Keybindings

Arbiter ships its own line editor. Bindings below are the complete set the editor responds to. Keys not listed are inserted literally.

Mouse (when layout.mouse is true)

Action	Effect
Left-click pane	Focus that pane
Left-click input	Focus pane + move caret
Left-click expandable block	Expand or collapse thinking / tool / truncated code
Wheel	Scroll pane / history list under the pointer
Drag split gutter	Resize adjacent panes
Left-click history row	Switch to that conversation
Right sidebar	Ignored (display-only)

Disable with "mouse": false under layout in ~/.arbiter/tui.json.

Editing

Key	Action
Backspace / ^H	Delete the character left of the cursor.
Delete	Delete the character under the cursor.
^A	Move cursor to the start of the line.
^E	Move cursor to the end of the line.
^B / ←	Move cursor one byte left.
^F / →	Move cursor one byte right.
^K	Kill from cursor to end of line.
^U	Kill the entire line.
^W	Kill the previous word — but only if no chord handler is bound. The default REPL binds ^W as a pane chord (see below); in that mode the previous-word kill is unavailable.
Tab	Tab-completion on the leading word (slash commands). Inserts a literal space if no completer is registered.
Enter	Submit the line.
^D	EOF if the buffer is empty (exits the REPL), else delete-forward.
^C	Abort the current line. Does not exit the process; just discards the buffer and redraws the prompt.
↑ / ↓	History navigation. Per-pane history persisted across sessions (see Sessions).

Scrollback

Key	Action
PgUp	Scroll the focused pane's scroll region up by ~half a screen.
PgDn	Scroll back down. At the live tail, PgDn is a no-op.
^O	Expand or collapse the truncated code / tool / thinking block in view (or click it).

Scrollback is visual-row aware: a wrapped paragraph counts as multiple rows for navigation, matching what the terminal actually drew. The scrollback ring is bounded (default 20k logical lines) — older content is evicted when the buffer fills.

Cancellation

Key	Action
Esc	Cancel any in-flight agent turn. The pane's input clears, the cancel handler pushes [interrupted] into scrollback, and the agent's pending HTTP request is aborted. A lone Esc with no follow-on within 50 ms triggers cancel; longer sequences (CSI escape codes from arrows / PgUp / etc.) are routed to the editor instead.

Pane chords (Ctrl-w prefix)

^W opens a 2-second window for a single follow-up byte. Inside that window:

Chord	Action
^W v	Vertical split — the focused pane is split into left/right children.
^W h	Horizontal split — focused pane split into top/bottom.
^W s	Toggle the session sidebar (wide terminals only).
^W w / ^W ^W	Cycle focus to the next pane (pre-order traversal of the layout tree).
^W z	Zoom / unzoom the focused pane (temporary maximize; siblings stay open).
^W c	Close the focused pane. Its exec thread is joined; in-flight turn is cancelled. Last remaining pane cannot be closed.
^W t	Toggle the conversation-history sidebar (left rail). Preference is saved to ~/.arbiter/tui.json.
^W b	Enter the conversation sidebar for selection. Auto-shows the sidebar if hidden. Use ↑/↓ and Enter; Esc cancels.

If the chord byte doesn't match any of the above, it's silently dropped — the editor returns to the normal input state. ^W followed by a regular character does not fall through to insertion; the chord window always consumes its byte.

Conversation sidebar (when focused via ^W b)

Key	Action
↑ / ↓	Move selection (+ New conversation at top, then prior threads newest-first).
j / k	Vim-style aliases for down / up.
Enter	Attach the selected conversation (or start a new one) to the focused pane. Sibling panes and the split layout are left alone.
m	Open an action menu on the selected row. Chat: Open · Rename · Move to… · Delete. Folder: Rename · New chat here · Delete folder. + New: New folder. Shortcuts (o/r/v/d, r/n/d, or f) jump to an action. Footer shows context hints while open.
r	Rename the selected chat or folder. Type on the title line (caption on the line below). Enter saves (rejects empty); Esc cancels rename (Esc again leaves the sidebar).
d	Soft-delete the selected chat, or delete the selected folder (chats are unfiled, not removed), after a Delete chat? y/n / Delete folder? y/n confirm.
n	Start a new conversation on the focused pane.
f	Create a new folder: type a name (caption New folder), Enter saves, Esc cancels. Also available from the + New row menu (m → New folder).
Esc	Cancel an in-progress rename / menu / move; otherwise return focus to the pane input.

Choosing Delete from the menu (or pressing d) enters the same confirm step: type y to soft-delete, any other key cancels.

The sidebar requires at least 72 terminal columns when enabled. Below that width it auto-hides even if toggled on.