fix(messaging-ui): stop Start-chat/Create buttons stretching full width

The new-conversation + channel-create forms are flex columns, so the submit
button stretched to full width and read as thin. Give it align-self:flex-start
+ a 38px height so it sizes to its label like a normal button.

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

packages/iios-messaging-ui/package.json

@@ -18,6 +18,10 @@
       "types": "./dist/adapters/kernel-client.d.ts",
       "import": "./dist/adapters/kernel-client.js"
     },
+    "./adapters/mock-inbox": {
+      "types": "./dist/adapters/mock-inbox.d.ts",
+      "import": "./dist/adapters/mock-inbox.js"
+    },
     "./conformance": {
       "types": "./dist/conformance.d.ts",
       "import": "./dist/conformance.js"
@@ -33,8 +37,9 @@
     "test": "vitest run"
   },
   "peerDependencies": {
+    "@insignia/iios-kernel-client": "*",
     "react": ">=18",
-    "@insignia/iios-kernel-client": "*"
+    "react-dom": ">=18"
   },
   "peerDependenciesMeta": {
     "@insignia/iios-kernel-client": {
@@ -46,6 +51,7 @@
     "@testing-library/dom": "^10.4.0",
     "@testing-library/react": "^16.1.0",
     "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
     "jsdom": "^26.0.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",

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

@@ -61,6 +61,10 @@ export interface MessagingAdapter {
    *  Absent => the composer offers no autocomplete (you can still type @text). */
   listMembers?(threadId: string): Promise<Person[]>;
 
+  /** The people you can start a conversation with (org directory). Drives the "New message"
+   *  people picker. Absent => the UI hides DM/group creation (you can still open channels). */
+  directory?(): Promise<Person[]>;
+
   // ── Channels (optional capability) ──────────────────────────────
   // A channel is just a third membership beyond dm/group: a discoverable, joinable room.
   // Implement all four to enable the channels UI; absent => the UI hides channels entirely.

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

@@ -0,0 +1,109 @@
+import type { InboxAdapter } from '../inbox/adapter';
+import type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from '../inbox/types';
+
+const PEOPLE: MailPerson[] = [
+  { id: 'pp_sofia', name: 'Sofia Ramirez', kind: 'staff' },
+  { id: 'pp_dan', name: 'Dan Whitaker', kind: 'staff' },
+  { id: 'cust_acme', name: 'Acme Roofing (Client)', kind: 'customer' },
+];
+
+interface MockMail {
+  subject: string;
+  messages: MailMessage[];
+}
+
+/**
+ * In-memory inbox for demos/tests. State is PER INSTANCE. Seeds a few work items (mention,
+ * needs-reply, alert) plus mail threads that fold into the Open view as MAIL rows.
+ */
+export class MockInboxAdapter implements InboxAdapter {
+  private seq = 100;
+  private readonly items: InboxItem[];
+  private readonly threads = new Map<string, MockMail>();
+  /** threadIds that surface as standalone MAIL rows (in addition to work items). */
+  private readonly mailFold = ['mt_welcome', 'mt_invoice'];
+
+  constructor(private readonly now: () => string = () => new Date().toISOString()) {
+    const at = this.now();
+    this.items = [
+      { id: 'in_1', kind: 'MENTION', state: 'OPEN', title: 'Sofia mentioned you', summary: '@you — can you confirm the Henderson scope?', priority: 'HIGH', threadId: 'mt_mention', createdAt: at },
+      { id: 'in_2', kind: 'NEEDS_REPLY', state: 'OPEN', title: 'Reply needed — Storm response', summary: 'Dan: crew rolling out at 7', priority: 'MEDIUM', threadId: 'mt_storm', createdAt: at },
+      { id: 'in_3', kind: 'SYSTEM_ALERT', state: 'OPEN', title: 'Ticket TK-204 updated', summary: 'Customer replied on the roof-leak case.', priority: 'LOW', createdAt: at },
+    ];
+    this.threads.set('mt_mention', {
+      subject: 'Henderson scope',
+      messages: [{ id: 'm1', actorId: 'pp_sofia', kind: 'EMAIL', at, html: '<p>Can you confirm the <b>Henderson</b> scope by EOD?</p>', text: 'Can you confirm the Henderson scope by EOD?', attachment: null }],
+    });
+    this.threads.set('mt_storm', {
+      subject: 'Storm response — East side',
+      messages: [{ id: 'm2', actorId: 'pp_dan', kind: 'EMAIL', at, html: '<p>Crew is rolling out at 7. Confirm the Henderson job?</p>', text: 'Crew rolling out at 7. Confirm the Henderson job?', attachment: null }],
+    });
+    this.threads.set('mt_welcome', {
+      subject: 'Welcome to the Founders Club',
+      messages: [{ id: 'm3', actorId: 'system', kind: 'EMAIL', at, html: '<p>Thanks for joining the <b>Founders Club</b>. Set up your account to get started.</p>', text: 'Thanks for joining the Founders Club.', attachment: null }],
+    });
+    this.threads.set('mt_invoice', {
+      subject: 'Invoice #1042 — Acme Roofing',
+      messages: [{ id: 'm4', actorId: 'cust_acme', kind: 'EMAIL', at, html: '<p>Attached is invoice <b>#1042</b> for the East-side job.</p>', text: 'Attached is invoice #1042 for the East-side job.', attachment: null }],
+    });
+  }
+
+  async listInbox(state?: InboxState): Promise<InboxItem[]> {
+    const showMail = !state || state === 'OPEN';
+    const work = this.items.filter((i) => (state ? i.state === state : true));
+    const mail: InboxItem[] = showMail
+      ? this.mailFold.map((tid) => {
+          const t = this.threads.get(tid)!;
+          const last = t.messages[t.messages.length - 1];
+          return {
+            id: `mail:${tid}`,
+            kind: 'MAIL',
+            state: 'OPEN' as InboxState,
+            title: t.subject,
+            ...(last?.text ? { summary: last.text } : {}),
+            priority: 'LOW',
+            threadId: tid,
+            createdAt: last?.at ?? this.now(),
+          };
+        })
+      : [];
+    return [...mail, ...work];
+  }
+
+  async transition(id: string, state: InboxState): Promise<void> {
+    const item = this.items.find((i) => i.id === id);
+    if (item) item.state = state;
+  }
+
+  async mailHistory(threadId: string): Promise<MailMessage[]> {
+    return [...(this.threads.get(threadId)?.messages ?? [])];
+  }
+
+  async mailReply(threadId: string, content: string, attachment?: MailAttachment): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (t) t.messages = [...t.messages, { id: `r_${this.seq++}`, actorId: 'me', kind: 'MESSAGE', at: this.now(), html: null, text: content || null, attachment: attachment ?? null }];
+  }
+
+  async uploadAttachment(file: File): Promise<MailAttachment> {
+    return { contentRef: `mock/${this.seq++}`, mimeType: file.type || 'application/octet-stream', sizeBytes: file.size, filename: file.name };
+  }
+
+  async directory(): Promise<MailPerson[]> {
+    return [...PEOPLE];
+  }
+
+  async composeInternal(recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void> {
+    const threadId = `mt_${this.seq++}`;
+    this.threads.set(threadId, { subject, messages: [{ id: `m_${this.seq++}`, actorId: 'me', kind: 'EMAIL', at: this.now(), html: `<p>${text}</p>`, text, attachment: attachments?.[0] ?? null }] });
+    this.mailFold.unshift(threadId);
+    void recipientUserId;
+  }
+
+  async composeExternal(target: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void> {
+    // A mock external send has no in-app thread — no-op beyond acknowledging.
+    void target;
+    void subject;
+    void text;
+    void attachments;
+  }
+}

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

@@ -159,7 +159,20 @@ export class MockAdapter implements MessagingAdapter {
     });
   }
 
+  async directory(): Promise<Person[]> {
+    return MOCK_PEOPLE.map((p) => ({ ...p }));
+  }
+
   async openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }> {
+    // A DM to someone you already have reuses the existing 1:1 thread (dedupe, like the live door).
+    if ((p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group')) === 'dm' && p.participantIds.length === 1) {
+      const target = p.participantIds[0];
+      for (const [id, t] of this.threads) {
+        if (t.membership === 'dm' && t.participants.length === 2 && t.participants.includes(ME) && t.participants.includes(target)) {
+          return { threadId: id };
+        }
+      }
+    }
     const membership = p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group');
     const threadId = `th_mock_${this.seq++}`;
     this.threads.set(threadId, {

packages/iios-messaging-ui/src/components/composer.tsx

@@ -0,0 +1,147 @@
+import { useMemo, useRef, useState, type ChangeEvent, type FormEvent, type KeyboardEvent } from 'react';
+import {
+  SPECIAL_MENTIONS,
+  insertMention,
+  resolveMentions,
+  trailingMentionQuery,
+} from '../mentions';
+import type { Attachment, Person, SendOpts } from '../types';
+
+interface Suggestion {
+  key: string;
+  label: string;
+  insert: string;
+}
+
+/**
+ * The message input: draft, @mention autocomplete, and attachment staging. Shared by the main
+ * Thread and the ThreadPane (which passes a parentInteractionId so a reply lands in the thread).
+ */
+export function Composer({
+  members,
+  canUpload,
+  upload,
+  onSend,
+  onTyping,
+  parentInteractionId,
+  placeholder = 'Type a message… @ to mention',
+}: {
+  members: Person[];
+  canUpload: boolean;
+  upload: (file: File) => Promise<Attachment>;
+  onSend: (text: string, opts?: SendOpts) => Promise<void>;
+  onTyping?: () => void;
+  parentInteractionId?: string;
+  placeholder?: string;
+}) {
+  const [draft, setDraft] = useState('');
+  const [sending, setSending] = useState(false);
+  const [staged, setStaged] = useState<Attachment | null>(null);
+  const [uploading, setUploading] = useState(false);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  const query = trailingMentionQuery(draft);
+  const suggestions = useMemo<Suggestion[]>(() => {
+    if (query === null) return [];
+    const q = query.toLowerCase();
+    const specials = SPECIAL_MENTIONS.filter((s) => s.startsWith(q)).map((s) => ({ key: `@${s}`, label: `@${s}`, insert: s }));
+    const people = members.filter((m) => m.name.toLowerCase().includes(q)).map((m) => ({ key: m.id, label: m.name, insert: m.name }));
+    return [...specials, ...people].slice(0, 6);
+  }, [query, members]);
+  const showSuggest = query !== null && suggestions.length > 0;
+
+  function pick(insert: string): void {
+    setDraft((d) => insertMention(d, insert));
+  }
+
+  async function onPickFile(e: ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file) return;
+    setUploading(true);
+    try {
+      setStaged(await upload(file));
+    } catch {
+      /* host surfaces upload errors */
+    } finally {
+      setUploading(false);
+    }
+  }
+
+  async function submit(e?: FormEvent): Promise<void> {
+    e?.preventDefault();
+    const text = draft.trim();
+    if ((!text && !staged) || sending) return;
+    const mentions = resolveMentions(text, members);
+    const att = staged;
+    setDraft('');
+    setStaged(null);
+    setSending(true);
+    try {
+      await onSend(text, {
+        ...(mentions.length ? { mentions } : {}),
+        ...(att ? { attachment: att } : {}),
+        ...(parentInteractionId ? { parentInteractionId } : {}),
+      });
+    } catch {
+      setStaged(att);
+    } finally {
+      setSending(false);
+    }
+  }
+
+  function onKeyDown(e: KeyboardEvent<HTMLInputElement>): void {
+    if (showSuggest && e.key === 'Enter') {
+      e.preventDefault();
+      pick(suggestions[0]!.insert);
+    }
+  }
+
+  return (
+    <form className="miu-composer" onSubmit={submit}>
+      {showSuggest ? (
+        <ul className="miu-suggest" role="listbox" aria-label="Mention suggestions">
+          {suggestions.map((s) => (
+            <li key={s.key}>
+              <button type="button" role="option" aria-selected="false" className="miu-suggest-item" onClick={() => pick(s.insert)}>
+                {s.label}
+              </button>
+            </li>
+          ))}
+        </ul>
+      ) : null}
+      {staged ? (
+        <div className="miu-staged">
+          📎 {staged.name}
+          <button type="button" className="miu-staged-x" onClick={() => setStaged(null)} aria-label="Remove attachment">
+            ✕
+          </button>
+        </div>
+      ) : null}
+      <div className="miu-composer-row">
+        {canUpload ? (
+          <>
+            <input ref={fileRef} type="file" className="miu-file-input" onChange={onPickFile} aria-label="Attach a file" />
+            <button type="button" className="miu-attach-btn" title="Attach a file" disabled={uploading} onClick={() => fileRef.current?.click()}>
+              {uploading ? '…' : '📎'}
+            </button>
+          </>
+        ) : null}
+        <input
+          className="miu-input"
+          value={draft}
+          placeholder={placeholder}
+          aria-label="Message"
+          onChange={(e) => {
+            setDraft(e.target.value);
+            onTyping?.();
+          }}
+          onKeyDown={onKeyDown}
+        />
+        <button type="submit" className="miu-send" disabled={(!draft.trim() && !staged) || sending}>
+          Send
+        </button>
+      </div>
+    </form>
+  );
+}

