commit 95cb7f1878f3ea08e22d39f18fb2989ca4ecc1e4
Author: Matthew Gantenbein <ganten1998@gmail.com>
Date: Sun, 31 May 2026 10:50:26 -0500
P0: workspace skeleton — daemon/TUI handshake over Unix socket
Four-crate workspace (hydra-ipc / hydra-core / hydrad / hydra) replacing
Loopback, structured like valentine/ivory-rust. NDJSON wire protocol with
zero macOS deps keeps the ratatui TUI off CoreAudio. Daemon binds the control
socket and answers Ping/GetState; TUI renders the Navi-themed shell with live
connection status. Theme is a swappable TOML (Navi default).
7/7 tests green; builds clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Diffstat:
19 files changed, 1757 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
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diff --git a/Cargo.toml b/Cargo.toml
@@ -0,0 +1,14 @@
+[workspace]
+members = ["crates/hydra-ipc", "crates/hydra-core", "crates/hydrad", "crates/hydra"]
+resolver = "2"
+
+[workspace.package]
+version = "0.1.0"
+edition = "2021"
+license = "GPL-3.0-or-later"
+authors = ["Ganten"]
+
+[workspace.dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+dirs = "5"
diff --git a/README.md b/README.md
@@ -0,0 +1,41 @@
+# Hydra
+
+A terminal-native, functional replacement for [Loopback](https://rogueamoeba.com/loopback/) —
+create virtual audio devices, capture per-app audio, combine inputs, monitor, and map
+channels, all from a `ratatui` TUI. Navy/cyan/amber [Navi](https://github.com/ganten7/navi-palette)
+theme, swappable.
+
+> macOS only. Per-app capture needs **macOS 14.4+** (Core Audio process taps); the virtual
+> driver is a fork of [BlackHole](https://github.com/ExistentialAudio/BlackHole) (GPL-3.0).
+
+## Architecture
+
+| Piece | Crate / dir | Role |
+|-------|-------------|------|
+| Daemon | `crates/hydrad` | Owns **all** CoreAudio state; persists routing; the only process that links the engine. |
+| Engine | `crates/hydra-core` | Routing model, config, CoreAudio FFI (taps / aggregates / IOProcs). |
+| Wire protocol | `crates/hydra-ipc` | Shared NDJSON types over a Unix socket. **No macOS deps** — keeps the TUI off CoreAudio. |
+| TUI / query | `crates/hydra` | `ratatui` client + (P5) `hydra query --sketchybar`. |
+| Driver | `driver/` *(P2)* | Forked BlackHole publishing dynamic devices from a JSON manifest. |
+
+The daemon runs as a per-user **LaunchAgent** (GUI session — required for tap TCC consent).
+Clients talk to it over `~/Library/Application Support/hydra/hydrad.sock`.
+
+## Status
+
+**Phase 0 — skeleton.** Workspace builds; daemon answers `Ping`/`GetState`; TUI renders the
+Navi-themed shell and shows live connection status. CoreAudio engine + driver land in P1–P3.
+
+## Run it
+
+```sh
+cargo run -p hydrad # terminal 1: start the daemon
+cargo run -p hydra # terminal 2: the TUI (press q to quit, r to refresh)
+cargo test # unit tests (model + wire-format round-trips + theme parsing)
+```
+
+Swap the theme: copy `themes/navi.toml` to `~/Library/Application Support/hydra/theme.toml`.
+
+## License
+
+GPL-3.0-or-later (the BlackHole-derived driver makes this obligatory for the whole work).
diff --git a/crates/hydra-core/Cargo.toml b/crates/hydra-core/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "hydra-core"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+hydra-ipc = { path = "../hydra-ipc" }
+serde.workspace = true
+serde_json.workspace = true
+dirs.workspace = true
+
+# CoreAudio FFI (process taps, aggregate devices, IOProcs) lands in P1. The engine
+# modules will be gated behind #[cfg(target_os = "macos")] so the pure model/config
+# layer stays portable and unit-testable.
diff --git a/crates/hydra-core/src/lib.rs b/crates/hydra-core/src/lib.rs
@@ -0,0 +1,10 @@
+//! Hydra's routing core: the domain model, config persistence, and (from P1 onward)
+//! the CoreAudio engine. Only the daemon (`hydrad`) links this crate; the TUI talks to
+//! the daemon over [`hydra_ipc`] and never touches CoreAudio.
