From 42ad8645010910df51cad51fab77edd5cafdaf91 Mon Sep 17 00:00:00 2001
From: Roger Deng <13251150+rogerdigital@users.noreply.github.com>
Date: Thu, 7 May 2026 17:04:27 +0800
Subject: [PATCH] fix(cli): detect MIME type for --file flag instead of
 hardcoding text/plain

The --file flag on `opencode run` was sending all non-directory
attachments as text/plain, breaking multimodal support for images,
PDFs, and other binary files. Use Filesystem.mimeType() to detect
the correct type from the file extension.

Closes #16723, #24698, #25353
---
 packages/opencode/src/cli/cmd/run.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/opencode/src/cli/cmd/run.ts b/packages/opencode/src/cli/cmd/run.ts
index a05b273e4489..56c406f6850f 100644
--- a/packages/opencode/src/cli/cmd/run.ts
+++ b/packages/opencode/src/cli/cmd/run.ts
@@ -333,7 +333,7 @@ export const RunCommand = effectCmd({
             process.exit(1)
           }
 
-          const mime = (await Filesystem.isDir(resolvedPath)) ? "application/x-directory" : "text/plain"
+          const mime = (await Filesystem.isDir(resolvedPath)) ? "application/x-directory" : await Filesystem.mimeType(resolvedPath)
 
           files.push({
             type: "file",