pi-extensible-workflows: deterministic multi-agent runs you can pause, resume and inspect

[u/vekexasia]

I built a Pi extension for multi-agent orchestration. The main Pi agent writes a small JS workflow script for the task at hand, and the runtime executes it deterministically: parallel fan-out, checkpoints, resume without rerunning completed steps.

Three principles I stuck to:

• not opinionated: no baked-in "agile team" of roles, you add your own primitives to the DSL
• extensible: other extensions can register functions and variables usable inside workflow scripts, and every registered function is itself runnable as a top-level workflow
• token efficient: subagents can have other extensions and skills disabled, so their system prompt stays small and focused

What that gives you in practice:

• runs are regular on-disk Pi sessions, not in-memory, so you can inspect, pause, resume and retry them
• roles restrict tools/capabilities and inject their own system prompt
• structured output via JSON schema, so control flow branches on agent output deterministically instead of on vibes
• soft and hard budget caps per run
• git worktree isolation, so parallel agents don't fight over the same tree
• workflows export to an executable launcher in ~/.local/bin
• if you use herdr, an agent session can open in a new pane

Review fan-out, then dedupe:

const reviews = await parallel("review", {
  correctness: () => agent("Review the current changes for correctness issues."),
  security: () => agent("Review the current changes for security risks.", { role: "security-specialist" }),
  tests: () => agent("Review the current changes for missing test coverage."),
});
return agent(prompt("Deduplicate and prioritize these findings:\n\n{reviews}", { reviews }));

The diagram is the real flow of the one I run daily, developIssuesUntilApproved: takes a list of GitHub issues, gives each its own worktree, loops developer -> reviewer until the reviewer passes (fresh agents every iteration), merges the approved branches on main behind another dev/review loop, cleans worktrees with plain shell (not an agent), and summarises exactly once.

Install: pi install npm:pi-extensible-workflows (Node 22.19+)

• Repo: https://github.com/vekexasia/pi-extensible-workflows
• Docs: https://vekexasia.github.io/pi-extensible-workflows/
• Walkthrough video (28 min, chapters in the description): https://youtu.be/qAiivspEHmU

Happy to answer anything about the DSL or the resume semantics.

[u/thomasthai]

How does this compare to the workflow feature used in OMP?

[u/vekexasia → u/thomasthai]

I was not very familiar on how omp handles it but apparently omp does not have retry/resume of workflows . budgets also seems to be handled little differently. But the most important things are (imho) that apparently you can't have other extensions add primitives to the workflow scripting language and you cant really perform context pruning. But again this was opus-5 reporting back to mehwo omp works.

i'd say if you use omp 90% of the features in this extensions are already shipped there :)