Fix TURBOQUANT backend selection in cuda.py

[mgoin]

Purpose

Added TURBOQUANT to the selection list of attention backends and removed specialized case.

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

[gemini-code-assist]

Code Review

This pull request integrates TURBOQUANT into the standard attention backend priority lists for CUDA platforms while removing the previous hardcoded bypass for TurboQuant KV cache types. Feedback indicates that moving TURBOQUANT to the end of the priority list is a regression that could lead to incorrect backend selection; it is recommended to use the kv_cache_dtype parameter to prioritize TURBOQUANT when explicitly requested while still allowing for standard validation.

[mergify]

Hi @mgoin, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10

[mergify]

Hi @mgoin, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10

[mergify]

Documentation preview: https://vllm--40060.org.readthedocs.build/en/40060/