+
+pub mod model;
+
+pub use model::RoutingState;
+
+/// Daemon/engine version, surfaced to clients in snapshots.
+pub const VERSION: &str = env!("CARGO_PKG_VERSION");
diff --git a/crates/hydra-core/src/model.rs b/crates/hydra-core/src/model.rs
@@ -0,0 +1,80 @@
+//! The routing domain model. This is the authoritative in-memory state the daemon owns;
+//! [`RoutingState::snapshot`] projects it into the wire types in [`hydra_ipc`].
+//!
+//! P0 keeps this intentionally thin — sources, channel maps, monitors, and the live
+//! `MixSnapshot` arrive with the CoreAudio engine in P1–P3.
+
+use hydra_ipc::{DeviceSummary, RouteSummary, StateSnapshot};
+
+/// A virtual audio device Hydra publishes via the forked HAL driver.
+#[derive(Debug, Clone)]
+pub struct VirtualDevice {
+ pub uid: String,
+ pub name: String,
+ pub channels: u32,
+}
+
+/// A routing definition: sources mixed onto a target virtual device's channels.
+#[derive(Debug, Clone)]
+pub struct Route {
+ pub id: String,
+ pub target_device_uid: String,
+ /// Whether the route's CoreAudio objects are currently live.
+ pub active: bool,
+}
+
+/// The daemon's complete routing state.
+#[derive(Debug, Default)]
+pub struct RoutingState {
+ pub devices: Vec<VirtualDevice>,
+ pub routes: Vec<Route>,
+}
+
+impl RoutingState {
+ /// Project into a wire-safe snapshot for clients.
+ pub fn snapshot(&self) -> StateSnapshot {
+ StateSnapshot {
+ daemon_version: crate::VERSION.to_string(),
+ devices: self
+ .devices
+ .iter()
+ .map(|d| DeviceSummary { uid: d.uid.clone(), name: d.name.clone(), channels: d.channels })
+ .collect(),
+ routes: self
+ .routes
+ .iter()
+ .map(|r| RouteSummary {
+ id: r.id.clone(),
+ target: r.target_device_uid.clone(),
+ source_count: 0,
+ active: r.active,
+ })
+ .collect(),
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn empty_snapshot_carries_version() {
+ let snap = RoutingState::default().snapshot();
+ assert_eq!(snap.daemon_version, crate::VERSION);
+ assert!(snap.devices.is_empty());
+ assert!(snap.routes.is_empty());
+ }
+
+ #[test]
+ fn snapshot_projects_devices_and_routes() {
+ let state = RoutingState {
+ devices: vec![VirtualDevice { uid: "hydra:main".into(), name: "Main".into(), channels: 16 }],
+ routes: vec![Route { id: "r1".into(), target_device_uid: "hydra:main".into(), active: true }],
+ };
+ let snap = state.snapshot();
+ assert_eq!(snap.devices[0].channels, 16);
+ assert_eq!(snap.routes[0].target, "hydra:main");
+ assert!(snap.routes[0].active);
+ }
+}
diff --git a/crates/hydra-ipc/Cargo.toml b/crates/hydra-ipc/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "hydra-ipc"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+dirs.workspace = true
diff --git a/crates/hydra-ipc/src/lib.rs b/crates/hydra-ipc/src/lib.rs
@@ -0,0 +1,152 @@
+//! Shared wire protocol for Hydra: the only crate both the daemon (`hydrad`) and the
+//! TUI/query binary (`hydra`) depend on. Deliberately has **zero** macOS / CoreAudio
+//! dependencies so the TUI can never accidentally link the audio engine.
+//!
+//! Transport is newline-delimited JSON (NDJSON) over a Unix-domain socket: one serde
+//! value per line, hand-debuggable with `nc`.
+
+use serde::{Deserialize, Serialize};
+use std::io::{self, BufRead, Write};
+use std::path::PathBuf;
+
+/// Bumped when the wire format changes incompatibly.
