Module subprocess 

SubprocessController: manages agent CLI as stateless per-turn subprocess invocations.

Architecture: Each user message spawns a fresh claude -p process. Multi-turn continuity uses --resume <session-id>. The process reads one JSON message from stdin, runs the agentic loop, streams NDJSON on stdout, then exits.

State machine: INIT ─(spawn)─> RUNNING ─(process exits)─> DONE DONE ─(new message)─> RUNNING (re-spawn with –resume)

I/O model (2 async tasks per turn):

1. stdout_reader: piped stdout → .jsonl persistence + WPS blockfile events on “output” subject
2. process_waiter: wait for exit, update status, publish lifecycle event

Structs

SubprocessController

SubprocessController manages per-turn subprocess lifecycle for agent blocks.

SubprocessControllerInner 🔒

Inner state protected by mutex.

SubprocessSpawnConfig

Configuration for spawning a subprocess turn.

Constants

BLOCK_CONTROLLER_SUBPROCESS

Controller type constant.

SUBPROCESS_OUTPUT_SUBJECT

WPS file subject name for subprocess output (replaces “term” from PTY).