b0e07f52d2
Devin provider models (devin-agent) advertise reasoning: true but no thinking.efforts metadata — Cascade selects effort by routing to sibling model ids, not a wire param. getSupportedEfforts(model) therefore returns []. clampAutoThinkingEffort previously short-circuited that empty supported list by returning the requested effort as-is, so the auto-thinking classifier-resolved level (e.g. low) reached stream.ts:1163 where requireSupportedEffort threw 'Thinking effort low is not supported by devin/<id>. Supported efforts: '. In --print mode the user saw the error text; in the TUI it was silently swallowed, producing the reported 'working then empty response' symptom. Returns undefined when supported is empty so the result mirrors clampThinkingLevelForModel's behavior on the same shape (the explicit --thinking low / high paths already worked because of this). Updates classifyDifficulty's return type to Effort | undefined and threads through to the existing #applyAutoThinkingLevel undefined-effort early-return. #applyAutoThinkingLevel also short-circuits the classifier call up front for these models — there is no effort to pick. Fixes #3356