Observed live: an overheated MI50 returns a single char repeated ("?????") as a
successful 200, which neither the timeout nor the exception fallback catches — so
a degraded GPU would silently save capped garbage gists. Validate each summary
call's output: flag text (>=24 non-space chars) whose most-common non-whitespace
char exceeds 50%, raise DegenerateOutput, and let the existing retry->cloud
fallback handle it. Real prose (top char <20%) won't false-positive; short output
is exempt; cloud garbage raises rather than looping.
Tests: _looks_degenerate flags repeated-char / passes real prose / ignores short;
degenerate MI50 output falls back to cloud; cloud garbage raises. 177 pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015yrEb5qpPGv2FjyxrB7LLk
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