diff --git a/sentry-javascript/17742/README.md b/sentry-javascript/17742/README.md
new file mode 100644
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+++ b/sentry-javascript/17742/README.md
@@ -0,0 +1,68 @@
+# Reproduction for sentry-javascript#17742
+
+**Issue:** https://github.com/getsentry/sentry-javascript/issues/17742
+
+## Description
+
+Breadcrumbs from background jobs leak into HTTP request error events in NestJS. Background jobs run outside the HTTP request context, so they add breadcrumbs to the default isolation scope. When a new HTTP request arrives, `httpServerIntegration` clones the default scope — inheriting all those stale breadcrumbs.
+
+This reproduction covers **all four** common NestJS background job patterns:
+
+| Framework | Decorator | External Dep | Env Var |
+|-----------|-----------|-------------|---------|
+| `@nestjs/schedule` | `@Interval` / `@Cron` | None | Always active |
+| `@nestjs/event-emitter` | `@OnEvent` | None | Always active |
+| `@nestjs/bullmq` | `@Processor` | Redis | `REDIS_URL` |
+| `nestjs-graphile-worker` | `@Task` | PostgreSQL | `DATABASE_URL` |
+
+## Steps to Reproduce
+
+1. Add a `.env` file with your Sentry DSN (and optionally Redis/PostgreSQL):
+   ```bash
+   SENTRY_DSN=<your-dsn>
+   # Optional:
+   # REDIS_URL=redis://localhost:6379
+   # DATABASE_URL=postgres://user:pass@localhost:5432/dbname
+   ```
+
+2. Install dependencies and run:
+   ```bash
+   npm install
+   npm run test:repro
+   ```
+
+3. Check the output for leaked breadcrumbs.
+
+## Expected Behavior
+
+The error event from `GET /trigger-error` should only contain its own breadcrumb:
+```
+=== Sentry Event Breadcrumbs (1 total) ===
+  [0] category=http-request, message=About to trigger an error in HTTP handler
+```
+
+## Actual Behavior
+
+```
+*** BUG CONFIRMED: Breadcrumbs leaked from background jobs! ***
+  Leaked: schedule-job: 3, event-job: 2
+```
+
+## Root Cause
+
+In `packages/node-core/src/integrations/http/httpServerIntegration.ts:185`:
+```ts
+const isolationScope = getIsolationScope().clone();
+```
+
+Background jobs execute on the default isolation scope (no HTTP request forked a new one). Their breadcrumbs accumulate on the default scope. When `httpServerIntegration` handles a new request, it clones the default scope — including all stale breadcrumbs from background jobs.
+
+## Environment
+
+- Node.js: v18+
+- @sentry/nestjs: ^10.2.0
+- @nestjs/core: ^10.0.0
+- @nestjs/schedule: ^6.1.1
+- @nestjs/event-emitter: latest
+- @nestjs/bullmq: latest (optional)
+- nestjs-graphile-worker: latest (optional)
diff --git a/sentry-javascript/17742/nest-cli.json b/sentry-javascript/17742/nest-cli.json
new file mode 100644
index 0000000..2566481
--- /dev/null
+++ b/sentry-javascript/17742/nest-cli.json
@@ -0,0 +1,5 @@
+{
+  "$schema": "https://json.schemastore.org/nest-cli",
+  "collection": "@nestjs/schematics",
+  "sourceRoot": "src"
+}
diff --git a/sentry-javascript/17742/package.json b/sentry-javascript/17742/package.json
new file mode 100644
index 0000000..89f427c
--- /dev/null
+++ b/sentry-javascript/17742/package.json
@@ -0,0 +1,30 @@
+{
+  "name": "repro-sentry-javascript-17742",
+  "version": "1.0.0",
+  "description": "Reproduction for sentry-javascript#17742 - NestJS leaking breadcrumbs",
+  "private": true,
+  "scripts": {
+    "build": "nest build",
+    "start": "nest start",
+    "test:repro": "npm run build && bash test-repro.sh"
+  },
+  "dependencies": {
+    "@nestjs/bullmq": "^11.0.4",
+    "@nestjs/common": "^10.0.0",
+    "@nestjs/core": "^10.0.0",
+    "@nestjs/event-emitter": "^3.0.1",
+    "@nestjs/platform-express": "^10.0.0",
+    "@nestjs/schedule": "^6.1.1",
+    "@sentry/nestjs": "^10.2.0",
+    "bullmq": "^5.69.3",
+    "dotenv": "^17.3.1",
+    "graphile-worker": "^0.16.6",
+    "nestjs-graphile-worker": "^0.9.1",
+    "reflect-metadata": "^0.2.2",
+    "rxjs": "^7.8.1"
+  },
+  "devDependencies": {
+    "@nestjs/cli": "^10.0.0",
+    "typescript": "^5.0.0"
+  }
+}
diff --git a/sentry-javascript/17742/src/app.controller.ts b/sentry-javascript/17742/src/app.controller.ts
new file mode 100644
index 0000000..a7817bd
--- /dev/null
+++ b/sentry-javascript/17742/src/app.controller.ts
