Download a checkpoint

Private beta. Your organization needs access; otherwise these calls return 403 beta_not_enabled. Contact Trajectory to request it. These helpers may change in a minor release. Requires trajectory-sdk 0.10.11 or later.

Download a checkpoint to use its weights outside Trajectory. You get the LoRA adapter, not a full model merged with its base.

Download with the SDK

from trajectory import Client
from trajectory.lib.beta import download_checkpoint

client = Client()
checkpoints = client.training.checkpoints.list("YOUR_TRAINING_RUN_ID")
checkpoint = max(checkpoints, key=lambda c: c.step_index)

path = download_checkpoint(client, checkpoint.checkpoint_id, "models/")
print(path)  # models/<checkpoint_id>/

The first request for a checkpoint prepares its export, which can take several minutes for a large adapter. Later requests reuse it. The directory holds the adapter files and manifest.json.

Argument	Default	Behavior
`output_dir`	`.`	Parent directory for `<checkpoint_id>/`.
`overwrite`	`False`	Replace an existing target. Otherwise `FileExistsError` is raised before any request.
`timeout`	`3600`	Seconds to wait for the export to be ready. `None` waits indefinitely.
`poll_interval`	`5`	Seconds between status checks.
`http_client`	New client	Your own `httpx2.Client` for the download.

A failed call leaves nothing behind and starts over the next time. Downloads do not resume.

Download from the platform

Open the training run, select a checkpoint, and choose Download weights. The button appears for deployable checkpoints when your organization has access.

Use the download link yourself

wait_for_checkpoint_export returns the ready export with a signed link, without downloading anything:

from trajectory.lib.beta import wait_for_checkpoint_export

export = wait_for_checkpoint_export(client, "YOUR_CHECKPOINT_ID")
print(export.download.url, export.download.size_bytes, export.download.url_expires_at)

The link lasts one hour. client.beta.checkpoint_exports.retrieve(export.export_id) returns a new one. client.beta.checkpoint_exports also has create and list, and sends the beta opt-in header for you.

Handle errors

Error	Meaning	What to do
`trajectory.lib.beta.CheckpointExportError`	The export failed or has no download link. The error’s `export` attribute holds it.	Call again to retry.
`TimeoutError`	The wait ended first. The server keeps preparing the export.	Call again to pick it up.
`zipfile.BadZipFile`	The downloaded ZIP is corrupt.	Call again to download it again.
403 `beta_not_enabled`	Your organization doesn’t have access.	Contact Trajectory.
409	This checkpoint can’t be downloaded.	Only Tinker checkpoints are supported.

Build a full model

Merging the adapter into its base model happens on your side. Tinker’s merge guide covers how, and its supported models are listed in the Cookbook. Evaluate the result on your own serving stack, because merging can reduce accuracy, especially at low precision.

Get started

Build and improve

Production learning

Checkpoint downloads

Reference

Download a checkpoint

Download with the SDK

Download from the platform

Use the download link yourself

Handle errors

Build a full model

​Download with the SDK

​Download from the platform

​Use the download link yourself

​Handle errors

​Build a full model

Download with the SDK

Download from the platform

Use the download link yourself

Handle errors

Build a full model