Remove model name validation

Replace mustBeModel (mustBeMember against hardcoded list) with
mustBeTextScalar so unknown model names are accepted while non-text
inputs like numerics are still rejected.

Note that we still keep the model list for tab completion and still validate
we can actively use all the models in the list on OpenAI. But this change
allows the use of other model names, whether new ones at OpenAI or on other
servers, in conjunction with BaseURL.

Author: ccreutzi

openAIChat.m

@@ -93,15 +93,15 @@
 
     properties
         %ModelName   Model name.
-        ModelName (1,1) string {mustBeModel} = "gpt-4o-mini"
+        ModelName = "gpt-4o-mini"
 
         %Verbosity   Verbosity level for the model output.
         Verbosity (1,1) string {mustBeVerbosity} = "auto"
 
         %ReasoningEffort   Reasoning effort level for reasoning models.
         ReasoningEffort (1,1) string {mustBeReasoningEffort} = "auto"
 
-        %BaseURL  Service baser URL.
+        %BaseURL  Service base URL.
         BaseURL (1,1) string = "https://api.openai.com/v1"
     end
 
@@ -115,7 +115,7 @@
             arguments
                 systemPrompt                       {llms.utils.mustBeTextOrEmpty} = []
                 nvp.Tools                    (1,:) {mustBeA(nvp.Tools, "openAIFunction")} = openAIFunction.empty
-                nvp.ModelName                (1,1) string {mustBeModel} = "gpt-4o-mini"
+                nvp.ModelName                      {mustBeTextScalar} = "gpt-4o-mini"
                 nvp.Temperature                    {llms.utils.mustBeValidTemperature} = 1
                 nvp.TopP                           {llms.utils.mustBeValidProbability} = 1
                 nvp.StopSequences                  {llms.utils.mustBeValidStop} = {}
@@ -239,7 +239,7 @@
             arguments
                 this                    (1,1) openAIChat
                 messages                      {mustBeValidMsgs}
-                nvp.ModelName           (1,1) string {mustBeModel} = this.ModelName
+                nvp.ModelName                 {mustBeTextScalar} = this.ModelName
                 nvp.Temperature               {llms.utils.mustBeValidTemperature} = this.Temperature
                 nvp.TopP                      {llms.utils.mustBeValidProbability} = this.TopP
                 nvp.StopSequences             {llms.utils.mustBeValidStop} = this.StopSequences
@@ -309,6 +309,11 @@
                 text = llms.internal.reformatOutput(text,nvp.ResponseFormat);
             end
         end
+
+        function this = set.ModelName(this, model)
+            mustBeTextScalar(model);
+            this.ModelName = string(model);
+        end
     end
 
     methods(Access=protected)
@@ -404,10 +409,6 @@ function mustBeIntegerOrEmpty(value)
     end
 end
 
-function mustBeModel(model)
-    mustBeMember(model,llms.openai.models);
-end
-
 function mustBeVerbosity(value)
     mustBeMember(value,llms.openai.verbosityValues);
 end

tests/topenAIChat.m

@@ -134,17 +134,17 @@ function jsonFormatWithSystemPrompt(testCase)
     "InvalidModelNameType", struct( ...
         "Property", "ModelName", ...
         "Value", table(1), ...
-        "Error", "MATLAB:validation:UnableToConvert"), ...
+        "Error", "MATLAB:validators:mustBeTextScalar"), ...
     ...
-    "InvalidModelNameSize", struct( ...
+    "InvalidModelNameNumeric", struct( ...
         "Property", "ModelName", ...
-        "Value", ["gpt-5-mini","gpt-5"], ...
-        "Error", "MATLAB:validation:IncompatibleSize"), ...
+        "Value", 0, ...
+        "Error", "MATLAB:validators:mustBeTextScalar"), ...
     ...
-    "InvalidModelNameValue", struct( ...
+    "InvalidModelNameSize", struct( ...
         "Property", "ModelName", ...
-        "Value", "llama-3.2", ...
-        "Error", "MATLAB:validators:mustBeMember"), ...
+        "Value", ["gpt-5-mini","gpt-5"], ...
+        "Error", "MATLAB:validators:mustBeTextScalar"), ...
     ...
     "InvalidTemperatureType", struct( ...
         "Property", "Temperature", ...
@@ -297,6 +297,22 @@ function jsonFormatWithSystemPrompt(testCase)
                 "ResponseFormat", {"text"} ...
             ) ...
         ), ...
+    "ModelNameAsCharVector", struct( ...
+        "Input",{{"APIKey","this-is-not-a-real-key","ModelName",'gpt-4o'}}, ...
+        "ExpectedWarning", '', ...
+        "VerifyProperties", struct( ...
+                "Temperature", {1}, ...
+                "TopP", {1}, ...
+                "StopSequences", {string([])}, ...
+                "PresencePenalty", {0}, ...
+                "FrequencyPenalty", {0}, ...
+                "TimeOut", {10}, ...
+                "FunctionNames", {[]}, ...
+                "ModelName", {"gpt-4o"}, ...
+                "SystemPrompt", {[]}, ...
+                "ResponseFormat", {"text"} ...
+            ) ...
+        ), ...
     "SystemPrompt", struct( ...
         "Input",{{"system prompt","APIKey","this-is-not-a-real-key"}}, ...
         "ExpectedWarning", '', ...
@@ -544,15 +560,11 @@ function jsonFormatWithSystemPrompt(testCase)
     ...
     "InvalidModelNameType",struct( ...
         "Input",{{ "ModelName", 0 }},...
-        "Error","MATLAB:validators:mustBeMember"),...
+        "Error","MATLAB:validators:mustBeTextScalar"),...
     ...
     "InvalidModelNameSize",struct( ...
         "Input",{{ "ModelName", ["gpt-4o-mini",  "gpt-4o-mini"] }},...
-        "Error","MATLAB:validation:IncompatibleSize"),...
-    ...
-    "InvalidModelNameOption",struct( ...
-        "Input",{{ "ModelName", "gpt" }},...
-        "Error","MATLAB:validators:mustBeMember"),...
+        "Error","MATLAB:validators:mustBeTextScalar"),...
     ...
     "InvalidTemperatureType",struct( ...
         "Input",{{ "Temperature" "2" }},...