Ingress

The same stack of rules can answer a web request, an inbound email, a scheduled tick, and an AI agent’s tool call. Whatever the wire protocol, the chassis wraps what arrives in one JSON envelope — payload plus a _txc.* namespace recording where it came from — and hands it to your rules. A rule doesn’t care which channel fired it unless it asks.

Channel	Arrives as	Envelope says
Web	HTTP request on :8080	@src = "http", @web.req.*
Email	Inbound mail via LMTP (behind Postfix)	@src = "lmtp", @lmtp.*
Cron	A scheduled tick	@src = "cron"
TCP	Line-delimited JSON on :5050	@src = "tcp"
AI agents	An MCP tool call	rules exposed as tools

So a support flow can read like a sentence: when mail arrives for support@, classify it; when the web form posts, enter the same flow; every morning at nine, sweep what’s still open. One stack, three channels — three beats of the same arc — no glue code.

Routing: which rules see the event

Before any rule fires, the ingress router answers two questions: which tenant does this event belong to, and which op stack should it enter? It matches on the channel’s natural key — the HTTP Host header, the mail recipient, the cron job name — and stamps the answer onto the envelope as @tenant and @stack.

A single-tenant chassis needs none of this; events fall through to the default boot stack and everything just works. Configure routing when you host multiple tenants or bind custom domains:

ingress:
  http:
    hosts:
      acme.example.com: { tenant: acme, stack: acme/web }
  lmtp:
    recipients:
      "support@acme.example": { tenant: acme, stack: acme/support }

Email is a first-class citizen

Inbound mail isn’t a webhook bolted on — the chassis speaks LMTP behind a standard Postfix, so a message becomes a normal event with recipient, subject, headers, body, and attachments readable by any rule. Each recipient routes independently to its own tenant and stack: support@acme.example can enter a different flow than billing@acme.example. And getting the address is one NS delegation — the chassis can run a subdomain’s DNS and synthesize the mail records itself (Domains).

AI agents speak it too

MCP (Model Context Protocol) runs in both directions: rules can expose themselves as tools that agents like Claude invoke (ingress), and a rule can call an external MCP tool with EXEC "mcp+https://…" (egress). An agent becomes one more participant in the flow — entering through the same envelope, leaving the same trace.

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Per-channel facts — request/response mapping, timeouts, flags — live in the protocol references, one page per channel.