test: keep webui CI hermetic offline

webui/queue_loader.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import os
 import re
 from dataclasses import dataclass
 from datetime import datetime, timezone
@@ -268,9 +269,23 @@ def load_queue_snapshot(
         )
 
     host = _host_from_url(project.remote_host)
-    pr_fetch = fetch_prs or _fetch_prs
-    issue_fetch = fetch_issues or _fetch_issues
-    using_live_fetch = fetch_prs is None or fetch_issues is None
+    offline_test = (os.environ.get("WEBUI_TEST_OFFLINE") or "").strip() in {
+        "1",
+        "true",
+        "yes",
+    }
+
+    def _empty_fetch(*_args, **_kwargs):
+        return [], _pagination_from_pages(
+            per_page=50,
+            pages_fetched=1,
+            returned_count=0,
+            is_final_page=True,
+        )
+
+    pr_fetch = fetch_prs or (_empty_fetch if offline_test else _fetch_prs)
+    issue_fetch = fetch_issues or (_empty_fetch if offline_test else _fetch_issues)
+    using_live_fetch = not offline_test and (fetch_prs is None or fetch_issues is None)
     auth = get_auth_header(host) if using_live_fetch else "test-auth"
     if using_live_fetch and not auth:
         return QueueSnapshot(
@@ -382,4 +397,4 @@ def snapshot_to_dict(snapshot: QueueSnapshot) -> dict[str, Any]:
             "prs": _page(snapshot.pr_pagination),
             "issues": _page(snapshot.issue_pagination),
         },
-    }
+    }