# `ExMCP.Server.Subscriptions.PubSub`
[🔗](https://github.com/azmaveth/ex_mcp/blob/v1.0.0/lib/ex_mcp/server/subscriptions/pub_sub.ex#L1)

Cluster fan-out adapter for modern MCP subscriptions.

The adapter keeps registrations in a configurable storage adapter on the
node that owns each listener and distributes untargeted publications over a
Phoenix.PubSub-compatible module. No Phoenix dependency is required by
ExMCP; applications that select this adapter must provide a module exporting
`subscribe/2` and `broadcast_from/4`.

Publications constrained to a `transport_ref` remain node-local because a
transport process is owned by exactly one registry.

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