zu-huggingface 0.2.4

Zu HuggingFace adapter: task models as typed tools/detectors/validators, behind the supply-chain guards

zu-huggingface

HuggingFace models behind Zu's typed ports. HuggingFace is not a model — it is the largest hub of open models across every modality — so "supporting it" means three different things, and this package draws the line cleanly (Engineering Design §8.3–8.5).

Chat / vision-language models as the policy — no code here

A chat or vision-language model that is the brain speaks the OpenAI chat API on all three HuggingFace serving surfaces (the router's /v1, a dedicated Endpoint's /v1, or a local vLLM server). So a HuggingFace model as the policy is the existing openai-compatible provider pointed at a HuggingFace base URL — the OpenRouter story exactly, no new adapter:

# agent.yaml — a HuggingFace multimodal model as the policy
model:    meta-llama/Llama-Vision-...        # any chat / VLM id on the Hub
provider: openai-compatible
options:
  base_url: https://router.huggingface.co/v1  # or an Endpoint, or local vLLM
  api_key_env: HF_TOKEN

Task models as tools, detectors, validators — this package

Most HuggingFace models are not chat models (OCR, ASR, detection, embeddings, classification, …), so they enter through the non-policy ports by their role (the port is the role, assigned per agent — §4.5):

Role	Class	Task
Tool	Transcribe (hf_transcribe)	speech → text (ASR)
Tool	ImageToText (hf_image_to_text)	image → text (OCR / caption)
Tool	DetectObjects (hf_detect)	image → labelled boxes
Tool	Embed (hf_embed)	text → vector (retrieval / grounding)
Tool	Classify (hf_classify)	text → labels
Tool	ZeroShotClassify (hf_zero_shot)	text + labels → scores
Tool	Summarize (hf_summarize)	text → text
Tool	Translate (hf_translate)	text → text
Detector	HfClassifierDetector	classify an observation → ESCALATE/stop
Validator	HfClassifierValidator	classify the result → fail/RETRY

Each is parameterised by a model id (and the role wrappers by the labels that matter), so they are wired by reference in config per agent rather than as zero-config entry points:

tools:
  - ref: zu_huggingface.tools:Transcribe
    args: { model: openai/whisper-large-v3 }
  - ref: zu_huggingface.tools:Embed
    args: { model: BAAI/bge-large-en-v1.5 }
detectors:
  - ref: zu_huggingface.roles:HfClassifierDetector
    args: { model: facebook/bart-large-mnli, candidate_labels: ["safe","unsafe"], escalate_on: ["unsafe"] }

The typed multimodal Content (Text/Image/Audio) from zu_core.content is the currency in and out — which is what lets a non-chat model slot into the loop as cleanly as a chat one.

Hosted vs local — one seam

Every tool depends only on the HfClient seam, so the same tool works:

• Hosted — InferenceClientBackend wraps huggingface_hub.InferenceClient (the serverless router or a dedicated Endpoint). Egresses to router.huggingface.co; HF_TOKEN is read from the environment inside the backend. pip install 'zu-huggingface[hosted]'.
• Local — PipelineBackend wraps transformers.pipeline for the air-gapped / on-prem case. Reaches no network. Every pipeline is built through the supply-chain guards. pip install 'zu-huggingface[local]' (plus a backend such as torch).

The supply chain — safe by default (§8.3)

Pulling a model from the Hub is a supply-chain surface. supply_chain.py enforces, by default:

• Pin + hash. A ModelPin should carry a full commit-sha revision; verify_file_hash checks a downloaded file's sha256.
• safetensors, not pickle. verify_model_source rejects .bin/.pt/.ckpt checkpoints (which execute on deserialisation) unless explicitly allowed.
• No remote code. safe_pipeline_kwargs forces trust_remote_code=False; assert_no_remote_code raises if it is relaxed.

The safe configuration is the default — there is nothing to turn on to be safe, only flags a reviewed case may relax.

Tests

Offline, no network, no model download: the tools and role wrappers are exercised against a fake HfClient, and the supply-chain guards are pure. uv run pytest packages/zu-huggingface.