chore: Migrate to transformers v5 (with v4 fallback for distill)

[rmitsch]

Description

Migrate sieves to allow transformers v5 while keeping the [distill] extra on v4 until setfit ships v5 support.

Related Issues

-

Changes Made

• Loosen the base transformers pin to >=4,<6 so downstream installs of bare sieves resolve to v5.
• Cap the [distill] extra at transformers<5 because setfit 1.1.3 (latest, Nov 2024) imports default_logdir from transformers.training_args, a symbol removed in v5. Drop this cap once setfit ships v5 support.
• Fix a latent bug in the HuggingFace zero-shot wrapper: mode="multi" was never a real pipeline kwarg and was silently ignored, meaning multi-label classification was always running in single-label mode. Replaced with the documented multi_label=True (works on both v4 and v5).
• Add a new [optimization] extra for optuna (now required by dspy's MIPROv2 optimizer; previously a transitive dep).
• Bump version to 1.0.3.

Downstream behavior: pip install sieves → transformers v5; pip install sieves[distill] → transformers v4. Sieves' own CI runs against v4 because the universal lockfile intersects both extras (acceptable trade-off given the minimal transformers integration surface in this repo — see comment in .github/workflows/test.yml).

Checklist

• Tests have been extended to cover changes in functionality
• Existing and new tests succeed
• Documentation updated (if applicable)
• Related issues linked

Screenshots/Examples (if applicable)

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR loosens the base transformers pin to >=4,<6 to allow v5 installs while capping the [distill] extra at <5 due to a setfit v5 incompatibility. It also fixes a latent bug where mode="multi" was silently ignored in the HuggingFace zero-shot wrapper (replaced with the documented multi_label=True), and adds a new [optimization] extra for optuna.

The issues raised in previous review threads — the multi_label kwarg conflict with _inference_kwargs, the strict version equality in validate_init_params, and the duplicate pre-commit entry — remain unaddressed in this revision.

Confidence Score: 4/5

Safe to merge with minor pre-existing issues; no new P0/P1 bugs introduced by this PR.

No new critical issues are introduced. The three previously flagged concerns (multi_label kwarg conflict, strict version equality check, duplicate pre-commit entry) remain open but are all P2 or pre-existing P2 items. The core dependency strategy is sound and well-commented.

sieves/model_wrappers/huggingface_.py and sieves/serialization.py have pre-existing P2 concerns from prior review threads that remain unaddressed.

Important Files Changed

Filename	Overview
sieves/model_wrappers/huggingface_.py	Fixes latent bug by replacing non-existent mode="multi" with multi_label=True; the fix is correct but placing the kwarg before **self._inference_kwargs prevents callers from overriding it (already flagged separately).
pyproject.toml	Loosens transformers pin to >=4,<6, adds [optimization] extra for optuna, constrains [distill] to transformers <5, and adds rolling exclude-newer = "3 days" uv config; duplicate pre-commit entry remains (flagged separately).
sieves/serialization.py	Version string bumped to 1.0.3; strict equality check in validate_init_params means configs saved with 1.0.2 will fail to deserialize (flagged in previous thread).
.github/workflows/test.yml	Adds optimization to the install extras and documents the intentional v4 constraint imposed by the distill extra in CI.
uv.lock	Lockfile regenerated to pick up dependency updates; adds exclude-newer-span and platform-specific resolution markers alongside many package version bumps.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["pip install sieves"] --> B["transformers>=4,<6\n(v5 resolved)"]
    C["pip install sieves[distill]"] --> D["transformers>=4,<5\n(v4 forced by setfit constraint)"]
    E["pip install sieves[optimization]"] --> F["optuna>=4,<5\n(for DSPy MIPROv2)"]
    B --> G["HuggingFace wrapper\nmulti_label=True fix active"]
    D --> H["SetFit / Model2Vec\ntransformers v4 only"]
    CI["CI: sieves[ingestion,distill,optimization,test]"] --> D
    CI --> I["Tests run against\ntransformers v4 only"]

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_{Reviews (2): Last reviewed commit: "chore: Migrate to transformers v5 (with ..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #258   +/-   ##
=======================================
  Coverage   91.99%   91.99%           
=======================================
  Files          80       80           
  Lines        4462     4462           
=======================================
  Hits         4105     4105           
  Misses        357      357           

Files with missing lines	Coverage Δ
sieves/model_wrappers/huggingface_.py	91.11% <ø> (ø)
sieves/serialization.py	98.85% <100.00%> (ø)

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