fix: address review feedback — remove redundant clause, add guard and tests

- Remove the redundant 4th OR clause from _catalog_has_provider() — the
  existing C1–C3 already handle compound provider IDs correctly (C2 IS
  a normalized-vs-raw comparison; the 4th clause was a strict subset).
- Add && _activeProvider guard to _isCrossProviderPick in messages.js
  to prevent spurious True when the profile has no configured default
  provider (reviewer's optional hardening suggestion).
- Add test_catalog_has_provider_compound_ids.py verifying that compound
  provider IDs like 'custom:glm-free-relay' are correctly recognized by
  the existing C1–C3 clauses.

api/routes.py

@@ -3196,18 +3196,7 @@ def _catalog_has_provider(
         provider_raw in raw_provider_ids
         or (provider_normalized and provider_normalized in raw_provider_ids)
         or (provider_normalized and provider_normalized in normalized_provider_ids)
-        # Compound provider IDs like "custom:zenmux-relay" normalize to
+
-        # "custom" which is a raw catalog provider_id.  The three checks
-        # above compare raw-vs-raw and normalized-vs-normalized but miss
-        # normalized-vs-raw for compound hints.  Without this, a
-        # @custom:relay-name:model selection is silently reverted to the
-        # profile default on every non-explicit turn because the catalog
-        # lookup fails and the fallback branch at line ~3932 fires.
-        or (
-            provider_normalized
-            and ":" in provider_raw
-            and provider_normalized in raw_provider_ids
-        )
     )
 
 

static/messages.js

@@ -1281,6 +1281,7 @@ async function send(){
     const _isCrossProviderPick = _modelState.model
       && _modelState.model_provider
       && _defaultModel
+      && _activeProvider
       && _modelState.model !== _defaultModel
       && String(_modelState.model_provider||'') !== String(_activeProvider||'');
     const _explicitPick = _pendingPickMatch || _isCrossProviderPick;

tests/test_catalog_has_provider_compound_ids.py

@@ -0,0 +1,66 @@
+"""Tests for _catalog_has_provider() with compound provider IDs.
+
+Compound provider IDs like "custom:zenmux-relay" or "custom:glm-free-relay"
+normalize to "custom" via _normalize_provider_id(). The existing three
+clauses in _catalog_has_provider() already handle these correctly:
+
+  C1: exact raw match  ("custom:zenmux-relay" ∈ raw_ids)
+  C2: normalized ∈ raw_ids  ("custom" ∈ raw_ids)
+  C3: normalized ∈ norm_ids ("custom" ∈ norm_ids)
+
+This test guards against regressions and verifies that no 4th clause is
+needed for compound IDs.
+"""
+from __future__ import annotations
+
+from api.routes import _catalog_has_provider
+
+
+def test_compound_provider_exact_raw_match():
+    """C1: exact raw match for a compound ID like 'custom:zenmux-relay'."""
+    assert _catalog_has_provider(
+        "custom:zenmux-relay",
+        "custom",
+        {"custom:zenmux-relay"},
+        {"custom"},
+    )
+
+
+def test_compound_provider_normalized_in_raw_ids():
+    """C2: normalized form 'custom' found in raw_provider_ids."""
+    assert _catalog_has_provider(
+        "custom:zenmux-relay",
+        "custom",
+        {"custom"},
+        {"custom"},
+    )
+
+
+def test_compound_provider_normalized_in_norm_ids():
+    """C3: normalized form 'custom' found in normalized_provider_ids."""
+    assert _catalog_has_provider(
+        "custom:zenmux-relay",
+        "custom",
+        {"other"},
+        {"custom"},
+    )
+
+
+def test_compound_provider_not_found():
+    """Returns False when neither raw nor normalized form is in the catalog."""
+    assert not _catalog_has_provider(
+        "custom:unknown-relay",
+        "custom",
+        {"openrouter", "nous"},
+        {"openrouter", "nous"},
+    )
+
+
+def test_compound_provider_glm_free_relay():
+    """Real-world case: custom:glm-free-relay providing z-ai/glm-5.2-free."""
+    assert _catalog_has_provider(
+        "custom:glm-free-relay",
+        "custom",
+        {"custom:glm-free-relay"},
+        {"custom"},
+    )