Add buffered crop UI and API controls

app/vision.py

@@ -89,6 +89,7 @@ def detect_salient_object(image: np.ndarray) -> BBox | None:
 
 def square_bbox(bbox: BBox, image_shape: tuple[int, int, int], buffer_ratio: float = 0.15) -> BBox:
     image_h, image_w = image_shape[:2]
+    buffer_ratio = max(0.0, min(buffer_ratio, 0.5))
     side = int(round(max(bbox.w, bbox.h) * (1 + buffer_ratio * 2)))
     side = max(1, min(side, image_w, image_h))
 
@@ -126,10 +127,10 @@ def _data_url(image_bytes: bytes, mime_type: str) -> str:
     return f"data:{mime_type};base64,{base64.b64encode(image_bytes).decode('ascii')}"
 
 
-def process_image(image_bytes: bytes, filename: str) -> dict[str, Any]:
+def process_image(image_bytes: bytes, filename: str, buffer_ratio: float = 0.15) -> dict[str, Any]:
     image = decode_image(image_bytes)
     bbox, method = select_primary_bbox(image)
-    square = square_bbox(bbox, image.shape)
+    square = square_bbox(bbox, image.shape, buffer_ratio=buffer_ratio)
     crop = crop_image(image, square)
     annotated = draw_square(image, square)
 
@@ -139,6 +140,7 @@ def process_image(image_bytes: bytes, filename: str) -> dict[str, Any]:
     return {
         "filename": filename,
         "method": method,
+        "buffer_ratio": buffer_ratio,
         "detected_bbox": bbox.__dict__,
         "square_bbox": square.__dict__,
         "source_size": {"width": int(image.shape[1]), "height": int(image.shape[0])},