+pub const PROTOCOL_VERSION: u32 = 1;
+
+/// `~/Library/Application Support/hydra` on macOS. The daemon keeps its socket, config,
+/// and theme here. Falls back to `/tmp/hydra` if the data dir can't be resolved.
+pub fn runtime_dir() -> PathBuf {
+ let mut p = dirs::data_dir().unwrap_or_else(|| PathBuf::from("/tmp"));
+ p.push("hydra");
+ p
+}
+
+/// Path to the daemon's control socket.
+pub fn socket_path() -> PathBuf {
+ let mut p = runtime_dir();
+ p.push("hydrad.sock");
+ p
+}
+
+// ── Request / response ────────────────────────────────────────────────────────
+
+/// A request from a client (TUI or `hydra query`) to the daemon.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum Command {
+ /// Liveness check.
+ Ping,
+ /// Fetch the current routing snapshot.
+ GetState,
+ /// Opt this connection into the server-push event stream (state deltas, meters).
+ Subscribe,
+ /// Ask the daemon to exit.
+ Shutdown,
+}
+
+/// The daemon's reply to a [`Command`].
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum Response {
+ Pong { version: u32 },
+ State(StateSnapshot),
+ Ok,
+ Error(String),
+}
+
+/// Server-initiated push messages (only sent after [`Command::Subscribe`]).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum Event {
+ StateChanged(StateSnapshot),
+}
+
+// ── Snapshot types ────────────────────────────────────────────────────────────
+
+/// A read-only view of the daemon's routing state, safe to render or print.
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+pub struct StateSnapshot {
+ pub daemon_version: String,
+ pub devices: Vec<DeviceSummary>,
+ pub routes: Vec<RouteSummary>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DeviceSummary {
+ pub uid: String,
+ pub name: String,
+ pub channels: u32,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RouteSummary {
+ pub id: String,
+ pub target: String,
+ pub source_count: usize,
+ pub active: bool,
+}
+
+// ── NDJSON framing ────────────────────────────────────────────────────────────
+
+fn invalid_data<E: std::fmt::Display>(e: E) -> io::Error {
+ io::Error::new(io::ErrorKind::InvalidData, e.to_string())
+}
+
+/// Serialize `msg` as a single JSON line and flush it to `w`.
+pub fn write_msg<W: Write, T: Serialize>(w: &mut W, msg: &T) -> io::Result<()> {
+ let mut line = serde_json::to_vec(msg).map_err(invalid_data)?;
+ line.push(b'\n');
+ w.write_all(&line)?;
+ w.flush()
+}
+
+/// Read one JSON line from `r`. Returns `Ok(None)` on clean EOF.
+pub fn read_msg<R: BufRead, T: for<'de> Deserialize<'de>>(r: &mut R) -> io::Result<Option<T>> {
+ let mut line = String::new();
+ if r.read_line(&mut line)? == 0 {
+ return Ok(None);
+ }
+ let trimmed = line.trim_end();
+ if trimmed.is_empty() {
+ return Ok(None);
+ }
+ serde_json::from_str(trimmed).map(Some).map_err(invalid_data)
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use std::io::BufReader;
+
+ #[test]
+ fn command_round_trips() {
+ let mut buf = Vec::new();
+ write_msg(&mut buf, &Command::Ping).unwrap();
+ let mut r = BufReader::new(&buf[..]);
+ let got: Option<Command> = read_msg(&mut r).unwrap();
+ assert!(matches!(got, Some(Command::Ping)));
+ }
+
+ #[test]
+ fn snapshot_round_trips() {
+ let snap = StateSnapshot {
+ daemon_version: "0.1.0".into(),
+ devices: vec![DeviceSummary { uid: "hydra:main".into(), name: "Main".into(), channels: 16 }],
+ routes: vec![RouteSummary { id: "r1".into(), target: "hydra:main".into(), source_count: 2, active: true }],
+ };
+ let mut buf = Vec::new();
+ write_msg(&mut buf, &Response::State(snap)).unwrap();
+ let mut r = BufReader::new(&buf[..]);
+ let got: Option<Response> = read_msg(&mut r).unwrap();
+ match got {
+ Some(Response::State(s)) => {
+ assert_eq!(s.devices.len(), 1);
+ assert_eq!(s.routes[0].source_count, 2);
+ }
+ other => panic!("unexpected: {other:?}"),
+ }
+ }
+
+ #[test]
+ fn eof_returns_none() {
+ let mut r = BufReader::new(&b""[..]);
+ let got: Option<Command> = read_msg(&mut r).unwrap();
+ assert!(got.is_none());
+ }
+}
diff --git a/crates/hydra/Cargo.toml b/crates/hydra/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "hydra"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "hydra"
+path = "src/main.rs"
+
+[dependencies]
+# The TUI depends on hydra-ipc ONLY — never hydra-core — so it can't link CoreAudio.
