Operator stream endpoint

The built-in operator endpoint carries authenticated, bounded NDJSON turns for the web console and other maintained operator clients. The terminal renderer and mono-agent tui command are removed in the published 0.26.0 release; the protocol remains because web, ACP, and jobs behavior depends on it.

Coverage: config. The compatibility identifier remains tui in configuration, environment variables, discovery metadata, channel/source ids, traces, and wire schema. It is a protocol identifier, not an available terminal product.

Configuration

{
  "tui": {
    "enabled": true,
    "host": "127.0.0.1",
    "port": 0,
    "basePath": "",
    "allowNonLoopback": false
  }
}

The endpoint defaults on, binds loopback, and chooses an ephemeral port. Set tui.enabled to false to disable it. MONO_AGENT_TUI_* remains the supported environment-variable family; use MONO_AGENT_TUI_API_KEY rather than placing a secret in source configuration.

Do not widen host without also setting allowNonLoopback: true and supplying an API key. Non-loopback exposure is an explicit trust-boundary decision. The endpoint preserves existing authentication, history, cancellation, attachment, structured AskUser, and agent-owned cron capability behavior.

Compatibility contract

The following names intentionally remain stable for existing clients and data:

• config keys under tui.* and environment keys under MONO_AGENT_TUI_*;
• discovery metadata at metadata.channels.tui and the tui channel/source id;
• /gui, TUI_WIRE_SCHEMA, startTuiAdapter, TuiAdapter*, and TUI_CONFIG_FIELDS in their existing public APIs;
• bounded event frames, owner authentication, history import, cancellation, attachment handling, and capability negotiation.

Serialized remote event frames remain capped at 256 KiB after UTF-8 NDJSON encoding. Oversized assistant-thought and tool-call payload fields are reduced and remeasured; another oversized event variant, or a minimal reducible event that still does not fit, becomes a bounded oversized_event marker. This does not imply complete artifact persistence.

For browser operation, see the web console. For offline diagnostics, use mono-agent runs list, mono-agent runs show <run-id>, and mono-agent config.