Add nvfp4_local_hessian to QUANT_CFG_CHOICES

[sungsooha]

What does this PR do?

Type of change: New feature

Wire up NVFP4_W4A4_WEIGHT_LOCAL_HESSIAN_CFG (from PR #788) to the hf_ptq.py CLI so it can be used via --qformat nvfp4_local_hessian.

One-line addition to QUANT_CFG_CHOICES dict.

Usage

python examples/llm_ptq/hf_ptq.py \
  --model Qwen/Qwen3-8B \
  --qformat nvfp4_local_hessian \
  --kv_cache_qformat fp8 \
  --export_fmt hf

Testing

Tested via modelopt-quantization CI pipeline (quant_flow) on GB200 (oci-hsg launcher) with Qwen3-8B. PTQ stage completed successfully.

Before your PR is "Ready for review"

• Is this change backward compatible?: ✅
• If you copied code from any other sources or added a new PIP dependency, did you follow guidance in CONTRIBUTING.md: N/A
• Did you write any new necessary tests?: N/A (wiring existing config to existing CLI)
• Did you update Changelog?: N/A

Additional Information

• NVFP4_W4A4_WEIGHT_LOCAL_HESSIAN_CFG was added in PR add local hessian calibration #788 but not exposed via the CLI.
• Also used in modelopt-quantization CI (quant_flow) for automated NVFP4 scale-setting sweeps.

Summary by CodeRabbit

• New Features
  • Added a new KV-cache quantization configuration option, expanding the available quantization choices for users. This provides an additional quantization mode to select from in configuration UIs and CLIs while preserving existing behavior and compatibility.

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📥 Commits

Reviewing files that changed from the base of the PR and between dce46d2dd7aac943fde29a5ac0ff87a72ecd6279 and d871382.

📒 Files selected for processing (1)

• examples/llm_ptq/hf_ptq.py

🚧 Files skipped from review as they are similar to previous changes (1)

• examples/llm_ptq/hf_ptq.py

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📝 Walkthrough

Walkthrough

Added a new KV quantization configuration key "nvfp4_local_hessian" to the example script, mapping it to mtq.NVFP4_W4A4_WEIGHT_LOCAL_HESSIAN_CFG in the QUANT_CFG_CHOICES dictionary.

Changes

Cohort / File(s)	Summary
KV Quantization Configuration examples/llm_ptq/hf_ptq.py	Added nvfp4_local_hessian option to QUANT_CFG_CHOICES, mapped to mtq.NVFP4_W4A4_WEIGHT_LOCAL_HESSIAN_CFG.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 4

✅ 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 accurately and concisely describes the main change: adding a new quantization configuration option to QUANT_CFG_CHOICES.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Security Anti-Patterns	✅ Passed	The pull request introduces no security anti-patterns as defined in SECURITY.md. The change is a minimal dictionary entry that exposes an existing, well-tested quantization configuration.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.30%. Comparing base (7c33d85) to head (d871382).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1065   +/-   ##
=======================================
  Coverage   70.29%   70.30%           
=======================================
  Files         227      227           
  Lines       25860    25854    -6     
=======================================
- Hits        18179    18176    -3     
+ Misses       7681     7678    -3     

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