Side threads and subagents

A teammate can work on more than one thing at a time. A side thread is a second conversation with the same teammate that you start. A subagent is a worker the teammate starts. Both open in the Threads pane on the right.

Side threads

Your teammate is in the middle of a long build, and you want to ask it about something else without derailing it. Choose More → Start a side thread (“Another topic with” the teammate’s name, “in parallel”).

The thread opens at once in the right-hand pane, empty. The first thing you say in it becomes its title. It is the same teammate, with the same folders, tools and permissions, but it runs in a context of its own. A new side thread is told the main conversation’s last handoff note and its last few lines, so it knows what the teammate is busy with. After that, nothing said in the side thread reaches the main conversation, and the other way round.

While a side thread is running, a chip in the conversation’s header shows it (“Side:” and its title, or a count with a menu when there are several), and the main conversation has one line for it with Open.

A side thread lasts as long as the topic does:

• The teammate never closes it by itself. It is archived when you tell the teammate you are done, or press Archive in the thread.
• A quiet thread is parked. After three quiet hours, or a restart, no agent is running for it, but it stays in the list. Saying something in it picks it back up where it left off.
• An archived thread can come back. Open it and press Continue.

When a side thread is archived, the main conversation keeps its title and a one-line outcome. A closing note (the goal, what got done, what is still open, the key files) is written where the teammate’s own search can find it, so the main conversation can ask about it later.

A teammate runs at most three threads at a time. Starting another parks the one you have left alone longest. Parked and archived threads do not count.

Subagents

A teammate can hand a piece of its own work to a subagent: a fresh worker that runs as the teammate, in the same folder, with the same tools and model, but with none of the conversation. The teammate keeps talking to you while the subagent works, and tells you what it found when the report comes back.

While one is running, it shows at the top right of the message box, by its title, or as a count with a menu when there are several. Press it to read what the subagent is doing. Each subagent also leaves one line in the conversation with its result, and that line opens the run too. Runs are read-only. Stopping a Hotline Agent teammate stops its subagents.

Hotline Agent teammates start subagents with a tool of their own, up to four at a time. Claude Code and Codex show their own subagents the same way when their adapter reports them; other harnesses show the work as steps of the teammate’s turn.

The Threads pane

More → Threads opens the pane on its list. It shows everything running beside the open teammate’s main conversation:

• its side threads, and work threads other teammates handed it, first;
• its conversations with other teammates (Pair);
• subagent runs (Subagent);
• calls (Call).

Each row shows whether it is running, waiting on you, parked or closed, with its last line. Closed threads fold away at the bottom. A row opens the thread inside the pane, with Back to threads at the top. A permission card in any thread is answered where it is.

Drag the pane’s edge to resize it. In a narrow window, the pane lies over the conversation. Esc steps back from a thread to the list, then closes the pane.