[MM][Perf][CG] Support ViT full CUDA graph for Kimi-VL

[oguzhankir]

Purpose

Add ViT CUDA Graph support for Kimi-VL (KimiVLForConditionalGeneration), following the pattern established in #38061 (Qwen3-VL). Part of the tracker issue #38175.

Kimi-VL's MoonVitPretrainedModel contains .tolist() calls in its forward path (pos embedding interpolation, RoPE frequency computation, patch merging) that are incompatible with CUDA graph capture. This PR refactors moonvit.py to add a graph-safe path via precomputed metadata buffers, then wires kimi_vl.py to the SupportsEncoderCudaGraph protocol.

Test Plan

• Unit tests: pytest tests/v1/cudagraph/test_encoder_cudagraph.py -v
• Added Kimi-VL entry to tests/models/multimodal/generation/test_vit_cudagraph.py
• E2E benchmark on RTX 4090

Test Result

Unit tests: 36 passed ✅

E2E Benchmark — RTX 4090, moonshotai/Kimi-VL-A3B-Instruct, 2 images/req, 200 prompts @ 8 RPS:

Metric	No CG	With CG	Δ
Mean TTFT	132.91 ms	111.13 ms	↓ 16.4%
Median TTFT	130.88 ms	102.64 ms	↓ 21.6%
P99 TTFT	290.47 ms	193.25 ms	↓ 33.5%

CG config: encoder_cudagraph_token_budgets=[256,512,1024], encoder_cudagraph_max_vision_items_per_batch=4

Documentation

• Added KimiVLForConditionalGeneration row to docs/design/cuda_graphs_multimodal.md
• Added kimi_vl to MODELS_SUPPORT_VIT_CUDA_GRAPH in examples/generate/multimodal/vision_language_offline.py

[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.

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[mergify]

Documentation preview: https://vllm--41992.org.readthedocs.build/en/41992/

[gemini-code-assist]

Code Review

This pull request implements encoder CUDA graph support for the Kimi-VL model. It introduces the SupportsEncoderCudaGraph protocol to KimiVLForConditionalGeneration and refactors the underlying MoonVit components to allow precomputing grid-dependent metadata—such as positional embeddings, RoPE frequencies, and sequence lengths—outside of the captured CUDA graph. Additionally, it adds a CUDA-graph-safe patch merging implementation and includes tests and documentation updates for the new functionality. I have no feedback to provide.