jsonl-exec

Tiny structured-concurrency helpers for running a subprocess that emits JSON messages on stdout, reports text lines on stderr, and exposes stdout as a consumable async channel.

It intentionally does not parse provider-specific schemas or agent events. It just manages:

• process startup
• stdout JSON line parsing
• stderr callbacks
• async receive queue
• cancellation and process-tree cleanup

Example

from wm_jsonl_subprocess import JsonLineProcessOptions, open_json_line_process


async def main() -> None:
    async with open_json_line_process(
        JsonLineProcessOptions(
            cmd="claude",
            args=["-p", "Hello", "--output-format", "stream-json"],
            on_stderr=print,
        )
    ) as process:
        while True:
            message = await process.receive()
            if message is None:
                break
            print(message)