[ashwinsreedhar28]

When loading a model requires code from its own repository and TRUST_REMOTE_CODE isn't set, vLLM fails config validation with a ValidationError asking for trust_remote_code=True. The worker doesn't recognise that error, so it exits and is restarted into the same failure, and the job never gets an answer. I hit this with IFM/K2-Horizon-7B on v2.27.2 and v2.28.0: the worker failed config validation on every start, and the submitted job had no result after each 15-minute observation window (log, runs).

This adds it to startup_errors.classify, so the worker stays up and answers jobs with the fix: review the repository's code, then set TRUST_REMOTE_CODE=true. It's checked before the unsupported-architecture match on purpose. With remote code allowed, vLLM can serve an architecture it has no native class for through its Transformers backend: K2-Horizon loaded that way on v2.27.2 (vLLM 0.28.0, no K2-Horizon class).

How often this can come up: 8 of the 25 new-architecture repos in my sample map AutoModel* to repository code in config.json (data). That's potential exposure, not 8 reproduced failures; transformers can still use a built-in implementation when one exists.

Evidence:

check	result
python -m pytest tests	144 pass (142 on main + 2 new in tests/test_startup_errors.py, using the error text from the K2-Horizon log)
image from this branch at c1b457f (FROM vllm/vllm-openai:v0.32.0, build; the later commit only edits README.md) on Serverless, IFM/K2-Horizon-7B, 24 GB class, no TRUST_REMOTE_CODE	worker stays up; job FAILED with startup_error 2.8 min after endpoint creation: "IFM/K2-Horizon-7B ships its own modeling code on Hugging Face (an auto_map in its config.json), and vLLM only runs that code with TRUST_REMOTE_CODE=true. Review the repository's code, then set TRUST_REMOTE_CODE=true if you trust it. …" (result)
same image with TRUST_REMOTE_CODE=true	first request COMPLETED 4.6 min after endpoint creation (result)

The secret-gated jobs (dev image build, serverless-model-tests) don't run on a fork PR; happy for them to be mirrored like #352.

Study, build logs and results: https://github.com/ashwinsreedhar28/day0-ready

[promptless]

Promptless documentation updates

• Document vLLM worker startup error handling in Serverless troubleshooting adds a troubleshooting entry for the missing TRUST_REMOTE_CODE startup error and updates the TRUST_REMOTE_CODE environment variable description.