packages/iios-messaging-ui/src/components/message-item.tsx

@@ -0,0 +1,107 @@
+import { useState } from 'react';
+import { highlightMentions } from '../mentions';
+import type { Attachment } from '../types';
+import type { UiMessage } from '../hooks/use-messages';
+
+const REACTION_EMOJIS = ['👍', '❤️', '😂', '🎉', '👀'];
+
+const isImage = (mime: string): boolean => mime.startsWith('image/');
+
+function AttachmentView({ att }: { att: Attachment }) {
+  if (isImage(att.mime)) {
+    return (
+      <a href={att.url} target="_blank" rel="noreferrer" className="miu-att-img-link">
+        <img src={att.url} alt={att.name} className="miu-att-img" />
+      </a>
+    );
+  }
+  return (
+    <a href={att.url} target="_blank" rel="noreferrer" className="miu-att-file">
+      📎 {att.name}
+    </a>
+  );
+}
+
+/** One rendered message: bubble (with @mention highlighting), attachment, reactions, seen tick,
+ *  and — in the main thread only — a thread/reply affordance. */
+export function MessageItem({
+  message,
+  memberNames,
+  canReact,
+  onReact,
+  seen,
+  replyCount,
+  onOpenThread,
+}: {
+  message: UiMessage;
+  memberNames: string[];
+  canReact: boolean;
+  onReact: (messageId: string, emoji: string) => void;
+  seen: boolean;
+  /** Present only in the main thread (not inside the pane). undefined => no thread affordance. */
+  replyCount?: number;
+  onOpenThread?: (messageId: string) => void;
+}) {
+  const [pickerOpen, setPickerOpen] = useState(false);
+  const m = message;
+
+  return (
+    <div className={`miu-msg${message.mine ? ' is-mine' : ''}${message.pending ? ' is-pending' : ''}`}>
+      <div className="miu-bubble-row">
+        <div className="miu-bubble">
+          {m.text ? highlightMentions(m.text, memberNames) : null}
+          {m.attachment ? <AttachmentView att={m.attachment} /> : null}
+        </div>
+        <div className="miu-msg-actions">
+          {canReact ? (
+            <div className="miu-react-wrap">
+              <button type="button" className="miu-react-btn" title="React" onClick={() => setPickerOpen((p) => !p)}>
+                🙂
+              </button>
+              {pickerOpen ? (
+                <div className="miu-react-picker">
+                  {REACTION_EMOJIS.map((e) => (
+                    <button
+                      key={e}
+                      type="button"
+                      className="miu-react-emoji"
+                      onClick={() => {
+                        onReact(m.id, e);
+                        setPickerOpen(false);
+                      }}
+                    >
+                      {e}
+                    </button>
+                  ))}
+                </div>
+              ) : null}
+            </div>
+          ) : null}
+          {onOpenThread ? (
+            <button type="button" className="miu-react-btn" title="Reply in thread" onClick={() => onOpenThread(m.id)}>
+              💬
+            </button>
+          ) : null}
+        </div>
+      </div>
+
+      {m.reactions && m.reactions.length > 0 ? (
+        <div className="miu-reactions">
+          {m.reactions.map((r) => (
+            <button key={r.emoji} type="button" className={`miu-reaction${r.mine ? ' is-mine' : ''}`} onClick={() => canReact && onReact(m.id, r.emoji)}>
+              {r.emoji} {r.count}
+            </button>
+          ))}
+        </div>
+      ) : null}
+
+      {replyCount !== undefined && replyCount > 0 && onOpenThread ? (
+        <button type="button" className="miu-thread-link" onClick={() => onOpenThread(m.id)}>
+          💬 {replyCount} {replyCount === 1 ? 'reply' : 'replies'}
+        </button>
+      ) : null}
+
+      {message.mine && seen ? <span className="miu-seen">Seen</span> : null}
+    </div>
+  );
+}

packages/iios-messaging-ui/src/components/messenger.tsx

@@ -3,7 +3,9 @@ import { useConversations } from '../hooks/use-conversations';
 import { useAdapter } from '../provider';
 import { ConversationList } from './conversation-list';
 import { ChannelBrowser } from './channel-browser';
+import { NewConversation } from './new-conversation';
 import { Thread } from './thread';
+import { ThreadPane } from './thread-pane';
 
 /**
  * The drop-in messenger: sectioned conversation list (Channels / Direct messages) + open thread,
@@ -14,24 +16,41 @@ export function Messenger() {
   const { conversations, loading, error, refetch } = useConversations();
   const adapter = useAdapter();
   const channelsSupported = typeof adapter.browseChannels === 'function';
+  const directorySupported = typeof adapter.directory === 'function';
 
   const [selected, setSelected] = useState<string | null>(null);
   const [browsing, setBrowsing] = useState(false);
+  const [composing, setComposing] = useState(false); // "New message" people picker open
+  const [activeRoot, setActiveRoot] = useState<string | null>(null); // open thread pane's root message
 
   useEffect(() => {
-    if (browsing) return;
+    if (browsing || composing) return;
     if (selected && conversations.some((c) => c.threadId === selected)) return;
     setSelected(conversations[0]?.threadId ?? null);
-  }, [conversations, selected, browsing]);
+  }, [conversations, selected, browsing, composing]);
+
+  // Switching conversations (or into browse/compose) closes any open thread pane.
+  useEffect(() => setActiveRoot(null), [selected, browsing, composing]);
 
   const channels = useMemo(() => conversations.filter((c) => c.membership === 'channel'), [conversations]);
   const dms = useMemo(() => conversations.filter((c) => c.membership !== 'channel'), [conversations]);
 
   function pick(threadId: string): void {
     setBrowsing(false);
+    setComposing(false);
     setSelected(threadId);
   }
 
+  function openBrowse(): void {
+    setComposing(false);
+    setBrowsing(true);
+  }
+
+  function openCompose(): void {
+    setBrowsing(false);
+    setComposing(true);
+  }
+
   return (
     <div className="miu-messenger">
       <aside className="miu-sidebar">
@@ -42,12 +61,12 @@ export function Messenger() {
           <div className="miu-section">
             <div className="miu-section-head">
               <span>Channels</span>
-              <button type="button" className="miu-section-add" title="Browse channels" onClick={() => setBrowsing(true)}>
+              <button type="button" className="miu-section-add" title="Browse channels" onClick={openBrowse}>
                 ＋
               </button>
             </div>
             {channels.length > 0 ? (
-              <ConversationList conversations={channels} selectedId={browsing ? null : selected} onSelect={pick} />
+              <ConversationList conversations={channels} selectedId={browsing || composing ? null : selected} onSelect={pick} />
             ) : (
               <div className="miu-empty miu-empty-sm">Browse to join a channel.</div>
             )}
@@ -55,12 +74,17 @@ export function Messenger() {
         ) : null}
 
         <div className="miu-section">
-          {channelsSupported ? (
+          {channelsSupported || directorySupported ? (
             <div className="miu-section-head">
               <span>Direct messages</span>
+              {directorySupported ? (
+                <button type="button" className="miu-section-add" title="New message" onClick={openCompose}>
+                  ＋
+                </button>
+              ) : null}
             </div>
           ) : null}
-          <ConversationList conversations={dms} selectedId={browsing ? null : selected} onSelect={pick} />
+          <ConversationList conversations={dms} selectedId={browsing || composing ? null : selected} onSelect={pick} />
         </div>
       </aside>
 
@@ -72,10 +96,21 @@ export function Messenger() {
               pick(threadId);
             }}
           />
+        ) : composing ? (
+          <NewConversation
+            onCreated={(threadId) => {
+              refetch();
+              pick(threadId);
+            }}
+          />
         ) : (
-          <Thread threadId={selected} />
+          <Thread threadId={selected} activeRootId={activeRoot} onOpenThread={setActiveRoot} />
         )}
       </section>
+
+      {!browsing && !composing && selected && activeRoot ? (
+        <ThreadPane threadId={selected} rootId={activeRoot} onClose={() => setActiveRoot(null)} />
+      ) : null}
     </div>
   );
 }

packages/iios-messaging-ui/src/components/modal-portal.tsx

@@ -0,0 +1,35 @@
+import { useState, type ReactNode, type CSSProperties } from 'react';
+import { createPortal } from 'react-dom';
+
+// The SDK theme tokens. A body-portaled node is outside the `.miu-messenger`/`.miu-inbox`
+// subtree that defines these, so we copy their resolved values onto the portal root.
+const THEME_VARS = [
+  '--miu-bg', '--miu-panel', '--miu-panel-2', '--miu-border',
+  '--miu-text', '--miu-muted', '--miu-accent', '--miu-accent-text', '--miu-radius',
+] as const;
+
+function copyThemeVars(): Record<string, string> {
+  if (typeof document === 'undefined') return {};
+  const src = document.querySelector('.miu-messenger, .miu-inbox');
+  if (!src) return {};
+  const cs = getComputedStyle(src);
+  const out: Record<string, string> = {};
+  for (const v of THEME_VARS) {
+    const val = cs.getPropertyValue(v).trim();
+    if (val) out[v] = val;
+  }
+  return out;
+}
+
+/**
+ * Render an overlay into document.body so it escapes the host's stacking context and overflow.
+ * A host wrapper like `.view { position: relative; z-index: 1 }` traps a `position: fixed` overlay
+ * BELOW a sibling sticky header no matter how high its z-index — the only robust fix is to leave
+ * that stacking context entirely. Theme tokens are copied from the live surface (captured once on
+ * mount, synchronously, so there is no unstyled first paint) and re-applied on the portal root.
+ */
+export function ModalPortal({ children }: { children: ReactNode }) {
+  const [vars] = useState<Record<string, string>>(copyThemeVars);
+  if (typeof document === 'undefined') return null;
+  return createPortal(<div className="miu-portal" style={vars as CSSProperties}>{children}</div>, document.body);
+}

packages/iios-messaging-ui/src/components/new-conversation.test.tsx

@@ -0,0 +1,66 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { Messenger } from './messenger';
+
+function mount(adapter = new MockAdapter()) {
+  render(
+    <MessagingProvider adapter={adapter}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+  return adapter;
+}
+
+describe('MockAdapter directory + openThread', () => {
+  it('directory lists people you can message', async () => {
+    const a = new MockAdapter();
+    const people = await a.directory();
+    expect(people.some((p) => p.name === 'Dan Whitaker')).toBe(true);
+  });
+
+  it('one participant opens a dm; two+ open a group with a subject', async () => {
+    const a = new MockAdapter();
+    const dm = await a.openThread({ participantIds: ['pp_dan'], membership: 'dm' });
+    const list = await a.listConversations();
+    expect(list.find((c) => c.threadId === dm.threadId)?.membership).toBe('dm');
+
+    const group = await a.openThread({ participantIds: ['pp_dan', 'pp_priya'], membership: 'group', subject: 'Roof crew' });
+    const g = (await a.listConversations()).find((c) => c.threadId === group.threadId);
+    expect(g?.membership).toBe('group');
+    expect(g?.title).toBe('Roof crew');
+  });
+
+  it('opening a dm with the same person reuses the existing thread', async () => {
+    const a = new MockAdapter();
+    const first = await a.openThread({ participantIds: ['pp_priya'], membership: 'dm' });
+    const second = await a.openThread({ participantIds: ['pp_priya'], membership: 'dm' });
+    expect(second.threadId).toBe(first.threadId);
+  });
+});
+
+describe('<Messenger /> new conversation flow', () => {
+  it('opens the picker from the Direct messages +, and starting a chat leaves the picker', async () => {
+    mount();
+    // Open the "New message" picker.
+    fireEvent.click(await screen.findByTitle('New message'));
+    expect(await screen.findByText('New message')).toBeTruthy();
+
+    // Pick a person and start a DM.
+    fireEvent.click(await screen.findByText('Dan Whitaker'));
+    fireEvent.click(screen.getByText('Start chat'));
+
+    // The picker closes (we're back in a thread view — the picker heading is gone).
+    await waitFor(() => expect(screen.queryByText('Start chat')).toBeNull());
+  });
+
+  it('selecting two people switches the action to group create', async () => {
+    mount();
+    fireEvent.click(await screen.findByTitle('New message'));
+    fireEvent.click(await screen.findByText('Dan Whitaker'));
+    fireEvent.click(await screen.findByText('Priya Nair'));
+    expect(screen.getByText(/Create group \(2\)/)).toBeTruthy();
+    expect(screen.getByLabelText('Group name')).toBeTruthy();
+  });
+});