@@ -0,0 +1,12 @@
+import { Controller, Get } from "@nestjs/common";
+import { AppService } from "./app.service";
+
+@Controller()
+export class AppController {
+  constructor(private readonly appService: AppService) {}
+
+  @Get("trigger-error")
+  triggerError(): string {
+    return this.appService.triggerError();
+  }
+}
diff --git a/sentry-javascript/17742/src/app.module.ts b/sentry-javascript/17742/src/app.module.ts
new file mode 100644
index 0000000..5c956d1
--- /dev/null
+++ b/sentry-javascript/17742/src/app.module.ts
@@ -0,0 +1,95 @@
+import { DynamicModule, Module } from "@nestjs/common";
+import { APP_FILTER } from "@nestjs/core";
+import { EventEmitterModule } from "@nestjs/event-emitter";
+import { ScheduleModule } from "@nestjs/schedule";
+import { SentryGlobalFilter, SentryModule } from "@sentry/nestjs/setup";
+import { AppController } from "./app.controller";
+import { AppService } from "./app.service";
+import { ScheduleJobService } from "./schedule-job.service";
+import { EventJobService } from "./event-job.service";
+
+/**
+ * Build imports and providers dynamically based on available services.
+ * - Schedule + EventEmitter: always enabled (no external deps)
+ * - BullMQ: enabled when REDIS_URL is set
+ * - Graphile Worker: enabled when DATABASE_URL is set
+ */
+function getOptionalImports(): DynamicModule[] {
+  const imports: DynamicModule[] = [];
+
+  if (process.env.REDIS_URL) {
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      const { BullModule } = require("@nestjs/bullmq");
+      imports.push(
+        BullModule.forRoot({ connection: { url: process.env.REDIS_URL } })
+      );
+      imports.push(BullModule.registerQueue({ name: "background-queue" }));
+      console.log("[Config] BullMQ enabled (REDIS_URL set)");
+    } catch (e) {
+      console.log("[Config] BullMQ not available");
+    }
+  } else {
+    console.log("[Config] BullMQ disabled (set REDIS_URL to enable)");
+  }
+
+  if (process.env.DATABASE_URL) {
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      const { GraphileWorkerModule } = require("nestjs-graphile-worker");
+      imports.push(
+        GraphileWorkerModule.forRoot({
+          connectionString: process.env.DATABASE_URL,
+        })
+      );
+      console.log("[Config] Graphile Worker enabled (DATABASE_URL set)");
+    } catch (e) {
+      console.log("[Config] Graphile Worker not available");
+    }
+  } else {
+    console.log("[Config] Graphile Worker disabled (set DATABASE_URL to enable)");
+  }
+
+  return imports;
+}
+
+function getOptionalProviders(): any[] {
+  const providers: any[] = [];
+
+  if (process.env.REDIS_URL) {
+    try {
+      const { BullmqJobProcessor, BullmqJobProducer } = require("./bullmq-job.processor");
+      providers.push(BullmqJobProcessor, BullmqJobProducer);
+    } catch (e) {}
+  }
+
+  if (process.env.DATABASE_URL) {
+    try {
+      const { GraphileJobHandler, GraphileJobProducer } = require("./graphile-job.service");
+      providers.push(GraphileJobHandler, GraphileJobProducer);
+    } catch (e) {}
+  }
+
+  return providers;
+}
+
+@Module({
+  imports: [
+    SentryModule.forRoot(),
+    ScheduleModule.forRoot(),
+    EventEmitterModule.forRoot(),
+    ...getOptionalImports(),
+  ],
+  controllers: [AppController],
+  providers: [
+    {
+      provide: APP_FILTER,
+      useClass: SentryGlobalFilter,
+    },
+    AppService,
+    ScheduleJobService,
+    EventJobService,
+    ...getOptionalProviders(),
+  ],
+})
+export class AppModule {}
diff --git a/sentry-javascript/17742/src/app.service.ts b/sentry-javascript/17742/src/app.service.ts
new file mode 100644
index 0000000..a110ea7
--- /dev/null
+++ b/sentry-javascript/17742/src/app.service.ts
@@ -0,0 +1,21 @@
+import { Injectable } from "@nestjs/common";
+import * as Sentry from "@sentry/nestjs";
+
+@Injectable()
+export class AppService {
+  triggerError(): string {
+    // Add a breadcrumb specific to this HTTP request
+    Sentry.addBreadcrumb({
+      category: "http-request",
+      message: "About to trigger an error in HTTP handler",
+      level: "error",
+    });
+
+    // Throw an exception — the SentryGlobalFilter captures it automatically.
