feat: accept xhigh effort for Anthropic (#24439)

coderd/x/chatd/chatprovider/chatprovider.go

@@ -663,6 +663,7 @@ func ReasoningEffortFromChat(provider string, value *string) *string {
 			string(fantasyanthropic.EffortLow),
 			string(fantasyanthropic.EffortMedium),
 			string(fantasyanthropic.EffortHigh),
+			string(fantasyanthropic.EffortXHigh),
 			string(fantasyanthropic.EffortMax),
 		)
 	case fantasyopenrouter.Name:

coderd/x/chatd/chatprovider/chatprovider_test.go

@@ -208,6 +208,12 @@ func TestReasoningEffortFromChat(t *testing.T) {
 			input:    ptr.Ref("max"),
 			want:     ptr.Ref(string(fantasyanthropic.EffortMax)),
 		},
+		{
+			name:     "AnthropicXHighEffort",
+			provider: "anthropic",
+			input:    ptr.Ref("xhigh"),
+			want:     ptr.Ref(string(fantasyanthropic.EffortXHigh)),
+		},
 		{
 			name:     "OpenRouterEffort",
 			provider: "openrouter",