packages/iios-messaging-ui/src/components/new-conversation.tsx

@@ -0,0 +1,97 @@
+import { useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { Person } from '../types';
+
+/**
+ * Start a direct message or a group — Slack-style. Pick people from the org directory: one selected
+ * opens a DM (deduped by the adapter), two or more create a group with an optional name. Shown in
+ * the main pane like the channel browser.
+ */
+export function NewConversation({ onCreated }: { onCreated?: (threadId: string) => void }) {
+  const adapter = useAdapter();
+  const [people, setPeople] = useState<Person[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [q, setQ] = useState('');
+  const [selected, setSelected] = useState<string[]>([]);
+  const [name, setName] = useState('');
+  const [busy, setBusy] = useState(false);
+
+  useEffect(() => {
+    if (!adapter.directory) {
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    adapter
+      .directory()
+      .then((p) => {
+        if (alive) {
+          setPeople(p);
+          setError(null);
+        }
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter]);
+
+  const filtered = people.filter((p) => p.name.toLowerCase().includes(q.trim().toLowerCase()));
+  const isGroup = selected.length > 1;
+  const canStart = selected.length >= 1 && !busy;
+
+  function toggle(id: string): void {
+    setSelected((s) => (s.includes(id) ? s.filter((x) => x !== id) : [...s, id]));
+  }
+
+  async function start(): Promise<void> {
+    if (!canStart) return;
+    setBusy(true);
+    setError(null);
+    try {
+      const res = await adapter.openThread({
+        participantIds: selected,
+        membership: isGroup ? 'group' : 'dm',
+        ...(isGroup && name.trim() ? { subject: name.trim() } : {}),
+      });
+      onCreated?.(res.threadId);
+    } catch (e) {
+      setError(e instanceof Error ? e.message : String(e));
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  return (
+    <div className="miu-browser">
+      <div className="miu-browser-head">New message</div>
+      <div className="miu-newconv">
+        <input className="miu-input" value={q} onChange={(e) => setQ(e.target.value)} placeholder="Search people…" aria-label="Search people" />
+        {isGroup ? (
+          <input className="miu-input" value={name} onChange={(e) => setName(e.target.value)} placeholder="Group name (optional)" aria-label="Group name" />
+        ) : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        <div className="miu-browser-list">
+          {loading && people.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+          {!loading && filtered.length === 0 ? <div className="miu-empty">No people found.</div> : null}
+          {filtered.map((p) => (
+            <label key={p.id} className={`miu-person-row${selected.includes(p.id) ? ' is-active' : ''}`}>
+              <input type="checkbox" checked={selected.includes(p.id)} onChange={() => toggle(p.id)} />
+              <span className="miu-browser-name">{p.name}</span>
+              <span className="miu-pill">{p.kind}</span>
+            </label>
+          ))}
+        </div>
+        <button type="button" className="miu-send" onClick={() => void start()} disabled={!canStart}>
+          {busy ? 'Starting…' : isGroup ? `Create group (${selected.length})` : 'Start chat'}
+        </button>
+      </div>
+    </div>
+  );
+}

packages/iios-messaging-ui/src/components/thread-pane.test.tsx

@@ -0,0 +1,36 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { Messenger } from './messenger';
+import { MockAdapter } from '../adapters/mock';
+
+function mount() {
+  return render(
+    <MessagingProvider adapter={new MockAdapter()}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+}
+
+describe('Slack-style thread pane', () => {
+  it('opens a thread on 💬, posts a reply into it, and shows the reply count on the parent', async () => {
+    mount();
+    // Wait for the auto-selected thread's message to render WITH its actions (not just the sidebar
+    // preview), then open the thread pane via the message's reply affordance (💬).
+    const replyButtons = await screen.findAllByTitle('Reply in thread');
+    fireEvent.click(replyButtons[0]!);
+    expect(await screen.findByText('Thread')).toBeTruthy(); // pane header
+
+    // The pane's composer (placeholder "Reply…") — send a threaded reply.
+    const replyInput = screen.getByPlaceholderText('Reply…') as HTMLInputElement;
+    fireEvent.change(replyInput, { target: { value: 'on it' } });
+    // The pane has its own Send; grab the last one (pane is rendered after the main composer).
+    const sends = screen.getAllByText('Send');
+    fireEvent.click(sends[sends.length - 1]!);
+
+    // The reply shows in the pane (replies are hidden from the main thread, so this is unique)...
+    await waitFor(() => expect(screen.getByText('on it')).toBeTruthy());
+    // ...and the parent now advertises the reply count as a thread-link button in the main thread.
+    await waitFor(() => expect(screen.getByRole('button', { name: /1 reply/ })).toBeTruthy());
+  });
+});

packages/iios-messaging-ui/src/components/thread-pane.tsx

@@ -0,0 +1,60 @@
+import { useMemo } from 'react';
+import { useMessages } from '../hooks/use-messages';
+import { useMembers } from '../hooks/use-members';
+import { Composer } from './composer';
+import { MessageItem } from './message-item';
+
+/**
+ * The Slack-style thread side panel: the root message + its replies + a composer that posts back
+ * into the thread (parentInteractionId = root). Uses its own useMessages on the same thread; the
+ * shared adapter subscription keeps it and the main view in sync.
+ */
+export function ThreadPane({
+  threadId,
+  rootId,
+  onClose,
+}: {
+  threadId: string;
+  rootId: string;
+  onClose: () => void;
+}) {
+  const { messages, send, react, upload, seenIds, sendTyping, canReact, canUpload } = useMessages(threadId);
+  const members = useMembers(threadId);
+  const memberNames = useMemo(() => members.map((m) => m.name), [members]);
+
+  const root = useMemo(() => messages.find((m) => m.id === rootId), [messages, rootId]);
+  const replies = useMemo(() => messages.filter((m) => m.parentInteractionId === rootId), [messages, rootId]);
+
+  return (
+    <aside className="miu-pane">
+      <header className="miu-pane-head">
+        <span>Thread</span>
+        <button type="button" className="miu-pane-close" onClick={onClose} aria-label="Close thread">
+          ✕
+        </button>
+      </header>
+
+      <div className="miu-messages miu-pane-messages">
+        {root ? (
+          <MessageItem message={root} memberNames={memberNames} canReact={canReact} onReact={(id, e) => void react(id, e)} seen={seenIds.has(root.id)} />
+        ) : (
+          <div className="miu-empty">Message not found.</div>
+        )}
+        <div className="miu-pane-divider">{replies.length} {replies.length === 1 ? 'reply' : 'replies'}</div>
+        {replies.map((m) => (
+          <MessageItem key={m.id} message={m} memberNames={memberNames} canReact={canReact} onReact={(id, e) => void react(id, e)} seen={seenIds.has(m.id)} />
+        ))}
+      </div>
+
+      <Composer
+        members={members}
+        canUpload={canUpload}
+        upload={upload}
+        onSend={send}
+        onTyping={sendTyping}
+        parentInteractionId={rootId}
+        placeholder="Reply…"
+      />
+    </aside>
+  );
+}

packages/iios-messaging-ui/src/components/thread.tsx

@@ -1,124 +1,61 @@
-import { useMemo, useState, type FormEvent, type KeyboardEvent } from 'react';
+import { useMemo } from 'react';
 import { useMessages } from '../hooks/use-messages';
 import { useMembers } from '../hooks/use-members';
-import {
-  SPECIAL_MENTIONS,
-  highlightMentions,
-  insertMention,
-  resolveMentions,
-  trailingMentionQuery,
-} from '../mentions';
-
-interface Suggestion {
-  key: string;
-  label: string;
-  insert: string;
-}
+import { Composer } from './composer';
+import { MessageItem } from './message-item';
 
 /**
- * One conversation: message list + composer, driven by useMessages. Adds @mention autocomplete
- * (from the thread's members) and highlights mentions in message bodies. Transport-agnostic.
+ * The main conversation view: top-level messages + composer. Replies (messages with a
+ * parentInteractionId) are hidden here and live in the ThreadPane — a message with replies shows a
+ * "N replies" link that opens it. @mentions, reactions, and attachments all work.
  */
-export function Thread({ threadId }: { threadId: string | null }) {
-  const { messages, loading, error, send, typingUserIds, seenIds, sendTyping } = useMessages(threadId);
+export function Thread({
+  threadId,
+  activeRootId,
+  onOpenThread,
+}: {
+  threadId: string | null;
+  activeRootId?: string | null;
+  onOpenThread?: (rootId: string) => void;
+}) {
+  const { messages, loading, error, send, react, upload, typingUserIds, seenIds, sendTyping, canReact, canUpload } = useMessages(threadId);
   const members = useMembers(threadId);
-  const [draft, setDraft] = useState('');
-  const [sending, setSending] = useState(false);
-
   const memberNames = useMemo(() => members.map((m) => m.name), [members]);
-  const query = trailingMentionQuery(draft);
-  const suggestions = useMemo<Suggestion[]>(() => {
-    if (query === null) return [];
-    const q = query.toLowerCase();
-    const specials = SPECIAL_MENTIONS.filter((s) => s.startsWith(q)).map((s) => ({ key: `@${s}`, label: `@${s}`, insert: s }));
-    const people = members.filter((m) => m.name.toLowerCase().includes(q)).map((m) => ({ key: m.id, label: m.name, insert: m.name }));
-    return [...specials, ...people].slice(0, 6);
-  }, [query, members]);
-  const showSuggest = query !== null && suggestions.length > 0;
 
-  function pick(insert: string): void {
-    setDraft((d) => insertMention(d, insert));
-  }
-
-  async function submit(e?: FormEvent): Promise<void> {
-    e?.preventDefault();
-    const text = draft.trim();
-    if (!text || sending) return;
-    const mentions = resolveMentions(text, members);
-    setDraft('');
-    setSending(true);
-    try {
-      await send(text, mentions.length ? { mentions } : undefined);
-    } catch {
-      // surfaced via the hook's error
-    } finally {
-      setSending(false);
-    }
-  }
-
-  function onKeyDown(e: KeyboardEvent<HTMLInputElement>): void {
-    if (showSuggest && e.key === 'Enter') {
-      e.preventDefault();
-      pick(suggestions[0]!.insert);
-    }
-  }
+  const topLevel = useMemo(() => messages.filter((m) => !m.parentInteractionId), [messages]);
+  const replyCount = useMemo(() => {
+    const counts = new Map<string, number>();
+    for (const m of messages) if (m.parentInteractionId) counts.set(m.parentInteractionId, (counts.get(m.parentInteractionId) ?? 0) + 1);
+    return counts;
+  }, [messages]);
 
   if (!threadId) {
     return <div className="miu-empty miu-thread-empty">Select a conversation.</div>;
   }
 
   return (
-    <div className="miu-thread">
+    <div className={`miu-thread${activeRootId ? ' has-pane' : ''}`}>
       <div className="miu-messages">
         {loading && messages.length === 0 ? <div className="miu-empty">Loading…</div> : null}
         {error ? <div className="miu-empty miu-error">{error}</div> : null}
-        {messages.map((m) => (
-          <div key={m.id} className={`miu-msg${m.mine ? ' is-mine' : ''}${m.pending ? ' is-pending' : ''}`}>
-            <div className="miu-bubble">{highlightMentions(m.text, memberNames)}</div>
-            {m.reactions && m.reactions.length > 0 ? (
-              <div className="miu-reactions">
-                {m.reactions.map((r) => (
-                  <span key={r.emoji} className={`miu-reaction${r.mine ? ' is-mine' : ''}`}>
-                    {r.emoji} {r.count}
-                  </span>
-                ))}
-              </div>
-            ) : null}
-            {m.mine && seenIds.has(m.id) ? <span className="miu-seen">Seen</span> : null}
-          </div>
+        {topLevel.map((m) => (
+          <MessageItem
+            key={m.id}
+            message={m}
+            memberNames={memberNames}
+            canReact={canReact}
+            onReact={(id, emoji) => void react(id, emoji)}
+            seen={seenIds.has(m.id)}
+            replyCount={replyCount.get(m.id) ?? 0}
+            {...(onOpenThread ? { onOpenThread } : {})}
+          />
         ))}
         {typingUserIds.length > 0 ? (
           <div className="miu-typing">{typingUserIds.length === 1 ? 'typing…' : 'several people are typing…'}</div>
         ) : null}
       </div>
 
-      <form className="miu-composer" onSubmit={submit}>
-        {showSuggest ? (
-          <ul className="miu-suggest" role="listbox" aria-label="Mention suggestions">
-            {suggestions.map((s) => (
-              <li key={s.key}>
-                <button type="button" role="option" aria-selected="false" className="miu-suggest-item" onClick={() => pick(s.insert)}>
-                  {s.label}
-                </button>
-              </li>
-            ))}
-          </ul>
-        ) : null}
-        <input
-          className="miu-input"
-          value={draft}
-          placeholder="Type a message… @ to mention"
-          aria-label="Message"
-          onChange={(e) => {
-            setDraft(e.target.value);
-            sendTyping();
-          }}
-          onKeyDown={onKeyDown}
-        />
-        <button type="submit" className="miu-send" disabled={!draft.trim() || sending}>
-          Send
-        </button>
-      </form>
+      <Composer members={members} canUpload={canUpload} upload={upload} onSend={send} onTyping={sendTyping} />
     </div>
   );
 }

packages/iios-messaging-ui/src/hooks/use-messages.ts

@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useAdapter } from '../provider';
 import { isOwnMessage } from '../types';
-import type { Message, SendOpts } from '../types';
+import type { Attachment, Message, SendOpts } from '../types';
 
 const TYPING_TTL_MS = 3500;
 
@@ -15,6 +15,7 @@ export interface MessagesState {
   error: string | null;
   send: (content: string, opts?: SendOpts) => Promise<void>;
   react: (messageId: string, emoji: string) => Promise<void>;
+  upload: (file: File) => Promise<Attachment>;
   typingUserIds: string[];
   seenIds: Set<string>;
   sendTyping: () => void;
@@ -147,6 +148,14 @@ export function useMessages(threadId: string | null): MessagesState {
     [adapter, threadId],
   );
 
+  const upload = useCallback(
+    async (file: File): Promise<Attachment> => {
+      if (!adapter.upload) throw new Error('uploads are not supported by this adapter');
+      return adapter.upload(file);
+    },
+    [adapter],
+  );
+
   const sendTyping = useCallback(() => {
     if (threadId) adapter.sendTyping(threadId);
   }, [adapter, threadId]);
@@ -196,6 +205,7 @@ export function useMessages(threadId: string | null): MessagesState {
     error,
     send,
     react,
+    upload,
     typingUserIds,
     seenIds: seenMine,
     sendTyping,

