Group messages default to **require mention** (metadata mention or safe regex patterns). Applies to WhatsApp, Telegram, Discord, Google Chat, and iMessage group chats.

Visible replies are controlled separately. Normal direct, group, and channel requests default to automatic final delivery: final assistant text posts through the legacy visible reply path. Set `"message_tool"` when a chat should only post visible output after the agent calls `message(action=send)`. If the model returns final text without calling the message tool, that final text stays private and the gateway verbose log records suppressed payload metadata.

Visible replies are controlled separately. Normal group and channel requests default to automatic final delivery: final assistant text posts through the legacy visible reply path. Some harnesses, including Codex, default direct/source chats to message-tool delivery so visible output only posts after the agent calls `message(action=send)`. If the model returns final text without calling the message tool, that final text stays private and the gateway verbose log records suppressed payload metadata.

Tool-only visible replies require a model/runtime that reliably calls tools, and are recommended for shared ambient rooms on latest-generation models such as GPT 5.5. If

the session log shows assistant text with `didSendViaMessagingTool: false`, the

```json5

{

messages: {

visibleReplies: "automatic", // global default for direct/source chats

visibleReplies: "automatic", // force old automatic final replies for direct/source chats

groupChat: {

historyLimit: 50,

unmentionedInbound: "room_event", // always-on unmentioned room chatter becomes quiet context

`messages.groupChat.unmentionedInbound: "room_event"` submits unmentioned always-on group/channel messages as quiet room context on supported channels. Mentioned messages, commands, and direct messages remain user requests. See [Ambient room events](/channels/ambient-room-events) for complete Discord, Slack, and Telegram examples.

`messages.visibleReplies` is the global source-event default; `messages.groupChat.visibleReplies` overrides it for group/channel source events. When `messages.visibleReplies` is unset, direct/source chats use automatic final delivery across runtimes. Channel allowlists and mention gating still decide whether an event is processed.

`messages.visibleReplies` is the global source-event default; `messages.groupChat.visibleReplies` overrides it for group/channel source events. When `messages.visibleReplies` is unset, direct/source chats use the selected runtime or harness default. The Codex harness defaults direct/source chats to message-tool delivery; set `messages.visibleReplies: "automatic"` to use automatic final delivery. Channel allowlists and mention gating still decide whether an event is processed.

#### DM history limits