Apus attaches normalized MessagePresentation metadata to outbound Matrix m.room.message events under the com.apus.presentation content key.

Stock Matrix clients keep rendering the plain text body. Apus-aware clients can read the structured metadata and render native UI such as buttons, selects, context rows, and dividers.

Event content

{
  "msgtype": "m.text",
  "body": "Select model\n\nChoose model:\n- DeepSeek",
  "com.apus.presentation": {
    "version": 1,
    "type": "message.presentation",
    "title": "Select model",
    "tone": "info",
    "blocks": [
      {
        "type": "select",
        "placeholder": "Choose model",
        "options": [
          {
            "label": "DeepSeek",
            "value": "/model deepseek/deepseek-chat -s"
          }
        ]
      }
    ]
  }
}

• version is the metadata schema version; the current version is 1. type is a stable discriminator, always "message.presentation". The Matrix adapter only emits payloads with exactly this version and type; clients should likewise ignore unknown versions they cannot safely interpret, unknown type values, and unknown block types.
• title and tone (info, success, warning, danger, neutral) are optional hints.
• Buttons and select options can carry a typed action ({ "type": "command", "command": "/..." } or { "type": "callback", "value": "..." }) alongside the legacy string value. Prefer action when both are present.

Fallback behavior

Apus always renders a readable plain text fallback into body. The structured metadata is additive and must not be required for basic Matrix interoperability.

Fallback rendering rules:

• title, text, and context content renders as plain lines.
• Buttons with a command action render as label: `/command` so the command stays copyable. Buttons with a callback action or only a legacy value render label-only so opaque callback values stay private; disabled buttons are always label-only. URL and web-app buttons render as label: URL.
• Select blocks render the placeholder (or Options:) as a heading plus label-only option lines.
• If nothing renders, for example a divider-only presentation, the body falls back to ---.

Unsupported clients keep showing the fallback text. Apus-aware clients may prefer the structured metadata for display while preserving the fallback for copy, search, notifications, and accessibility.

Supported blocks

The Matrix outbound adapter advertises native support for:

• buttons
• select
• context
• divider

text blocks are always supported through the fallback body. Treat all blocks as best-effort presentation hints; ignore unknown fields and block types rather than failing the whole message.

Interactions

This metadata does not add Matrix callback semantics. Button and select values are fallback interaction payloads, usually slash commands or text commands. A Matrix client that wants to support interaction resolves the control value (action.command, then action.value, then value) and sends it back to the room as a normal message.

For example, a button with value /model deepseek/deepseek-chat -s can be handled by sending that value as an encrypted Matrix text message in the same room. The explicit session flag prevents a configured-default update regardless of the model selection scope setting.

Relationship to approval metadata

com.apus.presentation is for general rich message presentation.

Approval prompts use the dedicated com.apus.approval metadata because approvals carry safety-sensitive state, decisions, and exec/plugin details. If both metadata keys are present on the same event, clients should prefer the dedicated approval renderer.

Media messages

When a reply contains multiple media URLs, Apus sends one Matrix event per media URL. Caption text and presentation metadata attach only to the first event so clients get one stable structured payload without duplicate renderers. The same rule applies when long text is chunked across events: the metadata rides on the first event only.

Keep presentation metadata compact. Large user-visible text should stay in body and use the normal Matrix text chunking path.