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

@@ -0,0 +1,32 @@
+import type { MailAttachment, InboxItem, InboxState, MailMessage, MailPerson } from './types';
+
+/**
+ * The inbox seam. A host implements this; the SDK renders it. Mirrors MessagingAdapter's philosophy:
+ * `listInbox` returns the UNIFIED feed (work items + mail folded in) so the folding logic lives in
+ * one place (the adapter, which knows both sources). Compose methods are optional and degrade.
+ */
+export interface InboxAdapter {
+  /** The unified inbox: work items + mail threads as rows, filtered by state (mail shows in OPEN). */
+  listInbox(state?: InboxState): Promise<InboxItem[]>;
+
+  /** Transition a work item's state (Done/Snooze/Archive…). Mail rows are not transitioned. */
+  transition(id: string, state: InboxState): Promise<void>;
+
+  /** Messages of one mail thread (HTML + text parts) for the reader. */
+  mailHistory(threadId: string): Promise<MailMessage[]>;
+
+  /** Reply into an existing mail thread, optionally with one attachment. */
+  mailReply(threadId: string, content: string, attachment?: MailAttachment): Promise<void>;
+
+  // ── Attachments (optional) — absent hides the attach affordance ──
+  /** Upload a file to storage, returning a reference to send with a reply/compose. */
+  uploadAttachment?(file: File): Promise<MailAttachment>;
+
+  // ── Compose (optional) — absent hides the "New message" affordance ──
+  /** People you can compose an in-app message to. */
+  directory?(): Promise<MailPerson[]>;
+  /** App-to-app mail (no SMTP) to a registered user's in-app inbox. */
+  composeInternal?(recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void>;
+  /** External email (SMTP) to an address. */
+  composeExternal?(target: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void>;
+}

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

@@ -0,0 +1,174 @@
+import { useCallback, useEffect, useState } from 'react';
+import { useInboxAdapter } from './provider';
+import type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from './types';
+
+export interface InboxData {
+  items: InboxItem[];
+  loading: boolean;
+  error: string | null;
+  transition: (id: string, state: InboxState) => Promise<void>;
+  refetch: () => void;
+}
+
+/** The unified inbox for a given filter state. Refetches when the filter changes. */
+export function useInbox(state?: InboxState): InboxData {
+  const adapter = useInboxAdapter();
+  const [items, setItems] = useState<InboxItem[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    let alive = true;
+    setLoading(true);
+    adapter
+      .listInbox(state)
+      .then((list) => {
+        if (!alive) return;
+        setItems(list);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (!alive) return;
+        setError(e instanceof Error ? e.message : String(e));
+        setItems([]);
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, state, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+  const transition = useCallback(
+    async (id: string, next: InboxState) => {
+      await adapter.transition(id, next);
+      setNonce((n) => n + 1);
+    },
+    [adapter],
+  );
+
+  return { items, loading, error, transition, refetch };
+}
+
+export interface MailThreadState {
+  messages: MailMessage[];
+  loading: boolean;
+  error: string | null;
+  reply: (content: string, attachment?: MailAttachment) => Promise<void>;
+  canAttach: boolean;
+  upload: (file: File) => Promise<MailAttachment>;
+  refetch: () => void;
+}
+
+/** One mail thread: history + reply. */
+export function useMailThread(threadId: string | null): MailThreadState {
+  const adapter = useInboxAdapter();
+  const [messages, setMessages] = useState<MailMessage[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    if (!threadId) {
+      setMessages([]);
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    setLoading(true);
+    adapter
+      .mailHistory(threadId)
+      .then((m) => {
+        if (!alive) return;
+        setMessages(m);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, threadId, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+  const reply = useCallback(
+    async (content: string, attachment?: MailAttachment) => {
+      if (!threadId) return;
+      await adapter.mailReply(threadId, content, attachment);
+      setNonce((n) => n + 1);
+    },
+    [adapter, threadId],
+  );
+  const upload = useCallback(
+    async (file: File) => {
+      if (!adapter.uploadAttachment) throw new Error('attachments are not supported by this adapter');
+      return adapter.uploadAttachment(file);
+    },
+    [adapter],
+  );
+
+  return { messages, loading, error, reply, canAttach: typeof adapter.uploadAttachment === 'function', upload, refetch };
+}
+
+export interface ComposeState {
+  supported: boolean;
+  directory: MailPerson[];
+  sendInternal: (recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]) => Promise<void>;
+  sendExternal: (target: string, subject: string, text: string, attachments?: MailAttachment[]) => Promise<void>;
+  canAttach: boolean;
+  upload: (file: File) => Promise<MailAttachment>;
+}
+
+/** Compose a new message — in-app (to a person) or external (to an email). */
+export function useCompose(): ComposeState {
+  const adapter = useInboxAdapter();
+  const supported = typeof adapter.composeInternal === 'function';
+  const [directory, setDirectory] = useState<MailPerson[]>([]);
+
+  useEffect(() => {
+    if (!adapter.directory) return;
+    let alive = true;
+    adapter
+      .directory()
+      .then((d) => {
+        if (alive) setDirectory(d);
+      })
+      .catch(() => {
+        if (alive) setDirectory([]);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter]);
+
+  const sendInternal = useCallback(
+    async (recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]) => {
+      if (!adapter.composeInternal) throw new Error('compose is not supported by this adapter');
+      await adapter.composeInternal(recipientUserId, subject, text, attachments);
+    },
+    [adapter],
+  );
+  const sendExternal = useCallback(
+    async (target: string, subject: string, text: string, attachments?: MailAttachment[]) => {
+      if (!adapter.composeExternal) throw new Error('compose is not supported by this adapter');
+      await adapter.composeExternal(target, subject, text, attachments);
+    },
+    [adapter],
+  );
+  const upload = useCallback(
+    async (file: File) => {
+      if (!adapter.uploadAttachment) throw new Error('attachments are not supported by this adapter');
+      return adapter.uploadAttachment(file);
+    },
+    [adapter],
+  );
+
+  return { supported, directory, sendInternal, sendExternal, canAttach: typeof adapter.uploadAttachment === 'function', upload };
+}

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

@@ -0,0 +1,97 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { InboxProvider } from './provider';
+import { Inbox } from './inbox';
+import { MockInboxAdapter } from '../adapters/mock-inbox';
+
+function mount() {
+  return render(
+    <InboxProvider adapter={new MockInboxAdapter()}>
+      <Inbox />
+    </InboxProvider>,
+  );
+}
+
+describe('mock inbox adapter', () => {
+  it('unifies work items + mail in the Open view; other states drop mail', async () => {
+    const a = new MockInboxAdapter();
+    const open = await a.listInbox('OPEN');
+    expect(open.some((i) => i.kind === 'MAIL')).toBe(true);
+    expect(open.some((i) => i.kind === 'MENTION')).toBe(true);
+    const done = await a.listInbox('DONE');
+    expect(done.some((i) => i.kind === 'MAIL')).toBe(false);
+  });
+
+  it('transition moves a work item out of Open', async () => {
+    const a = new MockInboxAdapter();
+    await a.transition('in_3', 'DONE');
+    expect((await a.listInbox('OPEN')).some((i) => i.id === 'in_3')).toBe(false);
+    expect((await a.listInbox('DONE')).some((i) => i.id === 'in_3')).toBe(true);
+  });
+
+  it('mail reply appends to the thread', async () => {
+    const a = new MockInboxAdapter();
+    await a.mailReply('mt_welcome', 'thanks!');
+    expect((await a.mailHistory('mt_welcome')).some((m) => m.text === 'thanks!')).toBe(true);
+  });
+
+  it('reply carries an uploaded attachment', async () => {
+    const a = new MockInboxAdapter();
+    const ref = await a.uploadAttachment(new File(['x'], 'plan.pdf', { type: 'application/pdf' }));
+    expect(ref).toMatchObject({ filename: 'plan.pdf', mimeType: 'application/pdf' });
+    await a.mailReply('mt_welcome', '', ref);
+    const last = (await a.mailHistory('mt_welcome')).at(-1)!;
+    expect(last.attachment?.filename).toBe('plan.pdf');
+  });
+
+  it('composeInternal carries a first attachment onto the new thread', async () => {
+    const a = new MockInboxAdapter();
+    const ref = await a.uploadAttachment(new File(['x'], 'quote.png', { type: 'image/png' }));
+    await a.composeInternal('pp_sofia', 'Quote', 'see attached', [ref]);
+    const open = await a.listInbox('OPEN');
+    const row = open.find((i) => i.title === 'Quote')!;
+    expect((await a.mailHistory(row.threadId!)).at(-1)?.attachment?.filename).toBe('quote.png');
+  });
+});
+
+describe('<Inbox /> (rendered)', () => {
+  it('lists items and opens a mail thread on click', async () => {
+    mount();
+    // A folded mail row is present.
+    const welcome = await screen.findByText('Welcome to the Founders Club');
+    fireEvent.click(welcome);
+    // The reader opens with a reply box.
+    expect(await screen.findByLabelText('Reply')).toBeTruthy();
+  });
+
+  it('replies into a mail thread', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('Welcome to the Founders Club'));
+    const input = (await screen.findByLabelText('Reply')) as HTMLInputElement;
+    fireEvent.change(input, { target: { value: 'got it' } });
+    fireEvent.click(screen.getByText('Reply'));
+    await waitFor(() => expect(screen.getByText('got it')).toBeTruthy());
+  });
+
+  it('attaches a file into a mail reply', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('Welcome to the Founders Club'));
+    const file = new File(['data'], 'roof.pdf', { type: 'application/pdf' });
+    fireEvent.change(await screen.findByLabelText('Attach file'), { target: { files: [file] } });
+    // The pending chip shows the file, then Reply sends it.
+    await screen.findByText(/roof\.pdf/);
+    fireEvent.click(screen.getByText('Reply'));
+    await waitFor(() => expect(screen.getAllByText(/roof\.pdf/).length).toBeGreaterThan(0));
+  });
+
+  it('composes an in-app message and it shows in the inbox', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('New message'));
+    // pick a recipient
+    fireEvent.click(await screen.findByText('Sofia Ramirez'));
+    fireEvent.change(screen.getByLabelText('Subject'), { target: { value: 'Quick q' } });
+    fireEvent.change(screen.getByLabelText('Message body'), { target: { value: 'ping' } });
+    fireEvent.click(screen.getByText('Send'));
+    await waitFor(() => expect(screen.getByText('Quick q')).toBeTruthy());
+  });
+});

