fix(media): support URL-safe Base64 in media data URIs

langfuse/media.py

@@ -291,7 +291,10 @@ def _parse_base64_data_uri(
             if not content_type:
                 raise ValueError("Content type is empty")
 
-            return base64.b64decode(actual_data), cast(MediaContentType, content_type)
+            translation_table = str.maketrans("-_", "+/")
+            decoded_data = base64.b64decode(actual_data.translate(translation_table))
+
+            return decoded_data, cast(MediaContentType, content_type)
 
         except Exception as e:
             logger.error("Error parsing base64 data URI", exc_info=e)

tests/unit/test_media.py

@@ -262,3 +262,16 @@ def test_resolve_media_references_uses_configured_httpx_client():
     httpx_client.get.assert_called_once_with(
         "https://example.com/test.jpg", timeout=fetch_timeout_seconds
     )
+
+def test_init_with_urlsafe_base64_data_uri():
+    original_bytes = b"\xfb\xff"
+    urlsafe_base64 = base64.urlsafe_b64encode(original_bytes).decode()
+
+    media = LangfuseMedia(
+        base64_data_uri=f"data:application/octet-stream;base64,{urlsafe_base64}"
+    )
+
+    assert media._source == "base64_data_uri"
+    assert media._content_type == "application/octet-stream"
+    assert media._content_bytes == original_bytes
+