frontend/llm: respect AI student project limit in AI formula generato…

…r; throw proper error when querying client/llm without an enabled LLM for a specific tag

src/packages/frontend/client/llm.ts

@@ -82,10 +82,13 @@ export class LLMClient {
     system ??= getSystemPrompt(model, path);
 
     if (!redux.getStore("projects").hasLanguageModelEnabled(project_id, tag)) {
-      return `Language model support is not currently enabled ${
-        project_id ? "in this project" : "on this server"
-      }.`;
+      throw new Error(
+        `Language model support is not currently enabled ${
+          project_id ? "in this project" : "on this server"
+        }. [tag=${tag}]`,
+      );
     }
+
     input = input.trim();
     if (chatStream == null) {
       if (!input || input == "test") {

src/packages/frontend/codemirror/extensions/ai-formula.tsx

@@ -20,6 +20,8 @@ import { unreachable } from "@cocalc/util/misc";
 
 type Mode = "tex" | "md";
 
+const LLM_USAGE_TAG = `generate-formula`;
+
 interface Opts {
   mode: Mode;
   text?: string;
@@ -50,7 +52,7 @@ function AiGenFormula({ mode, text = "", project_id, cb }: Props) {
 
   const enabled = redux
     .getStore("projects")
-    .hasLanguageModelEnabled(project_id);
+    .hasLanguageModelEnabled(project_id, LLM_USAGE_TAG);
 
   function getPrompt() {
     const description = input || text;
@@ -132,12 +134,17 @@ function AiGenFormula({ mode, text = "", project_id, cb }: Props) {
       setGenerating(true);
       setFormula("");
       setFullReply("");
-      const tag = `generate-formula`;
-      track("chatgpt", { project_id, tag, mode, type: "generate", model });
+      track("chatgpt", {
+        project_id,
+        tag: LLM_USAGE_TAG,
+        mode,
+        type: "generate",
+        model,
+      });
       const reply = await webapp_client.openai_client.query({
         input: getPrompt(),
         project_id,
-        tag,
+        tag: LLM_USAGE_TAG,
         model,
         system: "",
       });