cos — overview

cos is the cosmix daemon family: every Rust crate that runs a node in a cosmix mesh, plus the substrate libraries they share. Where mix is the language you drive the mesh with, cos is what actually runs on each node — a set of long-running daemons that speak the Bus mesh protocol, expose their state as typed property namespaces, and are operable from the outside by agents and scripts.

This page is the orientation: what cos is, how the workspace is laid out, how it fits with its sibling repos, and where to go next.

What cos is

A single Cargo workspace of ~33 crates, split three ways:

  • Daemons — the long-running services: an Bus broker, a mail server, a web server, an authoritative DNS server, a knowledge indexer, and an agent supervisor — with the Wayland compositor and native apps in the sibling src/desktop/ workspace.
  • Helpers & adapters — CLI subcrates and integration shims the daemons lean on (the MCP bridge, the Claude SDK adapter, the mail data store, the mail auth / rules / spam subcrates).
  • Libraries — the shared substrate (cosmix-lib-*): property store, mesh peering, node identity, WireGuard config, logging, agent runtime pieces, and protocol codecs.

Every daemon is built to be legible (query its state as structured data), modifiable (write its config through structured channels, not ad-hoc file edits), and reconstructible (build and run it from a clean clone). Those three criteria are the substrate's design filter — the point of cos is a system an AI agent can observe, change, and rebuild.

The components

Pick any component in the sidebar for its own page.

Daemons

  • noded — the Bus broker. Every mesh node runs one; it routes service.node.bus addresses across the mesh.
  • maild — JMAP-native mail daemon (SMTP + IMAP + JMAP, Bayesian spam classifier, Sieve-style rules).
  • webd — multi-vhost HTTPS with automatic ACME certificates; server-rendered web UI over Datastar SSE.
  • dnsd — authoritative WireGuard-mesh DNS, zones generated from the mesh inventory.
  • indexd — vector knowledge base; auto-indexes workspaces on commit and powers agent recall.
  • desktop — the CosMix desktop: cosmix-comp (Smithay + Bevy Wayland compositor), the ctk toolkit and the native apps; protocol coverage on cosmix-comp.
  • agentd — agent supervision.
  • powerd — event-driven UPower battery and power-source state.
  • mprisd — event-driven MPRIS2 media-player state and delegated controls.

Bridge & libraries

  • mcp — the Claude Code MCP bridge; exposes cosmix surfaces as MCP tools plus a knowledge / skill-learning loop.
  • libraries — the shared cosmix-lib-* substrate crates.

How it fits — bus ← mix ← cos

cos is one of three public sibling repos with a one-way dependency order:

  • bus — the Bus protocol family. Depends on nothing.
  • mix — the language. Depends on bus.
  • cos — the daemon family. Depends on both: its config, DNS, mail, and agent crates consume the mix strict-data parser, and every daemon speaks Bus.

Neither sibling depends on cos. Build bus and mix first (see Build & install); the workspace clones expect sibling checkouts at $COSMIX and $COSMIX.

Building

# cos depends on two sibling checkouts under $HOME
git clone https://github.com/markc/cosmix $COSMIX
git clone https://github.com/markc/cosmix $COSMIX
git clone https://github.com/markc/cosmix $COSMIX

# build the whole daemon family (release)
cd $COSMIX/src && cargo build --workspace --release

Each daemon reads a small root-owned bootstrap config (/etc/cosmix/<daemon>/config.toml) before it contacts the mesh, then joins the Bus broker and exposes its runtime state through property namespaces.

See also