feat: add deployable alpha silo

hub/src/deployment/siloRateLimit.ts

@@ -0,0 +1,25 @@
+export class SiloFixedWindowRateLimiter {
+  private windowStartedAt: number;
+  private used = 0;
+
+  constructor(readonly limit: number, readonly windowMs: number, now = Date.now()) {
+    if (!Number.isSafeInteger(limit) || limit <= 0) throw new Error("rate limit must be a positive integer");
+    if (!Number.isSafeInteger(windowMs) || windowMs <= 0) throw new Error("rate window must be a positive integer");
+    this.windowStartedAt = now;
+  }
+
+  consume(now = Date.now()): { readonly allowed: true } | { readonly allowed: false; readonly retryAfterSeconds: number } {
+    if (now >= this.windowStartedAt + this.windowMs) {
+      this.windowStartedAt = now;
+      this.used = 0;
+    }
+    if (this.used >= this.limit) {
+      return {
+        allowed: false,
+        retryAfterSeconds: Math.max(1, Math.ceil((this.windowStartedAt + this.windowMs - now) / 1000)),
+      };
+    }
+    this.used += 1;
+    return { allowed: true };
+  }
+}