diff --git a/src/env.mjs b/src/env.mjs
index f8346d4..a967441 100644
--- a/src/env.mjs
+++ b/src/env.mjs
@@ -12,6 +12,8 @@ export const env = createEnv({
     AI_MODEL: z.string().min(1).optional(),
     // Rate limit driver: "memory" (default, single-instance) or "redis" (distributed).
     RATE_LIMIT_DRIVER: z.enum(["memory", "redis"]).default("memory"),
+    // Cache driver: "memory" (default, single-instance LRU) or "redis" (distributed).
+    CACHE_DRIVER: z.enum(["memory", "redis"]).default("memory"),
     // Upstash Redis REST credentials (only required when RATE_LIMIT_DRIVER=redis).
     UPSTASH_REDIS_REST_URL: z.string().url().optional(),
     UPSTASH_REDIS_REST_TOKEN: z.string().min(1).optional(),
@@ -31,6 +33,7 @@ export const env = createEnv({
     AI_BASE_URL: process.env.AI_BASE_URL,
     AI_MODEL: process.env.AI_MODEL,
     RATE_LIMIT_DRIVER: process.env.RATE_LIMIT_DRIVER,
+    CACHE_DRIVER: process.env.CACHE_DRIVER,
     UPSTASH_REDIS_REST_URL: process.env.UPSTASH_REDIS_REST_URL,
     UPSTASH_REDIS_REST_TOKEN: process.env.UPSTASH_REDIS_REST_TOKEN,
     CRON_SECRET: process.env.CRON_SECRET,