fix: include reasoning_content field for DeepSeek Reasoner models#11290
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RomneyDa merged 2 commits intoMar 21, 2026
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DeepSeek Reasoner API requires the reasoning_content field on every assistant message, even when no thinking message precedes it (e.g. in resumed sessions). Previously, appendReasoningFieldsIfSupported returned early when prevMessage was missing or not a thinking role, causing 400 "Missing reasoning_content field" errors. Now reasoning_content defaults to an empty string when no thinking content is available. Fixes continuedev#11285 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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I have read the CLA Document and I hereby sign the CLA |
RomneyDa
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Mar 20, 2026
| // Default to empty string to avoid 400 "Missing reasoning_content field". | ||
| if (includeReasoningContent) { | ||
| msg.reasoning_content = hasThinkingContent | ||
| ? (prevMessage.content as string) |
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@mvanhorn is it possible to remove this typecast? I think MessageContent can be an array of text content for example. There are some utilities in the codebase to render any message content to string. Or did I miss reason for type cast?
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Replaced both as string casts with stripImages() from core/util/messageContent in 8cd24cb. That handles the MessagePart[] case properly.
Replace `as string` typecasts with stripImages() which safely handles both string and MessagePart[] content types. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
reasoning_contenton every assistant message, butappendReasoningFieldsIfSupportedreturned early when no thinking message preceded the assistant message (e.g. in resumed sessions)reasoning_contentdefaults to an empty string whenincludeReasoningContentFieldis true but no thinking content is available, preventing 400 "Missing reasoning_content field" errorsHow it works
includeReasoningContentcheck before the early return guard so it always runs for providers that need itreasoning,reasoning_details) still require a preceding thinking messageTest plan
reasoning_details, notreasoning_content)Fixes #11285
🤖 Generated with Claude Code
Summary by cubic
Always include
reasoning_contentfor DeepSeek Reasoner models, defaulting to an empty string when no priorthinkingmessage exists. Prevents 400 errors in resumed sessions and safely handles mixed message content.includeReasoningContentFieldbefore the early return and setmsg.reasoning_contentto the previousthinkingcontent or "" if missing.stripImagesto populatereasoning_contentandreasoning, handling string orMessagePart[]content; keepreasoning_detailsunchanged and only set when athinkingmessage is present.Written for commit 8cd24cb. Summary will update on new commits.