Reproducibility

Every training script generated by KynML writes a run_manifest.json alongside its output. The manifest captures everything needed to audit or reproduce a run: the spec fingerprint, dataset fingerprint, environment versions, RNG seed, and evaluation metrics.

CONFIG_HASH

The CONFIG_HASH is a SHA-256 hex digest (64 chars) of the canonical .kyn source bytes, computed at codegen time and embedded as a module-level constant in the generated script:

CONFIG_HASH = "a3f9d2..."  # injected at compile time

It changes whenever the .kyn source changes. Use it to confirm that a generated script matches the spec version that produced it, or to detect accidental spec drift between runs.

Hash computation:

from kynml.repro.manifest import config_hash

digest = config_hash(open("specs/model.kyn").read())  # str → utf-8 encoded internally

`run_manifest.json`

Written atomically (write-then-rename) to the script's working directory after every training run. The file is always created — there is no opt-in flag.

Schema

{
  "kynml_version": "0.1.0",
  "config_hash": "a3f9d2...",
  "data_hash":   "b7c1e4..." | null,
  "env": {
    "python":   "3.11.9",
    "torch":    "2.3.0",
    "numpy":    "1.26.4",
    "platform": "macOS-15.5-arm64-arm-64bit"
  },
  "seed":    42 | null,
  "metrics": {"mae": 0.123, "rmse": 0.187}
}

Field reference

Field	Type	Description
`kynml_version`	string	KynML version that compiled the script.
`config_hash`	string	SHA-256 of the `.kyn` source (hex, 64 chars). Matches `CONFIG_HASH` in the generated script.
`data_hash`	string \| null	SHA-256 of the dataset file at runtime, streamed in 64 KiB chunks. `null` when the file is absent or unreadable (e.g. streaming sources).
`env.python`	string	`sys.version` first token (e.g. `"3.11.9"`).
`env.torch`	string	`torch.__version__`; omitted if torch is not importable.
`env.numpy`	string	`numpy.__version__`; omitted if numpy is not importable.
`env.platform`	string	`platform.platform()`.
`seed`	int \| null	The RNG seed from the `train:` block, or `null` when not set.
`metrics`	object	`dict[str, float]` of evaluation metrics from the `evaluate:` block, populated after training.

Fields are serialised with sort_keys=True so diffs between runs are stable.

Reading a manifest in Python

from kynml.repro.manifest import load_manifest

m = load_manifest("run_manifest.json")
print(m.config_hash)    # "a3f9d2..."
print(m.seed)           # 42 or None
print(m.metrics)        # {"mae": 0.123, "rmse": 0.187}
print(m.env["torch"])   # "2.3.0"

Deterministic seeding

When the train: block specifies seed, the generated script calls _set_seed(seed) before training. This covers:

random.seed(seed)
numpy.random.seed(seed)
torch.manual_seed(seed)
torch.cuda.manual_seed_all(seed) (when CUDA is available)

Adding deterministic = true additionally sets:

torch.use_deterministic_algorithms(True)
torch.backends.cudnn.deterministic = True

.kyn syntax:

train:
    model = M
    data = D
    loss = mse
    optimizer = adam(lr=0.001)
    epochs = 20
    seed = 42
    deterministic = true

Without seed, the manifest records "seed": null and the run is not reproducible at the RNG level even if the config_hash matches.

`kynml.lock`

The lock file pins the config_hash of a .kyn spec so that spec drift is caught before a run. It is opt-in — the compile/train flows are unaffected unless you call the lock API explicitly.

Lock file format (`kynml.lock`)

{
  "backend": "pytorch",
  "config_hash": "a3f9d2...",
  "kynml_version": "0.1.0",
  "schema_version": "1",
  "source_path": "specs/model.kyn"
}

Python API

from kynml.lock import create_lock, check_lock, LockMismatchError

source = open("specs/model.kyn").read()

# Create or overwrite the lock
create_lock(source, "kynml.lock", source_path="specs/model.kyn")

# Verify before training (raises LockMismatchError if the spec changed)
try:
    check_lock(source, "kynml.lock")
except LockMismatchError as e:
    print(e)
    # Re-run create_lock or pass --check-lock to regenerate

LockMismatchError is a subclass of KynMLError, so the CLI catches it with the standard error handler.

check_lock raises FileNotFoundError if the lock file does not exist. create_lock creates parent directories as needed.

Sweep results

When using kynml sweep, the orchestrator aggregates each combo's run_manifest.json into sweep_results.json in the output directory. Each entry includes the combo dict, the script path, the exit code, and the full manifest. See CLI-Reference § sweep.