diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..ff34caf
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,4 @@
+# Preserve byte-exact upstream snapshots for source-manifest SHA-256.
+wechat-campaign-200-r2/src/upstream/* -text
+campaign-200-r2/*.mjs -text
+campaign-200-r2/*.json -text