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

@@ -0,0 +1,328 @@
+import { useEffect, useRef, useState, type FormEvent } from 'react';
+import { ModalPortal } from '../components/modal-portal';
+import { useCompose, useInbox, useMailThread } from './hooks';
+import type { InboxItem, InboxState, MailAttachment, MailPerson } from './types';
+
+const fmtBytes = (n: number): string => {
+  if (!n) return '';
+  if (n < 1024) return `${n} B`;
+  if (n < 1024 * 1024) return `${Math.round(n / 1024)} KB`;
+  return `${(n / (1024 * 1024)).toFixed(1)} MB`;
+};
+
+const FILTERS: { value: InboxState; label: string }[] = [
+  { value: 'OPEN', label: 'Open' },
+  { value: 'SNOOZED', label: 'Snoozed' },
+  { value: 'DONE', label: 'Done' },
+  { value: 'ARCHIVED', label: 'Archived' },
+];
+
+const KIND_LABEL: Record<string, string> = {
+  MAIL: 'Mail',
+  MENTION: 'Mention',
+  NEEDS_REPLY: 'Needs reply',
+  SYSTEM_ALERT: 'Alert',
+  SUPPORT_UPDATE: 'Support',
+};
+
+const timeOf = (iso?: string): string => {
+  if (!iso) return '';
+  const d = new Date(iso);
+  return Number.isNaN(+d) ? '' : d.toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' });
+};
+
+/** The unified inbox: work items + mail in one list; click a threaded row to read + reply. */
+export function Inbox() {
+  const [filter, setFilter] = useState<InboxState>('OPEN');
+  const { items, loading, error, transition, refetch } = useInbox(filter);
+  const compose = useCompose();
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [composing, setComposing] = useState(false);
+
+  useEffect(() => {
+    if (selectedId && items.some((i) => i.id === selectedId)) return;
+    setSelectedId(items[0]?.id ?? null);
+  }, [items, selectedId]);
+
+  const selected = items.find((i) => i.id === selectedId) ?? null;
+
+  return (
+    <div className="miu-inbox">
+      <div className="miu-inbox-bar">
+        <div className="miu-inbox-filters">
+          {FILTERS.map((f) => (
+            <button key={f.value} type="button" className={`miu-tab${filter === f.value ? ' is-active' : ''}`} onClick={() => setFilter(f.value)}>
+              {f.label}
+            </button>
+          ))}
+        </div>
+        {compose.supported ? (
+          <button type="button" className="miu-send" onClick={() => setComposing(true)}>
+            New message
+          </button>
+        ) : null}
+      </div>
+
+      <div className="miu-inbox-body">
+        <aside className="miu-inbox-list">
+          {loading && items.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+          {error ? <div className="miu-empty miu-error">{error}</div> : null}
+          {!loading && items.length === 0 ? <div className="miu-empty">Nothing here — you&apos;re all caught up 🎉</div> : null}
+          {items.map((it) => (
+            <button key={it.id} type="button" className={`miu-inbox-row${it.id === selectedId ? ' is-active' : ''}`} onClick={() => setSelectedId(it.id)}>
+              <span className="miu-inbox-glyph" aria-hidden="true">{it.kind === 'MAIL' ? '✉' : it.kind === 'MENTION' ? '@' : '•'}</span>
+              <span className="miu-inbox-main">
+                <span className="miu-inbox-row-top">
+                  <span className="miu-pill">{KIND_LABEL[it.kind] ?? it.kind}</span>
+                  <span className="miu-inbox-title">{it.title}</span>
+                </span>
+                {it.summary ? <span className="miu-inbox-summary">{it.summary}</span> : null}
+              </span>
+              {it.state !== 'OPEN' ? <span className="miu-pill">{it.state.toLowerCase()}</span> : null}
+            </button>
+          ))}
+        </aside>
+
+        <section className="miu-inbox-detail">
+          {selected ? <Detail item={selected} onTransition={(s) => void transition(selected.id, s)} /> : <div className="miu-empty miu-thread-empty">Select an item to read.</div>}
+        </section>
+      </div>
+
+      {composing ? <ComposeModal onClose={() => setComposing(false)} onSent={() => { setComposing(false); refetch(); }} /> : null}
+    </div>
+  );
+}
+
+function Detail({ item, onTransition }: { item: InboxItem; onTransition: (state: InboxState) => void }) {
+  return (
+    <div className="miu-detail">
+      {item.state === 'OPEN' && item.kind !== 'MAIL' ? (
+        <div className="miu-detail-actions">
+          <button type="button" className="miu-tab" onClick={() => onTransition('SNOOZED')}>Snooze</button>
+          <button type="button" className="miu-tab" onClick={() => onTransition('DONE')}>Done</button>
+          <button type="button" className="miu-tab" onClick={() => onTransition('ARCHIVED')}>Archive</button>
+        </div>
+      ) : null}
+      {item.threadId ? (
+        <MailReader threadId={item.threadId} subject={item.title} />
+      ) : (
+        <div className="miu-detail-body">
+          <div className="miu-detail-title">{item.title}</div>
+          {item.summary ? <div className="miu-detail-summary">{item.summary}</div> : null}
+        </div>
+      )}
+    </div>
+  );
+}
+
+/** 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 [draft, setDraft] = useState('');
+  const [sending, setSending] = useState(false);
+  const [pending, setPending] = useState<MailAttachment | null>(null);
+  const [attaching, setAttaching] = useState(false);
+  const [attachErr, setAttachErr] = useState<string | null>(null);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  async function pick(e: React.ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file) return;
+    setAttaching(true);
+    setAttachErr(null);
+    try {
+      setPending(await upload(file));
+    } catch (err) {
+      setAttachErr(err instanceof Error ? err.message : String(err));
+    } finally {
+      setAttaching(false);
+    }
+  }
+
+  async function submit(e: FormEvent): Promise<void> {
+    e.preventDefault();
+    const text = draft.trim();
+    if ((!text && !pending) || sending) return;
+    const att = pending;
+    setDraft('');
+    setPending(null);
+    setSending(true);
+    try {
+      await reply(text, att ?? undefined);
+    } catch {
+      setDraft(text);
+      setPending(att);
+    } finally {
+      setSending(false);
+    }
+  }
+
+  return (
+    <div className="miu-mail">
+      <header className="miu-mail-head">{subject || '(no subject)'}</header>
+      <div className="miu-mail-body">
+        {loading && messages.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        {messages.map((m) => (
+          <article key={m.id} className="miu-mail-msg">
+            <div className="miu-mail-meta">
+              <span>{m.kind === 'EMAIL' ? 'Email' : 'Reply'}{m.actorId ? ` · ${m.actorId}` : ''}</span>
+              <span>{timeOf(m.at)}</span>
+            </div>
+            {m.html ? (
+              <iframe sandbox="" srcDoc={m.html} title="mail body" className="miu-mail-frame" />
+            ) : m.text ? (
+              <div className="miu-mail-text">{m.text}</div>
+            ) : null}
+            {m.attachment ? (
+              <span className="miu-attach-chip">📎 {m.attachment.filename ?? 'attachment'}{m.attachment.sizeBytes ? ` · ${fmtBytes(m.attachment.sizeBytes)}` : ''}</span>
+            ) : null}
+          </article>
+        ))}
+      </div>
+      <form className="miu-composer" onSubmit={submit}>
+        {attachErr ? <div className="miu-empty miu-error">{attachErr}</div> : null}
+        {pending ? (
+          <div className="miu-attach-pending">
+            <span className="miu-attach-chip">📎 {pending.filename ?? 'attachment'}{pending.sizeBytes ? ` · ${fmtBytes(pending.sizeBytes)}` : ''}</span>
+            <button type="button" className="miu-attach-x" onClick={() => setPending(null)} aria-label="Remove attachment">✕</button>
+          </div>
+        ) : null}
+        <div className="miu-composer-row">
+          {canAttach ? (
+            <>
+              <input ref={fileRef} type="file" hidden onChange={pick} aria-label="Attach file" />
+              <button type="button" className="miu-attach-btn" onClick={() => fileRef.current?.click()} disabled={attaching || !!pending} title="Attach a file" aria-label="Attach a file">
+                {attaching ? '…' : '📎'}
+              </button>
+            </>
+          ) : null}
+          <input className="miu-input" value={draft} onChange={(e) => setDraft(e.target.value)} placeholder="Reply…" aria-label="Reply" />
+          <button type="submit" className="miu-send" disabled={(!draft.trim() && !pending) || sending}>Reply</button>
+        </div>
+      </form>
+    </div>
+  );
+}
+
+function ComposeModal({ onClose, onSent }: { onClose: () => void; onSent: () => void }) {
+  const compose = useCompose();
+  const [mode, setMode] = useState<'internal' | 'external'>('internal');
+  const [recipient, setRecipient] = useState('');
+  const [subject, setSubject] = useState('');
+  const [body, setBody] = useState('');
+  const [q, setQ] = useState('');
+  const [busy, setBusy] = useState(false);
+  const [err, setErr] = useState<string | null>(null);
+  const [attachments, setAttachments] = useState<MailAttachment[]>([]);
+  const [attaching, setAttaching] = useState(false);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  const filtered = compose.directory.filter((p) => p.name.toLowerCase().includes(q.trim().toLowerCase()));
+  const canSend = !!recipient && !!subject.trim() && (!!body.trim() || attachments.length > 0) && !busy && !attaching;
+
+  async function pick(e: React.ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file || attachments.length >= 10) return;
+    setAttaching(true);
+    setErr(null);
+    try {
+      const ref = await compose.upload(file);
+      setAttachments((a) => [...a, ref]);
+    } catch (e2) {
+      setErr(e2 instanceof Error ? e2.message : String(e2));
+    } finally {
+      setAttaching(false);
+    }
+  }
+
+  async function send(): Promise<void> {
+    if (!canSend) return;
+    setBusy(true);
+    setErr(null);
+    const atts = attachments.length > 0 ? attachments : undefined;
+    try {
+      if (mode === 'internal') await compose.sendInternal(recipient, subject.trim(), body.trim(), atts);
+      else await compose.sendExternal(recipient.trim(), subject.trim(), body.trim(), atts);
+      onSent();
+    } catch (e) {
+      setErr(e instanceof Error ? e.message : String(e));
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  return (
+    <ModalPortal>
+      <div className="miu-modal-overlay" onMouseDown={onClose}>
+      <div className="miu-modal" role="dialog" aria-modal="true" onMouseDown={(e) => e.stopPropagation()}>
+        <div className="miu-modal-head">
+          <span>New message</span>
+          <button type="button" className="miu-pane-close" onClick={onClose} aria-label="Close">✕</button>
+        </div>
+        <div className="miu-modal-body">
+          <div className="miu-compose-modes">
+            <button type="button" className={`miu-tab${mode === 'internal' ? ' is-active' : ''}`} onClick={() => { setMode('internal'); setRecipient(''); }}>In-app</button>
+            <button type="button" className={`miu-tab${mode === 'external' ? ' is-active' : ''}`} onClick={() => { setMode('external'); setRecipient(''); }}>Email</button>
+          </div>
+
+          {mode === 'internal' ? (
+            <div className="miu-field">
+              <span className="miu-field-lbl">To (person)</span>
+              <input className="miu-input" value={q} onChange={(e) => setQ(e.target.value)} placeholder="Search people…" aria-label="Search people" />
+              <div className="miu-people">
+                {filtered.length === 0 ? <div className="miu-empty">No people found.</div> : null}
+                {filtered.map((p: MailPerson) => (
+                  <label key={p.id} className={`miu-person${recipient === p.id ? ' is-active' : ''}`}>
+                    <input type="radio" name="miu-recipient" checked={recipient === p.id} onChange={() => setRecipient(p.id)} />
+                    <span>{p.name}</span>
+                    <span className="miu-pill">{p.kind}</span>
+                  </label>
+                ))}
+              </div>
+            </div>
+          ) : (
+            <div className="miu-field">
+              <span className="miu-field-lbl">To (email)</span>
+              <input className="miu-input" value={recipient} onChange={(e) => setRecipient(e.target.value)} placeholder="name@company.com" aria-label="To email" />
+            </div>
+          )}
+
+          <div className="miu-field">
+            <span className="miu-field-lbl">Subject</span>
+            <input className="miu-input" value={subject} onChange={(e) => setSubject(e.target.value)} placeholder="Subject" aria-label="Subject" />
+          </div>
+          <div className="miu-field">
+            <span className="miu-field-lbl">Message</span>
+            <textarea className="miu-input miu-textarea" value={body} onChange={(e) => setBody(e.target.value)} placeholder="Write your message…" rows={5} aria-label="Message body" />
+          </div>
+          {compose.canAttach ? (
+            <div className="miu-field">
+              <span className="miu-field-lbl">Attachments</span>
+              <div className="miu-attach-list">
+                {attachments.map((a, i) => (
+                  <span key={`${a.contentRef}-${i}`} className="miu-attach-pending">
+                    <span className="miu-attach-chip">📎 {a.filename ?? 'attachment'}{a.sizeBytes ? ` · ${fmtBytes(a.sizeBytes)}` : ''}</span>
+                    <button type="button" className="miu-attach-x" onClick={() => setAttachments((prev) => prev.filter((_, j) => j !== i))} aria-label="Remove attachment">✕</button>
+                  </span>
+                ))}
+                <input ref={fileRef} type="file" hidden onChange={pick} aria-label="Attach file" />
+                <button type="button" className="miu-tab" onClick={() => fileRef.current?.click()} disabled={attaching || attachments.length >= 10}>
+                  {attaching ? 'Uploading…' : '📎 Attach'}
+                </button>
+              </div>
+            </div>
+          ) : null}
+          {err ? <div className="miu-empty miu-error">{err}</div> : null}
+        </div>
+        <div className="miu-modal-foot">
+          <button type="button" className="miu-tab" onClick={onClose}>Cancel</button>
+          <button type="button" className="miu-send" onClick={() => void send()} disabled={!canSend}>{busy ? 'Sending…' : 'Send'}</button>
+        </div>
+      </div>
+      </div>
+    </ModalPortal>
+  );
+}

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

@@ -0,0 +1,16 @@
+import { createContext, useContext, type ReactNode } from 'react';
+import type { InboxAdapter } from './adapter';
+
+const InboxContext = createContext<InboxAdapter | null>(null);
+
+export function InboxProvider({ adapter, children }: { adapter: InboxAdapter; children: ReactNode }) {
+  return <InboxContext.Provider value={adapter}>{children}</InboxContext.Provider>;
+}
+
+/** Access the host-injected inbox adapter. Throws outside a provider — a missing provider is a
+ *  wiring bug, and failing loudly beats a confusing null-deref three layers down. */
+export function useInboxAdapter(): InboxAdapter {
+  const adapter = useContext(InboxContext);
+  if (!adapter) throw new Error('useInboxAdapter must be used within an <InboxProvider>');
+  return adapter;
+}

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

@@ -0,0 +1,42 @@
+// Domain types for the inbox surface (work items + mail). Zero transport imports.
+
+export type InboxState = 'OPEN' | 'SNOOZED' | 'DONE' | 'ARCHIVED' | 'CANCELLED' | 'STALE';
+
+/** A unified inbox row — a work item (mention/needs-reply/alert) OR a mail thread. */
+export interface InboxItem {
+  id: string;
+  kind: string; // MAIL | MENTION | NEEDS_REPLY | SYSTEM_ALERT | …
+  state: InboxState;
+  title: string;
+  summary?: string;
+  priority: string;
+  /** Present when the row opens a conversation/mail thread. */
+  threadId?: string;
+  createdAt: string;
+}
+
+/** A mail attachment reference (bytes live in storage; the reader resolves a display URL). */
+export interface MailAttachment {
+  contentRef: string;
+  mimeType: string;
+  sizeBytes: number;
+  filename: string | null;
+}
+
+/** One message in a mail thread — HTML and/or plain text, optionally an attachment. */
+export interface MailMessage {
+  id: string;
+  actorId: string | null;
+  kind: string;
+  at: string;
+  html: string | null;
+  text: string | null;
+  attachment: MailAttachment | null;
+}
+
+/** A person you can compose an in-app message to. */
+export interface MailPerson {
+  id: string;
+  name: string;
+  kind: 'staff' | 'customer';
+}

packages/iios-messaging-ui/src/index.ts

@@ -15,6 +15,14 @@ export { Messenger } from './components/messenger';
 export { ConversationList } from './components/conversation-list';
 export { ChannelBrowser } from './components/channel-browser';
 export { Thread } from './components/thread';
+export { ThreadPane } from './components/thread-pane';
+
+// ── Inbox domain (work items + mail) ──
+export { InboxProvider, useInboxAdapter } from './inbox/provider';
+export { useInbox, useMailThread, useCompose } from './inbox/hooks';
+export { Inbox, MailReader } from './inbox/inbox';
+export type { InboxAdapter } from './inbox/adapter';
+export type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from './inbox/types';
 
 export type { MessagingAdapter } from './adapter';
 export type { ConversationsState } from './hooks/use-conversations';

