# `Jido.Messaging.Signal.Ext.CorrelationId`
[🔗](https://github.com/agentjido/jido_messaging/blob/v1.0.0/lib/jido_messaging/signal/ext/correlation_id.ex#L1)

Signal extension for message correlation tracking in Jido.Messaging.

This extension provides a simple `correlation_id` field for tracing related
messages through the messaging pipeline. It's used to link:

- Inbound messages to their processing events
- Agent triggers to their responses
- Delivery attempts to their outcomes

## Usage

The correlation ID is automatically populated by `Jido.Messaging.Signal` functions:

    # Automatically added when emitting signals
    Jido.Messaging.Signal.emit_received(message, context)

    # The signal will have:
    # signal.extensions["correlationid"] == %{"id" => "msg_abc123"}

## Relationship to Jido.Signal.Ext.Trace

This extension is complementary to the trace extension (`correlation` namespace):

- **Trace extension**: Full distributed tracing with `trace_id`, `span_id`, `parent_span_id`
- **CorrelationId extension**: Simple message-level correlation for messaging workflows

Use trace extension for cross-service distributed tracing.
Use this extension for message-level correlation within the messaging domain.

## Registration

Call `ensure_registered/0` at application startup to register this extension:

    Jido.Messaging.Signal.Ext.CorrelationId.ensure_registered()

# `ensure_registered`

```elixir
@spec ensure_registered() :: :ok
```

Ensures the extension is registered with the signal registry.

This should be called at application startup or before using signals
with correlation IDs. Safe to call multiple times.

# `validate_data`

```elixir
@spec validate_data(term()) :: {:ok, term()} | {:error, String.t()}
```

Validates data according to this extension's schema.

## Parameters
- `data` - The data to validate

## Returns
`{:ok, validated_data}` if valid, `{:error, reason}` otherwise

## Examples

    iex> MyExt.validate_data(%{user_id: "123"})
    {:ok, %{user_id: "123"}}

    iex> MyExt.validate_data(%{})
    {:error, "required :user_id option not found"}

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*Consult [api-reference.md](api-reference.md) for complete listing*