spawnInteractive == spawnAgent in process-spawner, but interactive (broker-PTY) steps have weaker completion guarantees — unify or document

[khaliqgant]

Summary

In `dist/process-spawner.js`, `spawnAgent` and `spawnInteractive` are implemented identically — both `runCommand(buildAgentCommand(agent, task))`, and `buildCommand` (~line 21) always uses `definition.nonInteractiveArgs(...)`. So at the process-spawner layer there is no behavioral difference between a worker and an interactive agent.

Yet interactive agents in practice run via a broker-PTY-backed path (`agent-relay-broker pty --agent-name ...`) whose completion detection is the flaky one (see the owner-completion issue), while `interactive: false` agents go through spawnAgent and reliably complete on process exit.

Ask

• Document the two execution backends (process-spawner vs broker-PTY) and where step-executor routes each (`if (agent.interactive === false) spawnAgent else spawnInteractive`).
• Give the broker-PTY interactive path the SAME completion guarantee as the process-exit path, or unify them.
• If spawnInteractive is meant to differ from spawnAgent, make it actually differ + documented; the dead-identical methods are currently misleading.

Evidence

step-executor.js routes on `agent.interactive === false`; process-spawner.js methods are byte-identical; coordinator.js/channel-messenger.js exclude `interactive:false` agents from message edges. The observed reliability gap is NOT explained by process-spawner — it lives in the broker-PTY path used for interactive agents.