fix: back off after Reddit access denials

src/reddit/api.ts

@@ -17,6 +17,13 @@ export class RedditRateLimitError extends Error {
   }
 }
 
+export class RedditAccessDeniedError extends Error {
+  constructor(public readonly subreddit: string) {
+    super(`Reddit denied listing access for r/${subreddit} (HTTP 403)`);
+    this.name = 'RedditAccessDeniedError';
+  }
+}
+
 function getRateLimitDelayMs(headers: unknown): number {
   if (!headers || typeof headers !== 'object') return 60_000;
 
@@ -108,6 +115,7 @@ export function findSellerDomain(text: string, domains: string[]): string | null
 export class RedditApiClient {
   private client: AxiosInstance;
   private browserContext: BrowserContext | null = null;
+  private consecutiveListing403s = 0;
 
   constructor(
     config: Config,
@@ -185,6 +193,7 @@ export class RedditApiClient {
         .filter((post: RedditPost) => this.isValidPost(post, type));
 
       this.logger.debug(`Fetched ${posts.length} valid ${type} posts from r/${subreddit}`);
+      this.consecutiveListing403s = 0;
       return posts;
     } catch (error) {
       if (axios.isAxiosError(error)) {
@@ -193,7 +202,22 @@ export class RedditApiClient {
           return [];
         }
         if (error.response?.status === 403) {
-          this.logger.warn(`Subreddit r/${subreddit} is private or quarantined`);
+          this.consecutiveListing403s += 1;
+          const denied = new RedditAccessDeniedError(subreddit);
+
+          // One 403 can genuinely be a private or quarantined subreddit. A
+          // second consecutive denial from unrelated listings is a strong
+          // signal that Reddit is temporarily rejecting this session/IP.
+          if (this.consecutiveListing403s >= 2) {
+            const cooldownMs = 120_000;
+            this.requestScheduler.extendCooldown(cooldownMs);
+            this.logger.warn(
+              `Reddit is temporarily denying listing requests (consecutive HTTP 403s); pausing for ${cooldownMs / 1000}s`,
+            );
+            throw new RedditRateLimitError(cooldownMs);
+          }
+
+          this.logger.warn(`${denied.message}; it may be private, quarantined, or a temporary Reddit block`);
           return [];
         }
         const rateLimitError = this.toRateLimitError(error);