# Encore Go Pubsub

> Asynchronous messaging in Encore Go via `pubsub.NewTopic` and `pubsub.NewSubscription` from `encore.dev/pubsub` — broadcast events, decouple producers from consumers, and run background handlers.

- **Type:** Skill
- **Install:** `agentstack add skill-encoredev-skills-go-pubsub`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [encoredev](https://agentstack.voostack.com/s/encoredev)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [encoredev](https://github.com/encoredev)
- **Source:** https://github.com/encoredev/skills/tree/main/encore/go-pubsub
- **Website:** https://encore.dev

## Install

```sh
agentstack add skill-encoredev-skills-go-pubsub
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Encore Go Pub/Sub

## Instructions

Pub/Sub is for asynchronous messaging between services. Producers publish events to a `Topic`; consumers attach `Subscription`s to react. Resources must be declared as package-level variables — never inside functions.

## Topics

```go
package events

import "encore.dev/pubsub"

type OrderCreatedEvent struct {
    OrderID string `json:"order_id"`
    UserID  string `json:"user_id"`
    Total   int    `json:"total"`
}

// Package level declaration
var OrderCreated = pubsub.NewTopic[*OrderCreatedEvent]("order-created", pubsub.TopicConfig{
    DeliveryGuarantee: pubsub.AtLeastOnce,
})
```

### Publishing

```go
msgID, err := events.OrderCreated.Publish(ctx, &events.OrderCreatedEvent{
    OrderID: "123",
    UserID:  "user-456",
    Total:   9999,
})
```

### Subscriptions

```go
package notifications

import (
    "context"
    "myapp/events"
    "encore.dev/pubsub"
)

var _ = pubsub.NewSubscription(events.OrderCreated, "send-confirmation-email",
    pubsub.SubscriptionConfig[*events.OrderCreatedEvent]{
        Handler: sendConfirmationEmail,
    },
)

func sendConfirmationEmail(ctx context.Context, event *events.OrderCreatedEvent) error {
    // Send email...
    return nil
}
```

### Topic References

Pass topic access to library code while maintaining static analysis:

```go
// Create a reference with publish permission
ref := pubsub.TopicRef[pubsub.Publisher[*OrderCreatedEvent]](OrderCreated)

// Use the reference in library code
func publishEvent(ref pubsub.Publisher[*OrderCreatedEvent], event *OrderCreatedEvent) error {
    _, err := ref.Publish(ctx, event)
    return err
}
```

## Delivery Guarantees

- `pubsub.AtLeastOnce` (default): may deliver duplicates → handlers must be idempotent.
- `pubsub.ExactlyOnce`: stricter, capped throughput (AWS 300 msg/s/topic, GCP 3000+ msg/s/region). Does not deduplicate on the publish side.

## Guidelines

- Topics and subscriptions must be declared as package-level variables.
- Subscription handlers must be idempotent (at-least-once delivery is the default).
- Subscription handlers receive a `context.Context` and the event pointer; return an `error` to retry per the topic's retry policy.
- Don't do heavy synchronous work in `Publish` callers — `Publish` returns once the message is queued.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [encoredev](https://github.com/encoredev)
- **Source:** [encoredev/skills](https://github.com/encoredev/skills)
- **License:** Apache-2.0
- **Homepage:** https://encore.dev

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-encoredev-skills-go-pubsub
- Seller: https://agentstack.voostack.com/s/encoredev
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.