Fix ExplainerHub add_dashboard_route after first request

RELEASE_NOTES.md

@@ -7,6 +7,7 @@
 - Allow FeatureInputComponent (what-if inputs) to customize numeric ranges and rounding, and apply min/max/step to inputs.
 - Improve compatibility with AutoGluon/custom wrappers by coercing pandas `DataFrame` outputs from `predict_proba`/`predict` to numpy arrays before indexing in classifier/regression helper paths.
 - Harden one-vs-all scorer handling so `make_one_vs_all_scorer` also accepts classifiers whose `predict_proba` returns a pandas `DataFrame`.
+- Fix ExplainerHub `add_dashboard_route` after first request by allowing dynamic dashboard registration/setup during route-triggered add, and add a regression test for issue #269.
 
 ## Version 0.5.6:
 

TODO.md

@@ -1,15 +1,14 @@
 # TODO
 
 **Meta**
-- Last triage: 2026-02-05
+- Last triage: 2026-02-06
 - Owner: @oegedijk
 - Rules: link an issue when possible; include size S/M/L; mark blockers.
 
 **Now**
 - [M][Explainers][#273] categorical columns with NaNs: sorting and column preservation.
 
 **Next**
-- [M][Hub][#269] add_dashboard endpoint fails after first request (Flask blueprint lifecycle).
 - [M/L][Components][#262] add filters for random transaction selection in whatif tab.
 - [S][Methods][#220] get_contrib_df accepts list/array input.
 - [M][Components][#176] FeatureInputComponent hide parameters.

explainerdashboard/dashboards.py

@@ -18,6 +18,7 @@
 import inspect
 import requests
 import logging
+from contextlib import contextmanager
 from typing import Dict, List, Optional, Union
 from pathlib import Path
 from copy import deepcopy
@@ -1715,6 +1716,18 @@ def remove_dashboard(self, dashboard_name):
             if self.users and not self.dbs_open_by_default:
                 self._protect_dashviews(self.index_page)
 
+    @contextmanager
+    def _allow_dynamic_setup_after_first_request(self):
+        """Temporarily bypass Flask setup lock for dynamic add_dashboard_route updates."""
+        original = getattr(self.app, "_got_first_request", None)
+        if original:
+            self.app._got_first_request = False
+        try:
+            yield
+        finally:
+            if original is not None:
+                self.app._got_first_request = original
+
     def add_dashboard(self, dashboard: ExplainerDashboard, **kwargs):
         """Add a dashboard to the hub
 
@@ -1777,11 +1790,14 @@ def add_dashboard(self, dashboard: ExplainerDashboard, **kwargs):
         config = deepcopy(dashboard.to_yaml(return_dict=True))
         config["dashboard"]["params"]["logins"] = None
 
-        self.dashboards.append(
-            ExplainerDashboard.from_config(
-                dashboard.explainer, config, **update_kwargs(kwargs, **update_params)
+        with self._allow_dynamic_setup_after_first_request():
+            self.dashboards.append(
+                ExplainerDashboard.from_config(
+                    dashboard.explainer,
+                    config,
+                    **update_kwargs(kwargs, **update_params),
+                )
             )
-        )
 
         self.dashboard_names.append(dashboard.name)
 
@@ -1804,14 +1820,15 @@ def inner():
                 inner.__name__ = "return_dashboard_" + dashboard.name
                 return inner
 
-        if self.users:
-            self.app.route(f"/{self.base_route}/_{dashboard.name}")(
-                login_required(dashboard_route(dashboard))
-            )
-        else:
-            self.app.route(f"/{self.base_route}/_{dashboard.name}")(
-                dashboard_route(dashboard)
-            )
+        with self._allow_dynamic_setup_after_first_request():
+            if self.users:
+                self.app.route(f"/{self.base_route}/_{dashboard.name}")(
+                    login_required(dashboard_route(dashboard))
+                )
+            else:
+                self.app.route(f"/{self.base_route}/_{dashboard.name}")(
+                    dashboard_route(dashboard)
+                )
         return dashboard.name
 
     @classmethod

tests/hub/test_hub.py

@@ -1,4 +1,6 @@
-from explainerdashboard import ExplainerHub
+from pathlib import Path
+
+from explainerdashboard import ExplainerDashboard, ExplainerHub
 
 
 def test_hub_users(explainer_hub):
@@ -36,3 +38,34 @@ def test_hub_to_zip(explainer_hub, tmp_path_factory):
     tmp_path = tmp_path_factory.mktemp("tmp_hub")
     explainer_hub.to_zip(tmp_path / "hub.zip")
     assert (tmp_path / "hub.zip").exists()
+
+
+def test_add_dashboard_route_after_first_request_adds_dashboard(
+    precalculated_rf_classifier_explainer,
+    precalculated_rf_regression_explainer,
+    tmp_path,
+):
+    db1 = ExplainerDashboard(precalculated_rf_classifier_explainer, name="db1")
+    db2 = ExplainerDashboard(precalculated_rf_regression_explainer, name="db2")
+
+    explainer_path = tmp_path / "db2.joblib"
+    db2_yaml = tmp_path / "db2.yaml"
+    db2.explainer.dump(explainer_path)
+    db2.to_yaml(db2_yaml, explainerfile=str(explainer_path))
+
+    hub = ExplainerHub(
+        [db1],
+        users_file=str(Path.cwd() / "tests" / "test_assets" / "users.yaml"),
+        add_dashboard_route=True,
+        add_dashboard_pattern=str(tmp_path / "{}.yaml"),
+    )
+    hub.app.config["TESTING"] = True
+    client = hub.app.test_client()
+
+    # Simulate the app already serving requests before dynamic add.
+    response = client.get("/")
+    assert response.status_code in (200, 302)
+
+    response = client.get("/add_dashboard/db2")
+    assert response.status_code == 302
+    assert "db2" in hub.dashboard_names