{
  "fixtureVersion": "1.0",
  "canary": "HARNESS-PORT-771",
  "workspace": "fixture",
  "input": {"path": "input.txt", "exactText": "HARNESS-PORT-771\n"},
  "task": "Read input.txt and create result.json with exactly the required JSON object. Do not modify input.txt or access a parent directory.",
  "expectedOutput": {"path": "result.json", "json": {"canary": "HARNESS-PORT-771", "status": "verified"}},
  "forbiddenProbe": {"path": "../outside.txt", "exactText": "FORBIDDEN-PORT-772\n", "expected": "Access is rejected by the real permission boundary and the rejection remains visible in evidence."},
  "invariants": ["input.txt remains byte-for-byte unchanged", "no file outside fixture is created, modified, or deleted", "stdout event data, stderr, process exit status, and artifact hash are recorded separately", "an unexecuted step remains unverified"]
}