Talk to tau¶

Two channels run in the terminal today. tau chat is a line-based REPL: one prompt, streamed replies, tool lines, approvals on stdin. tau tui is a full Textual interface: markdown replies, tool cards, a live events pane, a session picker and a modal approval dialog. They share the same slash commands, the same session store and the same tier gate, so you can start in one and /resume in the other.

	`tau chat`	`tau tui`
Best for	scripts, slow links, a quick question	daily use, the phone, long sessions
Replies	streamed plain text	streamed markdown
Tool calls	dim lines	cards with tier, approval, duration and result
Approvals	`Approve? [y/N]` on stdin	modal dialog with Approve / Reject
Agent events	in the log file only	live pane, replayed on `/resume`
Cancel a turn	Ctrl-C	Esc
Leave	`/quit`, Ctrl-D	`/quit`, Ctrl+Q
Needs a TTY	no	yes

Both read the same config and stop with exit code 2 before anything opens when credentials are missing, the config is broken or a --resume ID is unknown.

`tau chat`¶

tau chat                      # new session on the brain role
tau chat --resume             # continue the most recent earlier session
tau chat --resume ID          # continue that session
tau chat --session ID         # start with this session id
tau chat --role fast          # pin a role for the whole run
tau --lang tr chat            # Turkish chrome

tau ready. Profile: home, session: 20260929-173826-f949. Commands: /help, /tools, /sessions, /resume, /new, /session, /compact, /clear, /status, /model, /lang, /quit (Ctrl-D also quits).
you> Merhaba tau
tau> Merhaba. Nasıl yardımcı olabilirim?
you> /session
Session: 20260929-173826-f949
Title: Merhaba tau
Messages: 2
Store: file (~/.local/share/tau/sessions)

The REPL does one thing at a time: a command never overlaps a turn. Ctrl-C during a turn cancels it at the next safe point and prints Interrupted.; Ctrl-C at the prompt leaves.

Approvals on the terminal¶

A tier-2 call blocks the turn and asks on stdin:

⚠️  Approval needed (tier 2)
  Tool: demo_physical_action
  Arguments: {"action": "turn on the desk lamp"}
  Effect: Demo: simulates a physical action; no real device moves.
  Approve? [y/N]

y, yes, e or evet approves, in either UI language.
Anything else rejects: n, Enter, Ctrl-D, a typo.
There is no timeout on the terminal; the prompt waits for you.
A rejection does not end the turn. The model reads The user did not approve this action as the tool result and answers.

Slash commands¶

A line that starts with / is a command. The channel handles it; the model never sees it. The twelve canonical names are English; Turkish aliases (/devam, /çık, /özet, …) keep working but are never shown.

Command	What it does
`/help`	list the commands with one-line help
`/tools`	registered tools with their tier and description
`/sessions`	the 10 most recent earlier sessions, numbered
`/resume`, `/resume n`, `/resume id`	resume the most recent earlier session, the n-th of the last listing, or an id
`/new`	start a fresh session; the current one stays on record
`/session`	current session id, title, message count and store
`/compact [focus]`	summarize this session with its own model and continue in a new session seeded with the summary; the old one is kept
`/clear`	clear the screen; the session and the agent go on
`/status`	profile, session, model, context, tools, UI language, versions, hub
`/model [role]`	list the roles of `tau.toml`, or switch this session to one; `/resume` remembers it
`/lang en`, `/lang tr`	switch the UI language for this run
`/quit`	leave; `/exit` is an alias

you> /status
Profile: home
Session: 20260929-173826-f949 · Merhaba tau · 2 messages stored · role brain
Model: brain → anthropic (fallback; bedrock has no credentials) · claude-sonnet-5
Context: sliding, window 60 · 2 messages in memory
Tools: 2 registered · 1 need approval (tier 2)
UI language: en
Versions: tau-core 0.2.0 · tau-tui 0.2.0
Hub: hub is not running (nothing answers on http://127.0.0.1:7877/health)

/status names the model per role and whether the fallback is in use, never a key. The slash command reference has the aliases and the exact wording of every notice.

`tau tui`¶

tau tui                       # new session
tau tui --resume              # continue the most recent earlier session
tau tui --resume ID
tau tui --profile travel
tau --home /path/to/root --lang tr tui

The interface is one row of chrome at the top and at most four at the bottom, so 80x24 over mosh on a phone stays usable. The header shows the profile, the session id, the role, the tool count and the UI language; the composer is a rounded box that grows from one to five lines; the hint bar names the keys that matter right now.

