Webhooks - Osmosis

Webhooks notify your systems when runs finish. Osmosis sends a POST request with a JSON payload to a URL you configure, once per completed run.

Setup

Open Workspace Settings → Webhooks (owners and admins only):

Enter your Webhook URL. It must use HTTPS on port 443 and resolve to a public address. URLs that point at private or internal networks are rejected.
Turn on Deliver events and click Save.
Click Send test payload to confirm your receiver gets a webhook.test event.

Turn off Deliver events to pause deliveries without losing the URL. To remove the webhook entirely, clear the Webhook URL and click Save.

Events

Event	Sent when
`training_run.completed`	A training run finishes
`eval_run.completed`	An evaluation run finishes
`webhook.test`	You click Send test payload

Payload

Every request is a POST with Content-Type: application/json and this envelope:

{
  "event": "training_run.completed",
  "timestamp": "2026-07-15T22:14:05.123456+00:00",
  "data": {}
}

`training_run.completed` and `eval_run.completed`

The data object has the same shape for both events:

Field	Description
`id`	The run ID
`name`	The run name
`status`	Final status of the run: `finished`, `failed`, or `stopped`
`started_at`	When the run started, ISO 8601
`completed_at`	When the run finished, ISO 8601
`duration_seconds`	Total run duration in seconds
`model_name`	Name of the model used by the run
`dataset`	`{ "id", "name" }` of the dataset, or `null`
`rollout`	`{ "id", "name" }` of the rollout, or `null`
`platform_url`	Link to the run detail page in the platform
`latest_metrics`	For training runs, the latest logged value of each run metric keyed by metric name. For evaluation runs, the run’s final aggregate results, including the reward distribution (`reward_stats`)

Training run example:

{
  "event": "training_run.completed",
  "timestamp": "2026-07-15T22:14:05.123456+00:00",
  "data": {
    "id": "a1b2c3d4-0000-0000-0000-000000000000",
    "name": "my-training-run",
    "status": "finished",
    "started_at": "2026-07-15T20:01:12+00:00",
    "completed_at": "2026-07-15T22:14:03+00:00",
    "duration_seconds": 7971,
    "model_name": "Qwen3-8B",
    "dataset": { "id": "d1e2f3a4-0000-0000-0000-000000000000", "name": "my-dataset" },
    "rollout": { "id": "r1s2t3u4-0000-0000-0000-000000000000", "name": "my-rollout" },
    "platform_url": "https://platform.osmosis.ai/my-workspace/training/a1b2c3d4-0000-0000-0000-000000000000",
    "latest_metrics": {
      "rollout/raw_reward": 0.82,
      "eval/validation/reward": 0.79,
      "train/entropy_loss": 1.24,
      "rollout/response_lengths": 512,
      "rollout/total_lengths": 1930,
      "rollout/truncated_ratio": 0.03
    }
  }
}

For evaluation runs, latest_metrics contains the final aggregate results instead:

"latest_metrics": {
  "total_runs": 200,
  "graded": 198,
  "passed": 154,
  "failed": 44,
  "skipped": 2,
  "pass_rate": 0.78,
  "pass_threshold": 0.5,
  "score": 0.71,
  "reward_stats": {
    "mean": 0.71,
    "median": 0.74,
    "std": 0.18,
    "min": 0.05,
    "max": 0.98,
    "pass_at_k": { "1": 0.78, "4": 0.91 }
  },
  "total_tokens": 1834520,
  "total_duration_ms": 5421000
}

`webhook.test`

Field	Description
`workspace`	The workspace name
`message`	A confirmation message

Delivery

Each attempt times out after 5 seconds. Failed deliveries are retried up to 2 times with backoff.
Any 2xx response counts as delivered. Redirects are not followed.
Delivery is best effort: a webhook failure never affects the run itself.

​Setup

​Events

​Payload

​training_run.completed and eval_run.completed

​webhook.test

​Delivery