diff --git a/src/reddit/api.ts b/src/reddit/api.ts
index 0a9cedf..66abb7c 100644
--- a/src/reddit/api.ts
+++ b/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);
diff --git a/src/reddit/request-coordinator.ts b/src/reddit/request-coordinator.ts
index 41c0f47..0889480 100644
--- a/src/reddit/request-coordinator.ts
+++ b/src/reddit/request-coordinator.ts
@@ -39,10 +39,13 @@ export class RedditRequestCoordinator implements RedditRequestScheduler {
     try {
       const waitMs = this.nextRequestAt - this.now();
       if (waitMs > 0) await this.sleep(waitMs);
-      const result = await request();
-      this.nextRequestAt = Math.max(this.nextRequestAt, this.now() + this.minRequestIntervalMs);
-      return result;
+      return await request();
     } finally {
+      // A rejected request still reached Reddit. In particular, 403 responses
+      // are often a temporary anti-abuse block, so immediately trying the next
+      // subreddit turns one denial into a burst. Keep the same spacing after
+      // every attempted request; an explicit 429 cooldown remains authoritative.
+      this.nextRequestAt = Math.max(this.nextRequestAt, this.now() + this.minRequestIntervalMs);
       release();
     }
   }
diff --git a/src/utils/logger.ts b/src/utils/logger.ts
index 14294f0..4624619 100644
--- a/src/utils/logger.ts
+++ b/src/utils/logger.ts
@@ -1,5 +1,6 @@
 import winston from 'winston';
 import Transport from 'winston-transport';
+import { toJsonSafe } from './json-safe.js';
 
 export type Logger = winston.Logger;
 
@@ -37,27 +38,35 @@ export function attachLogSink(logger: Logger, sink: LogSink): void {
 }
 
 function safeStringify(value: unknown): string {
-  const seen = new WeakSet<object>();
   try {
-    return JSON.stringify(value, (_key, val) => {
-      if (typeof val === 'object' && val !== null) {
-        if (seen.has(val)) return '[Circular]';
-        seen.add(val);
-      }
-      if (typeof val === 'bigint') return val.toString();
-      return val;
-    });
+    return JSON.stringify(toJsonSafe(value));
   } catch (err) {
     return `[Unserializable: ${(err as Error).message}]`;
   }
 }
 
+/** Strip credentials and network internals before either console or file output. */
+const redactLogMetadata = winston.format((info) => {
+  const record = info as Record<string, unknown>;
+  const { level, message, timestamp, ...metadata } = record;
+  const safeMetadata = toJsonSafe(metadata);
+  for (const key of Object.keys(metadata)) delete record[key];
+  if (safeMetadata && !Array.isArray(safeMetadata) && typeof safeMetadata === 'object') {
+    Object.assign(record, safeMetadata);
+  }
+  record.level = level;
+  record.message = message;
+  if (timestamp !== undefined) record.timestamp = timestamp;
+  return info;
+});
+
 export function createLogger(): Logger {
   return winston.createLogger({
     level: process.env.LOG_LEVEL || 'info',
     format: winston.format.combine(
       winston.format.timestamp(),
       winston.format.errors({ stack: true }),
+      redactLogMetadata(),
       winston.format.json()
     ),
     transports: [
diff --git a/tests/reddit-api.test.ts b/tests/reddit-api.test.ts
index f3db3ed..a9b77be 100644
--- a/tests/reddit-api.test.ts
+++ b/tests/reddit-api.test.ts
@@ -490,7 +490,7 @@ describe('RedditApiClient', () => {
       expect(result).toEqual([]);
     });
 
-    it('returns empty array for 403 private subreddit', async () => {
+    it('returns empty array and explains an initial 403 access denial', async () => {
       const error = { isAxiosError: true, response: { status: 403 } };
       const mockAxios = { get: vi.fn().mockRejectedValue(error) };
       vi.mocked(axios.create).mockReturnValue(mockAxios as any);
@@ -498,6 +498,23 @@ describe('RedditApiClient', () => {
       const client2 = new RedditApiClient(getTestConfig(), logger);
       const result = await client2.getNewPosts('private');
       expect(result).toEqual([]);
+      expect(logger.logs).toContainEqual(expect.objectContaining({
+        level: 'warn', message: expect.stringContaining('HTTP 403'),
+      }));
+    });
+
+    it('treats consecutive 403 listing responses as a temporary Reddit block', async () => {
+      const error = { isAxiosError: true, response: { status: 403 } };
+      const mockAxios = { get: vi.fn().mockRejectedValue(error) };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const scheduler: RedditRequestScheduler = { schedule: async (request) => await request(), extendCooldown: vi.fn() };
+      const client2 = new RedditApiClient(getTestConfig(), logger, scheduler);
+
+      await expect(client2.getNewPosts('first')).resolves.toEqual([]);
+      await expect(client2.getNewPosts('second')).rejects.toMatchObject({
+        name: 'RedditRateLimitError', retryAfterMs: 120_000,
+      });
+      expect(scheduler.extendCooldown).toHaveBeenCalledWith(120_000);
     });
 
     it('throws a compact error with the Reddit rate-limit reset delay on 429', async () => {
diff --git a/tests/reddit-request-coordinator.test.ts b/tests/reddit-request-coordinator.test.ts
index bfdf70a..a01a398 100644
--- a/tests/reddit-request-coordinator.test.ts
+++ b/tests/reddit-request-coordinator.test.ts
@@ -55,4 +55,18 @@ describe('RedditRequestCoordinator', () => {
     await second;
     expect(sleeps).toEqual([16_000]);
   });
+
+  it('paces a queued request after a failed attempt without an explicit cooldown', async () => {
+    let now = 0;
+    const sleeps: number[] = [];
+    const coordinator = new RedditRequestCoordinator(6_500, {
+      now: () => now,
+      sleep: async (ms) => { sleeps.push(ms); now += ms; },
+    });
+
+    await expect(coordinator.schedule(async () => { throw new Error('403'); })).rejects.toThrow('403');
+    await coordinator.schedule(async () => undefined);
+
+    expect(sleeps).toEqual([6_500]);
+  });
 });