+hydra-ipc = { path = "../hydra-ipc" }
+ratatui = "0.29"
+crossterm = "0.28"
+serde.workspace = true
+serde_json.workspace = true
+dirs.workspace = true
+toml = "0.8"
diff --git a/crates/hydra/src/app.rs b/crates/hydra/src/app.rs
@@ -0,0 +1,66 @@
+//! TUI application state and the actions that mutate it. Rendering lives in `ui.rs`.
+
+use hydra_ipc::{Command, Response, StateSnapshot};
+
+use crate::client::Client;
+
+/// Whether we're currently talking to the daemon.
+#[derive(Debug, Clone)]
+pub enum Connection {
+ Connected { protocol: u32 },
+ Disconnected { reason: String },
+}
+
+pub struct App {
+ pub connection: Connection,
+ pub snapshot: StateSnapshot,
+ pub status: String,
+ pub should_quit: bool,
+}
+
+impl App {
+ pub fn new() -> Self {
+ let mut app = App {
+ connection: Connection::Disconnected { reason: "not yet connected".into() },
+ snapshot: StateSnapshot::default(),
+ status: String::new(),
+ should_quit: false,
+ };
+ app.refresh();
+ app
+ }
+
+ /// (Re)connect to the daemon, ping it, and pull the latest snapshot.
+ pub fn refresh(&mut self) {
+ match Client::connect() {
+ Ok(client) => match client.request(Command::Ping) {
+ Ok(Response::Pong { version }) => {
+ self.connection = Connection::Connected { protocol: version };
+ self.pull_state(&client);
+ self.status = "connected".into();
+ }
+ Ok(other) => {
+ self.connection = Connection::Disconnected { reason: format!("unexpected reply: {other:?}") };
+ }
+ Err(e) => {
+ self.connection = Connection::Disconnected { reason: e.to_string() };
+ }
+ },
+ Err(e) => {
+ self.connection = Connection::Disconnected { reason: format!("daemon not reachable ({e})") };
+ }
+ }
+ }
+
+ fn pull_state(&mut self, client: &Client) {
+ match client.request(Command::GetState) {
+ Ok(Response::State(snap)) => self.snapshot = snap,
+ Ok(other) => self.status = format!("unexpected state reply: {other:?}"),
+ Err(e) => self.status = format!("GetState failed: {e}"),
+ }
+ }
+
+ pub fn quit(&mut self) {
+ self.should_quit = true;
+ }
+}
diff --git a/crates/hydra/src/client.rs b/crates/hydra/src/client.rs
@@ -0,0 +1,28 @@
+//! Thin blocking client to the `hydrad` control socket. P0 does simple one-shot
+//! request/response calls; the persistent subscribe/event stream arrives in P4.
+
+use std::io::{BufReader, BufWriter};
+use std::os::unix::net::UnixStream;
+
+use hydra_ipc::{read_msg, write_msg, Command, Response};
+
+pub struct Client {
+ stream: UnixStream,
+}
+
+impl Client {
+ /// Connect to the daemon's socket, or error if it isn't running.
+ pub fn connect() -> std::io::Result<Self> {
+ let stream = UnixStream::connect(hydra_ipc::socket_path())?;
+ Ok(Self { stream })
+ }
+
+ /// Send one command and read exactly one response.
+ pub fn request(&self, cmd: Command) -> std::io::Result<Response> {
+ let mut writer = BufWriter::new(self.stream.try_clone()?);
+ let mut reader = BufReader::new(self.stream.try_clone()?);
+ write_msg(&mut writer, &cmd)?;
+ read_msg::<_, Response>(&mut reader)?
