TUI display types

Keep small shared types independent of the UI model and runtime. These are rendering/adapter types, not the canonical session history or protocol schema. The complete interface defines exact fields.

Shell UI commands and pages

Shell Security, Agent and Chat page state belongs to Model. Approval, revocation, management and moderator-input reactions belong to Controller_types, not to this module’s cmd.

Chat transcript helpers

role = string and message = role * string hold displayed role/text. Roles are not validated by this alias; rendering also uses developer, reasoning and tool labels. They do not replace identity-bearing History_entry.t or Projected_message.t.

let seed : Chat_tui.Types.message list =
  [ "developer", "You are a helpful assistant."; "user", "Hello!" ]

Streaming buffers

Streaming buffers belong to Model, not a public Types.msg_buffer record. Deltas update the display incrementally before the connection closes. Stable projected IDs identify rows; current array indexes are layout positions, not durable identities.

Commands

Persist_session, Start_streaming, and Cancel_streaming each carry a unit -> unit thunk. Cmd executes these with host-owned lifetime and error handling. This compatibility abstraction is distinct from Agent_protocol.Command and Controller_types.reaction.

Patches

Model.apply_patch applies these in-place on the UI owner:

Patch	Effect
Ensure_buffer	Ensure an ID-keyed streaming display buffer
Append_text	Append delta text and reflect it in the displayed row
Set_function_name	Associate tool name with buffer ID
Associate_tool_call	Correlate streaming item ID with tool call ID
Set_function_output	Record tool output text
Update_reasoning_idx	Record reasoning-summary correlation
Add_user_message	Add a display row only; does not append canonical history
Add_placeholder_message	Add a transient UI-only notice

Callers maintaining canonical state must append an allocated history entry separately; native clients instead receive authoritative server projections. Do not persist a placeholder or send display-only live tool activity to a model.

Tool-output classification

Apply_patch, Read_file { path }, Read_directory { path }, and Other { name } select specialized display/highlighting. This metadata is derived in the TUI and is not itself durable conversation state.

Runtime settings

settings contains parallel_tool_calls : bool, default true through default_settings (). It is a legacy local execution setting; CLI flags do not override native/daemon runtime policy.

Known limitations

The UI model is mutable; these patches are not immutable-state transformations. String roles and thunk commands do not enforce semantic authority, durability, or cancellation. Keep those responsibilities in the host.