# Trigger.dev Advanced Tasks (v4)

**Advanced patterns and features for writing tasks**

## Tags & Organization

```ts
import { task, tags } from "@trigger.dev/sdk";

export const processUser = task({
  id: "process-user",
  run: async (payload: { userId: string; orgId: string }, { ctx }) => {
    // Add tags during execution
    await tags.add(`user_${payload.userId}`);
    await tags.add(`org_${payload.orgId}`);

    return { processed: true };
  },
});

// Trigger with tags
await processUser.trigger(
  { userId: "123", orgId: "abc" },
  { tags: ["priority", "user_123", "org_abc"] } // Max 10 tags per run
);

// Subscribe to tagged runs
for await (const run of runs.subscribeToRunsWithTag("user_123")) {
  console.log(`User task ${run.id}: ${run.status}`);
}
```

**Tag Best Practices:**

- Use prefixes: `user_123`, `org_abc`, `video:456`
- Max 10 tags per run, 1-64 characters each
- Tags don't propagate to child tasks automatically

## Batch Triggering v2

Enhanced batch triggering with larger payloads and streaming ingestion.

### Limits

- **Maximum batch size**: 1,000 items (increased from 500)
- **Payload per item**: 3MB each (increased from 1MB combined)
- Payloads > 512KB automatically offload to object storage

### Rate Limiting (per environment)

| Tier | Bucket Size | Refill Rate |
|------|-------------|-------------|
| Free | 1,200 runs | 100 runs/10 sec |
| Hobby | 5,000 runs | 500 runs/5 sec |
| Pro | 5,000 runs | 500 runs/5 sec |

### Concurrent Batch Processing

| Tier | Concurrent Batches |
|------|-------------------|
| Free | 1 |
| Hobby | 10 |
| Pro | 10 |

### Usage

```ts
import { myTask } from "./trigger/myTask";

// Basic batch trigger (up to 1,000 items)
const runs = await myTask.batchTrigger([
  { payload: { userId: "user-1" } },
  { payload: { userId: "user-2" } },
  { payload: { userId: "user-3" } },
]);

// Batch trigger with wait
const results = await myTask.batchTriggerAndWait([
  { payload: { userId: "user-1" } },
  { payload: { userId: "user-2" } },
]);

for (const result of results) {
  if (result.ok) {
    console.log("Result:", result.output);
  }
}

// With per-item options
const batchHandle = await myTask.batchTrigger([
  {
    payload: { userId: "123" },
    options: {
      idempotencyKey: "user-123-batch",
      tags: ["priority"],
    },
  },
  {
    payload: { userId: "456" },
    options: {
      idempotencyKey: "user-456-batch",
    },
  },
]);
```

## Debouncing

Consolidate multiple triggers into a single execution by debouncing task runs with a unique key and delay window.

### Use Cases

- **User activity updates**: Batch rapid user actions into a single run
- **Webhook deduplication**: Handle webhook bursts without redundant processing
- **Search indexing**: Combine document updates instead of processing individually
- **Notification batching**: Group notifications to prevent user spam

### Basic Usage

```ts
await myTask.trigger(
  { userId: "123" },
  {
    debounce: {
      key: "user-123-update",  // Unique identifier for debounce group
      delay: "5s",              // Wait duration ("5s", "1m", or milliseconds)
    },
  }
);
```

### Execution Modes

**Leading Mode** (default): Uses payload/options from the first trigger; subsequent triggers only reschedule execution time.

```ts
// First trigger sets the payload
await myTask.trigger({ action: "first" }, {
  debounce: { key: "my-key", delay: "10s" }
});

// Second trigger only reschedules - payload remains "first"
await myTask.trigger({ action: "second" }, {
  debounce: { key: "my-key", delay: "10s" }
});
// Task executes with { action: "first" }
```

**Trailing Mode**: Uses payload/options from the most recent trigger.

```ts
await myTask.trigger(
  { data: "latest-value" },
  {
    debounce: {
      key: "trailing-example",
      delay: "10s",
      mode: "trailing",
    },
  }
);
```