+ .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::UnexpectedEof, "daemon closed connection"))
+ }
+}
diff --git a/crates/hydra/src/main.rs b/crates/hydra/src/main.rs
@@ -0,0 +1,66 @@
+//! `hydra` — the terminal UI (and, from P5, the `query` subcommand for SketchyBar).
+//! P0: connect to `hydrad`, show connection status + (empty) routing state, Navi-themed.
+
+mod app;
+mod client;
+mod theme;
+mod ui;
+
+use std::error::Error;
+use std::io::{self, Stdout};
+use std::time::Duration;
+
+use crossterm::{
+ event::{self, Event, KeyCode, KeyEventKind},
+ execute,
+ terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
+};
+use ratatui::{backend::CrosstermBackend, Terminal};
+
+use app::App;
+use theme::Theme;
+
+type Tui = Terminal<CrosstermBackend<Stdout>>;
+
+fn main() -> Result<(), Box<dyn Error>> {
+ let mut terminal = setup_terminal()?;
+ let theme = Theme::load();
+ let result = run(&mut terminal, theme);
+ restore_terminal(&mut terminal)?;
+ result
+}
+
+fn run(terminal: &mut Tui, theme: Theme) -> Result<(), Box<dyn Error>> {
+ let mut app = App::new();
+ while !app.should_quit {
+ terminal.draw(|f| ui::draw(f, &app, &theme))?;
+
+ // Poll so the UI stays responsive; no busy loop.
+ if event::poll(Duration::from_millis(250))? {
+ if let Event::Key(key) = event::read()? {
+ if key.kind == KeyEventKind::Press {
+ match key.code {
+ KeyCode::Char('q') | KeyCode::Esc => app.quit(),
+ KeyCode::Char('r') => app.refresh(),
+ _ => {}
+ }
+ }
+ }
+ }
+ }
+ Ok(())
+}
+
+fn setup_terminal() -> Result<Tui, Box<dyn Error>> {
+ enable_raw_mode()?;
+ let mut stdout = io::stdout();
+ execute!(stdout, EnterAlternateScreen)?;
+ Ok(Terminal::new(CrosstermBackend::new(stdout))?)
+}
+
+fn restore_terminal(terminal: &mut Tui) -> Result<(), Box<dyn Error>> {
+ disable_raw_mode()?;
+ execute!(terminal.backend_mut(), LeaveAlternateScreen)?;
+ terminal.show_cursor()?;
+ Ok(())
+}
diff --git a/crates/hydra/src/theme.rs b/crates/hydra/src/theme.rs
@@ -0,0 +1,140 @@
+//! Swappable color theme. Defaults to the Navi palette but loads
+//! `~/Library/Application Support/hydra/theme.toml` (or a `--theme <path>`) if present,
+//! so the palette is configurable from day one and never hardcoded into widgets.
+
+use ratatui::style::Color;
+use serde::Deserialize;
+use std::path::{Path, PathBuf};
+
+/// Resolved colors used across the UI. Semantic roles, not raw palette names.
+#[derive(Debug, Clone)]
+pub struct Theme {
+ pub bg: Color,
+ pub bg_elevated: Color,
+ pub fg: Color,
+ pub fg_dim: Color,
+ /// Lone amber anchor — used sparingly for the primary accent.
+ pub accent: Color,
+ /// Ghost-light cyan — titles, cursor, active highlights.
+ pub ghost: Color,
+ pub border: Color,
+ pub success: Color,
+ pub warning: Color,
+ pub danger: Color,
+}
+
+impl Default for Theme {
+ /// The Navi palette (semantic subset). See ~/Dropbox/Projects/Libs/navi-palette.
+ fn default() -> Self {
+ Theme {
+ bg: rgb(0x10, 0x1e, 0x2e), // Deep Night Blue (main-bg)
+ bg_elevated: rgb(0x14, 0x2c, 0x4a), // Space Cadet (region-bg)
+ fg: rgb(0xe0, 0xf0, 0xff), // Alice Blue
+ fg_dim: rgb(0x78, 0x98, 0xb8), // Cadet Grey
+ accent: rgb(0xf0, 0x90, 0x30), // Amber (warm anchor)
+ ghost: rgb(0x40, 0xe8, 0xff), // Electric Cyan (ghost light)
+ border: rgb(0x26, 0x50, 0x80), // Payne's Grey
+ success: rgb(0x00, 0xe8, 0x98), // Caribbean Green
+ warning: rgb(0xf0, 0x90, 0x30), // Amber
+ danger: rgb(0xff, 0x60, 0x60), // Bittersweet
+ }
+ }
+}
+
+impl Theme {
+ /// Load from the standard config location, falling back to the Navi default.
