cleanup: remove dead SDPA patches

[OnePunchMonk]

Transformers 5.x routes attention through sdpa_attention.py and no longer calls the _prepare_4d_causal_attention_mask* or _expand_mask functions that these patches targeted. This makes the following patches dead code:

• llama_patch_multipack.py (patched _prepare_4d_causal_attention_mask*)
• llama_expand_mask.py (patched _expand_mask, never called)
• Related utility functions in monkeypatch/utils.py

Closes #3331

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Summary by CodeRabbit

• Refactor
  • Removed Llama model-specific attention mask patches and related utility functions.
  • Removed expand_mask test suite and configuration entries.

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Run ID: 02e7f832-499a-41b6-a9fe-0396d0a791b8

📥 Commits

Reviewing files that changed from the base of the PR and between 23ad40b and 3118b1a.

📒 Files selected for processing (6)

• _quarto.yml
• src/axolotl/loaders/patch_manager.py
• src/axolotl/monkeypatch/llama_expand_mask.py
• src/axolotl/monkeypatch/llama_patch_multipack.py
• src/axolotl/monkeypatch/utils.py
• tests/test_expand_mask.py

💤 Files with no reviewable changes (5)

• _quarto.yml
• tests/test_expand_mask.py
• src/axolotl/loaders/patch_manager.py
• src/axolotl/monkeypatch/llama_expand_mask.py
• src/axolotl/monkeypatch/llama_patch_multipack.py

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📝 Walkthrough

Walkthrough

This PR removes deprecated Llama monkeypatch utilities and sample-packing logic that are no longer used by Transformers. The changes include deletion of llama_expand_mask.py and llama_patch_multipack.py modules, removal of related helper functions from utils.py, removal of sample-packing invocation from PatchManager, and deletion of associated tests.

Changes

Cohort / File(s)	Summary
Configuration _quarto.yml	Removed two monkeypatch entries (llama_expand_mask and llama_patch_multipack) from documentation.
Patch Manager src/axolotl/loaders/patch_manager.py	Removed _patch_llama_sample_packing method and its invocation in _patch_llama_derived_model, eliminating sample-packing-specific patching logic for llama-derived models.
Monkeypatch Modules src/axolotl/monkeypatch/llama_expand_mask.py, src/axolotl/monkeypatch/llama_patch_multipack.py, src/axolotl/monkeypatch/utils.py	Deleted llama_expand_mask.py and llama_patch_multipack.py entirely. Removed three utility functions from utils.py: mask_2d_to_4d, patched_prepare_4d_causal_attention_mask, and patched_prepare_4d_causal_attention_mask_for_sdpa.
Tests tests/test_expand_mask.py	Deleted test file for _expand_mask function including TestExpandMask test class and related test methods.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• drop old patches and code that are no longer needed #3007: Removes legacy Llama sample-packing and attendant monkeypatches (expand_mask, multipack, mask utils) and corresponding PatchManager sample-packing logic.
• bump hf deps #2735: Broad removal and update of monkeypatches including llama/mllama patches and PatchManager changes directly related to this cleanup.

Suggested reviewers

• SalmanMohammadi
• NanoCode012

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'cleanup: remove dead SDPA patches' is concise and directly describes the main change: removing obsolete monkeypatch code related to SDPA.
Linked Issues check	✅ Passed	All code changes align with issue #3331 requirements: removed llama_patch_multipack.py, llama_expand_mask.py, and related utility functions from monkeypatch/utils.py as dead code no longer called by Transformers 5.x.
Out of Scope Changes check	✅ Passed	All changes are in-scope cleanups directly addressing the removal of dead SDPA patches identified in the linked issue.

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