backend: immagini BMP ammesse nelle rotte visione (Refs #99)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/backend/api/routers/vision.py

@@ -40,14 +40,22 @@ _IMAGE_EXTENSIONS = {
     "image/png": "png",
     "image/gif": "gif",
     "image/webp": "webp",
+    "image/bmp": "bmp",          # #99
+    "image/x-ms-bmp": "bmp",     # #99
 }
 
+# #99: the Opto bench cameras save BMP and the worker decodes it (PIL), so the
+# vision routes accept it on top of files.py's list. files.py is untouched: its
+# attachments are served by extension and BMP is not meant to be shown there.
+_VISION_IMAGE_TYPES = ALLOWED_IMAGE_TYPES | {"image/bmp", "image/x-ms-bmp"}
+
 # Sniffed from the first bytes, independent of the declared Content-Type: a
 # text file uploaded as "image/png" passes the header check above and must
-# still be caught before it reaches the worker as a bare 500 (#15). BMP and
-# TIFF are included even though `_IMAGE_EXTENSIONS` does not accept them,
-# because PIL - and so the worker - can decode both; this check only refuses
-# what is not a real image at all, it does not narrow the allow-list above.
+# still be caught before it reaches the worker as a bare 500 (#15). TIFF is
+# included even though the allow-list does not accept it (PIL, and so the
+# worker, can decode it; browsers do not show it in the result); BMP is now
+# also allowed (#99). This check only refuses what is not a real image at all,
+# it does not narrow the allow-list above.
 _IMAGE_SIGNATURES: tuple[tuple[bytes, ...], ...] = (
     (b"\x89PNG\r\n\x1a\n",),         # PNG
     (b"\xff\xd8\xff",),              # JPEG
@@ -83,7 +91,7 @@ async def _read_image(image: UploadFile) -> bytes:
     is in hand - the same two-step convention `files.py::upload_file` already
     uses, reused rather than reinvented here.
     """
-    if image.content_type not in ALLOWED_IMAGE_TYPES:
+    if image.content_type not in _VISION_IMAGE_TYPES:  # #99
         raise HTTPException(
             status_code=status.HTTP_400_BAD_REQUEST,
             detail=f"File type {image.content_type} not allowed. Must be an image.",