Messaging

Messages are individual communications within a chat thread.

Messages can include text, media attachments, rich link previews, special effects (like confetti or fireworks), and reactions. All messages are associated with a specific chat and sent from a phone number you own.

Messages support delivery status tracking, read receipts, and editing capabilities.

Send a URL as a link part to deliver it with a rich preview card showing the page’s title, description, and image (when available). A link part must be the only part in the message — it cannot be combined with text or media parts. To send a URL without a preview card, include it in a text part instead.

Limitations:

• A link part cannot be combined with other parts in the same message.
• Maximum URL length: 2,048 characters.

An app_clip part sends a registered App Clip — not only Linq’s Apple Pay checkout, but any partner’s own App Clip. Like a link part it must be the only part in the message, and it is iMessage only — it never downgrades to SMS or RCS. The payment-checkout use of this part is covered in the Payments section.

For regulated or sensitive conversations, opt in to the ephemeral messages tier by contacting your Linq support contact. When enabled, every message on the covered phone numbers is given a retention window configured for your account. After that window, the message’s text, formatting, and attachment references are no longer retrievable through the API — see the Attachments row below for how the attachment media itself is handled. Metadata about the message is retained: message identifiers, timestamps, phone numbers, and delivery state. Metadata retention is not bounded by this window. Bounded operational copies, such as backups and delivery queues, expire on their own separate schedules. There is no per-message flag; ephemerality is applied automatically based on your configuration.

The window can be set anywhere from 60 minutes to 24 hours, and defaults to 24 hours. Ask your Linq support contact to configure a shorter window; it cannot be changed through the API.

You can request it at two scopes:

Scope	Effect
Partner-wide	Every outbound and inbound message on every phone number under your account has its content removed from the API surface after your configured window. Metadata is retained.
Per phone number	Only the specified phone numbers have message content removed from the API surface this way. The rest follow the standard message-retention policy.

Behavioral differences vs the standard default:

Aspect	Standard	Ephemeral
Retention	Retained per the standard message-retention policy	Hard backstop: your configured window (60 minutes – 24 hours, default 24 hours) from when the message is created
After expiry	Message stays retrievable	Message content is no longer retrievable — GET /v3/messages/{messageId} returns 404 and it no longer appears in GET /v3/chats/{chatId}/messages
Content on expiry	N/A	Text, formatting, and attachment references are removed from the API surface, not blanked out in place. Metadata (identifiers, timestamps, phone numbers, delivery state) is retained; its retention is not bounded by this window
Attachments	Retained	Media sent on the ephemeral attachments tier is removed on its own storage backstop — within roughly 24–48 hours of upload — independently of the message window, so it can outlast a window shorter than a day. Attachments on the persistent tier (including pre-uploads via POST /v3/attachments) are kept until you DELETE them
Cross-partner isolation	Enforced	Enforced

How the retention window works:

• The window runs from message creation (created_at). It is configured for your account (60 minutes – 24 hours, default 24 hours) and cannot be set per message.
• Attachment media follows its own storage backstop rather than the message window — see the Attachments row above.
• Expiry is delivery-independent — the clock starts when the message is created, not when it is delivered or read.
• Deletion happens shortly after the window, not exactly at it. A background sweep runs every ~5 minutes, so a message typically stops being retrievable within about 5 minutes of its expiry, and longer while a backlog is being worked through. Treat the window as the guaranteed minimum retention, never as an exact deletion time or an upper bound.

What you observe:

• No expiry timestamp is exposed. API responses and webhook payloads do not include the deletion time, and they do not report your configured window either — so if you are on a window shorter than 24 hours you cannot derive a message’s expiry from the API today. Track the window you agreed with your Linq support contact and compute created_at + window yourself.
• No deletion webhook is sent. There is no message.deleted event — a message simply stops being retrievable once its window passes.
• The attachment backstop is separate from the message window. API retrievability (the 404 behavior above) ends at your configured window. Ephemeral-tier media objects are removed on their own storage backstop — within roughly 24–48 hours of upload — which is independent of the message window and can outlast a window shorter than a day. Removal of the corresponding entries from the sending device happens asynchronously and can complete after the backstop.
• Delivery is unaffected. Ephemeral messages send, deliver, and fire the usual message.sent / message.received and status webhooks exactly like standard messages. Only retention changes.

When to choose ephemeral:

• You have a compliance requirement that the platform must not retain message content beyond a short window.
• The conversation is high-sensitivity (PHI, financial, identity verification) and you do not want it sitting in storage long-term.
• Your application is the system of record — you capture what you need from the delivery webhook in real time and do not rely on reading message history back from Linq later.

Important: ephemeral applies in both directions — messages you send and messages received by the phone numbers in that scope. Because Linq can no longer return the message once its window passes, persist anything you need to keep from the webhook payload at the time it is delivered.