[Model] add GLM-5.3-Flash support

[ZJY0516]

Purpose

@JaredforReal did most of the work for this day0 support 933876c, thanks!

add support for https://huggingface.co/zai-org/GLM-5.3-Flash

Please use docker image to run this model, see https://recipes.vllm.ai/zai-org/GLM-5.3-Flash

Only the first commit 933876c is fully verified

Test Plan

Test Result

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

[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.

[yangqinghao-cmss]

This cannot be used. How can such a problem be resolved?

[drakosha]

Same request on SM90 here (2x H200 NVL, TP2, no DP/EP, GLM-5.3-Flash NVFP4 on main):
你好 returns a normal greeting, finish_reason: stop, and prompt_tokens is 13,
the same count your run shows. So your chat template and tokenization are fine, the
prompt does reach the engine.

At temperature: 0 what you got is not a sampling artifact either: the model emits
memorized training text and then degenerates into one repeated phrase, which is what
a healthy LM does when the context has no influence on it. Suspect the attention and
state path or weight loading, not sampling.

Your fingerprint is tp4-dp2-ep, ours is plain tp2. Bisect one knob at a time and
stop at the first sane answer: drop EP, then DP, then MTP if enabled, then
--kv-cache-dtype auto. Worth posting with the result: the Using ... attention backend startup line, the kv_cache_dtype from the engine config dump, and which
commit d9105ea80 is. If the checkpoint is a third-party quantization, try
zai-org/GLM-5.3-Flash first, since fluent but context-blind output is also what a
bad quantized load looks like.

This PR is merged, so a new issue will get more eyes than a comment here.

AI assistance was used for this comment.

[gaby]

@ZJY0516 @ywang96 Any idea why support for GLM-5.3-Flash was not added to the 0.29.0 release?

See #56007

[ZJY0516]

@ZJY0516 @ywang96 Any idea why support for GLM-5.3-Flash was not added to the 0.29.0 release?

See #56007

sorry about this, the branch cut is before merging model support PR