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

@@ -149,6 +149,86 @@
 .miu-msg.is-pending {
   opacity: 0.6;
 }
+.miu-bubble-row {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+.miu-msg.is-mine .miu-bubble-row {
+  flex-direction: row-reverse;
+}
+.miu-msg-actions {
+  display: flex;
+  gap: 2px;
+  flex-shrink: 0;
+}
+.miu-thread-link {
+  align-self: flex-start;
+  margin-top: 3px;
+  padding: 3px 9px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-accent);
+  font-size: 12px;
+  font-weight: 600;
+  cursor: pointer;
+}
+.miu-msg.is-mine .miu-thread-link {
+  align-self: flex-end;
+}
+.miu-react-wrap {
+  position: relative;
+  flex-shrink: 0;
+}
+.miu-react-btn {
+  border: none;
+  background: none;
+  cursor: pointer;
+  opacity: 0;
+  font-size: 14px;
+  padding: 2px;
+  transition: opacity 0.12s;
+}
+.miu-msg:hover .miu-react-btn {
+  opacity: 0.6;
+}
+.miu-react-btn:hover {
+  opacity: 1;
+}
+.miu-react-picker {
+  position: absolute;
+  /* Open downward + right-aligned so it never clips against the top of the scroll area
+     (the reported bug) or spills past the right edge. */
+  top: 100%;
+  right: 0;
+  margin-top: 4px;
+  display: flex;
+  gap: 2px;
+  padding: 4px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
+  z-index: 5;
+  width: max-content;
+}
+/* On my own (right-aligned) messages, anchor the picker to the left instead so it stays in view. */
+.miu-msg.is-mine .miu-react-picker {
+  right: auto;
+  left: 0;
+}
+.miu-react-emoji {
+  border: none;
+  background: none;
+  cursor: pointer;
+  font-size: 16px;
+  padding: 2px 4px;
+  border-radius: 6px;
+}
+.miu-react-emoji:hover {
+  background: var(--miu-panel-2);
+}
 .miu-reactions {
   display: flex;
   gap: 4px;
@@ -160,10 +240,35 @@
   border-radius: 999px;
   border: 1px solid var(--miu-border);
   background: var(--miu-panel-2);
+  color: var(--miu-text);
+  cursor: pointer;
 }
 .miu-reaction.is-mine {
   border-color: var(--miu-accent);
 }
+
+/* attachments */
+.miu-att-img-link {
+  display: inline-block;
+  margin-top: 4px;
+}
+.miu-att-img {
+  max-width: 260px;
+  max-height: 220px;
+  border-radius: 8px;
+  border: 1px solid var(--miu-border);
+}
+.miu-att-file {
+  display: inline-block;
+  margin-top: 4px;
+  padding: 6px 10px;
+  border-radius: 8px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  color: var(--miu-text);
+  text-decoration: none;
+  font-size: 13px;
+}
 .miu-seen {
   font-size: 11px;
   color: var(--miu-muted);
@@ -189,10 +294,87 @@
 .miu-composer {
   position: relative;
   display: flex;
+  flex-direction: column;
   gap: 8px;
   padding: 12px;
   border-top: 1px solid var(--miu-border);
 }
+.miu-composer-row {
+  display: flex;
+  gap: 8px;
+}
+.miu-file-input {
+  display: none;
+}
+.miu-attach-btn {
+  flex-shrink: 0;
+  width: 38px;
+  border-radius: 10px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  cursor: pointer;
+  font-size: 16px;
+}
+.miu-staged {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  align-self: flex-start;
+  padding: 5px 10px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  font-size: 13px;
+}
+.miu-staged-x {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  padding: 0;
+  line-height: 1;
+}
+
+/* inbox mail attachments */
+.miu-attach-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 4px 10px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  color: var(--miu-text);
+  font-size: 12.5px;
+  max-width: 100%;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.miu-mail-msg .miu-attach-chip {
+  margin-top: 6px;
+}
+.miu-attach-pending {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+}
+.miu-attach-x {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  padding: 0 2px;
+  line-height: 1;
+  font-size: 12px;
+}
+.miu-attach-list {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 8px;
+}
 .miu-suggest {
   position: absolute;
   left: 12px;
@@ -318,6 +500,38 @@
   gap: 5px;
   cursor: pointer;
 }
+/* new conversation (DM / group) picker */
+.miu-newconv {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+/* Submit buttons in the stacked create/compose forms size to content, not full width. */
+.miu-newconv .miu-send,
+.miu-channel-create .miu-send {
+  align-self: flex-start;
+  height: 38px;
+}
+.miu-person-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 8px 10px;
+  border: 1px solid var(--miu-border);
+  border-radius: 10px;
+  background: var(--miu-panel);
+  cursor: pointer;
+}
+.miu-person-row:hover {
+  border-color: var(--miu-accent);
+}
+.miu-person-row.is-active {
+  border-color: var(--miu-accent);
+  background: color-mix(in srgb, var(--miu-accent) 10%, var(--miu-panel));
+}
+.miu-person-row .miu-browser-name {
+  flex: 1 1 auto;
+}
 .miu-browser-list {
   display: flex;
   flex-direction: column;
@@ -377,6 +591,345 @@
   color: var(--miu-muted);
 }
 
+/* thread pane (Slack-style) */
+.miu-pane {
+  width: 340px;
+  flex-shrink: 0;
+  display: flex;
+  flex-direction: column;
+  min-height: 0;
+  border-left: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+}
+.miu-pane-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 12px 16px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+}
+.miu-pane-close {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  font-size: 15px;
+}
+.miu-pane-messages {
+  background: var(--miu-bg);
+}
+.miu-pane-divider {
+  font-size: 11.5px;
+  color: var(--miu-muted);
+  text-align: center;
+  margin: 4px 0;
+  padding-bottom: 4px;
+  border-bottom: 1px solid var(--miu-border);
+}
+
+/* ── Inbox ── */
+.miu-inbox {
+  --miu-bg: #0e0e13;
+  --miu-panel: #16161d;
+  --miu-panel-2: #1d1d26;
+  --miu-border: #262631;
+  --miu-text: #e9e9ef;
+  --miu-muted: #9a9aa7;
+  --miu-accent: #fda913;
+  --miu-accent-text: #1a1206;
+  --miu-radius: 12px;
+
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+  color: var(--miu-text);
+  background: var(--miu-bg);
+  font-family: system-ui, -apple-system, 'Segoe UI', sans-serif;
+  font-size: 14px;
+}
+.miu-inbox-bar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+  padding: 10px 12px;
+  border-bottom: 1px solid var(--miu-border);
+}
+.miu-inbox-filters {
+  display: flex;
+  gap: 4px;
+}
+.miu-tab {
+  padding: 6px 12px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  font: inherit;
+  font-size: 13px;
+  cursor: pointer;
+}
+.miu-tab.is-active {
+  background: var(--miu-accent);
+  color: var(--miu-accent-text);
+  border-color: var(--miu-accent);
+  font-weight: 700;
+}
+.miu-inbox-body {
+  flex: 1;
+  min-height: 0;
+  display: flex;
+}
+.miu-inbox-list {
+  width: 340px;
+  flex-shrink: 0;
+  overflow-y: auto;
+  border-right: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+}
+.miu-inbox-row {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
+  width: 100%;
+  padding: 12px 14px;
+  border: none;
+  border-bottom: 1px solid var(--miu-border);
+  background: transparent;
+  color: inherit;
+  text-align: left;
+  cursor: pointer;
+  font: inherit;
+}
+.miu-inbox-row:hover,
+.miu-inbox-row.is-active {
+  background: var(--miu-panel-2);
+}
+.miu-inbox-glyph {
+  width: 26px;
+  height: 26px;
+  flex-shrink: 0;
+  border-radius: 7px;
+  display: grid;
+  place-items: center;
+  color: var(--miu-muted);
+  background: var(--miu-panel-2);
+  font-weight: 700;
+}
+.miu-inbox-main {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+.miu-inbox-row-top {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+.miu-pill {
+  flex-shrink: 0;
+  font-size: 10.5px;
+  font-weight: 700;
+  padding: 1px 7px;
+  border-radius: 999px;
+  color: var(--miu-muted);
+  background: var(--miu-panel-2);
+  text-transform: capitalize;
+}
+.miu-inbox-title {
+  font-weight: 600;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-inbox-summary {
+  color: var(--miu-muted);
+  font-size: 12.5px;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-inbox-detail {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  background: var(--miu-bg);
+}
+.miu-detail {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+}
+.miu-detail-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 6px;
+  padding: 10px 14px;
+  border-bottom: 1px solid var(--miu-border);
+}
+.miu-detail-body {
+  padding: 22px;
+}
+.miu-detail-title {
+  font-weight: 700;
+  font-size: 16px;
+  margin-bottom: 6px;
+}
+.miu-detail-summary {
+  color: var(--miu-muted);
+  line-height: 1.55;
+}
+
+/* mail reader */
+.miu-mail {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+}
+.miu-mail-head {
+  padding: 12px 18px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+  font-size: 15px;
+}
+.miu-mail-body {
+  flex: 1;
+  min-height: 0;
+  overflow-y: auto;
+  padding: 16px;
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+.miu-mail-msg {
+  border: 1px solid var(--miu-border);
+  border-radius: var(--miu-radius);
+  background: var(--miu-panel);
+  overflow: hidden;
+}
+.miu-mail-meta {
+  display: flex;
+  justify-content: space-between;
+  padding: 7px 12px;
+  border-bottom: 1px solid var(--miu-border);
+  font-size: 12px;
+  color: var(--miu-muted);
+}
+.miu-mail-frame {
+  width: 100%;
+  height: 200px;
+  border: none;
+  background: #fff;
+}
+.miu-mail-text {
+  padding: 12px;
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+/* compose modal — portaled to <body>, so carry SDK theme-token defaults here (the host's
+   own token mapping + a synchronous copy on the portal root override these). */
+.miu-portal {
+  --miu-bg: #0e0e13;
+  --miu-panel: #16161d;
+  --miu-panel-2: #1d1d26;
+  --miu-border: #262631;
+  --miu-text: #e9e9ef;
+  --miu-muted: #9a9aa7;
+  --miu-accent: #fda913;
+  --miu-accent-text: #1a1206;
+  --miu-radius: 12px;
+}
+.miu-modal-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 2147483000;
+  background: rgba(2, 2, 6, 0.6);
+  display: grid;
+  place-items: center;
+  padding: 20px;
+}
+.miu-modal {
+  width: 100%;
+  max-width: 520px;
+  max-height: 88vh;
+  display: flex;
+  flex-direction: column;
+  border: 1px solid var(--miu-border);
+  border-radius: 16px;
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  font-family: system-ui, -apple-system, 'Segoe UI', sans-serif;
+}
+.miu-modal-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 16px 18px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+}
+.miu-modal-body {
+  padding: 16px 18px;
+  overflow-y: auto;
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+.miu-modal-foot {
+  display: flex;
+  justify-content: flex-end;
+  gap: 8px;
+  padding: 14px 18px;
+  border-top: 1px solid var(--miu-border);
+}
+.miu-compose-modes {
+  display: flex;
+  gap: 6px;
+}
+.miu-field {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+.miu-field-lbl {
+  font-size: 12.5px;
+  font-weight: 600;
+  color: var(--miu-muted);
+}
+.miu-textarea {
+  resize: vertical;
+  min-height: 90px;
+}
+.miu-people {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  max-height: 180px;
+  overflow-y: auto;
+}
+.miu-person {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 7px 10px;
+  border-radius: 10px;
+  cursor: pointer;
+}
+.miu-person.is-active {
+  background: var(--miu-panel-2);
+}
+.miu-person span:nth-of-type(1) {
+  flex: 1;
+}
+
 /* misc */
 .miu-empty {
   padding: 24px;

packages/iios-messaging-ui/tsup.config.ts

@@ -6,10 +6,10 @@ export default defineConfig({
   // entry, never reachable from `index`, because it imports vitest, and bundling
   // that into the main barrel would drag a test runner into every consumer's
   // production build.
-  entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts', 'src/styles.css'],
+  entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/mock-inbox.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts', 'src/styles.css'],
   format: ['esm'],
   // Types only for the TS entries — styles.css has no .d.ts (and tsc chokes on a .css root file).
-  dts: { entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts'] },
+  dts: { entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/mock-inbox.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts'] },
   clean: true,
   external: ['react', 'react-dom', 'vitest', '@insignia/iios-kernel-client'],
 });

packages/iios-service/prisma/migrations/20260722101158_provider_credentials/migration.sql