+    // EXPECTED: Only the "http-request" breadcrumb should appear on the event
+    // ACTUAL (BUG): Breadcrumbs from background jobs leak into this event
+    //   because the HTTP request's isolation scope was cloned from the default
+    //   scope, which was polluted by background job breadcrumbs
+    throw new Error("Test error to check breadcrumb isolation");
+  }
+}
diff --git a/sentry-javascript/17742/src/bullmq-job.processor.ts b/sentry-javascript/17742/src/bullmq-job.processor.ts
new file mode 100644
index 0000000..554126b
--- /dev/null
+++ b/sentry-javascript/17742/src/bullmq-job.processor.ts
@@ -0,0 +1,49 @@
+import { Processor, WorkerHost } from "@nestjs/bullmq";
+import { Injectable, OnModuleInit } from "@nestjs/common";
+import { InjectQueue } from "@nestjs/bullmq";
+import { Queue, Job } from "bullmq";
+import * as Sentry from "@sentry/nestjs";
+
+/**
+ * Case 3: @nestjs/bullmq
+ * BullMQ processors run outside HTTP request context on the default isolation scope.
+ */
+@Processor("background-queue")
+export class BullmqJobProcessor extends WorkerHost {
+  private jobCount = 0;
+
+  async process(job: Job): Promise<void> {
+    this.jobCount++;
+    console.log(
+      `[@nestjs/bullmq] Processing job #${this.jobCount}: ${job.name}`
+    );
+
+    Sentry.addBreadcrumb({
+      category: "bullmq-job",
+      message: `BullMQ job #${this.jobCount} processed`,
+      level: "info",
+    });
+
+    console.log(`[@nestjs/bullmq] Job #${this.jobCount} done`);
+  }
+}
+
+/**
+ * Service that periodically adds jobs to the BullMQ queue.
+ */
+@Injectable()
+export class BullmqJobProducer implements OnModuleInit {
+  private jobCount = 0;
+
+  constructor(@InjectQueue("background-queue") private queue: Queue) {}
+
+  onModuleInit() {
+    setInterval(async () => {
+      this.jobCount++;
+      await this.queue.add("background-task", {
+        id: this.jobCount,
+      });
+      console.log(`[@nestjs/bullmq] Added job #${this.jobCount} to queue`);
+    }, 5000);
+  }
+}
diff --git a/sentry-javascript/17742/src/event-job.service.ts b/sentry-javascript/17742/src/event-job.service.ts
new file mode 100644
index 0000000..8145126
--- /dev/null
+++ b/sentry-javascript/17742/src/event-job.service.ts
@@ -0,0 +1,36 @@
+import { Injectable } from "@nestjs/common";
+import { EventEmitter2 } from "@nestjs/event-emitter";
+import { OnEvent } from "@nestjs/event-emitter";
+import * as Sentry from "@sentry/nestjs";
+
+/**
+ * Case 2: @nestjs/event-emitter
+ * Event handlers run outside HTTP request context on the default isolation scope.
