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Fork is Nullspace’s main differentiator for agent and evaluator workflows. Do expensive setup once, fork the sandbox, then let each branch mutate files, processes, and services independently.

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Branch warm state

from nullspace import Sandbox

parent = Sandbox.create(template="base")
parent.files.write("/workspace/state.txt", "common\n")

child = parent.fork()
parent.files.write("/workspace/state.txt", "parent\n")
child.files.write("/workspace/state.txt", "child\n")

print(parent.files.read("/workspace/state.txt").strip())
print(child.files.read("/workspace/state.txt").strip())

child.kill()
parent.kill()

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Use cases

  • Fan out prompt, patch, or evaluator variants from one prepared repo.
  • Test destructive changes in a child without touching the parent.
  • Keep a warm parent while retrying independent plans in children.

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Behavior

Parent and child each receive their own sandbox ID and routing credentials. Shared volumes are remounted in the child; the external volume data is shared according to volume mount permissions.