---
name: swarm
description: Fan out N parallel workers, drain them, and return one report. Use for
  /swarm, 'swarm this', or parallel coverage, races, gauntlets, and exploration.
license: MIT
---

## Host integration

Read [the Hapstack runtime contract](../hap-mode/references/runtime.md) once per task before model selection, delegation, external actions, or scheduling. Its host mappings and authorization rules govern the host-specific steps below.


# Swarm

Fan out N parallel cloud workers. They may cover separate slices, race the same brief, or mix both. The parent waits, aggregates, and returns one report.

## Start

Open a todolist with one entry per phase before launching anything.

1. Frame
2. Fan out
3. Aggregate
4. Report

## Phase A: Frame

1. State the done predicate and the artifact or report the swarm must return.
2. Choose the shape. Partition into slices, race N workers on identical briefs, or mix both. For a race or mixed shape, declare `first pass`, `rank all`, or `best-of` before spawning.
3. Set N from the user or derive it from the shape. N is total workers, not the cloud concurrency limit.
4. Pick the worker model from `swarm workers` through the runtime contract's project-first, XDG-aware configuration lookup. If that role is missing, use `inherit-parent`. For `auto` or `inherit-parent`, omit `model` so the workers run on the parent model. Resolve configured models against the live catalog using the runtime contract. If an entry is unavailable, report it and obtain a supported choice; never guess an ID or claim model diversity that is unavailable.
5. Give each worker its own writable output when it writes. When workers verify or measure commits, each brief names the exact SHAs. A measurement brief also names the method (sample count, what one sample is, order). The worker records both in its result.

## Phase B: Fan out

Spawn authorized workers through the host’s supported delegation interface, each with the configured role, scoped brief, and an isolated output location. Retain task/session IDs. Do not assume cloud execution or pass legacy environment fields.

When a worker must start from a non-default pushed branch, pass `cloud_base_branch`.

Every brief stands alone. Include the goal, scope, exact slice or race arm, how to verify, and what to report. Reports use `PASS`, `ISSUES`, or `BLOCKED` with evidence. A worker that can prove a defect reports `ISSUES` and lists every issue it can prove, not only the first.

If a worker drops out, proceed with N-1 and note it.

## Phase C: Aggregate

Read the terminal results. Drop a result that does not record the SHAs and method its brief names, and respawn that worker once. After a second miss, record a gap. A gap does not count as a pass. For coverage, every required slice needs a result. For a race, apply the selection rule declared up front. Use first pass, rank all, or best-of. Do not paste raw worker dumps.

Keep a compact result table, one-line evidenced issues, and explicit gaps or dropouts.

## Phase D: Report

Return one consolidated in-chat report with the table, issue one-liners, gaps or dropouts, and the race rule when used.