tau-cli-term

tau-cli-term is the high-level prompt layer used by Tau's terminal UI. It sits between the application (tau-cli) and the raw terminal engine (tau-cli-term-raw).

Responsibilities

This crate owns prompt features that need application-shaped data but should not live in the low-level renderer:

command and argument completion candidate construction,
completion menu rendering as tau-term-screen styled blocks,
prompt-local binding actions such as prompt history search, undo/redo, external editing, and shell insertion,
$EDITOR / $VISUAL resolution and terminal pause/resume around external programs,
conversion from raw terminal events into the smaller high-level Event API consumed by tau-cli.

Boundaries

tau-cli-term-raw owns terminal state and editing mechanics: raw mode, crossterm events, key dispatch, multiline buffer editing, completion menu lifecycle, prompt history navigation, undo/redo, redraw scheduling, and screen rendering.

tau-cli-term owns prompt semantics that depend on configured commands or external tools. It may call raw named actions, but it should not duplicate the raw editing state machine.

First-non-whitespace : enters intrinsic command mode before configured prompt-text completion rules run. A doubled prefix is literal prompt syntax: ::text remains visible while editing but is stored canonically as :text in both raw editable history and the high-level history-search list.

tau-cli owns application behavior. High-level binding actions unknown to this crate are surfaced as Event::Action(String) and interpreted by tau-cli; this crate should not interpret application actions or provider/role behavior.

Tau-specific prompt content can still be supplied through explicit hooks. For example, CompletionData::set_agent_mention_completer and CompletionData::set_session_completer let the application provide @ agent and & session candidates while this crate owns only token detection, replacement ranges, and menu presentation.

Binding action model

Bindings arrive from config as strings. The dispatch order is:

raw named actions recognized by tau-cli-term-raw::Term::is_named_action,
prompt-local actions parsed by PromptShellAction::parse,
simple unknown action names surfaced as Event::Action(String) for the application.

Colon-form prompt actions are crate-local protocols:

shell-prompt-insert:<mode>:<command> inserts command stdout at the cursor,
shell-prompt-edit:<mode>:<command> edits the current prompt through a temp file,
prompt-history-search:<mode>:<command> feeds indexed prompt history rows to a picker command.

The application-owned shell-prompt-edit-chat action reuses the same editor path after loading the selected durable conversation.

The <mode> segment is trim to strip leading/trailing command output whitespace or raw to preserve command output as-is.

Malformed or unknown colon-form actions fail locally instead of being forwarded as application actions.

History model

The raw layer is authoritative for editable prompt-history navigation. This crate keeps a submitted-prompt list only for prompt-history search input. When a prompt is submitted, it is appended here and the raw layer has already recorded the editable history entry.

External editor context