Don't try and keep _lines private

README.md

@@ -56,7 +56,7 @@ Completions populate the cell with a custom data type which includes the complet
 
 To obtain the text value for use in formulas, use the `VALUETOTEXT()` function. To obtain other request/response data, use dot notation to the property path (e.g. `A123.response.model`).
 
-To view the completion data, open the entity card. The `_lines` property provides a line-by-line view of the completion content.
+To view the completion data, open the entity card. The `lines` property provides a line-by-line view of the completion content.
 
 To extract a final answer that follows a chain of thought, you could use a formula such as:
 

src/functions/functions.mjs

@@ -73,7 +73,7 @@ export async function chatComplete(messages, params, invocation) {
         _entityKind: COMPLETION_ENTITY_KIND,
 
         // For visibility of newlines without needing to use cell text wrap.
-        _lines:
+        lines:
           json.choices.length === 1
             ? json.choices[0].message.content.split('\n')
             : json.choices.map((choice) => choice.message.content.split('\n')),

testFramework/completionEntityStub.mjs

@@ -15,7 +15,7 @@ export function makeCompletionEntity({
         basicType: 'String',
         basicValue: 'openai-excel-functions:chat-completion',
       },
-      _lines: undefined, // Not for programmatic use
+      lines: (content ?? '').split('\n'),
       requestBody: {
         type: 'Entity',
         basicType: 'Error',