diff --git a/tools/export-github.sh b/tools/export-github.sh
index cbcb788f..907408e8 100755
--- a/tools/export-github.sh
+++ b/tools/export-github.sh
@@ -244,10 +244,19 @@ fi
 git log --oneline -3
 
 # --- 5. bundle for transfer (full bundle: stateless, fetch takes only new) ---
-# Carries the branch that was published, not a hardcoded main.
-git bundle create "$OUT/shopdb-flask-pub.bundle" HEAD "$BRANCH" --tags
-git bundle verify "$OUT/shopdb-flask-pub.bundle" >/dev/null
-echo "bundle: $OUT/shopdb-flask-pub.bundle"
+#
+# ONE BUNDLE PER BRANCH, named after it.
+#
+# This wrote a single shopdb-flask-pub.bundle whatever it published, which was
+# fine while only main was ever published and became a trap the moment it was
+# not: exporting a site branch silently overwrote the bundle holding main's
+# work, and the work PC's documented `git fetch <bundle> main` then failed
+# because that ref was no longer in the file. Two branches cannot share one
+# filename.
+BUNDLE="$OUT/shopdb-flask-pub-$BRANCH.bundle"
+git bundle create "$BUNDLE" HEAD "$BRANCH" --tags
+git bundle verify "$BUNDLE" >/dev/null
+echo "bundle: $BUNDLE"
 
 # --- 6. optional per-instance dists (both bases: /ops = dev, /shopdb = prod) ---
 # Two instances run on the box; each needs its own base-path build. Always
@@ -266,7 +275,7 @@ cat <<EOF
 
 On the work PC (in the shopdb-flask-pub clone):
   git checkout $BRANCH
-  git fetch <path-to>\shopdb-flask-pub.bundle $BRANCH
+  git fetch <path-to>\shopdb-flask-pub-$BRANCH.bundle $BRANCH
   git merge --ff-only FETCH_HEAD
   git push origin $BRANCH
 EOF