Add live stage-code golden tests

test/golden/README.md

@@ -0,0 +1,32 @@
+# Stage-code golden tests
+
+These tests call the running FastAPI service and its configured FastGPT
+workflow. Each conversation step asserts only the `nextStageCode` carried by
+the SSE `stage_code` event.
+
+Edit `cases.json` to add or update conversation cases:
+
+```json
+{
+  "name": "example",
+  "clientMode": "browser_addon",
+  "steps": [
+    {
+      "text": "继续",
+      "expect": {
+        "stageCode": "browser_addon.1002"
+      }
+    }
+  ]
+}
+```
+
+Start the API, then run:
+
+```bash
+RUN_GOLDEN=1 \
+GOLDEN_BASE_URL=http://127.0.0.1:8000 \
+pytest -m golden_live test/golden -v
+```
+
+Without `RUN_GOLDEN=1`, the cases are skipped and do not make network calls.