test(observability): validate sidebar route coverage

scripts/check_observability_ui.py

@@ -246,6 +246,15 @@ def scan_nav_contract() -> list[str]:
         if active_page not in base_text:
             findings.append(f"{BASE_PATH}: momo-observability-mode list missing `{active_page}`")
 
+        route_suffix = url.replace("/observability", "", 1) or "/"
+        route_pattern = re.compile(
+            r"@admin_observability_bp\.route\(\s*['\"]"
+            + re.escape(route_suffix)
+            + r"['\"]"
+        )
+        if route_text and not route_pattern.search(route_text):
+            findings.append(f"{ROUTE_PATH}: missing route `{route_suffix}` for `{label}`")
+
     sidebar_observability_links = set(re.findall(r'href="(/observability/[^"]+)"', shell_text))
     expected_links = {url for _, _, url, _ in OBSERVABILITY_NAV_ITEMS}
     extra_links = sorted(sidebar_observability_links - expected_links)