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

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Branch warm state

from nullspace import Machine

parent = Machine.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()

import { Machine } from "@nullspace/sdk";

const parent = await Machine.create({ template: "base" });
await parent.files.write("/workspace/state.txt", "common\n");

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

console.log((await parent.files.read("/workspace/state.txt")).trim());
console.log((await child.files.read("/workspace/state.txt")).trim());

await child.destroy();
await parent.destroy();

# Fork a running machine into an independent child.
nullspace machine fork mch_123

curl -X POST "${NULLSPACE_API_URL}/v1/machines/mch_123/fork" \
  -H "Authorization: Bearer ${NULLSPACE_API_KEY}" \
  -H "Content-Type: application/json"

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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 machine ID and routing credentials. Shared volumes are remounted in the child; the external volume data is shared according to volume mount permissions.