diff --git a/lib/formula-session.sh b/lib/formula-session.sh
index fb6b9ea..0318b7b 100644
--- a/lib/formula-session.sh
+++ b/lib/formula-session.sh
@@ -414,8 +414,14 @@ build_graph_section() {
        --project-root "$PROJECT_REPO_ROOT" \
        --output "$report" 2>>"$LOG_FILE"; then
     # shellcheck disable=SC2034
-    GRAPH_SECTION=$(printf '\n## Structural analysis\n```json\n%s\n```\n' \
-      "$(cat "$report")")
+    local report_content
+    report_content="$(cat "$report")"
+    # shellcheck disable=SC2034
+    GRAPH_SECTION="
+## Structural analysis
+\`\`\`json
+${report_content}
+\`\`\`"
     log "graph report generated: $(jq -r '.stats | "\(.nodes) nodes, \(.edges) edges"' "$report")"
   else
     log "WARN: build-graph.py failed — continuing without structural analysis"