In trailing mode, these options update with each trigger:
- `payload` — task input data
- `metadata` — run metadata
- `tags` — run tags (replaces existing)
- `maxAttempts` — retry attempts
- `maxDuration` — maximum compute time
- `machine` — machine preset

### Important Notes

- Idempotency keys take precedence over debounce settings
- Compatible with `triggerAndWait()` — parent runs block correctly on debounced execution
- Debounce key is scoped to the task

## Concurrency & Queues

```ts
import { task, queue } from "@trigger.dev/sdk";

// Shared queue for related tasks
const emailQueue = queue({
  name: "email-processing",
  concurrencyLimit: 5, // Max 5 emails processing simultaneously
});

// Task-level concurrency
export const oneAtATime = task({
  id: "sequential-task",
  queue: { concurrencyLimit: 1 }, // Process one at a time
  run: async (payload) => {
    // Critical section - only one instance runs
  },
});

// Per-user concurrency
export const processUserData = task({
  id: "process-user-data",
  run: async (payload: { userId: string }) => {
    // Override queue with user-specific concurrency
    await childTask.trigger(payload, {
      queue: {
        name: `user-${payload.userId}`,
        concurrencyLimit: 2,
      },
    });
  },
});

export const emailTask = task({
  id: "send-email",
  queue: emailQueue, // Use shared queue
  run: async (payload: { to: string }) => {
    // Send email logic
  },
});
```

## Error Handling & Retries

```ts
import { task, retry, AbortTaskRunError } from "@trigger.dev/sdk";

export const resilientTask = task({
  id: "resilient-task",
  retry: {
    maxAttempts: 10,
    factor: 1.8, // Exponential backoff multiplier
    minTimeoutInMs: 500,
    maxTimeoutInMs: 30_000,
    randomize: false,
  },
  catchError: async ({ error, ctx }) => {
    // Custom error handling
    if (error.code === "FATAL_ERROR") {
      throw new AbortTaskRunError("Cannot retry this error");
    }

    // Log error details
    console.error(`Task ${ctx.task.id} failed:`, error);

    // Allow retry by returning nothing
    return { retryAt: new Date(Date.now() + 60000) }; // Retry in 1 minute
  },
  run: async (payload) => {
    // Retry specific operations
    const result = await retry.onThrow(
      async () => {
        return await unstableApiCall(payload);
      },
      { maxAttempts: 3 }
    );

    // Conditional HTTP retries
    const response = await retry.fetch("https://api.example.com", {
      retry: {
        maxAttempts: 5,
        condition: (response, error) => {
          return response?.status === 429 || response?.status >= 500;
        },
      },
    });

    return result;
  },
});
```

## Machines & Performance

```ts
export const heavyTask = task({
  id: "heavy-computation",
  machine: { preset: "large-2x" }, // 8 vCPU, 16 GB RAM
  maxDuration: 1800, // 30 minutes timeout
  run: async (payload, { ctx }) => {
    // Resource-intensive computation
    if (ctx.machine.preset === "large-2x") {
      // Use all available cores
      return await parallelProcessing(payload);
    }

    return await standardProcessing(payload);
  },
});

// Override machine when triggering
await heavyTask.trigger(payload, {
  machine: { preset: "medium-1x" }, // Override for this run
});
```

**Machine Presets:**

- `micro`: 0.25 vCPU, 0.25 GB RAM
- `small-1x`: 0.5 vCPU, 0.5 GB RAM (default)
- `small-2x`: 1 vCPU, 1 GB RAM
- `medium-1x`: 1 vCPU, 2 GB RAM
- `medium-2x`: 2 vCPU, 4 GB RAM
- `large-1x`: 4 vCPU, 8 GB RAM
- `large-2x`: 8 vCPU, 16 GB RAM

