* Add regression guard for batched left-padded generation (#1066, #3699)
Three layers of tests plus a path-filtered CI workflow so the left-padding
position_ids / attention-mask bug class cannot silently return:
- tests/utils/test_prepare_inputs_ast_guard.py: import-free AST checks on
_fast_prepare_inputs_for_generation (cumsum-from-mask branch present,
cache_position only as fallback, no mask truncation, model families wired)
- tests/utils/test_prepare_inputs_leftpad.py: CPU behavioral unit test with
synthetic left-padded masks and fake caches; exact expected position_ids
for prefill and cached decode
- tests/utils/test_batched_leftpad_generation_gpu.py: optional GPU e2e,
solo vs batched prefix match, skipped without CUDA
- .github/workflows/batch-inference-guard.yml: ubuntu-latest CPU job running
the two deterministic layers on PRs touching unsloth/models/**
Validated: all pass on main; both CPU layers fail at 6d0f8643~1 (pre #4100)
and at 332eabf3~1 (pre #2216), reproducing the historical bug signatures.
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* Cite staging proof in batch-inference-guard header (staging-2 PRs 170/171)
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* Fold left-padding guard into consolidated Core CI; merge AST + behavioral tests
No new workflow and no new CI job: the guard now runs as one HARD GATE step
inside consolidated-tests-ci.yml, right after the callback signature drift
detector, where the CPU torch stack is already installed. The AST structural
checks and the behavioral unit tests live in a single file
(tests/utils/test_prepare_inputs_leftpad.py); the AST layer stays stdlib-only
with unsloth imported lazily inside the behavioral tests, so import breakage
cannot mask the structural checks.
Revalidated after the merge: 11 assertions pass on main, 8 fail at
6d0f8643~1 (pre #4100).
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* Update staging proof reference for consolidated gate (PRs 170/172)
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