@@ -0,0 +1,26 @@
+-- CreateTable
+CREATE TABLE "IiosProviderCredential" (
+    "id" TEXT NOT NULL,
+    "scopeId" TEXT NOT NULL,
+    "providerType" TEXT NOT NULL,
+    "cipherText" TEXT NOT NULL,
+    "iv" TEXT NOT NULL,
+    "authTag" TEXT NOT NULL,
+    "keyVersion" INTEGER NOT NULL DEFAULT 1,
+    "displayHints" JSONB,
+    "enabled" BOOLEAN NOT NULL DEFAULT true,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "IiosProviderCredential_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "IiosProviderCredential_scopeId_idx" ON "IiosProviderCredential"("scopeId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "IiosProviderCredential_scopeId_providerType_key" ON "IiosProviderCredential"("scopeId", "providerType");
+
+-- AddForeignKey
+ALTER TABLE "IiosProviderCredential" ADD CONSTRAINT "IiosProviderCredential_scopeId_fkey" FOREIGN KEY ("scopeId") REFERENCES "IiosScope"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+

packages/iios-service/prisma/schema.prisma

@@ -317,10 +317,33 @@ model IiosScope {
   callbacks     IiosCallbackRequest[]
   notificationSubscriptions IiosNotificationSubscription[]
   messageTemplates IiosMessageTemplate[]
+  providerCredentials IiosProviderCredential[]
 
   @@index([orgId, appId, tenantId])
 }
 
+/// A tenant's own credentials for an egress provider (BYO: Twilio SMS, own SMTP, …).
+/// The secret is sealed with AES-256-GCM under the platform key (IIOS_CRED_KEY); only
+/// `displayHints` (non-secret, e.g. from-number / SID last-4) is ever read back out.
+/// One row per (scope, providerType). Resolved at send time by the channel's provider.
+model IiosProviderCredential {
+  id           String    @id @default(cuid())
+  scopeId      String
+  scope        IiosScope @relation(fields: [scopeId], references: [id], onDelete: Cascade)
+  providerType String    // TWILIO_SMS | SMTP | WHATSAPP_CLOUD | …
+  cipherText   String    // base64(AES-256-GCM ciphertext of the JSON config)
+  iv           String    // base64 nonce
+  authTag      String    // base64 GCM auth tag
+  keyVersion   Int       @default(1)
+  displayHints Json?     // non-secret display fields (fromNumber, sidLast4, …)
+  enabled      Boolean   @default(true)
+  createdAt    DateTime  @default(now())
+  updatedAt    DateTime  @updatedAt
+
+  @@unique([scopeId, providerType])
+  @@index([scopeId])
+}
+
 /// A channel-specific handle (phone/email/portal user). NOT identity — stays
 /// UNVERIFIED until MDM resolves it; no silent merge.
 model IiosSourceHandle {

packages/iios-service/src/capability/capability.module.ts

@@ -2,15 +2,20 @@ import { Module } from '@nestjs/common';
 import { MediaModule } from '../media/media.module';
 import { CapabilityProviderRegistry } from './capability.registry';
 import { CapabilityBroker } from './capability.broker';
+import { ProviderCredentialService } from './provider-credential.service';
+import { ProviderCredentialController } from './provider-credential.controller';
 
 /**
  * The governed egress boundary (P9 slice 1). Exports the broker + registry so the
  * outbound layer routes all sends through policy + obligations + a pluggable
  * provider. PLATFORM_PORTS (for the opa gate) comes from the @Global PlatformModule.
+ * Also owns per-scope BYO provider credentials (Twilio SMS, …) — sealed at rest and
+ * resolved by the channel providers at send time.
  */
 @Module({
   imports: [MediaModule],
-  providers: [CapabilityProviderRegistry, CapabilityBroker],
-  exports: [CapabilityBroker, CapabilityProviderRegistry],
+  controllers: [ProviderCredentialController],
+  providers: [CapabilityProviderRegistry, CapabilityBroker, ProviderCredentialService],
+  exports: [CapabilityBroker, CapabilityProviderRegistry, ProviderCredentialService],
 })
 export class CapabilityModule {}

packages/iios-service/src/capability/capability.registry.ts

@@ -4,6 +4,9 @@ import { SandboxProvider } from './sandbox.provider';
 import { HttpProvider } from './http.provider';
 import { EmailProvider } from './email.provider';
 import { SmtpProvider, smtpFallbackFromEnv, smtpIdentityFromEnv, storageResolver } from './smtp.provider';
+import { TwilioSmsProvider, type TwilioCreds } from './twilio-sms.provider';
+import { credKeyFromEnv } from './secret-crypto';
+import { ProviderCredentialService } from './provider-credential.service';
 import { STORAGE_PORT, type StoragePort } from '../media/storage.port';
 
 const DEFAULT_CHANNELS = ['WEBHOOK', 'EMAIL', 'SMS', 'WHATSAPP', 'PORTAL'];
@@ -21,7 +24,10 @@ const DEFAULT_CHANNELS = ['WEBHOOK', 'EMAIL', 'SMS', 'WHATSAPP', 'PORTAL'];
 export class CapabilityProviderRegistry {
   private readonly byChannel = new Map<string, CapabilityProvider>();
 
-  constructor(@Optional() @Inject(STORAGE_PORT) private readonly storage?: StoragePort) {
+  constructor(
+    @Optional() @Inject(STORAGE_PORT) private readonly storage?: StoragePort,
+    @Optional() private readonly credentials?: ProviderCredentialService,
+  ) {
     for (const ch of DEFAULT_CHANNELS) this.register(new SandboxProvider([ch]));
     for (const ch of DEFAULT_CHANNELS) {
       const url = process.env[`IIOS_PROVIDER_URL_${ch}`];
@@ -36,6 +42,12 @@ export class CapabilityProviderRegistry {
       const resolver = this.storage ? storageResolver(this.storage) : undefined;
       this.register(new SmtpProvider(smtp, smtpFallbackFromEnv() ?? undefined, undefined, resolver));
     }
+    // BYO SMS via each tenant's own Twilio creds (resolved per scope at send time). Registered
+    // only when the platform key + credential store are present — else SMS stays on the sandbox.
+    if (credKeyFromEnv() && this.credentials) {
+      const creds = this.credentials;
+      this.register(new TwilioSmsProvider((scopeId) => creds.resolve(scopeId, 'TWILIO_SMS') as Promise<TwilioCreds | null>));
+    }
   }
 
   register(provider: CapabilityProvider): void {

packages/iios-service/src/capability/provider-credential.controller.ts

@@ -0,0 +1,54 @@
+import { BadRequestException, Body, Controller, Get, Headers, Param, Put } from '@nestjs/common';
+import { SessionVerifier } from '../platform/session.verifier';
+import { ActorResolver, type MessagePrincipal } from '../identity/actor.resolver';
+import { ProviderCredentialService } from './provider-credential.service';
+import { TwilioCredentialsDto } from './provider-credential.dto';
+
+const SUPPORTED = new Set(['TWILIO_SMS']);
+
+/**
+ * Per-scope BYO integration credentials. The caller's attested session decides the scope, so a
+ * tenant can only read/write ITS OWN provider credentials. The secret is sealed by the service;
+ * GET returns a masked status (never the token). be-crm gates this behind tenant-admin policy.
+ */
+@Controller('v1/providers')
+export class ProviderCredentialController {
+  constructor(
+    private readonly session: SessionVerifier,
+    private readonly actors: ActorResolver,
+    private readonly credentials: ProviderCredentialService,
+  ) {}
+
+  @Put(':providerType/credentials')
+  async put(
+    @Param('providerType') providerType: string,
+    @Body() body: TwilioCredentialsDto,
+    @Headers('authorization') authorization?: string,
+  ) {
+    this.assertSupported(providerType);
+    const scope = await this.actors.resolveScope(this.principal(authorization));
+    await this.credentials.upsert(scope.id, providerType, {
+      accountSid: body.accountSid,
+      authToken: body.authToken,
+      fromNumber: body.fromNumber,
+    });
+    return this.credentials.status(scope.id, providerType);
+  }
+
+  @Get(':providerType/credentials')
+  async get(@Param('providerType') providerType: string, @Headers('authorization') authorization?: string) {
+    this.assertSupported(providerType);
+    const scope = await this.actors.resolveScope(this.principal(authorization));
+    return this.credentials.status(scope.id, providerType);
+  }
+
+  private assertSupported(providerType: string): void {
+    if (!SUPPORTED.has(providerType)) throw new BadRequestException(`unsupported providerType: ${providerType}`);
+  }
+
+  private principal(authorization?: string): MessagePrincipal {
+    const token = (authorization ?? '').replace(/^Bearer\s+/i, '');
+    if (!token) throw new BadRequestException('Authorization bearer token is required');
+    return this.session.verify(token);
+  }
+}

packages/iios-service/src/capability/provider-credential.dto.ts

@@ -0,0 +1,11 @@
+import { IsNotEmpty, IsString } from 'class-validator';
+
+/**
+ * PUT /v1/providers/TWILIO_SMS/credentials — a tenant's own Twilio credentials. Step 1 supports
+ * TWILIO_SMS only; when a second provider (SMTP, …) is added, switch to a per-type validated body.
+ */
+export class TwilioCredentialsDto {
+  @IsString() @IsNotEmpty() accountSid!: string;
+  @IsString() @IsNotEmpty() authToken!: string;
+  @IsString() @IsNotEmpty() fromNumber!: string;
+}

packages/iios-service/src/capability/provider-credential.service.spec.ts

@@ -0,0 +1,79 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { ProviderCredentialService } from './provider-credential.service';
+
+const KEY_B64 = Buffer.alloc(32, 7).toString('base64');
+
+/** Minimal in-memory stand-in for prisma.iiosProviderCredential (upsert/findUnique). */
+function fakePrisma() {
+  const rows = new Map<string, Record<string, unknown>>();
+  const k = (scopeId: string, providerType: string) => `${scopeId}::${providerType}`;
+  return {
+    _rows: rows,
+    iiosProviderCredential: {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      async upsert({ where, create, update }: any) {
+        const key = k(where.scopeId_providerType.scopeId, where.scopeId_providerType.providerType);
+        const existing = rows.get(key);
+        const row = existing ? { ...existing, ...update } : { ...create };
+        rows.set(key, row);
+        return row;
+      },
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      async findUnique({ where }: any) {
+        return rows.get(k(where.scopeId_providerType.scopeId, where.scopeId_providerType.providerType)) ?? null;
+      },
+    },
+  };
+}
+
+function make(prisma: ReturnType<typeof fakePrisma>, env: NodeJS.ProcessEnv): ProviderCredentialService {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const s = new ProviderCredentialService(prisma as any);
+  s.env = env;
+  return s;
+}
+
+describe('ProviderCredentialService', () => {
+  let prisma: ReturnType<typeof fakePrisma>;
+  let svc: ProviderCredentialService;
+
+  beforeEach(() => {
+    prisma = fakePrisma();
+    svc = make(prisma, { IIOS_CRED_KEY: KEY_B64 } as NodeJS.ProcessEnv);
+  });
+
+  it('seals the secret at rest — plaintext token never stored', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' });
+    const stored = JSON.stringify([...prisma._rows.values()]);
+    expect(stored).not.toContain('tok_secret');
+    expect(stored).toContain('cipherText');
+  });
+
+  it('resolves back the exact config it sealed', async () => {
+    const cfg = { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' };
+    await svc.upsert('scope_1', 'TWILIO_SMS', cfg);
+    expect(await svc.resolve('scope_1', 'TWILIO_SMS')).toEqual(cfg);
+  });
+
+  it('status is masked — reveals hints, never the token', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC1234567', authToken: 'tok_secret', fromNumber: '+15550001111' });
+    const status = await svc.status('scope_1', 'TWILIO_SMS');
+    expect(status).toMatchObject({ configured: true, enabled: true, hints: { fromNumber: '+15550001111', sidLast4: '4567' } });
+    expect(JSON.stringify(status)).not.toContain('tok_secret');
+  });
+
+  it('reports not-configured for an unknown scope', async () => {
+    expect(await svc.status('nope', 'TWILIO_SMS')).toEqual({ configured: false });
+    expect(await svc.resolve('nope', 'TWILIO_SMS')).toBeNull();
+  });
+
+  it('does not resolve a disabled credential', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC123', authToken: 't', fromNumber: '+1' }, { enabled: false });
+    expect(await svc.resolve('scope_1', 'TWILIO_SMS')).toBeNull();
+  });
+
+  it('throws when the platform key is absent (fail closed, never store plaintext)', async () => {
+    const noKey = make(prisma, {} as NodeJS.ProcessEnv);
+    await expect(noKey.upsert('s', 'TWILIO_SMS', { accountSid: 'A', authToken: 't', fromNumber: '+1' })).rejects.toThrow(/IIOS_CRED_KEY/);
+  });
+});

