[Bug]: SVG image attachments are rejected by T3 Code #10936

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1. CPRewrite

   added

   bugSomething is broken or behaving incorrectly.Something is broken or behaving incorrectly.

   needs-triageIssue needs maintainer review and initial categorization.Issue needs maintainer review and initial categorization.

   on Sep 9, 2026
2. juliusmarminge commented on Sep 9, 2026

   

   juliusmarminge

   on Sep 9, 2026

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   Thanks for the report — this is working as designed after the #6020 fix, but the design-file request is a reasonable follow-up (not a wash duplicate).

   What happens today
   The composer classifies anything under image/* that providers cannot take as a vision image as unsupported-image and refuses it at attach time. SVG (image/svg+xml) is in that bucket, along with TIFF.

   That check lives in apps/web/src/components/chat/composerAttachmentFiles.ts / ChatComposer.tsx, backed by PROVIDER_SEND_TURN_SUPPORTED_IMAGE_MIME_TYPES in packages/contracts (GIF, JPEG, PNG, WebP). HEIC/HEIF are a special convert-to-raster path. Mobile uses the same rule.

   Why it exists
   #6020 accepted SVG, then Claude failed with Unsupported Claude image attachment type 'image/svg+xml'. #6574 / 93376e45 moved that failure to attach time on purpose. Tests still say “reject unsupported image types instead of attaching them as generic files.”

   What you want
   Attaching SVG source for designs is a different path. The server already accepts { type: "file", mimeType: "image/svg+xml" } as a generic file, and Claude/OpenCode only send raster types as vision — other files ride as a prompt path. Your rename-to-.txt/.html workaround works because that skips the image/* reject and uses the file path.

   Not doing

   • Reopening [Bug]: SVG images cannot be pasted into chat, they are accepted and show up as images in chat but a separate error shows "Unsupported Claude image attachment type 'image/svg+xml'. " #6020 or treating this as a regression
   • Sending SVG as a vision image (that is the [Bug]: SVG images cannot be pasted into chat, they are accepted and show up as images in chat but a separate error shows "Unsupported Claude image attachment type 'image/svg+xml'. " #6020 failure mode)

   Next
   Product call (@julius) on whether to keep the hard reject or add an SVG exception that stages it as a generic file (not an image). Rasterizing to PNG would not preserve design source. Served-SVG XSS is already sandboxed (#5916).

   Until then, attach via rename, or put the .svg in the workspace and mention the path.
3. juliusmarminge

   added

   enhancementRequested improvement or new capability.Requested improvement or new capability.

   via-triageFiled through npx t3 triageFiled through npx t3 triage

   needs-julius

   and removed

   bugSomething is broken or behaving incorrectly.Something is broken or behaving incorrectly.

   needs-triageIssue needs maintainer review and initial categorization.Issue needs maintainer review and initial categorization.

   on Sep 9, 2026