diff --git a/deploy/nexus/genome-raw-commit.sh b/deploy/nexus/genome-raw-commit.sh
index dae028e..f7dfa24 100644
--- a/deploy/nexus/genome-raw-commit.sh
+++ b/deploy/nexus/genome-raw-commit.sh
@@ -28,7 +28,8 @@ set -a; . "${HOME}/.config/knowledge-genome.env"; set +a
 vault="${GENOME_VAULTS_ROOT}/${genome}"
 fid="${genome}-public"
 authors_map="${GENOME_VAULTS_ROOT}/.authors.json"
-clone_url="http://${FORGEJO_USER}@${FORGEJO_HOST}/${FORGEJO_OWNER}/${genome}.git"
+# GENOME_PUSH_URL is a test seam: defaults to the Forgejo loopback URL in production.
+clone_url="${GENOME_PUSH_URL:-http://${FORGEJO_USER}@${FORGEJO_HOST}/${FORGEJO_OWNER}/${genome}.git}"
 export GIT_ASKPASS=/usr/local/bin/genome-askpass
 
 [[ -d "${vault}/.git" ]] || { printf '{"status":"error","reason":"vault absent","genome":"%s"}\n' "$genome"; exit 1; }