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bug: run --file hardcodes text/plain MIME type for all files #16723
Description
Problem
The run command's --file flag hardcodes text/plain MIME type for all non-directory files, making binary file attachments (images, audio, video) non-functional.
In packages/opencode/src/cli/cmd/run.ts:
const mime = (await Filesystem.isDir(resolvedPath))
? "application/x-directory"
: "text/plain"Expected behavior
MIME type should be detected from the file (e.g. via extension or magic bytes) so that opencode run --file image.png -m "describe this" correctly passes the image as image/png.
Reproduction
opencode run --format json --file photo.jpg -m "describe this image"The file is sent as text/plain regardless of actual content type, so the model receives corrupted/unusable binary data.
Suggested fix
Use file extension or content-based MIME detection (e.g. mime-types package or Node's built-in detection) instead of the hardcoded "text/plain" fallback.
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andrea-tomassi commentedon Apr 18, 2026
I've been debugging this while working on a vision pipeline that uses
opencode run --file screenshot.pngwith a vLLM-hosted multimodal model via theopenai-compatibleprovider.Root cause in
run.ts: Line 331 hardcodesmime: "text/plain"for all--filearguments. This causesprompt.tsto route images through the text/Read path (line 1065) instead of the binary/base64 multimodal path (line 1184+).I noticed PR #23291 adds MIME sniffing via magic bytes in
message-v2.tsandread.ts, but therun.ts --filecode path isn't covered there — so this issue would remain open even after that PR merges.Additional downstream issue: Even after fixing the MIME in
run.ts, there's a second bug in@ai-sdk/[email protected]. The provider at line 158 constructsdata:${mediaType};base64,${convertToBase64(part.data)}, butpart.dataarrives as a full data URL string (e.g.data:image/png;base64,...) fromconvertToModelMessages. SinceconvertToBase64()returns strings as-is, the result is double-encoded:data:image/png;base64,data:image/png;base64,.... This doesn't affect the dedicated@ai-sdk/openaior@ai-sdk/anthropicproviders (they have their own message conversion), which likely explains why it's gone unnoticed — it only impactsopenai-compatibleusers sending images via file attachment.I'm planning to file the AI SDK issue on
vercel/aiseparately. Happy to submit a PR for therun.tsfix here if that's welcome.fix(cli): detect MIME type for --file flag instead of hardcoding text…
antl3x commentedon May 7, 2026
@thdxr @kitlangton any ETA ?
github-actions commentedon Jul 7, 2026
To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.
feat(opencode): let the model actually see attached images
feat(opencode): let the model actually see attached images
feat(opencode): let the model actually see attached images