Problem:
We trained a LoRA adapter for Apple's FoundationModels framework using their TAMM (Training Adapter for Model Modification)
toolkit v0.2.0 on macOS 26 beta 4. The adapter trains successfully but fails to load with: "Adapter is not compatible with the
current system base model."
TAMM 2.0 contains export/constants.py with: BASE_SIGNATURE = "9799725ff8e851184037110b422d891ad3b92ec1"
Findings:
Adapter Export Process:
In export_fmadapter.py
def write_metadata(...):
self_dict[MetadataKeys.BASE_SIGNATURE] = BASE_SIGNATURE # Hardcoded value
The Compatibility Check:
- When loading an adapter, Apple's system compares the adapter's baseModelSignature with the current system model
- If they don't match: compatibleAdapterNotFound error
- The error doesn't reveal the expected signature
Questions:
- How is BASE_SIGNATURE derived from the base model?
- Is it SHA-1 of base-model.pt or some other computation?
- Can we compute the correct signature for beta 4?
- Or do we need Apple to release TAMM v0.3.0 with updated signature?
Topic:
Machine Learning & AI
SubTopic:
Foundation Models
Tags:
Core ML
Create ML
tensorflow-metal
Apple Intelligence