fix: resolve Mistral API compatibility issues #2440
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Fixes "Unexpected role 'user' after role 'tool'" error that occurs when switching from Claude to Mistral models mid-conversation. Mistral has stricter message sequence requirements than other providers. - Add fixMistralMessageSequence() function to detect tool→user sequences - Insert intermediate assistant messages to maintain proper conversation flow - Apply fix for models containing "mistral" or "devstral" in their name - Preserve valid sequences unchanged Resolves issue where users get API errors when switching between providers during conversations with tool usage.
Resolves 'Unsupported content type in assistant message: undefined' error by ensuring the inserted assistant message has the proper structure expected by the AI SDK.
Mistral API requires tool call IDs to be alphanumeric with exactly 9 characters. Convert IDs like 'toolu_01CBhTTz95qkd9LJMdC9sf8t' to 'toolu01CB'. Fixes 'Tool call id was toolu_01CBhTTz95qkd9LJMdC9sf8t but must be a-z, A-Z, 0-9, with a length of 9' error.
Filter on providerID rather than individual model names to ensure all Mistral models receive the necessary API compatibility transforms, including future model variants.
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Summary
Fixes multiple Mistral API compatibility issues that occur when using Mistral models with tool calling:
AI_APICallError: Unexpected role 'user' after role 'tool'by inserting assistant messages between tool and user messages to maintain proper conversation flowError: Unsupported content type in assistant message: undefinedby ensuring inserted messages have proper AI SDK structureRoot Cause
Mistral API requirements:
toolInvocationsfieldSolution
Added Mistral-specific transforms in
packages/opencode/src/provider/transform.ts:normalizeMistralToolCallIds()- converts tool call IDs to 9-character alphanumeric formatfixMistralMessageSequence()- inserts assistant messages to maintain proper sequenceTest Plan
Files Changed
packages/opencode/src/provider/transform.ts- Added Mistral-specific message transformsResolves API errors that occur when using Mistral models with tool calling functionality.