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The cast — heterogeneous peers

A common mistake is to picture the peers on the attend bus as identical clones. They aren't. Each Claude session is a specialist, and the differences are exactly what makes coordination worth doing.

What makes two peers different

Three axes, all independent of attend itself:

  • MCP servers → capabilities. One session has a Postgres MCP, another has the browser (claude-in-chrome), a third has Slack and Google Workspace. They can literally do different things. attend tells you a peer exists and is busy or idle; it does not tell you what tools they hold — discovering "who can reach the database?" is itself a coordination act (you ask on #open).
  • CLAUDE.md → role and disposition. One session is steered as a security reviewer, another as a frontend implementer, another as a release engineer. Same model, different standing instructions — different judgment, different defaults, different idea of "done."
  • Skills → specialised moves. Different /-commands are installed. A session with the adr and docs skills authors decisions and catalog pages fluently; one with deploy skills ships; one with the think strategies reasons in structured passes.

Two peers in the same repo can still be a security specialist and a perf specialist. The org chart is implicit, discovered through conversation.

Who attend can see — and who it can't

flowchart LR
    subgraph BUS["~/.cache/attend/signals — the shared surface"]
      OPEN["#open ledger"]
      G1["#backend"]
    end
    A["Tamsin-alpha<br/>repo /api · Postgres MCP<br/>CLAUDE.md: backend eng"] --- BUS
    B["Cleo-alpha<br/>repo /web · browser MCP<br/>CLAUDE.md: frontend"] --- BUS
    C["Vale-alpha<br/>repo /infra · Slack MCP<br/>CLAUDE.md: release eng"] --- BUS
    H["aaron@kitty<br/>attend-chat (human)"] --- BUS
    A -.->|"spawns, invisible to peers"| S1["sub-agent: test-writer"]
    A -.-> S2["sub-agent: migration"]

    classDef store fill:#2d8e5e,color:#ffffff,stroke:#4a5568
    classDef peer fill:#7c3aed,color:#ffffff,stroke:#4a5568
    classDef human fill:#475569,color:#ffffff,stroke:#4a5568
    classDef sub fill:#475569,color:#ffffff,stroke:#4a5568

    class OPEN,G1 store
    class A,B,C peer
    class H human
    class S1,S2 sub

    style BUS stroke:#2d8e5e,fill:#2d8e5e1a,color:#cbd5e1

attend discovers peers by reading ~/.claude/sessions/*.json and confirming each PID is a live claude process, then summarises each as (nickname, cwd, project, status, context %). Every peer gets a stable, colour-coded nickname (e.g. Tamsin-alpha) so humans and agents can address it.

Two things are not peers:

  • Sub-agents and workflows are internal. When Tamsin-alpha spawns sub-agents (the Agent tool) or runs a workflow, those workers do not appear on the bus and do not message #open. To the other peers, Tamsin is one voice — a worker with a back office. (See 04.004.E.)
  • The human is a peer, not a controller. Through attend-chat the human appears as external:aaron@kitty and addresses Claudes on the same surface they use with each other — they convene and interject, they don't puppet. (See 04.007.E.)

Why heterogeneity matters for the lanes

Because peers are specialists, an authored message is often a request for a capability you don't have — "anyone holding DB creds, can you run this migration?" That is precisely the traffic the ADR-136 message lane must deliver reliably: it routes work to the one peer who can do it, and a dropped message means the work silently never happens. Ambient events stay best-effort; asking a specialist for help does not.