@linked.cm/messaging

A shape-agnostic, transport-agnostic messaging engine for LINKED applications.

It provides three things and deliberately nothing else:

• Messaging — the transport seam. spaces(), threads(), messages(), send(), plus optional additive verbs (react, sendReply, edit, remove, report, ignoreAuthor, sendMedia, sendData, sendSignal, setTyping, markRead). A transport implements only what it supports; the UI never shows a dead control.
• createMessagingStore — an in-memory reference implementation of that seam, for demos, tests, and offline states.
• MessageClient — a themeable chat UI that renders any Messaging.

Install

npm install @linked.cm/messaging

What it does not know

No channel taxonomy, no interactive-card vocabulary, no branding, no product copy. Every host-specific decision arrives as a render prop:

<MessageClient
  store={transport}
  activeThreadId={active}
  onActiveThread={setActive}
  threadIcon={(t) => iconFor(t.kind)}
  renderCard={(data, thread) => <MyCard data={data} thread={thread} />}
  renderAvatar={(author) => <MyAvatar id={author.id} />}
  renderQR={(value, size) => <MyQR value={value} size={size} />}
/>

That is what lets the same UI run against the in-memory store and against a live transport with no component changes:

import { createMessagingStore } from '@linked.cm/messaging';
import { createMatrixMessaging } from '@linked.cm/matrix/client';

const store = demo
  ? createMessagingStore(seed)
  : await createMatrixMessaging(session, config);

Identity

createMessagingStore is the in-memory reference transport for demos and tests. It does not authenticate anyone. seed.me is only the display author stamped on messages the store appends. There is no default person: construction throws if me is missing, and a send is dropped when the resolved author has no id, so a signed-out session is not filled in with a fabricated speaker.

A host that uses the store outside a demo passes me as a function of its verified session. A hardcoded author is demo data, not a signed-in user. A live app should use a real transport (for example @linked.cm/matrix), which takes its session from the host.

MsgThread.audience is a host-defined string. The engine carries it and does not render or interpret it. Age bands and who may read a thread stay in the host.

Safety

The default client has accessible report, mute, block, own-delete, and authorized moderator-remove controls. Pass a MessageSafetyController to persist product-level actions. A transport-native report/ignore is also used when available, but the API keeps the semantics honest: a Matrix ignore is a one-way mute, never a bilateral block.

For conversations between strangers, a host can provide MessageSafetyController.checkOutgoingText. The client awaits that preflight before the transport receives the message. A host can return silent: true for a rejected message; the client then consumes the draft without displaying a moderation result and never calls the transport. Non-silent failures leave the text in the composer and display only the host's safe user-facing explanation. Scanning policy and diagnostics stay server-side.

filterUnsafeMessages, createSlidingWindowRateLimiter, and runMessageTextSafetyCheck are reusable without the UI. The scan helper requires an injected scanner and records when none is available; this package does not claim that a keyword list or empty seam is content moderation. Durable RDF records and moderation lifecycle operations live in @linked.cm/safety.

Styling

The client is styled with LINKED design tokens (--bg-panel, --space-md, --radius-lg, …) supplied by @_linked/css. It defines no colours of its own, so it inherits the host's theme in both light and dark.

Import the stylesheet once:

import '@linked.cm/messaging/styles.css';

Transports

| Package | Transport | | ------------------- | ---------------------------------- | | built in | createMessagingStore — in-memory | | @linked.cm/matrix | Matrix homeserver + appservice |

The package targets @_linked/core ^2.25.0 and registers under the LINKED package identity @_linked/messaging.