[ROCm][Bugfix] Forward router-weight flag in Quark OCP MX AITER MoE

[Bortlesboat]

Refs #40008.

This keeps the Quark OCP MX AITER apply path from silently falling back at runtime after weights may have been prepared for AITER/CK, and forwards apply_router_weight_on_input into rocm_aiter_fused_experts so routing-weight-on-input models preserve the same semantics as the modular and fused fallback paths.

Why this is not duplicating an existing PR:

• gh issue view 40008 --repo vllm-project/vllm --comments
• gh pr list --repo vllm-project/vllm --state open --search "40008 in:body" returned no matches when this PR was opened.
• gh pr list --repo vllm-project/vllm --state open --search "Unsupported kernel config for moe heuristic dispatch" returned no matches when this PR was opened.
• gh pr list --repo vllm-project/vllm --state open --search "moe heuristic dispatch rocm" only found [ROCm] Enable dual-stream MoE shared experts, AITER sparse MLA workaround, and GLM-5-FP8 weight loading fix #38665, which is a different ROCm lane.

Tests run:

• wsl.exe --cd /mnt/c/Users/andre/.config/superpowers/worktrees/vllm/vllm-rocm-moe-heuristic-40008 bash -lc 'PYTHONPATH=$PWD uv run --no-project --python 3.12 --with torch==2.11.0 --with pytest --with-requirements requirements/common.txt --with-requirements requirements/test/cuda.in python -m pytest tests/model_executor/layers/test_quark_ocp_mx_moe.py -q' -> 2 passed
• wsl.exe --cd /mnt/c/Users/andre/.config/superpowers/worktrees/vllm/vllm-rocm-moe-heuristic-40008 bash -lc 'uv run --no-project --python 3.12 --with ruff ruff check vllm/model_executor/layers/quantization/quark/quark_moe.py tests/model_executor/layers/test_quark_ocp_mx_moe.py' -> All checks passed!
• wsl.exe --cd /mnt/c/Users/andre/.config/superpowers/worktrees/vllm/vllm-rocm-moe-heuristic-40008 bash -lc 'uv run --no-project --python 3.12 --with ruff ruff format --check vllm/model_executor/layers/quantization/quark/quark_moe.py tests/model_executor/layers/test_quark_ocp_mx_moe.py' -> 2 files already formatted
• git diff --check -> passed

AI assistance: I used Codex to help draft the patch and regression tests, then reviewed the diff and local verification before updating this PR.

[gemini-code-assist]

Code Review

This pull request introduces a fallback mechanism in the Quark OCP MX MoE implementation to use the Triton-based fused_experts kernel when the ROCm AITER kernel encounters an unsupported configuration. However, the review feedback identifies a critical flaw: weights are shuffled into a specific layout for AITER during the loading process, making them incompatible with the standard layout expected by the fallback kernel, which would lead to silent data corruption. Additionally, the rocm_aiter_fused_experts call is missing the apply_router_weight_on_input argument, and the new unit tests are noted to be misleading as they do not account for the weight layout mismatch that would occur in production.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[Bortlesboat]

Closing — #39801 (merged Apr 27) introduces an _AITER_NATIVE_OCP_MX_SCHEMES = ("w_mxfp4",) allowlist in QuarkOCP_MX_MoEMethod.__init__ that sets emulate=True for the mixed schemes (w_mxfp4_a_mxfp6_*, w_fp6_e3m2_a_fp6_e3m2, etc.) before the AITER weight shuffle. That's the cleaner fix for #40008: it avoids the silent-correctness risk @gemini-code-assist flagged here (the runtime fallback would have run fused_experts on AITER-shuffled weights).

If MI355 still hits the heuristic dispatch error on the allowlisted w_mxfp4 scheme specifically, that's worth its own narrower repro on a separate issue.

[Bortlesboat]

Closing per the comment above — superseded by #39801 (merged Apr 27).