Decision — Bus commands and app actions

Status: accepted 2026-10-24. Amends verb classes, instance verb families, executed commands, egui applications and commands take parameters.

The decision

• A dotted name a service answers is a Bus command. The command registry, command classes and command families keep the meaning the verb registry, classes and families had. Payloads say command, as the frame header already does.
• An app's registry entry is an action. <app>.actions lists them, <app>.execute runs one, <app>.action.executed publishes each run, and the registry crate is libs/action. The MCP edge tools are app_actions and app_execute.
• One refusal per kind: rc 10 with UNKNOWN_COMMAND for an unknown Bus command, from every component; UNKNOWN_ACTION for an unknown action.
• "Verb" is retired outside history (superseded decisions and changelogs). tools/terminology_gate.mix refuses it elsewhere.

Why

Most command names are not verbs, the wire and Mix already say "command", and ARexx, whose model Mix follows, sends commands to ports. Readers who know HTTP take "verb" to mean a closed method set, which in MixOS is the command class. Agents read these docs cold, so one concept gets one word, and one word means one concept.

Consequences

• Command registry schema 5: commands.conf.mix, gate tools/command_registry.mix.
• Every component's unknown-name refusal is renamed; tests and pages follow.
• Names other systems own keep their words: the generic bridge protocol's engine.commands and engine.execute, and polkit's action.lookup("verb").
• Stored state moves with the code: the props store renames its events column on open, and an install migrates hostd's standing grants (commands:) and receipts ("command").
• No aliases: the change is wire-breaking and ships in one release.