# `mix reach.otp`
[🔗](https://github.com/elixir-vibe/reach/blob/v2.2.0/lib/mix/tasks/reach.otp.ex#L1)

Shows GenServer state machines, missing message handlers, and hidden coupling.

    mix reach.otp
    mix reach.otp UserWorker
    mix reach.otp --format json

## Options

  * `--format` — output format: `text` (default), `json`, `oneline`
  * `--concurrency` — show Task/monitor/spawn and supervisor topology
  * `--state` — focus on state-machine output (accepted for canonical CLI compatibility)
  * `--messages` — focus on message-handler output (accepted for canonical CLI compatibility)
  * `--supervision` — focus on supervision output (accepted for canonical CLI compatibility)

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