+ */
+@Injectable()
+export class EventJobService {
+  private eventCount = 0;
+
+  constructor(private eventEmitter: EventEmitter2) {
+    // Emit events periodically to simulate background event processing
+    setInterval(() => {
+      this.eventEmitter.emit("background.task", {
+        id: Date.now(),
+      });
+    }, 4000);
+  }
+
+  @OnEvent("background.task")
+  handleBackgroundEvent(payload: { id: number }) {
+    this.eventCount++;
+    console.log(`[@nestjs/event-emitter] Event #${this.eventCount} received`);
+
+    Sentry.addBreadcrumb({
+      category: "event-job",
+      message: `Event handler #${this.eventCount} executed`,
+      level: "info",
+    });
+
+    console.log(`[@nestjs/event-emitter] Event #${this.eventCount} done`);
+  }
+}
diff --git a/sentry-javascript/17742/src/graphile-job.service.ts b/sentry-javascript/17742/src/graphile-job.service.ts
new file mode 100644
index 0000000..815a226
--- /dev/null
+++ b/sentry-javascript/17742/src/graphile-job.service.ts
@@ -0,0 +1,63 @@
+import { Injectable, OnModuleInit } from "@nestjs/common";
+import { Task, TaskHandler } from "nestjs-graphile-worker";
+import { WorkerService } from "nestjs-graphile-worker";
+import * as Sentry from "@sentry/nestjs";
+
+/**
+ * Case 4: nestjs-graphile-worker
+ * Graphile worker tasks run outside HTTP request context on the default isolation scope.
+ */
+@Injectable()
+@Task("background-graphile-task")
+export class GraphileJobHandler {
+  private taskCount = 0;
+
+  @TaskHandler()
+  async handler(payload: { id: number }) {
+    this.taskCount++;
+    console.log(
+      `[nestjs-graphile-worker] Task #${this.taskCount} running`
+    );
+
+    Sentry.addBreadcrumb({
+      category: "graphile-job",
+      message: `Graphile task #${this.taskCount} executed`,
+      level: "info",
+    });
+
+    console.log(
+      `[nestjs-graphile-worker] Task #${this.taskCount} done`
+    );
+  }
+}
+
+/**
+ * Service that periodically adds tasks to the graphile-worker queue.
+ */
+@Injectable()
+export class GraphileJobProducer implements OnModuleInit {
+  private taskCount = 0;
+
+  constructor(private readonly workerService: WorkerService) {}
+
+  async onModuleInit() {
+    // Start the graphile-worker runner so it actually processes tasks
+    this.workerService.run().catch((err) => {
+      console.error("[nestjs-graphile-worker] Runner error:", err);
+    });
+
+    setInterval(async () => {
+      this.taskCount++;
+      try {
+        await this.workerService.addJob("background-graphile-task", {
+          id: this.taskCount,
+        });
+        console.log(
+          `[nestjs-graphile-worker] Added task #${this.taskCount} to queue`
+        );
+      } catch (e) {
+        // Silently ignore if worker service isn't ready
+      }
+    }, 6000);
+  }
+}
diff --git a/sentry-javascript/17742/src/instrument.ts b/sentry-javascript/17742/src/instrument.ts
new file mode 100644
index 0000000..1f891fb
--- /dev/null
+++ b/sentry-javascript/17742/src/instrument.ts
@@ -0,0 +1,45 @@
+import "dotenv/config";
+import * as Sentry from "@sentry/nestjs";
+
+Sentry.init({
+  dsn: process.env.SENTRY_DSN || "",
+  debug: false,
+  tracesSampleRate: 1.0,
+  beforeSend(event) {
+    const breadcrumbs = event.breadcrumbs || [];
+    console.log(
+      `\n=== Sentry Event Breadcrumbs (${breadcrumbs.length} total) ===`
+    );
+
+    // Group breadcrumbs by category
+    const categories = new Map<string, number>();
+    breadcrumbs.forEach((bc, i) => {
+      const cat = bc.category || "unknown";
+      categories.set(cat, (categories.get(cat) || 0) + 1);
+      console.log(`  [${i}] category=${cat}, message=${bc.message}`);
+    });
+
+    // Check for leaked breadcrumbs from each background job type
+    const leakCategories = [
+      "schedule-job",
+      "event-job",
+      "bullmq-job",
+      "graphile-job",
+    ];
+
+    const leaks = leakCategories
+      .filter((cat) => categories.has(cat))
+      .map((cat) => `${cat}: ${categories.get(cat)}`);
+
+    if (leaks.length > 0) {
