Your First Agent
In Fletch, each agent works in its own workspace — an isolated checkout of your repo (a lightweight clone that borrows your repo’s history), inside a macOS sandbox. Two agents can never edit the same files, because they’re working different checkouts. Spawning an agent is how you create a workspace.
Spawn an agent
Section titled “Spawn an agent”- Click + New agent on a project (or press ⌘N) to open a draft.
- Under “What should be the first task?”, describe the task in the composer.
- Pick the agent and model from the model picker (Claude Code is the default). Optionally change the base branch (defaults to
main) or reroll the generated name. - Press Enter to spawn.
Fletch creates an isolated checkout for the agent — forked from the freshest state of your base branch — and launches the agent’s CLI there under a sandbox. The draft pane shows exactly where it will live before you spawn.
Watch it work
Section titled “Watch it work”- The chat view shows the agent’s reasoning and tool calls as a readable transcript.
- If you enable the experimental native view, you can flip to the agent’s raw terminal (available after its first turn).
- Turn on the Code, Git, Run, and Terminal side panels in Settings to review diffs, manage git, run your project, and open a shell in the workspace.
Isolation
Section titled “Isolation”Each agent runs under a per-agent sandbox — macOS Seatbelt by default, or an opt-in Docker container — that denies writes everywhere except its own workspace, temp directories, and the agent’s own config/cache. Under Seatbelt it can still read files and use the network. How the two engines differ, and why the checkout design matters, is covered in Security & Sandboxing.
Finishing up
Section titled “Finishing up”When you’re done, archive the workspace to hide it while keeping a restorable snapshot, or discard it to remove the checkout and its branch permanently. Both are one click in the workspace. And if a session is worth continuing in a new direction instead, you can fork it.