Ask the agent to delegate independent parts of your task to subagents. Each subagent works in a separate conversation and reports back to the agent in your original thread, called the parent thread.
When to use subagents
Use subagents for independent work that can happen alongside the main task, such as investigating separate parts of a codebase, implementing independent parts of a change, or getting another agent to check an existing change.
Ask the agent to use subagents and describe the work you want delegated. Delegation defaults to Only When Asked. To let the agent delegate whenever it finds that useful, choose Max in Settings > Subagents > Delegation. Choose Off to disable delegation.
Keep tightly dependent steps in the main thread when the next step needs the result of the previous one. Delegating that work adds a handoff rather than letting tasks run in parallel.
Profiles
A profile describes a subagent’s role and chooses its model. Delta includes three profiles:
- Worker implements changes with full tool access.
- Scout gathers information from the codebase or the web.
- Reviewer checks existing changes.
Delta selects default models for these profiles. You can change each profile’s model and thinking effort in Settings > Subagents. See Agent profiles settings for model choices and adding custom profiles.
Access to your files
By default, Worker and Reviewer subagents use isolated copies of the parent’s Delta worktrees. Their changes do not merge back automatically. Ask the parent agent to merge the child’s work when you want to bring it in. Scout uses the parent’s checkout directly, so its edits take effect immediately.
Use Configure with Delta in Settings > Subagents to change a profile’s worktree mode. See Agent profiles settings.
Scout and Reviewer do not have file-editing tools, but both can change files through terminal commands. Don’t treat either profile as read-only. A Scout’s terminal commands can affect the parent’s checkout while the main agent is still working.
Follow their work
New subagents run as ordinary subthreads nested under their parent in the sidebar. Open one to read its conversation, send a message to steer it, or continue the work yourself. Each starts with a fresh conversation and the task context supplied by its parent, rather than inheriting the parent’s transcript.
Messages between agents appear as folded Sent Agent Message and Received Agent Message events; expand an event to read the message. Agents can also message another thread. The parent receives the subagent’s final result automatically. You can send a follow-up in the child thread or ask the parent to message it. Worker subagents can delegate to children of their own; Scout and Reviewer cannot. Each child’s final result goes to its immediate parent. Subagents created before Delta 0.20.0 keep their previous automatic-merge behavior.
Press Cmd+F on macOS or Ctrl+F on Linux and Windows to search the focused
subagent conversation. Press Escape there to stop that subagent.
New agent-created subthreads appear under Plain in the desktop sidebar filter, alongside forks. Subagents remains available for older attached subagents, alongside Reviews and Merge children. An expanded parent shows the ten newest matching children by default. Choose Show N more to reveal the rest, or change Subthreads Per Thread in Settings > Sidebar.
Click a subagent to open it as primary, or hold Cmd on macOS or Ctrl
on Linux and Windows while clicking to open it in a tab. You can also use the
sidebar row’s Open in Tab button. Closing a subagent tab does not stop its
work.
On desktop and web, View All Subthreads (Cmd+J on macOS or Ctrl+J
on Linux and Windows) opens a picker for the parent’s children. Filter by
kind, and press Tab to show or hide archived children. The picker remembers
your selected filter when reopened.
Models and configuration
In Settings > Subagents, choose each profile’s default model and thinking effort. To use a different model for a particular provider, open that provider’s Model Preferences in LLM Providers.
Delta checks for model choices in this order:
- Your provider-specific model choice.
- Your default model choice for the profile.
- Delta’s built-in default.
If you haven’t set a choice, Delta moves to the next option. Worker defaults to the parent’s model. With ChatGPT sign-in, your plan affects the built-in Scout and Reviewer defaults; explicit profile model choices take precedence.
Use Subagents settings to control delegation, concurrency limits, and whether the parent can override the profile’s model choice.
Claude Agent can’t be used in a subagent profile. Claude’s own subagents appear as read-only child threads in a Claude Agent thread.
What’s next
- Settings covers delegation controls and custom profiles.
- Models & Providers covers connecting providers and choosing models.
- Review & Sync Changes covers reviewing the resulting changes and bringing them into your repository.