Module flow 

Dynamic-workflow combinator core (P1).

A pure-Rust async combinator layer that reproduces the semantics of Claude Code “dynamic workflows” — [parallel] (barrier, fail-soft), [pipeline] (no-barrier per-item streaming), phase/log observability, and a run-wide concurrency cap — on top of the existing AgentRunner. A “workflow” is ordinary developer-written async Rust against these free functions; we do not embed a script engine, IR, or macro DSL.

These primitives are the deliberate duals of the compile-time workflow agents in crate::agent::workflow: [parallel] is fail-SOFT where ParallelAgent is fail-FAST, and [pipeline] has NO inter-item barrier where SequentialAgent advances stage-by-stage. Both layers coexist; nothing existing is changed.

Load-bearing invariant

The Err -> None collapse lives only in [parallel]/[pipeline] at the join/stage boundary, never inside [agent]. If agent() swallowed errors, the concurrency backstop (and, in later phases, the token budget) would stop propagating and silently break. Control errors must reach the caller; only agent-domain failures collapse to None.

Re-exports

pub use agent::agent;

pub use ctx::ProviderFactory;

pub use ctx::WorkflowCtx;

pub use event::log;

pub use event::phase;

pub use parallel::parallel;

pub use parallel::thunk;

pub use pipeline::pipeline;

Modules

agent

agent — the atomic unit of a workflow: spawn one sub-agent.

budget

Budget — a shared, lock-free, hard-ceiling spend pool for a workflow run.

ctx

WorkflowCtx — the shared run context threaded into every combinator.

event

Workflow-level events and the phase() / log() observability helpers.

journal

RunJournal — deterministic resume for workflow runs.

parallel

parallel — a BARRIER fan-out that is fail-SOFT and submission-ordered.

pipeline

pipeline — NO-BARRIER per-item streaming through a chain of stages.

progress

ProgressTracker — fold WorkflowEvents into a live RunProgress snapshot, the Rust analog of Claude Code’s /workflows progress view.

worktree

Git-worktree isolation for flow agent leaves (P5b).

Functions

workflow

Run body as a nested sub-workflow sharing this run’s budget, journal, concurrency cap, runaway backstop, and cancellation. Exactly one level of nesting is allowed: calling workflow() from inside a body returns Error::Config.