Context

The cookbook architecture-demos spec tracks StableLM as status: blocked. No prior aprender issue covers this loader.

Family

• Name: stablelm
• Vendor: Stability AI
• HF architectures: StableLmForCausalLM
• HF pattern: stabilityai/stablelm-*
• Reference checkpoints: stabilityai/stablelm-2-1_6b, stabilityai/stablelm-2-zephyr-1_6b, stabilityai/stablelm-zephyr-3b

Acceptance criteria

• contracts/model-families/stablelm.yaml exists with size_variants for 1_6b and 3b
• Loader handles StableLM-specific partial_rotary_factor (typical 0.25 for stablelm-2)
• Discriminator distinguishes StableLM from Llama (presence of partial_rotary_factor < 1.0 + LayerNorm instead of RMSNorm)
• Inference smoke pass against stablelm-2-1_6b (smallest mainstream variant)

Unblock impact

• Cookbook manifest flips from blocked to certified
• Sub-2B variant is small enough for the dim-smoke regression suite

Cookbook reference

• manifest.yaml entry — name: stablelm block