When an OpenAI-compatible proxy (e.g. cmkey.cn, one-api Anthropic channels)
returns a well-formed HTTP 200 whose summary content is null or empty/
whitespace-only, _generate_summary coerced it to "" and stored a prefix-only
summary — silently replacing the compacted turns with nothing. The model then
lost all in-progress context after compression (#11978, #11914).
_validate_llm_response already guards None / empty-choices, so those never
reach the compressor; the gap was a well-formed response with empty *content*.
Now treat empty content as a summary failure: raise so it routes through the
existing main-model fallback then transient cooldown, dropping the turns
without a summary rather than wiping context with an empty one.
Also narrow the bare 'except RuntimeError' so only genuine 'No LLM provider
configured' errors take the 600s no-provider cooldown; empty/invalid-response
RuntimeErrors from a configured provider now correctly get the main-model
fallback instead of being misrouted into the long no-provider cooldown.
Reported by @Hung2124; area identified by @annguyenNous in #39590.
Teknium
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