Dev-only GenServer that triggers recompilation on router source changes.

It watches the router's own source file and every handler module's source file, via RpcElixir.Router.source_files/1. Middleware and custom-type modules are not watched, even though editing them changes the output.

Requires the optional :file_system dep. Without it, init/1 warns and returns :ignore. The process never starts.

It is Phoenix-specific. Without :endpoint or :on_change there is nothing to do on a change. Non-Phoenix apps do not need it. Mix.Tasks.Compile.ElixirTsRpc already regenerates the client on each Elixir recompile.

Usage

# lib/my_app/application.ex  (Phoenix projects only)
children = [
  {RpcElixir.Watcher, router: MyApp.Router, endpoint: MyAppWeb.Endpoint}
]

Options

• :router (required) — the RPC router module. A missing :router raises KeyError, even when :file_system is absent.

• :endpoint — a Phoenix endpoint. The watcher calls Phoenix.CodeReloader.reload/1 on each relevant change. That reloads only the endpoint's :reloadable_compilers, which by default excludes :elixir_ts_rpc. So add it there, or the client is not regenerated:

  reloadable_compilers: [:gettext, :elixir, :app, :elixir_ts_rpc]

  Use :on_change instead to call codegen directly.

• :on_change — {mod, fun, args} invoked on change. Takes precedence over :endpoint when both are given.

• :debounce_ms — coalesces rapid file events. Defaults to 200.

Restart expectations

The linked FileSystem process starts inside init/1. The watcher traps exits, so a FileSystem crash arrives as a message rather than killing the watcher silently. The watcher then stops with {:filesystem_exited, reason}. The supervisor is expected to restart the pair.