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AWS sagemaker: Document SageMaker AI Training session APIs for model customization

Service: sagemaker · 2026-10-15 · Documentation low

File: sagemaker/latest/dg/customizing-models-access.md

Summary

Adds a Training session APIs section (stateful session operations such as forward_backward/optim_step/sample) with a code sample, a new row in the access-method comparison table, and a mention that SageMaker AI manages infrastructure and tenant isolation.

Security assessment

This is product/API documentation for a new orchestration interface. Tenant isolation is only mentioned as a managed property of the service; no configuration, permission, or vulnerability detail is added, so it is not security documentation.

Evidence

+Use the SageMaker AI Training session APIs when a predefined workflow is too rigid. Instead of submitting a complete training script, you open a stateful session and call training operations — `forward_backward()`, `optim_step()`, `sample()` — as individual API calls, then compose them into whatever procedure your technique requires. The model stays loaded between calls, so you can write custom loss functions, run multi-turn reinforcement learning with elastic rollouts, and chain multiple procedures in one session. SageMaker AI manages the underlying infrastructure and tenant isolation.

Diff

diff --git a/sagemaker/latest/dg/customizing-models-access.md b/sagemaker/latest/dg/customizing-models-access.md
index b3a241f..a3d59f1 100644
--- a//sagemaker/latest/dg/customizing-models-access.md
+++ b//sagemaker/latest/dg/customizing-models-access.md
@@ -7 +7 @@
-Studio UIPython SDK V3Recipes (Training Jobs + HyperPod)HP-CLI
+Studio UIPython SDK V3Training session APIsRecipes (Training Jobs + HyperPod)HP-CLI
@@ -20,0 +21 @@ Agent (Model customization skills) | [Serverless](./customize-model.html) | Natu
+Python SDK (`ServiceClient`) | Serverless ([Training session APIs](./customizing-models-training-sessions.html)) | Custom training loops, multi-turn reinforcement learning (RL), multi-stage pipelines | Operation-level — orchestrate `forward_backward()`, `sample()`, `optim_step()` as API calls  
@@ -97,0 +99,19 @@ Use `ModelTrainer` for full control over instance selection:
+## Training session APIs
+
+Use the SageMaker AI Training session APIs when a predefined workflow is too rigid. Instead of submitting a complete training script, you open a stateful session and call training operations — `forward_backward()`, `optim_step()`, `sample()` — as individual API calls, then compose them into whatever procedure your technique requires. The model stays loaded between calls, so you can write custom loss functions, run multi-turn reinforcement learning with elastic rollouts, and chain multiple procedures in one session. SageMaker AI manages the underlying infrastructure and tenant isolation.
+    
+    
+    from sagemaker.train.training_session import ServiceClient, AdamParams
+    
+    svc = ServiceClient(region="us-west-2", role_arn="arn:aws:iam::111122223333:role/MyRole")
+    tc = svc.create_lora_training_client(base_model="gpt-oss-20b", rank=32, alpha=64)
+    
+    for batch in data_loader:
+        tc.forward_backward(batch, loss_fn="cross_entropy")
+        tc.optim_step(AdamParams(learning_rate=5e-5))
+    
+    print(tc.save_state().result().model_package_arn)
+    tc.stop()
+
+For more information, see [Training session APIs](./customizing-models-training-sessions.html).
+