subagent-orchestration

name	subagent-orchestration
description	How and when to delegate work to subagents via the `subagent` tool (Explore, Plan). Use when a task involves codebase recon or implementation planning that would benefit from an isolated, read-only context window instead of doing it all inline.

Subagent Orchestration

You (the parent session) can delegate scoped work to focused subagents, each running in its own isolated pi process with its own context window. Use this to keep your own context clean and to parallelize independent work.

When to delegate

Delegate when a piece of work is:

• Self-contained: it doesn't need your full conversation history, just a task and some context you can state explicitly.
• Isolable: it would otherwise burn a lot of your context window (e.g. broad codebase search, reading many files) for a result you can summarize down to a few paragraphs.
• Parallelizable: several independent instances of it can run at once (e.g. exploring two unrelated areas of a large codebase in the same turn).

Do not delegate trivial one-line changes, or work that fundamentally needs your full conversation context to do correctly — that's what context (below) is for, but if almost everything is relevant, delegation adds overhead for no benefit.

Bundled agents

Agent	Use for	Tools	Model	Notes
Explore	Fast, read-only recon: find files, entry points, data flow	read, bash, grep, find, ls	Fast/cheap model, falls back to your current model	Reports compressed findings, never edits
Plan	Turn Explore's findings (or your own) into a concrete implementation plan	read, bash, grep, find, ls	Inherits your current model	Never edits

Both bundled agents are read-only. There is no bundled agent that writes — do any actual editing yourself, in the parent session, after Explore/Plan give you what you need.

Subagents cannot themselves call subagent — they are leaves, not orchestrators. Keep all delegation decisions in your own (parent) session.

A project can add its own agents (including ones that write) as .pi/agents/<name>.md files — same frontmatter convention as the bundled agents above. See agentScope below.

The context field — always fill it in

A subagent gets only its task string, plus a small automatic digest of your last few conversation turns (as a fallback, not a substitute). It does not see the files you've already read, tool results you've already seen, or decisions you've already made unless you put them in context.

Always pass context with whatever the subagent actually needs:

• File paths and line numbers you already found.
• Decisions already made ("use approach B, not A, because...").
• Constraints ("don't touch files under vendor/").

A subagent given a bare one-line task and no context will waste its own turns re-discovering things you already know.

Modes

• single — one agent, one task. Default choice.
• parallel — tasks: [...], up to 8 tasks / 4 concurrent. Use for independent work that can run at once, e.g. Exploreing two unrelated parts of a codebase together.

There is no chain mode. For a fixed pipeline (e.g. explore then plan), just call subagent twice in sequence yourself and pass the first call's output back in as the second call's context — you are already the orchestrator holding both results.

Recommended pattern

clarify -> Explore -> Plan -> implement it yourself -> confirm before any risky follow-up

This is guidance, not a rigid workflow — decide per task whether you need both steps. For a small, well-understood change, skip straight to implementing it yourself.

Observability

Every run writes status.json, events.jsonl, and a full transcript.md to ~/.pi/agent/subagent-runs/<runId>/ for later inspection.