# Clients

A client is anything that drives the server. Every client speaks the
same gRPC service (see [Architecture](./architecture.md)): it sends
**commands** (browse the library, change the queue, control playback)
and subscribes to the **update stream** that pushes the current queue,
play state, track position, capture progress, and the frequency
spectrum as they change. Nothing is polled — each client redraws from
the pushed updates, so several clients driving one server always agree
on what is playing.

Because the contract is one shared service, the clients are the same
program wearing different skins. They differ only in how you interact
with them, not in what they can do.

```d2
direction: right

server: crabidy-server {
  shape: rectangle
}

tui: cbd-tui (terminal)
web: cbd-web (browser)
cbd: cbd (server + TUI)
cli: CLI subcommands

tui -> server: gRPC
web -> server: gRPC-web
cli -> server: gRPC (one-shot)
cbd -> server: localhost gRPC
```

- [Terminal UI — cbd-tui](./clients/tui.md) — the ratatui/crossterm
  terminal client, driven by vim-style keys.
- [Web client — cbd-web](./clients/web.md) — a Leptos/WASM browser
  client with the same functionality, served by the server itself.
- [The cbd bundle](./clients/cbd.md) — server and terminal client in
  one process for the single-machine case.
- [Command line](./clients/cli.md) — every binary is also a clap CLI;
  the `library`/`queue`/`global` subcommands are a scriptable remote
  control.

All clients authenticate the same way, using the role name as the
basic-auth user (see [Roles and authorization](./auth.md)). Connection
defaults live in each client's own config file (see
[Configuration](./config.md)).