fix(config): keep anonymous custom endpoints in picker when /v1/models probe fails

When an anonymous custom endpoint (bare base_url, not a named custom_providers[] entry) fails its /v1/models probe, the provider group was silently dropped from the model picker entirely. This made the endpoint unusable even when /v1/chat/completions would work fine.

The fix adds an elif branch: if pid == 'custom', a cfg_base_url is configured, but no models were returned by the probe, the group is still added with an empty model list. Users can then select the Custom group and type a model ID manually in the picker's free-form input.

Closes #2542.

api/config.py

@@ -3807,6 +3807,18 @@ def get_available_models() -> dict:
                                 "models": models_for_group,
                             }
                         )
+                    elif pid == "custom" and cfg_base_url:
+                        # Anonymous custom endpoint: /v1/models probe may have
+                        # failed (e.g. llama-server, lightweight relay), but the
+                        # chat endpoint itself may still work.  Add the group
+                        # with an empty model list so the user can type a model
+                        # ID manually rather than being blocked by a silent
+                        # probe failure (#2542).
+                        groups.append({
+                            "provider": provider_name,
+                            "provider_id": pid,
+                            "models": [],
+                        })
         else:
             if default_model:
                 label = _get_label_for_model(default_model, groups)

tests/test_issue2542_anonymous_custom_endpoint.py

@@ -0,0 +1,33 @@
+"""Tests for anonymous custom endpoint fallback in get_available_models().
+
+Verifies that when /v1/models probe fails for an anonymous custom endpoint
+(configured via bare base_url, not custom_providers[]), the provider group
+is still added to the picker with an empty model list so the user can type
+a model ID manually (#2542).
+"""
+
+import re
+
+REPO = __file__.rsplit("/", 2)[-3] if "/" in __file__ else "."
+CONFIG_PY = open(f"{REPO}/api/config.py").read() if REPO != "." else ""
+
+
+def test_custom_anonymous_endpoint_empty_models_fallback_in_get_available_models():
+    """get_available_models() must add a 'custom' provider group with empty
+    models when cfg_base_url is set but the /v1/models probe returned nothing
+    (anonymous endpoint — no match in custom_providers[])."""
+    assert 'elif pid == "custom" and cfg_base_url:' in CONFIG_PY, (
+        "Anonymous custom endpoints with failed /v1/models probe must get "
+        "an empty-model fallback group instead of being silently dropped (#2542)"
+    )
+    # Verify the empty models dict is correct
+    assert '"models": []' in CONFIG_PY.split('elif pid == "custom" and cfg_base_url:')[1].split("groups.append")[1][:200], (
+        "The fallback group must have an empty models list"
+    )
+
+
+def test_revert_custom_endpoint_fallback_comment():
+    """The #2542 comment should reference the issue."""
+    assert "#2542" in CONFIG_PY, (
+        "The fallback should reference the issue number for traceability"
+    )