Routing and versions - CoreWeave Docs

Routing defines which model serves a task version. Every target contains a model reference, non-negative weight, and optional parameter overrides.

Weights are relative

Weights do not need to add to 100. A configuration with weights 3 and 1 sends approximately 75% and 25%. A zero-weight target stays available in the configuration but receives no new weighted traffic. Use zero weight to preserve the previous model for visibility and easy rollback after a full promotion.

Sticky routing

When a request supplies wandb.thread_id or gen_ai.conversation.id, the proxy deterministically keeps that conversation on one target for the routing revision. Without a conversation ID, each request is selected independently.

Target parameters

Expand Parameters under a model to add values such as temperature, reasoning effort, response format, or provider-specific controls. Numbers, booleans, arrays, and objects are parsed from JSON; other text remains a string. The stored override wins over the same field supplied by the caller.

Save to an existing or new version

Open the task’s Routing page. Add or edit targets, choose the destination in the version bar, and select Save routing. The version bar is part of the same save action:

choose an existing version to replace its desired routing;
choose the new-version option to create it only when you click Save routing;
call the new version with task@vN.

Publishing is asynchronous. A saved desired configuration is serving only after its deployment status becomes Applied at the same revision.

Deleting a version makes callers pinned to it receive 404 responses. Version 1 cannot be deleted.

API: Replace routing for a task version (PUT /tasks/{alias}/versions/{version}/routing)

Routing updates replace the whole target list. Keep the previous model at weight 0 when you want it available for rollback:

curl --request PUT \
  --url "https://distillation.training.wandb.ai/v1/tasks/ticket-classifier/versions/2/routing" \
  --header "Authorization: Bearer $WANDB_API_KEY" \
  --header "Wandb-Entity: your-team" \
  --header "Content-Type: application/json" \
  --data '{
    "targets": [
      {"model_ref": "openai/gpt-5.6-sol", "weight": 0},
      {"model_ref": "wandb-inference/your-fine-tuned-model", "weight": 1}
    ]
  }'

Poll the returned routing state until deployment is applied at the current revision. See Replace version routing.

Last modified on August 25, 2026

​Weights are relative

​Sticky routing

​Target parameters

​Save to an existing or new version

Weights are relative

Sticky routing

Target parameters

Save to an existing or new version