> ## Documentation Index
> Fetch the complete documentation index at: https://docs.posthook.io/llms.txt
> Use this file to discover all available pages before exploring further.

# How Posthook Works

> Understand the hook lifecycle from scheduling to delivery

## Hook Lifecycle

<Steps>
  <Step title="Schedule">
    You call `POST /hooks` with a path, payload, and a time. The hook is immediately committed to a **durable message queue** before the API returns `201`. This guarantees your hook is safely accepted even during traffic spikes or database maintenance.
  </Step>

  <Step title="Persist">
    The hook is pulled off the queue and written to a high-availability **PostgreSQL** cluster for long-term tracking and dashboard visibility.
  </Step>

  <Step title="Wait">
    The hook remains dormant until its scheduled delivery time.
  </Step>

  <Step title="Dispatch">
    Due hooks are atomically claimed and published to a durable outgoing queue.
  </Step>

  <Step title="Deliver">
    The hook is picked up from the outgoing queue. Before making the HTTP request, a **distributed lock** is acquired to minimize duplicate deliveries. The request includes your payload, hook metadata, and [cryptographic signatures](/essentials/security).
  </Step>

  <Step title="Resolve">
    * **2xx** → `completed`. Delivery is done.
    * **Non-2xx or timeout** → `retry`. Retries follow your [retry configuration](/essentials/scheduling#per-hook-retry-override). After exhausting all attempts → `failed` and a [notification](/essentials/project-settings#notifications) is sent.
  </Step>
</Steps>

## Hook Statuses

The API exposes four statuses. Internal states (like dispatching or in-flight) are abstracted into `pending`.

| Status      | Meaning                                                          |
| ----------- | ---------------------------------------------------------------- |
| `pending`   | Scheduled and waiting for delivery time, or currently in-flight. |
| `retry`     | Delivery failed. Waiting for the next retry attempt.             |
| `completed` | Delivered successfully (2xx response). Terminal.                 |
| `failed`    | All retries exhausted. Terminal.                                 |

```
pending → completed              (first attempt succeeds)
pending → retry → completed      (succeeds after retries)
pending → retry → failed         (all retries exhausted)
```

## Multi-Zone Redundancy

All infrastructure runs across **multiple availability zones** within a region:

* **Compute** — Kubernetes cluster with automatic rescheduling on zone failure.
* **Messaging** — Google Cloud Pub/Sub, a global service with no single zone dependency.
* **Storage** — PostgreSQL with synchronous replication and automatic failover.
* **Caching and Locking** — Valkey with replicas across zones for deduplication availability.

## What Gets Sent

When Posthook delivers a hook, it sends an HTTP POST with your payload, hook metadata, and signature headers. See [Receiving Webhooks](/essentials/receiving-webhooks) for the full request format and framework-specific handler examples.