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POST
Checkpoint a session

Authorizations

Authorization
string
header
required

API key with the vk_ prefix. Create one from the dashboard.

Path Parameters

session_id
string
required

Session ID

Body

application/json
label
string | null

Free-text label, at most 128 characters.

Response

The new checkpoint

Note the absence of s3_prefix: storage layout is not part of the API. The custom-models design already ruled against exposing bucket paths, and keeping them internal is what let C1 add a new prefix without an API change.

object
string
required
id
string
required
job_id
string
required
step
integer<int32>
required

Trainer global_step. Also addressable as <job_id>@<step>.

kind
string
required
payload
string
required

"resumable" (includes optimizer state) or "weights" (servable only).

size_bytes
integer<int64>
required
file_count
integer<int32>
required
status
string
required
pinned
boolean
required
created_at
string<date-time>
required
metrics
any

Loss/reward at this step, so picking the best step is a list call.

expires_at
string<date-time> | null