packages/iios-service/src/capability/provider-credential.service.ts

@@ -0,0 +1,70 @@
+import { BadRequestException, Injectable } from '@nestjs/common';
+import { Prisma } from '@prisma/client';
+import { PrismaService } from '../prisma/prisma.service';
+import { credKeyFromEnv, sealSecret, openSecret, type SealedSecret } from './secret-crypto';
+
+/** A provider config is an opaque JSON bag; each provider knows its own shape. */
+export type ProviderConfig = Record<string, unknown>;
+
+export interface CredentialStatus {
+  configured: boolean;
+  enabled?: boolean;
+  hints?: Record<string, unknown>;
+}
+
+/** Non-secret display fields surfaced by `status` — NEVER the secret itself. */
+function hintsFor(providerType: string, config: ProviderConfig): Record<string, unknown> {
+  if (providerType === 'TWILIO_SMS') {
+    const sid = String(config.accountSid ?? '');
+    return { fromNumber: config.fromNumber ?? null, sidLast4: sid.slice(-4) };
+  }
+  return {};
+}
+
+/**
+ * The tenant's BYO integration credentials, one row per (scope, providerType). The secret is
+ * sealed with AES-256-GCM under the platform key before it touches the DB; only non-secret
+ * `displayHints` are ever read back. `resolve` decrypts on demand at send time; `status` never
+ * returns the secret. Fail-closed: no platform key ⇒ upsert throws (we refuse to store plaintext).
+ */
+@Injectable()
+export class ProviderCredentialService {
+  /** Overridable in tests; defaults to the process env (holds IIOS_CRED_KEY). */
+  env: NodeJS.ProcessEnv = process.env;
+
+  constructor(private readonly prisma: PrismaService) {}
+
+  async upsert(scopeId: string, providerType: string, config: ProviderConfig, opts?: { enabled?: boolean }): Promise<void> {
+    const key = credKeyFromEnv(this.env);
+    if (!key) throw new BadRequestException('IIOS_CRED_KEY is not configured — cannot store integration credentials');
+    const sealed = sealSecret(JSON.stringify(config), key);
+    const enabled = opts?.enabled ?? true;
+    const displayHints = hintsFor(providerType, config) as Prisma.InputJsonValue;
+    await this.prisma.iiosProviderCredential.upsert({
+      where: { scopeId_providerType: { scopeId, providerType } },
+      create: { scopeId, providerType, ...sealed, displayHints, enabled },
+      update: { ...sealed, displayHints, enabled },
+    });
+  }
+
+  /** Decrypt the config for send-time use. Null when unconfigured, disabled, or no key. */
+  async resolve(scopeId: string, providerType: string): Promise<ProviderConfig | null> {
+    const row = await this.prisma.iiosProviderCredential.findUnique({
+      where: { scopeId_providerType: { scopeId, providerType } },
+    });
+    if (!row || !row.enabled) return null;
+    const key = credKeyFromEnv(this.env);
+    if (!key) return null;
+    const sealed: SealedSecret = { cipherText: row.cipherText, iv: row.iv, authTag: row.authTag, keyVersion: row.keyVersion };
+    return JSON.parse(openSecret(sealed, key)) as ProviderConfig;
+  }
+
+  /** Masked view for the admin UI — configured + hints, never the secret. */
+  async status(scopeId: string, providerType: string): Promise<CredentialStatus> {
+    const row = await this.prisma.iiosProviderCredential.findUnique({
+      where: { scopeId_providerType: { scopeId, providerType } },
+    });
+    if (!row) return { configured: false };
+    return { configured: true, enabled: row.enabled, hints: (row.displayHints ?? {}) as Record<string, unknown> };
+  }
+}

packages/iios-service/src/capability/secret-crypto.spec.ts

@@ -0,0 +1,38 @@
+import { describe, it, expect } from 'vitest';
+import { credKeyFromEnv, sealSecret, openSecret, SECRET_KEY_VERSION } from './secret-crypto';
+
+const KEY = Buffer.alloc(32, 7); // deterministic 32-byte key for tests
+
+describe('secret-crypto', () => {
+  it('round-trips a secret through seal → open', () => {
+    const sealed = sealSecret('sk_live_abc123', KEY);
+    expect(sealed.keyVersion).toBe(SECRET_KEY_VERSION);
+    expect(sealed.cipherText).not.toContain('sk_live_abc123');
+    expect(openSecret(sealed, KEY)).toBe('sk_live_abc123');
+  });
+
+  it('produces a distinct ciphertext each time (random IV)', () => {
+    const a = sealSecret('same', KEY);
+    const b = sealSecret('same', KEY);
+    expect(a.cipherText).not.toBe(b.cipherText);
+    expect(a.iv).not.toBe(b.iv);
+  });
+
+  it('fails to open with the wrong key', () => {
+    const sealed = sealSecret('top-secret', KEY);
+    expect(() => openSecret(sealed, Buffer.alloc(32, 9))).toThrow();
+  });
+
+  it('fails to open if the ciphertext is tampered (GCM auth)', () => {
+    const sealed = sealSecret('top-secret', KEY);
+    const bad = { ...sealed, cipherText: Buffer.from('deadbeef', 'hex').toString('base64') };
+    expect(() => openSecret(bad, KEY)).toThrow();
+  });
+
+  it('credKeyFromEnv returns null when unset and rejects a wrong-length key', () => {
+    expect(credKeyFromEnv({})).toBeNull();
+    expect(() => credKeyFromEnv({ IIOS_CRED_KEY: Buffer.alloc(16).toString('base64') })).toThrow(/32 bytes/);
+    const key = credKeyFromEnv({ IIOS_CRED_KEY: KEY.toString('base64') });
+    expect(key?.length).toBe(32);
+  });
+});

packages/iios-service/src/capability/secret-crypto.ts

@@ -0,0 +1,46 @@
+import { createCipheriv, createDecipheriv, randomBytes } from 'node:crypto';
+
+/**
+ * Envelope for a tenant secret sealed with AES-256-GCM. Stored as base64 columns on
+ * IiosProviderCredential; the plaintext (a provider config JSON string) never touches disk.
+ */
+export interface SealedSecret {
+  cipherText: string;
+  iv: string;
+  authTag: string;
+  keyVersion: number;
+}
+
+/** Bumped only when the platform master key rotates; lets old rows decrypt under an old key. */
+export const SECRET_KEY_VERSION = 1;
+
+/**
+ * Resolve the 32-byte platform master key from `IIOS_CRED_KEY` (base64). Returns null when
+ * unset (so egress providers that need it stay unregistered / fail closed) but THROWS on a
+ * present-but-malformed key — a wrong-length key is an operator error, not a "disabled" state.
+ */
+export function credKeyFromEnv(env: NodeJS.ProcessEnv = process.env): Buffer | null {
+  const raw = env.IIOS_CRED_KEY;
+  if (!raw) return null;
+  const key = Buffer.from(raw, 'base64');
+  if (key.length !== 32) throw new Error('IIOS_CRED_KEY must decode to 32 bytes (base64-encoded 256-bit key)');
+  return key;
+}
+
+export function sealSecret(plaintext: string, key: Buffer): SealedSecret {
+  const iv = randomBytes(12);
+  const cipher = createCipheriv('aes-256-gcm', key, iv);
+  const enc = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);
+  return {
+    cipherText: enc.toString('base64'),
+    iv: iv.toString('base64'),
+    authTag: cipher.getAuthTag().toString('base64'),
+    keyVersion: SECRET_KEY_VERSION,
+  };
+}
+
+export function openSecret(sealed: SealedSecret, key: Buffer): string {
+  const decipher = createDecipheriv('aes-256-gcm', key, Buffer.from(sealed.iv, 'base64'));
+  decipher.setAuthTag(Buffer.from(sealed.authTag, 'base64'));
+  return Buffer.concat([decipher.update(Buffer.from(sealed.cipherText, 'base64')), decipher.final()]).toString('utf8');
+}

packages/iios-service/src/capability/twilio-sms.provider.spec.ts

@@ -0,0 +1,67 @@
+import { describe, it, expect, vi } from 'vitest';
+import type { CapabilityRequest } from '@insignia/iios-contracts';
+import { TwilioSmsProvider, type TwilioCreds } from './twilio-sms.provider';
+
+const CREDS: TwilioCreds = { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' };
+
+const req = (over: Partial<CapabilityRequest> = {}): CapabilityRequest => ({
+  capability: 'channel.send',
+  channelType: 'SMS',
+  scopeId: 'scope_1',
+  target: '+15557654321',
+  payload: { text: 'hello world' },
+  idempotencyKey: 'idem-1',
+  ...over,
+});
+
+describe('TwilioSmsProvider', () => {
+  it('resolves the scope creds and POSTs to Twilio, returning SENT with the message SID', async () => {
+    const http = vi.fn().mockResolvedValue({ ok: true, status: 201, json: async () => ({ sid: 'SM999' }), text: async () => '' });
+    const resolve = vi.fn().mockResolvedValue(CREDS);
+    const p = new TwilioSmsProvider(resolve, http);
+
+    const res = await p.send(req());
+
+    expect(resolve).toHaveBeenCalledWith('scope_1');
+    const [url, init] = http.mock.calls[0];
+    expect(url).toBe('https://api.twilio.com/2010-04-01/Accounts/AC123/Messages.json');
+    expect(init.method).toBe('POST');
+    expect(init.headers.authorization).toBe(`Basic ${Buffer.from('AC123:tok_secret').toString('base64')}`);
+    const body = new URLSearchParams(init.body as string);
+    expect(body.get('To')).toBe('+15557654321');
+    expect(body.get('From')).toBe('+15550001111');
+    expect(body.get('Body')).toBe('hello world');
+    expect(res).toMatchObject({ outcome: 'SENT', providerRef: 'SM999' });
+  });
+
+  it('fails closed as NOT_CONFIGURED when the scope has no creds', async () => {
+    const http = vi.fn();
+    const p = new TwilioSmsProvider(async () => null, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('NOT_CONFIGURED');
+    expect(http).not.toHaveBeenCalled();
+  });
+
+  it('fails closed as NOT_CONFIGURED when the request has no scope', async () => {
+    const p = new TwilioSmsProvider(async () => CREDS, vi.fn());
+    const res = await p.send(req({ scopeId: undefined }));
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('NOT_CONFIGURED');
+  });
+
+  it('surfaces a Twilio API error as FAILED (never throws)', async () => {
+    const http = vi.fn().mockResolvedValue({ ok: false, status: 401, json: async () => ({ code: 20003, message: 'Authenticate' }), text: async () => 'Authenticate' });
+    const p = new TwilioSmsProvider(async () => CREDS, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('TWILIO_20003');
+  });
+
+  it('surfaces a transport throw as FAILED', async () => {
+    const http = vi.fn().mockRejectedValue(new Error('network down'));
+    const p = new TwilioSmsProvider(async () => CREDS, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+  });
+});

packages/iios-service/src/capability/twilio-sms.provider.ts

@@ -0,0 +1,70 @@
+import type { CapabilityProvider, CapabilityRequest, ProviderResult } from '@insignia/iios-contracts';
+
+/** The decrypted Twilio config a tenant configures (BYO credentials). */
+export interface TwilioCreds {
+  accountSid: string;
+  authToken: string;
+  fromNumber: string;
+}
+
+/** Resolves a scope's Twilio creds (decrypting on demand); null when unconfigured/disabled. */
+export type TwilioCredResolver = (scopeId: string) => Promise<TwilioCreds | null>;
+
+/** Injectable HTTP sender so tests don't hit the network; prod uses fetch. */
+export type HttpSender = (url: string, init: { method: string; headers: Record<string, string>; body: string }) => Promise<{
+  ok: boolean;
+  status: number;
+  json: () => Promise<unknown>;
+  text: () => Promise<string>;
+}>;
+
+const defaultSender: HttpSender = (url, init) => fetch(url, init) as unknown as ReturnType<HttpSender>;
+
+/**
+ * SMS egress via Twilio, using the CALLER'S OWN credentials (resolved per scope at send time).
+ * Fail-closed: no scope or no configured creds ⇒ FAILED/NOT_CONFIGURED, nothing sent. A Twilio
+ * API error is surfaced as FAILED (never thrown), per the provider doctrine.
+ */
+export class TwilioSmsProvider implements CapabilityProvider {
+  readonly name = 'twilio-sms';
+  readonly channelTypes = ['SMS'];
+  readonly capabilities = { canSend: true, maxPayloadBytes: 1600 };
+
+  constructor(
+    private readonly resolve: TwilioCredResolver,
+    private readonly http: HttpSender = defaultSender,
+  ) {}
+
+  async send(req: CapabilityRequest): Promise<ProviderResult> {
+    const started = Date.now();
+    if (!req.scopeId) return { providerRef: 'unconfigured', outcome: 'FAILED', errorCode: 'NOT_CONFIGURED' };
+
+    const creds = await this.resolve(req.scopeId).catch(() => null);
+    if (!creds) return { providerRef: 'unconfigured', outcome: 'FAILED', errorCode: 'NOT_CONFIGURED' };
+
+    const body = new URLSearchParams({
+      To: req.target,
+      From: creds.fromNumber,
+      Body: String(req.payload.text ?? req.payload.body ?? ''),
+    }).toString();
+
+    try {
+      const res = await this.http(`https://api.twilio.com/2010-04-01/Accounts/${creds.accountSid}/Messages.json`, {
+        method: 'POST',
+        headers: {
+          authorization: `Basic ${Buffer.from(`${creds.accountSid}:${creds.authToken}`).toString('base64')}`,
+          'content-type': 'application/x-www-form-urlencoded',
+        },
+        body,
+      });
+      const latencyMs = Date.now() - started;
+      const payload = (await res.json().catch(() => ({}))) as { sid?: string; code?: number; message?: string };
+      if (!res.ok) {
+        return { providerRef: `twilio-${res.status}`, outcome: 'FAILED', errorCode: payload.code ? `TWILIO_${payload.code}` : `HTTP_${res.status}`, latencyMs };
+      }
+      return { providerRef: payload.sid ?? 'twilio-sent', outcome: 'SENT', latencyMs };
+    } catch (err) {
+      return { providerRef: 'twilio-error', outcome: 'FAILED', errorCode: (err as Error).message.slice(0, 60), latencyMs: Date.now() - started };
+    }
+  }
+}

pnpm-lock.yaml

@@ -340,6 +340,9 @@ importers:
       '@types/react':
         specifier: ^19.0.0
         version: 19.2.17
+      '@types/react-dom':
+        specifier: ^19.0.0
+        version: 19.2.3(@types/react@19.2.17)
       jsdom:
         specifier: ^26.0.0
         version: 26.1.0