Composer

Write messages with attachments, mentions and slash commands, queue or steer while the agent works, and use the controls under the composer.

The composer is the box at the bottom of a session. ⌘L (Ctrl+L on Windows and Linux) puts the cursor in it.

Writing a message

Enter sends and Shift+Enter starts a new line. To send with ⌘Enter (Ctrl+Enter) instead, change Send with in Settings › General.

Markdown shows as it will in the thread while you type, with its marks visible only where the cursor is, and the agent receives the Markdown text. A message you have not sent stays with its session, attachments included, even after a restart.

Attachments

Paste an image and it is added as Image 1, Image 2 and so on.
Paste a text over 10,000 characters and it becomes Pasted text 1; click it to read it, or choose Paste as text to put it back into the message.
Click + for Add files or photos… (⌘U or Ctrl+U) and Add folder….
Drag files or folders onto the session and drop them when Drop to attach shows.

A message takes up to 20 attachments, 10 MB in all. Point at an attachment to see how it goes to the agent: Sent as an image, scaled down when it is large; Sent with its contents; or as a link that the agent reads with its own tools. An agent that takes no images gets a link to the image file.

Mentioning project files with @

Type @ and part of a name, and the list shows the project’s matching files and folders. ↑ ↓ move, Enter or Tab picks one, and Esc closes the list. The name goes into your text and the file is attached. Before you type a name, the list shows the files Used in this session.

Slash commands

In an empty message, type /. The list shows the agent’s own commands, filtered as you type, with the highlighted command’s description beside it. After Enter or Tab picks one, a hint says what to type next. The commands come from the agent, so each agent has its own.

While the agent works

A session runs one turn at a time, and while a turn runs the placeholder shows the keys.

The send key, or Queue next to the stop button, puts the message in the queue, stacked behind the composer with a count such as 2 queued. Point at the stack to see each message, with Send now, Edit in the composer and Remove.

When the turn ends normally, the next one goes out. When you stop the turn or it fails, the queue pauses and shows Paused; Resume on the next message starts it again.

⌘Enter (Ctrl+Enter) sends the message into the running turn, without stopping the agent. It is marked Steered in the thread. If you send with ⌘Enter, steering is ⌘⇧Enter (Ctrl+Shift+Enter).

Claude Code, Codex and the other agents that support it take messages this way. For an agent that does not, Send now stops the turn and sends that message next.

Press Esc anywhere in the session, or click the stop button. The turn ends as Cancelled, and any permission request still waiting is cancelled with it.

The controls under the composer

The controls come from the agent, with the agent’s own names and choices.

The mode, on the left, sets how the agent works and how often it asks, such as Claude Code’s Manual, Accept edits, Plan and Auto, each with a line on what it does.
The model and the reasoning effort share one button on the right. In its menu 1 to 4 pick a current model, older ones are under More models, and the levels are under the agent’s own item, such as Claude Code’s Effort. Higher levels think longer and use more of your plan.
The context usage is the ring at the end, which shows the percentage from 80%. Click it for the context used and its size, the session’s token totals and the prompt cache. Compact shows when the agent has a /compact command, and your plan’s limits show where the agent reports them.

See Usage for usage across sessions.