+ pub fn load() -> Self {
+ Self::default_path()
+ .filter(|p| p.exists())
+ .and_then(|p| Self::from_file(&p).ok())
+ .unwrap_or_default()
+ }
+
+ /// `~/Library/Application Support/hydra/theme.toml`.
+ pub fn default_path() -> Option<PathBuf> {
+ dirs::data_dir().map(|d| d.join("hydra").join("theme.toml"))
+ }
+
+ /// Parse a theme file, using Navi defaults for any unspecified key.
+ pub fn from_file(path: &Path) -> Result<Self, Box<dyn std::error::Error>> {
+ let raw = std::fs::read_to_string(path)?;
+ let file: ThemeFile = toml::from_str(&raw)?;
+ let mut t = Theme::default();
+ let p = file.palette;
+ apply(&mut t.bg, p.bg);
+ apply(&mut t.bg_elevated, p.bg_elevated);
+ apply(&mut t.fg, p.fg);
+ apply(&mut t.fg_dim, p.fg_dim);
+ apply(&mut t.accent, p.accent);
+ apply(&mut t.ghost, p.ghost);
+ apply(&mut t.border, p.border);
+ apply(&mut t.success, p.success);
+ apply(&mut t.warning, p.warning);
+ apply(&mut t.danger, p.danger);
+ Ok(t)
+ }
+}
+
+#[derive(Debug, Deserialize)]
+struct ThemeFile {
+ #[allow(dead_code)]
+ name: Option<String>,
+ #[serde(default)]
+ palette: Palette,
+}
+
+#[derive(Debug, Default, Deserialize)]
+struct Palette {
+ bg: Option<String>,
+ bg_elevated: Option<String>,
+ fg: Option<String>,
+ fg_dim: Option<String>,
+ accent: Option<String>,
+ ghost: Option<String>,
+ border: Option<String>,
+ success: Option<String>,
+ warning: Option<String>,
+ danger: Option<String>,
+}
+
+const fn rgb(r: u8, g: u8, b: u8) -> Color {
+ Color::Rgb(r, g, b)
+}
+
+/// Parse `#rrggbb` (with or without the leading `#`).
+fn parse_hex(s: &str) -> Option<Color> {
+ let s = s.trim().trim_start_matches('#');
+ if s.len() != 6 {
+ return None;
+ }
+ let r = u8::from_str_radix(&s[0..2], 16).ok()?;
+ let g = u8::from_str_radix(&s[2..4], 16).ok()?;
+ let b = u8::from_str_radix(&s[4..6], 16).ok()?;
+ Some(Color::Rgb(r, g, b))
+}
+
+/// Overwrite `slot` only if `value` is present and parses.
+fn apply(slot: &mut Color, value: Option<String>) {
+ if let Some(c) = value.as_deref().and_then(parse_hex) {
+ *slot = c;
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn parses_hex_with_and_without_hash() {
+ assert_eq!(parse_hex("#40e8ff"), Some(Color::Rgb(0x40, 0xe8, 0xff)));
+ assert_eq!(parse_hex("101e2e"), Some(Color::Rgb(0x10, 0x1e, 0x2e)));
+ assert_eq!(parse_hex("nope"), None);
+ }
+
+ #[test]
+ fn default_is_navi() {
+ let t = Theme::default();
+ assert_eq!(t.ghost, Color::Rgb(0x40, 0xe8, 0xff));
+ assert_eq!(t.accent, Color::Rgb(0xf0, 0x90, 0x30));
+ }
+}
diff --git a/crates/hydra/src/ui.rs b/crates/hydra/src/ui.rs
@@ -0,0 +1,105 @@
+//! Ratatui rendering for the Hydra TUI. Pure view: reads [`App`] + [`Theme`], draws.
