fix: detect attachment mime from file contents (#23291)

packages/opencode/src/session/message-v2.ts

@@ -11,6 +11,7 @@ import { MessageTable, PartTable, SessionTable } from "./session.sql"
 import { ProviderError } from "@/provider"
 import { iife } from "@/util/iife"
 import { errorMessage } from "@/util/error"
+import { isMedia } from "@/util/media"
 import type { SystemError } from "bun"
 import type { Provider } from "@/provider"
 import { ModelID, ProviderID } from "@/provider/schema"
@@ -25,10 +26,7 @@ interface FetchDecompressionError extends Error {
 }
 
 export const SYNTHETIC_ATTACHMENT_PROMPT = "Attached image(s) from tool result:"
-
-export function isMedia(mime: string) {
-  return mime.startsWith("image/") || mime === "application/pdf"
-}
+export { isMedia }
 
 export const OutputLengthError = NamedError.create("MessageOutputLengthError", z.object({}))
 export const AbortedError = NamedError.create("MessageAbortedError", z.object({ message: z.string() }))