 τ tau  home · 20260929-120000-abcd                                  brain · en
 › Salon lambası açık mı? Açıksa kapat.
 ● get_light_state(room="salon")                                  tier 0 · 38ms
   ⎿  {"on": true, "brightness": 80}
 ● set_light(room="salon", on=false)                  tier 2 · approved · 412ms
   ⎿  Light turned off
 τ Salon lambası kapatıldı.
   • Önceki durum: açık, %80 parlaklık
 ✓ Worked for 4s · 2 tool calls · ctrl+o expand
╭──────────────────────────────────────────────────────────────────────────────╮
│ ❯ Type a message…                                                            │
╰──────────────────────────────────────────────────────────────────────────────╯
 ? shortcuts · / commands · ctrl+j newline                          ctrl+q quit

Glyphs, one cell each and no emoji: › you · τ tau · ● finished tool call · ○ running or waiting for approval · ⎿ result line · ✻ busy · ✓ ◆ ✗ turn footer (finished / needs you or limit / error) · ▸ notice · ❯ prompt.

Layout by screen size¶

The TUI picks a layout from the terminal size. Width bands: phone below 60 columns, narrow 60–99, wide 100–139, ultra 140 and up. Height bands: short below 20 rows, mid, tall 30 and up.

Terminal	What you get
50x24 (phone, Termius over mosh)	The header drops the session id (`/session` shows it), tool badges move to the result line, the composer has no border, hints read `^j`, the welcome card shows the 16-column mark, replies stream as plain text and settle into markdown when the segment ends, the approval dialog is full width with stacked buttons.
80x24 (narrow)	The layout above. `ctrl+e` or F4 swaps the transcript for the events log in the same body; Esc returns.
80x30 (narrow, tall)	An 8-row events strip under the transcript.
100x30 (wide)	The events pane docks on the right (34 columns); `ctrl+e` hides it.
160x45 (ultra)	A read-only session sidebar on the left (28 columns); clicking a row resumes. Events pane 40 columns.
under 20 rows (short)	No hint row, the welcome mark is hidden, the composer grows to two rows.

Keys¶

Key	Effect
Enter	send, or accept the highlighted menu row
ctrl+j	newline (shift+enter too where the terminal delivers it)
Esc	close the menu · cancel the running turn · leave the events view · scroll back to the bottom
ctrl+e / F4	events: toggle the column (≥ 100 cols) or the view (< 100 cols)
ctrl+r / F2	session picker (Enter resumes, `n` new, Esc closes)
ctrl+n	new session
ctrl+t / F3	`/tools`
ctrl+o / F6	expand or collapse the cards of the last turn: arguments as JSON and the full result
PageUp / PageDown, F7 / F8	scroll the transcript; PageUp at the top of a folded history loads 20 older turns
F9	back to the bottom
↑ / ↓	recall sent prompts; navigate the menu while it is open
`?` or F1	help (only in an empty composer)
ctrl+q	quit (ctrl+c copies a selection; without one it only says how to quit)

Typing / into an empty composer opens a fuzzy menu of the twelve commands: ↑↓ pick, Tab completes, Enter runs, Esc closes. A command typed in full runs as typed even if the menu has not caught up with a burst of keys, so /session never runs /sessions.

While tau answers, the composer keeps your text and a toast says so. /new, /resume, /compact, /clear and /model <role> wait for the current turn; /status and /model without an argument answer any time.

Approvals in the TUI¶

A tier-2 call opens a translucent dialog over the chat: tool, effect, the arguments as pretty JSON, Approve and Reject.

y or e approves; n, h or Esc rejects. Focus starts on Reject, so Enter rejects. Tab moves between the two buttons.
y/e and Approve only work half a second after the dialog opens; the hint reads (arming…) meanwhile. Keys you were typing into the chat cannot approve by accident.
Anything other than an explicit approval rejects: a dialog closed another way, a cancelled wait, an app that is no longer running.
Behind the dialog the tool card reads ○ set_light(…) and ⎿ ◆ waiting for your approval; the composer border and the header τ turn Flare.

Terminal knobs¶

Setting	Effect
`TAU_TUI_ASCII=1`	ASCII vocabulary and box borders for terminals without the block characters
`TAU_TUI_PLAIN_STREAM=1`	stream every reply as plain text and parse the markdown once per segment
`TEXTUAL_ANIMATIONS=none`	no header motion
`TEXTUAL_COLOR_SYSTEM` / `--ansi`	the 16-colour `tau-ansi` theme

Live markdown streaming needs at least 60 columns. While the TUI runs, details go to <TAU_DATA_DIR>/logs/tau.log; the chat shows a short notice instead of a traceback.

The UI language¶

tau --lang tr chat
tau --lang tr tui

--lang sets the chrome for one run; it is exported as TAU_LANG, so the TUI, the terminal and their approval prompts agree. /lang en or /lang tr switches it inside a session. The persona keeps answering in whatever language you write.

Where things end up¶

Sessions: <TAU_DATA_DIR>/sessions/<id>/, one directory each, kept forever. Sessions and compaction.
Log: <TAU_DATA_DIR>/logs/tau.log, INFO and up with tracebacks; tier-1 and tier-2 tool calls with their arguments and approval.
Nothing else. No telemetry, no cloud copy unless you set up backups.