+
+use ratatui::{
+ layout::{Constraint, Direction, Layout, Rect},
+ style::{Modifier, Style},
+ text::{Line, Span},
+ widgets::{Block, Borders, Paragraph},
+ Frame,
+};
+
+use crate::app::{App, Connection};
+use crate::theme::Theme;
+
+pub fn draw(f: &mut Frame, app: &App, theme: &Theme) {
+ let base = Style::default().bg(theme.bg).fg(theme.fg);
+ f.render_widget(Block::default().style(base), f.area());
+
+ let chunks = Layout::default()
+ .direction(Direction::Vertical)
+ .constraints([
+ Constraint::Length(4), // header
+ Constraint::Min(1), // body
+ Constraint::Length(1), // footer
+ ])
+ .split(f.area());
+
+ draw_header(f, chunks[0], app, theme);
+ draw_body(f, chunks[1], app, theme);
+ draw_footer(f, chunks[2], theme);
+}
+
+fn draw_header(f: &mut Frame, area: Rect, app: &App, theme: &Theme) {
+ let (state_label, state_color) = match &app.connection {
+ Connection::Connected { protocol } => {
+ (format!("● daemon connected (protocol v{protocol})"), theme.success)
+ }
+ Connection::Disconnected { reason } => (format!("○ disconnected — {reason}"), theme.danger),
+ };
+
+ let title = Line::from(vec![
+ Span::styled("✦ Hydra", Style::default().fg(theme.ghost).add_modifier(Modifier::BOLD)),
+ Span::styled(" · audio routing", Style::default().fg(theme.fg_dim)),
+ ]);
+ let status = Line::from(Span::styled(state_label, Style::default().fg(state_color)));
+
+ let block = Block::default()
+ .borders(Borders::ALL)
+ .border_style(Style::default().fg(theme.border))
+ .style(Style::default().bg(theme.bg));
+ f.render_widget(Paragraph::new(vec![title, status]).block(block), area);
+}
+
+fn draw_body(f: &mut Frame, area: Rect, app: &App, theme: &Theme) {
+ let block = Block::default()
+ .title(Span::styled(" routes ", Style::default().fg(theme.accent)))
+ .borders(Borders::ALL)
+ .border_style(Style::default().fg(theme.border))
+ .style(Style::default().bg(theme.bg));
+
+ let body: Vec<Line> = if app.snapshot.routes.is_empty() {
+ vec![
+ Line::from(""),
+ Line::from(Span::styled(" No routes yet.", Style::default().fg(theme.fg_dim))),
+ Line::from(Span::styled(
+ " Per-app capture + virtual devices arrive in the next phases.",
+ Style::default().fg(theme.fg_dim),
+ )),
+ ]
+ } else {
+ app.snapshot
+ .routes
+ .iter()
+ .map(|r| {
+ let dot = if r.active { theme.success } else { theme.fg_dim };
+ Line::from(vec![
+ Span::styled(" ● ", Style::default().fg(dot)),
+ Span::styled(format!("{} ", r.target), Style::default().fg(theme.fg)),
+ Span::styled(
+ format!("◀ {} sources", r.source_count),
+ Style::default().fg(theme.fg_dim),
+ ),
+ ])
+ })
+ .collect()
+ };
+
+ f.render_widget(Paragraph::new(body).block(block), area);
+}
+
+fn draw_footer(f: &mut Frame, area: Rect, theme: &Theme) {
+ let hint = Line::from(vec![
+ key("r", theme),
+ Span::styled(" refresh ", Style::default().fg(theme.fg_dim)),
+ key("q", theme),
+ Span::styled(" quit", Style::default().fg(theme.fg_dim)),
+ ]);
+ f.render_widget(Paragraph::new(hint).style(Style::default().bg(theme.bg)), area);
+}
+
+fn key<'a>(k: &'a str, theme: &Theme) -> Span<'a> {
+ Span::styled(
+ format!(" {k} "),
+ Style::default().fg(theme.bg).bg(theme.ghost).add_modifier(Modifier::BOLD),
+ )
+}
diff --git a/crates/hydrad/Cargo.toml b/crates/hydrad/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "hydrad"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "hydrad"
+path = "src/main.rs"
+
+[dependencies]
+hydra-core = { path = "../hydra-core" }
+hydra-ipc = { path = "../hydra-ipc" }
+serde_json.workspace = true
diff --git a/crates/hydrad/src/main.rs b/crates/hydrad/src/main.rs
@@ -0,0 +1,45 @@
+//! `hydrad` — the Hydra daemon. It owns all CoreAudio state (from P1) and is the only
+//! process that touches the audio engine. Clients connect over a Unix-domain socket.
