diff --git a/supabase/functions/ai-generate-plan/index.ts b/supabase/functions/ai-generate-plan/index.ts
index 1db2eef..f370b75 100644
--- a/supabase/functions/ai-generate-plan/index.ts
+++ b/supabase/functions/ai-generate-plan/index.ts
@@ -118,6 +118,10 @@ Deno.serve(async (req: Request): Promise<Response> => {
       SERVICE_ROLE_KEY,
     );
 
+    // Model name controlled via env var (single use)
+    const AI_GENERATE_PLAN_MODELO = Deno.env.get("AI_GENERATE_PLAN_MODELO") ??
+      "gpt-5-nano";
+
     const formData = await req.formData();
     const validation = parseAndValidate(formData);
     if (!validation.success) {
@@ -185,7 +189,7 @@ Deno.serve(async (req: Request): Promise<Response> => {
         : {};
 
     const aiStructuredPayload: StructuredResponseOptions = {
-      model: "gpt-5-nano",
+      model: AI_GENERATE_PLAN_MODELO,
       input: [
         { role: "system", content: systemPrompt },
         { role: "user", content: userPrompt },
diff --git a/supabase/functions/ai-generate-subject/index.ts b/supabase/functions/ai-generate-subject/index.ts
index 972ca2c..45457b0 100644
--- a/supabase/functions/ai-generate-subject/index.ts
+++ b/supabase/functions/ai-generate-subject/index.ts
@@ -170,6 +170,14 @@ Deno.serve(async (req: Request): Promise<Response> => {
       SERVICE_ROLE_KEY,
     );
 
+    // Model names (override via environment variables)
+    const AI_GENERATE_SUBJECT_UPDATE_MODELO = Deno.env.get(
+      "AI_GENERATE_SUBJECT_UPDATE_MODELO",
+    ) ?? "gpt-5-nano";
+    const AI_GENERATE_SUBJECT_INSERT_MODELO = Deno.env.get(
+      "AI_GENERATE_SUBJECT_INSERT_MODELO",
+    ) ?? "gpt-5-nano";
+
     // -----------------------------
     // JSON update flow
     // -----------------------------
@@ -307,7 +315,7 @@ Deno.serve(async (req: Request): Promise<Response> => {
           : {};
 
       const aiStructuredPayload: StructuredResponseOptions = {
-        model: "gpt-5-nano",
+        model: AI_GENERATE_SUBJECT_UPDATE_MODELO,
         input: [
           { role: "system", content: systemPrompt },
           { role: "user", content: userPrompt },
@@ -540,7 +548,7 @@ Deno.serve(async (req: Request): Promise<Response> => {
         : {};
 
     const aiStructuredPayload: StructuredResponseOptions = {
-      model: "gpt-5-nano",
+      model: AI_GENERATE_SUBJECT_INSERT_MODELO,
       input: [
         { role: "system", content: systemPrompt },
         { role: "user", content: userPrompt },
diff --git a/supabase/functions/create-chat-conversation/index.ts b/supabase/functions/create-chat-conversation/index.ts
index cbb3572..f06bc58 100644
--- a/supabase/functions/create-chat-conversation/index.ts
+++ b/supabase/functions/create-chat-conversation/index.ts
@@ -29,6 +29,13 @@ app.options(
 );
 
 const prefix = "/create-chat-conversation";
+// Model names (module-level) — pueden ser sobrescritos por variables de entorno
+const CREATE_CHAT_CONVERSATION_NONSTRUCTURED_MODELO = Deno.env.get(
+  "CREATE_CHAT_CONVERSATION_NONSTRUCTURED_MODELO",
+) ?? "gpt-5-nano";
+const CREATE_CHAT_CONVERSATION_STRUCTURED_MODELO = Deno.env.get(
+  "CREATE_CHAT_CONVERSATION_STRUCTURED_MODELO",
+) ?? "gpt-5-nano";
 
 app.get(`${prefix}/health`, (c) => withCors(jsonResponse({ ok: true })));
 
@@ -241,7 +248,7 @@ app.post(`${prefix}/conversations/:id/messages`, async (c) => {
     if (!wantsStructured) {
       await openai.responses.create({
         conversation: row.openai_conversation_id,
-        model: "gpt-5-nano",
+        model: CREATE_CHAT_CONVERSATION_NONSTRUCTURED_MODELO,
         input: [
           {
             role: "system",
@@ -284,7 +291,7 @@ app.post(`${prefix}/conversations/:id/messages`, async (c) => {
     const schema = pickSchemaFields(definicion, body.campos);
     const planForPrompt = safePlanForPrompt(plan);
 
-    const model = "gpt-5-nano";
+    const model = CREATE_CHAT_CONVERSATION_STRUCTURED_MODELO;
     const prompt = body.user_prompt ?? body.content;
 
     const resp = await openai.responses.create({
diff --git a/supabase/functions/generate-subject-suggestions/index.ts b/supabase/functions/generate-subject-suggestions/index.ts
index 027ab06..a6f1eb5 100644
--- a/supabase/functions/generate-subject-suggestions/index.ts
+++ b/supabase/functions/generate-subject-suggestions/index.ts
@@ -160,6 +160,11 @@ Deno.serve(async (req: Request): Promise<Response> => {
       SERVICE_ROLE_KEY,
     );
 
+    // Model name controlled via env var
+    const GENERATE_SUBJECT_SUGGESTIONS_MODELO = Deno.env.get(
+      "GENERATE_SUBJECT_SUGGESTIONS_MODELO",
+    ) ?? "gpt-5-mini";
+
     const { data: plan, error: planError } = await supabaseService
       .from("planes_estudio")
       .select("id,nombre,nivel,tipo_ciclo,numero_ciclos,datos")
@@ -276,7 +281,7 @@ Deno.serve(async (req: Request): Promise<Response> => {
     }
 
     const options: StructuredResponseOptions = {
-      model: "gpt-5-mini",
+      model: GENERATE_SUBJECT_SUGGESTIONS_MODELO,
       input: [
         { role: "system", content: systemPrompt },
         {