Modes

The TUI has one chat mode (PLAN / BUILD) and three UI modes (dev / production / on-host). They are independent: a production-mode TUI can still be in PLAN chat mode, and so on.

dev

Triggered by cast dev <agent>. The TUI connects to a local runtime on a dynamic port. The header is purple and shows just the agent name.

+---------------------------------------------------------------+
| . email-assistant                                  [PLAN]      |
+---------------------------------------------------------------+

• The runtime is killed when you quit the TUI.
• /undo, /redo, /sessions, /session …, /releases, /release, /deploy, and /upgrade are all available — you’re working on the agent on this machine.
• /connect switches to a different deployed agent (useful for comparing local behaviour to production).
• No bearer token is required.

production

Triggered by cast connect <agent-or-sha>. The TUI connects to a deployed A2A server over HTTPS. The header is green and includes the deployed version.

+---------------------------------------------------------------+
| . email-assistant (v1.6)                       [● LIVE  v1.6] |
+---------------------------------------------------------------+

• Bearer-token auth is added by cast connect; the TUI does not display the token, but the underlying A2A client carries it.
• The same slash commands work, but the destructive ones (/release, /deploy, /upgrade) are scoped to the currently-connected deployment’s agent.
• /connect lets you jump to a different deployment or to a different agent’s deployment without exiting the TUI.

on-host

Triggered by running cast-tui inside a DigitalOcean container (see on-host TUI). The header is also green, but no version badge appears because the TUI is talking to a local A2A server inside the same container.

+---------------------------------------------------------------+
| . email-assistant                                 [● LIVE]     |
+---------------------------------------------------------------+

The available commands are intentionally trimmed:

• /help — show the trimmed help (no agent-category commands).
• /clear — clear the chat.
• /copy — copy the last reply.
• /quit, /exit — exit the TUI.

There is no network exposure, no bearer token crossing a wire, and no chance of accidentally targeting a different deployment. The chat is effectively a local REPL against the deployed container’s runtime.

What the modes are NOT

• A security boundary. A production-mode TUI can still be tricked into running a destructive slash command if the agent’s prompt allows it. The mode is a visual cue and a UX contract, not a sandbox.
• Persistent. The mode is per-session. Each new TUI process starts in the default for that mode (PLAN in dev, PLAN in production).
• Configurable. There are no flags to change the default mode or the header colors. The header colors are part of the visual language.