## Idempotency

```ts
import { task, idempotencyKeys } from "@trigger.dev/sdk";

export const paymentTask = task({
  id: "process-payment",
  retry: {
    maxAttempts: 3,
  },
  run: async (payload: { orderId: string; amount: number }) => {
    // Automatically scoped to this task run, so if the task is retried, the idempotency key will be the same
    const idempotencyKey = await idempotencyKeys.create(`payment-${payload.orderId}`);

    // Ensure payment is processed only once
    await chargeCustomer.trigger(payload, {
      idempotencyKey,
      idempotencyKeyTTL: "24h", // Key expires in 24 hours
    });
  },
});

// Payload-based idempotency
import { createHash } from "node:crypto";

function createPayloadHash(payload: any): string {
  const hash = createHash("sha256");
  hash.update(JSON.stringify(payload));
  return hash.digest("hex");
}

export const deduplicatedTask = task({
  id: "deduplicated-task",
  run: async (payload) => {
    const payloadHash = createPayloadHash(payload);
    const idempotencyKey = await idempotencyKeys.create(payloadHash);

    await processData.trigger(payload, { idempotencyKey });
  },
});
```

## Metadata & Progress Tracking

```ts
import { task, metadata } from "@trigger.dev/sdk";

export const batchProcessor = task({
  id: "batch-processor",
  run: async (payload: { items: any[] }, { ctx }) => {
    const totalItems = payload.items.length;

    // Initialize progress metadata
    metadata
      .set("progress", 0)
      .set("totalItems", totalItems)
      .set("processedItems", 0)
      .set("status", "starting");

    const results = [];

    for (let i = 0; i < payload.items.length; i++) {
      const item = payload.items[i];

      // Process item
      const result = await processItem(item);
      results.push(result);

      // Update progress
      const progress = ((i + 1) / totalItems) * 100;
      metadata
        .set("progress", progress)
        .increment("processedItems", 1)
        .append("logs", `Processed item ${i + 1}/${totalItems}`)
        .set("currentItem", item.id);
    }

    // Final status
    metadata.set("status", "completed");

    return { results, totalProcessed: results.length };
  },
});

// Update parent metadata from child task
export const childTask = task({
  id: "child-task",
  run: async (payload, { ctx }) => {
    // Update parent task metadata
    metadata.parent.set("childStatus", "processing");
    metadata.root.increment("childrenCompleted", 1);

    return { processed: true };
  },
});
```

## Logging & Tracing

```ts
import { task, logger } from "@trigger.dev/sdk";

export const tracedTask = task({
  id: "traced-task",
  run: async (payload, { ctx }) => {
    logger.info("Task started", { userId: payload.userId });

    // Custom trace with attributes
    const user = await logger.trace(
      "fetch-user",
      async (span) => {
        span.setAttribute("user.id", payload.userId);
        span.setAttribute("operation", "database-fetch");

        const userData = await database.findUser(payload.userId);
        span.setAttribute("user.found", !!userData);

        return userData;
      },
      { userId: payload.userId }
    );

    logger.debug("User fetched", { user: user.id });

    try {
      const result = await processUser(user);
      logger.info("Processing completed", { result });
      return result;
    } catch (error) {
      logger.error("Processing failed", {
        error: error.message,
        userId: payload.userId,
      });
      throw error;
    }
  },
});
```

## Hidden Tasks

```ts
// Hidden task - not exported, only used internally
const internalProcessor = task({
  id: "internal-processor",
  run: async (payload: { data: string }) => {
    return { processed: payload.data.toUpperCase() };
  },
});

// Public task that uses hidden task
export const publicWorkflow = task({
  id: "public-workflow",
  run: async (payload: { input: string }) => {
    // Use hidden task internally
    const result = await internalProcessor.triggerAndWait({
      data: payload.input,
    });

    if (result.ok) {
      return { output: result.output.processed };
    }

    throw new Error("Internal processing failed");
  },
});
```

## Best Practices

- **Concurrency**: Use queues to prevent overwhelming external services
- **Retries**: Configure exponential backoff for transient failures
- **Idempotency**: Always use for payment/critical operations
- **Metadata**: Track progress for long-running tasks
- **Machines**: Match machine size to computational requirements
- **Tags**: Use consistent naming patterns for filtering
- **Debouncing**: Use for user activity, webhooks, and notification batching
- **Batch triggering**: Use for bulk operations up to 1,000 items
- **Error Handling**: Distinguish between retryable and fatal errors

Design tasks to be stateless, idempotent, and resilient to failures. Use metadata for state tracking and queues for resource management.