fix(mcp): correct file extension when image format mismatches#68
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haosenwang1018 wants to merge 1 commit intollmsresearch:mainfrom
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fix(mcp): correct file extension when image format mismatches#68haosenwang1018 wants to merge 1 commit intollmsresearch:mainfrom
haosenwang1018 wants to merge 1 commit intollmsresearch:mainfrom
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When the image generator saves JPEG data with a .png extension, the MCP tool result declares image/png but the actual content is JPEG, causing Anthropic API validation errors. Now _compress_for_api copies the file with the correct extension when a mismatch is detected between the magic-byte format and the file extension. Fixes llmsresearch#58
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@haosenwang1018 Thanks for the fix, the approach looks good and targeted. I checked this against current After that, this looks good to go. |
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Fixes #58
The MCP generate_diagram tool returns JPEG image data with an image/png media type, causing the Anthropic API to reject the tool result.
Root Cause: The image generator may produce JPEG data but save it with a .png extension. While _compress_for_api correctly detects the actual format via magic-byte inspection, the fastmcp Image class may infer the MIME type from the file extension, resulting in a mismatch.
Fix: In _compress_for_api, after detecting the actual image format, check whether the file extension matches. If not, copy the file with the correct extension before returning.
No behavior change when the extension already matches the format.