;
+  margin: 8px 12px 12px;
+}
+button.miu-attach-dl {
+  cursor: pointer;
+  color: var(--miu-text);
+}
+button.miu-attach-dl:hover {
+  border-color: var(--miu-accent);
+  color: var(--miu-accent);
 }
 .miu-attach-pending {
   display: inline-flex;
@@ -763,7 +771,7 @@
 .miu-detail {
   display: flex;
   flex-direction: column;
-  height: 100%;
+  flex: 1;
   min-height: 0;
 }
 .miu-detail-actions {
@@ -790,7 +798,7 @@
 .miu-mail {
   display: flex;
   flex-direction: column;
-  height: 100%;
+  flex: 1;
   min-height: 0;
 }
 .miu-mail-head {