Fix image uploads using the wrong format (#2380)

* fix(app): preserve image attachment MIME types

Image intake discarded clipboard and desktop path metadata, then guessed JPEG when a later file object had no type. Resolve MIME once at the platform boundary and require it downstream.

* fix(app): honor native picker MIME metadata

packages/app/src/attachments/file-types.test.ts

@@ -6,6 +6,7 @@ import {
   isRasterImageMimeType,
   isRasterImagePath,
   RASTER_IMAGE_FILE_EXTENSIONS,
+  resolveRasterImageMimeType,
 } from "./file-types";
 
 describe("attachment file types", () => {
@@ -37,4 +38,28 @@ describe("attachment file types", () => {
       new Set(["png", "jpg", "jpeg", "gif", "webp", "bmp", "heic", "heif", "avif", "tif", "tiff"]),
     );
   });
+
+  it("uses explicit raster MIME metadata before the filename", () => {
+    expect(
+      resolveRasterImageMimeType({ mimeType: "image/jpeg", path: "/tmp/screenshot.png" }),
+    ).toBe("image/jpeg");
+    expect(
+      resolveRasterImageMimeType({
+        mimeType: "image/png; charset=binary",
+        path: "/tmp/screenshot.jpg",
+      }),
+    ).toBe("image/png");
+  });
+
+  it("uses the filename only when MIME metadata is absent", () => {
+    expect(resolveRasterImageMimeType({ mimeType: "", path: "/tmp/screenshot.png" })).toBe(
+      "image/png",
+    );
+    expect(
+      resolveRasterImageMimeType({
+        mimeType: "application/octet-stream",
+        path: "/tmp/screenshot.png",
+      }),
+    ).toBeNull();
+  });
 });

packages/app/src/attachments/file-types.ts

@@ -41,18 +41,31 @@ export function getRasterImageMimeTypeFromPath(path: string): string | null {
   return RASTER_IMAGE_MIME_TYPE_BY_EXTENSION[getFileExtension(path)] ?? null;
 }
 
+export function resolveRasterImageMimeType(input: {
+  mimeType?: string | null;
+  path?: string | null;
+}): string | null {
+  const suppliedMimeType = input.mimeType?.trim();
+  if (suppliedMimeType) {
+    const normalizedMimeType = suppliedMimeType.split(";", 1)[0]?.trim().toLowerCase();
+    if (normalizedMimeType === "image/jpg") {
+      return "image/jpeg";
+    }
+    return normalizedMimeType && RASTER_IMAGE_MIME_TYPES.has(normalizedMimeType)
+      ? normalizedMimeType
+      : null;
+  }
+  return input.path ? getRasterImageMimeTypeFromPath(input.path) : null;
+}
+
 export function isRasterImagePath(path: string): boolean {
   return getRasterImageMimeTypeFromPath(path) !== null;
 }
 
 export function isRasterImageMimeType(mimeType: string | null | undefined): boolean {
-  const normalized = mimeType?.split(";", 1)[0]?.trim().toLowerCase();
-  return Boolean(normalized && RASTER_IMAGE_MIME_TYPES.has(normalized));
+  return resolveRasterImageMimeType({ mimeType }) !== null;
 }
 
 export function isRasterImageFile(file: Pick<File, "name" | "type">): boolean {
-  if (isRasterImageMimeType(file.type)) {
-    return true;
-  }
-  return file.type.trim().length === 0 && isRasterImagePath(file.name);
+  return resolveRasterImageMimeType({ mimeType: file.type, path: file.name }) !== null;
 }