harden state durability and disable destructive snapshot sync

src/config.js

@@ -49,6 +49,7 @@ function boolFromEnv(name, fallback) {
 }
 
 const parsed = {
+  nodeEnv: strFromEnv("NODE_ENV", "development"),
   port: intFromEnv("PORT", 3000),
   logLevel: strFromEnv("LOG_LEVEL", "info"),
   appBaseUrl: strFromEnv("APP_BASE_URL", "http://localhost:3000"),
@@ -100,7 +101,13 @@ const parsed = {
   },
 };
 
+parsed.allowInMemoryStateFallback = boolFromEnv(
+  "ALLOW_IN_MEMORY_STATE_FALLBACK",
+  parsed.nodeEnv !== "production",
+);
+
 const ConfigSchema = z.object({
+  nodeEnv: z.string().min(1),
   port: z.number().int().positive(),
   logLevel: z.enum(["fatal", "error", "warn", "info", "debug", "trace", "silent"]),
   appBaseUrl: z.string().min(1),
@@ -150,6 +157,7 @@ const ConfigSchema = z.object({
     stepCredits: z.number().int().positive(),
     maxCharsPerArticle: z.number().int().positive(),
   }),
+  allowInMemoryStateFallback: z.boolean(),
 });
 
 const config = ConfigSchema.parse(parsed);