jiggy-flow

Minimal, dependency-free Python projection of FLOW Run/0.

The SDK is prerelease software and requires Python 3.11 or newer. Install the latest published prerelease with python -m pip install --upgrade --pre jiggy-flow. See PyPI for available releases. Prereleases do not establish a stable compatibility promise. The SDK has no third-party runtime dependencies.

The Python guide walks through a complete method and a local Run/0 exchange. FLOW does not require Jig; execution support belongs to the chosen host. Its authoritative documents are Run SDK/0 and Run/0. This installed README contains a minimal quickstart.

Finite work uses handle() in the package's single FLOW.py entrypoint:

from jiggy.flow import RunContext, RunResult, handle


async def run(context: RunContext) -> RunResult:
    child = await context.call(
        operation_id="research:1",
        slot="research",
        intent="Research this request.",
        input=context.input,
    )
    return child


handle(run)

handle() owns the process's protocol stdin and stdout and handles exactly one root Run. Once called, it routes ordinary print() and sys.stdout output to diagnostic stderr, including output after handle() returns. Output written before handle() begins and raw writes to file descriptor 1 remain invalid protocol output. Handler cancellation uses ordinary asyncio.CancelledError. Cancelling a task awaiting call() sends the matching Run/0 cancellation notification.

call() invokes a declared local slot and returns the complete {"outcome": ..., "output": ...} result. Domain outcomes such as blocked or not-found are normal data; interpret them explicitly. Operational failures raise OperationError. The optional intent is advisory metadata, separate from the application input. An omitted channels map and channels={} retain distinct call identities. Calls have no method selector. A handler forwarding a result must declare any custom outcomes it can return in its own contract.

Optional FLOW.meta.json declares package metadata and dependency slots. Optional FLOW.contract.json owns input/result validation, custom outcomes, channels and caller attachments; settings.schema.json separately validates implementation settings. No descriptor is needed for unconstrained bounded input and a done result.

Direct channels

Channels exchange bounded JSON values while ordinary calls execute. On a host supporting the selected update contract, an application can filter Agent updates without confusing progress completion with the Agent's result:

import asyncio
from jiggy.flow import OperationError, RunContext, RunResult

async def run(context: RunContext) -> RunResult:
    updates = await context.channel(contract="./contracts/public-updates.json")

    async def invoke() -> RunResult:
        try:
            return await context.call(
                operation_id="answer", slot="agent", input=context.input,
                channels={"events": updates.send},
            )
        except (Exception, asyncio.CancelledError):
            try:
                await updates.receive.aclose()
            except (Exception, asyncio.CancelledError):
                pass  # Preserve the execution failure, including rejected admission.
            raise

    async def observe() -> None:
        try:
            async with updates.receive:
                async for value in updates.receive:
                    print(value, flush=True)  # Interpret and filter this contract's values.
        except OperationError as error:
            if error.code not in {"LAGGED", "DISCONNECTED"}:
                raise
            print("Progress delivery was incomplete.", flush=True)

    execution, observed = await asyncio.gather(invoke(), observe(), return_exceptions=True)
    if isinstance(execution, BaseException):
        raise execution
    if isinstance(observed, BaseException):
        raise observed
    return {"outcome": "done", "output": execution}

The package-local contract describes message meaning; the host must support that exact contract before dispatch. asyncio.gather starts execution and observation together and settles both. The application must still interpret the returned Agent outcome.

context.channels contains declared, host-granted endpoints. An unused endpoint can be passed through channels= on an ordinary call(). await sender.send(value) acknowledges host acceptance, not processing; await sender.close() seals the writer. await sender.close(error="LAGGED") declares incomplete observations: active receivers receive the stream failure, without cancelling execution. A prior clean end cannot be changed retroactively. Receivers provide one async iterator, start_sequence, and aclose(). Use async with or finally: await receiver.aclose() when iteration may stop early. Disposal settles prior reads and exposes a racing failure once; cancelling observation does not cancel the work.

Normal try/except remains sufficient for recoverable errors. Returning with unfinished owned work or an active unfinished receiver refuses success. Host ownership and cleanup—not channel EOF—determine execution completion.

Broadcast channels

Use await context.channel(delivery="broadcast") for one writer and independent receivers. The returned ChannelBroadcast has send and async subscribe():

updates = await context.channel(delivery="broadcast")
display = await updates.subscribe()
recorder = await updates.subscribe()

Pass the writer and each unused receiver through the same ordinary channels= call maps, then settle those calls. Each subscription is active immediately: consume it to its end or terminal failure, transfer it, or explicitly dispose it. The creator retains subscription authority when the writer moves; the source itself cannot move or enter JSON input. A later subscription receives only future values, with its actual start_sequence; there is no history replay.

A full subscriber fails with LAGGED without blocking the writer or another subscriber. Catch that error normally if incomplete observation is acceptable. No subscribers means no retained payload, not a queued history. Source closure rejects new subscriptions while existing subscribers drain their accepted prefixes. Channel completion still does not establish execution success.

The SDK supports direct and broadcast JSON channels, not binary transport, WebSockets or continuing Agent control. The wire ceilings remain 64 simultaneous requests and 65,536 request frames over the Run lifetime. Ordinary admission reserves one concurrent slot and endpoint-bounded request IDs for settlement; exhausted ordinary capacity waits or fails with RESOURCE_EXHAUSTED before consuming those reserves.