+      console.log(
+        `\n*** BUG CONFIRMED: Breadcrumbs leaked from background jobs! ***`
+      );
+      console.log(`  Leaked: ${leaks.join(", ")}`);
+    } else {
+      console.log("\n  No leaked breadcrumbs detected (isolation working).");
+    }
+    console.log("=== End Breadcrumbs ===\n");
+    return event;
+  },
+});
diff --git a/sentry-javascript/17742/src/main.ts b/sentry-javascript/17742/src/main.ts
new file mode 100644
index 0000000..c1f0591
--- /dev/null
+++ b/sentry-javascript/17742/src/main.ts
@@ -0,0 +1,23 @@
+import "./instrument";
+
+import { NestFactory } from "@nestjs/core";
+import { AppModule } from "./app.module";
+
+async function bootstrap() {
+  const app = await NestFactory.create(AppModule);
+  await app.listen(3000);
+  console.log("Server running on http://localhost:3000");
+  console.log("");
+  console.log("To reproduce the breadcrumb leaking issue:");
+  console.log(
+    "1. Wait ~10 seconds for background jobs to pollute the default scope"
+  );
+  console.log("2. curl http://localhost:3000/trigger-error");
+  console.log("");
+  console.log("Background job sources:");
+  console.log("  - @nestjs/schedule @Interval (always active)");
+  console.log("  - @nestjs/event-emitter @OnEvent (always active)");
+  console.log("  - @nestjs/bullmq @Processor (requires REDIS_URL)");
+  console.log("  - nestjs-graphile-worker @Task (requires DATABASE_URL)");
+}
+bootstrap();
diff --git a/sentry-javascript/17742/src/schedule-job.service.ts b/sentry-javascript/17742/src/schedule-job.service.ts
new file mode 100644
index 0000000..0479604
--- /dev/null
+++ b/sentry-javascript/17742/src/schedule-job.service.ts
@@ -0,0 +1,26 @@
+import { Injectable } from "@nestjs/common";
+import { Interval } from "@nestjs/schedule";
+import * as Sentry from "@sentry/nestjs";
+
+/**
+ * Case 1: @nestjs/schedule
+ * Scheduled jobs run outside HTTP request context on the default isolation scope.
+ */
+@Injectable()
+export class ScheduleJobService {
+  private jobCount = 0;
+
+  @Interval(3000)
+  handleScheduledJob() {
+    this.jobCount++;
+    console.log(`[@nestjs/schedule] Job #${this.jobCount} running`);
+
+    Sentry.addBreadcrumb({
+      category: "schedule-job",
+      message: `Scheduled job #${this.jobCount} executed`,
+      level: "info",
+    });
+
+    console.log(`[@nestjs/schedule] Job #${this.jobCount} done`);
+  }
+}
diff --git a/sentry-javascript/17742/test-repro.sh b/sentry-javascript/17742/test-repro.sh
new file mode 100755
index 0000000..64e65b9
--- /dev/null
+++ b/sentry-javascript/17742/test-repro.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+# Reproduction script for sentry-javascript#17742
+# Tests breadcrumb leaking from all background job frameworks:
+#   - @nestjs/schedule (always active)
+#   - @nestjs/event-emitter (always active)
+#   - @nestjs/bullmq (requires REDIS_URL)
+#   - nestjs-graphile-worker (requires DATABASE_URL)
+
+echo "=== Starting NestJS server ==="
+node dist/main.js &
+APP_PID=$!
+
+echo "Waiting for server to start and background jobs to run..."
+sleep 18
+
+echo ""
+echo "=== Triggering error to check for leaked breadcrumbs ==="
+curl -s http://localhost:3000/trigger-error
+echo ""
+
+sleep 3
+kill $APP_PID 2>/dev/null
+wait $APP_PID 2>/dev/null
diff --git a/sentry-javascript/17742/tsconfig.json b/sentry-javascript/17742/tsconfig.json
new file mode 100644
index 0000000..95f5641
--- /dev/null
+++ b/sentry-javascript/17742/tsconfig.json
@@ -0,0 +1,21 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "declaration": true,
+    "removeComments": true,
+    "emitDecoratorMetadata": true,
+    "experimentalDecorators": true,
+    "allowSyntheticDefaultImports": true,
+    "target": "ES2021",
+    "sourceMap": true,
+    "outDir": "./dist",
+    "baseUrl": "./",
+    "incremental": true,
+    "skipLibCheck": true,
+    "strictNullChecks": false,
+    "noImplicitAny": false,
+    "strictBindCallApply": false,
+    "forceConsistentCasingInFileNames": false,
+    "noFallthroughCasesInSwitch": false
+  }
+}