diff --git a/test/models/chat_test.rb b/test/models/chat_test.rb
index 7da1c78e5..accf5e0cb 100644
--- a/test/models/chat_test.rb
+++ b/test/models/chat_test.rb
@@ -47,7 +47,7 @@ class ChatTest < ActiveSupport::TestCase
       chat = @user.chats.start!(prompt, model: nil)
 
       assert_equal 2, chat.messages.count
-      assert_equal Provider::Openai::DEFAULT_MODEL, chat.messages.find_by!(type: "UserMessage").ai_model
+      assert_equal Chat.default_model, chat.messages.find_by!(type: "UserMessage").ai_model
     end
   end
 
@@ -58,31 +58,35 @@ class ChatTest < ActiveSupport::TestCase
       chat = @user.chats.start!(prompt, model: "")
 
       assert_equal 2, chat.messages.count
-      assert_equal Provider::Openai::DEFAULT_MODEL, chat.messages.find_by!(type: "UserMessage").ai_model
+      assert_equal Chat.default_model, chat.messages.find_by!(type: "UserMessage").ai_model
     end
   end
 
-  test "default_model returns claude when LLM_PROVIDER=anthropic and Anthropic is configured" do
+  # These three tests assert routing (which provider's effective_model wins),
+  # not the constant value itself — the assertion side reads through
+  # Provider::*.effective_model so ENV overrides like ANTHROPIC_MODEL /
+  # OPENAI_MODEL don't make the tests flake.
+  test "default_model returns Anthropic's effective_model when LLM_PROVIDER=anthropic and Anthropic is configured" do
     Provider::Anthropic.stubs(:configured?).returns(true)
     Setting.stubs(:llm_provider).returns("anthropic")
 
-    assert_equal Provider::Anthropic::DEFAULT_MODEL, Chat.default_model
+    assert_equal Provider::Anthropic.effective_model, Chat.default_model
   end
 
-  test "default_model falls back to OpenAI when Anthropic is preferred but unconfigured" do
+  test "default_model falls back to OpenAI's effective_model when Anthropic is preferred but unconfigured" do
     Provider::Anthropic.stubs(:configured?).returns(false)
     Provider::Openai.stubs(:configured?).returns(true)
     Setting.stubs(:llm_provider).returns("anthropic")
 
-    assert_equal Provider::Openai::DEFAULT_MODEL, Chat.default_model
+    assert_equal Provider::Openai.effective_model, Chat.default_model
   end
 
-  test "default_model uses Anthropic when OpenAI is unconfigured" do
+  test "default_model uses Anthropic's effective_model when OpenAI is unconfigured" do
     Provider::Anthropic.stubs(:configured?).returns(true)
     Provider::Openai.stubs(:configured?).returns(false)
     Setting.stubs(:llm_provider).returns("openai")
 
-    assert_equal Provider::Anthropic::DEFAULT_MODEL, Chat.default_model
+    assert_equal Provider::Anthropic.effective_model, Chat.default_model
   end
 
   test "creates with configured model when OPENAI_MODEL env is set" do