Research-driven resolution of OQ-01, OQ-02, OQ-05, OQ-06: - OQ-01: Remove ONNX Runtime from scope entirely — doesn't support activation extraction natively (optimum #972 closed as not planned), bloated model exports; burn/cublas via safetensors is a better future path - OQ-02: Codebook compresses ~65% (1,245 → 500-600 lines); add Package Structure and Extraction from PoC sections to codebook.md based on PoC analysis of metaspline firewall_codebook.py - OQ-05: Standalone API + thin adapter pattern (ADR-011); Phase 1 ships Firewall.screen() only, Phase 2 adds <100-line adapter packages for LlamaFirewall, OpenAI Agents SDK, NeMo Guardrails - OQ-06: TOML for file-based config — standard modern Python, two-way door Also: research OQ-03 rolling windows from taskgraph-semantic reference code, remove onnxruntime/optimum from dependencies, move streaming screening to Phase 2, add burn/cublas as Phase 3 alternative backend.
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2.1 KiB
ADR-006: PyTorch as Optional Dependency
Status
Accepted
Context
PyTorch is the inference backend for the detector model. However, PyTorch is large:
torch(CPU): ~200MB download, ~700MB installedtorch(CUDA): ~2.5GB download, ~5GB+ installed
Making PyTorch a required dependency would force a 200MB-2.5GB download on every user, even those who already have PyTorch installed. This is the standard problem for ML libraries, and the HuggingFace ecosystem has converged on a solution.
Decision
Make PyTorch an optional dependency via extras (pip install alknet-firewall[torch]). The base install includes all non-ML dependencies
(sklearn, huggingface-hub, safetensors, tokenizers, numpy). ML inference
backends are installed separately.
Use lazy imports with clear error messages when PyTorch is not installed:
try:
import torch
except ImportError:
raise ImportError(
"PyTorch is required for alknet-firewall inference. "
"Install with: pip install 'alknet-firewall[torch]' "
"or pip install torch --index-url https://download.pytorch.org/whl/cpu"
)
Consequences
Positive:
- Base install is ~30MB download, ~100MB installed — very lightweight
- Users with existing PyTorch installations don't re-download
- Follows HuggingFace ecosystem conventions (transformers, safetensors, HF hub all use this pattern)
- uv supports CPU/GPU torch variant selection via
[tool.uv.sources]and[[tool.uv.index]]
Negative:
- More complex dependency specification in pyproject.toml
- Users must read installation docs to choose the right extra
- Runtime import errors if users forget to install a backend
- CPU-only torch requires two-step install or uv configuration (can't be expressed in pip extras alone)
- PyTorch is the only supported inference backend; future alternatives (burn/cublas via safetensors) would require separate integration work
References
- modern-python-project-setup.md — Section 2: PyTorch handling
- python-ml-packaging.md — Section 1: PyTorch as dependency