+//!
+//! P0 scope: bind the socket, answer `Ping`/`GetState`, hold an (empty) routing state.
+
+mod server;
+
+use std::error::Error;
+use std::fs;
+use std::os::unix::fs::PermissionsExt;
+use std::os::unix::net::UnixListener;
+use std::sync::{Arc, Mutex};
+
+use hydra_core::RoutingState;
+
+fn main() -> Result<(), Box<dyn Error>> {
+ let sock = hydra_ipc::socket_path();
+ if let Some(dir) = sock.parent() {
+ fs::create_dir_all(dir)?;
+ }
+ // A stale socket from a previous run would make bind() fail with EADDRINUSE.
+ let _ = fs::remove_file(&sock);
+
+ let listener = UnixListener::bind(&sock)?;
+ fs::set_permissions(&sock, fs::Permissions::from_mode(0o600))?;
+ eprintln!("hydrad {} listening on {}", hydra_core::VERSION, sock.display());
+
+ let state = Arc::new(Mutex::new(RoutingState::default()));
+
+ for conn in listener.incoming() {
+ match conn {
+ Ok(stream) => {
+ let state = Arc::clone(&state);
+ std::thread::spawn(move || {
+ if let Err(e) = server::handle(stream, state) {
+ eprintln!("connection error: {e}");
+ }
+ });
+ }
+ Err(e) => eprintln!("accept error: {e}"),
+ }
+ }
+
+ Ok(())
+}
diff --git a/crates/hydrad/src/server.rs b/crates/hydrad/src/server.rs
@@ -0,0 +1,31 @@
+//! Per-connection request handling. Each accepted socket runs on its own thread and
+//! processes a stream of NDJSON [`Command`]s, replying with a [`Response`] to each.
+
+use std::error::Error;
+use std::io::{BufReader, BufWriter};
+use std::os::unix::net::UnixStream;
+use std::sync::{Arc, Mutex};
+
+use hydra_core::RoutingState;
+use hydra_ipc::{read_msg, write_msg, Command, Response, PROTOCOL_VERSION};
+
+pub fn handle(stream: UnixStream, state: Arc<Mutex<RoutingState>>) -> Result<(), Box<dyn Error>> {
+ let mut reader = BufReader::new(stream.try_clone()?);
+ let mut writer = BufWriter::new(stream);
+
+ while let Some(cmd) = read_msg::<_, Command>(&mut reader)? {
+ let resp = match cmd {
+ Command::Ping => Response::Pong { version: PROTOCOL_VERSION },
+ Command::GetState => Response::State(state.lock().unwrap().snapshot()),
+ // Server-push subscription lands in P4; acknowledge for now.
+ Command::Subscribe => Response::Ok,
+ Command::Shutdown => {
+ write_msg(&mut writer, &Response::Ok)?;
+ std::process::exit(0);
+ }
+ };
+ write_msg(&mut writer, &resp)?;
+ }
+
+ Ok(())
+}
diff --git a/themes/navi.toml b/themes/navi.toml
@@ -0,0 +1,17 @@
+# Hydra theme — Navi palette (default).
+# Copy to ~/Library/Application Support/hydra/theme.toml and edit to swap palettes.
+# Any omitted key falls back to the built-in Navi default.
+
+name = "Navi"
+
+[palette]
+bg = "#101e2e" # Deep Night Blue
+bg_elevated = "#142c4a" # Space Cadet
+fg = "#e0f0ff" # Alice Blue
+fg_dim = "#7898b8" # Cadet Grey
+accent = "#f09030" # Amber — lone warm anchor
+ghost = "#40e8ff" # Electric Cyan — ghost light
+border = "#265080" # Payne's Grey
+success = "#00e898" # Caribbean Green
+warning = "#f09030" # Amber
+danger = "#ff6060" # Bittersweet
