> ## Documentation Index
> Fetch the complete documentation index at: https://opentrain.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Preflight a Job Instruction Mutation

> Validate and sign one exact page mutation without changing live instructions.

Validates a complete `create`, `replace`, `patch`, `metadata`, or `archive`
operation without writing. Requires `instructions:write` and employer access to
the job.

<ParamField body="operation" type="object" required>
  The exact operation you intend to apply, including target IDs, concurrency checks, content, placement, and confirmation fields.
</ParamField>

The response includes findings, normalized content when applicable, rendered
HTML, the current and resulting tree checksums, a plan digest, and
`writesApplied: false`. When `canApply` is true, it also returns a short-lived
`preflightToken`. Submit the unchanged operation and that token to its mutation
endpoint. Changed input requires a new preflight.