---
name: start
description: "Callable Spawn subcommand with root and conductor modes. Default root mode plants, plans, and drives the sprint; conductor mode starts persistent Conductor subagents from a gated plan."
---

# start: select root or conductor mode

Start is Spawn's callable subcommand for one explicit run. It never selects an ambient sprint,
but it does bootstrap what is missing rather than returning it as operator work: `shepherd
doctor`, `shepherd init --confirm`, `shepherd run init <run>`. Then adopt the profile the state
calls for — `planter` and `shepherd` are root profiles this session moves between, never
dispatched. No seed: adopt `planter` and author one.

The default mode is `root`. The only alternative is `--mode conductor`. Reject unknown,
repeated, or conflicting mode values before dispatch.

Require a trusted explicit-run binding and successful `shepherd run show <run> --json`.
Native owns state, transitions, locks, and lanes. Never edit state, scan sibling runs, or replay
completed stages. Every task names scope, acceptance, gate, and durable result.

## Default `root` mode

Root mode owns optional Plant, Engineer plus Critic, then sprint. Plant and verify only when
the selected planted run lacks a verified seed. When no verified plan exists, one persistent
`shepherd:engineer` orients and revises against read-only `shepherd:critic` findings until
`shepherd plan verify --run <run>` and Critic GREEN hold. Planned or executing runs resume
without repeating them.

Root then drives selected lanes with Shepherd-owned `implementing`, `reviewing`, `debugging`,
and `verification`; use `artifact-work` for bounded non-code output and consume cited
`researching` reports. Keep a durable ledger, fresh bounded implementer per task, independent
spec and quality review, fix-and-re-review loops, and one broad final review. Parallel writers
must be file-disjoint. Root integrates verified outcomes and closes the sprint.

## `--mode conductor`

`--mode conductor` is execution-only and skips Plant and Engineer without suggesting them.
Require a verified `planned` or `executing` run, passing plan verification, and ready lanes.

Move a `planned` run first with `shepherd run transition --to executing <run>`. This is not
a formality. The dispatch guard admits Shepherd to Conductor only at `executing`, and that
transition is what populates lanes, so dispatching a conductor against a `planned` run is
denied against an empty lane list. Check the lane preconditions after the transition,
against the lanes it produced.

Initialize one persistent subagent per lane, led by `shepherd:conductor` under Shepherd-owned
`lane-execution`. Each owns only its ledger, briefs, fresh implementers,
artifact workers, independent reviewers, bounded debugging, verification, and durable handoff.
Parallel scopes must be disjoint. Conductors never integrate, close, or merge. Root does.
When Spawn calls this mode, return commits, evidence, findings, risks, and restart needs to
that same invocation; Spawn retains lifecycle, delivery, and authorized release custody.