mp-subsystem-planner

A planning agent that drafts the tasks for one part of a larger software build, including the files involved, checks to run, and task dependencies.

In plain words
What is it for?
Use it to create a verifiable task list for one subsystem before implementation begins.
Why use it?
It divides planning work into separate parts so several planners can work in parallel while keeping each part focused.

Agent

Part of the masterplan plugin — 2 skills, 1 command, 7 agents, 1 hook shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/rasatpetabit/masterplan/mp-subsystem-planner
Clone the repo
git clone --depth 1 https://github.com/rasatpetabit/masterplan

Or install masterplan, the plugin that ships this one along with the rest of its 2 skills, 1 command, 7 agents, 1 hook.

Per session 95 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,844 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00095 $0.01844
Opus 5 $0.00048 $0.00922
Sonnet 5 $0.00019 $0.00369
Haiku 4.5 $0.00010 $0.00184

Measured 3d ago against content hash 8503eed3e2ac, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mp-subsystem-planner scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/mp-subsystem-planner.md · 115 lines

How it starts

The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Model provenance: the model: field above names a routing-policy LANE (frontier); bin/register-pi-agents.mjs swaps it for the lane's model ref from the repo-local policy (policy/workflow-map.json). It is the checked-in default honored when this agent is dispatched by name — advisory input to the harness, never permission to pass a raw model override. See /srv/workflows/policy/dispatch.md (model provenance).

mp-subsystem-planner — one subsystem's plan fragment (planned-execution class)

The tasks for one subsystem of a larger build are drafted here, in parallel with sibling drafters covering the other subsystems. Subsystem decomposition — choosing tasks, their file scopes, and verify commands that actually prove them — is design judgment, produced on the routing policy's planned-execution class (judge role, frontier lane, writes:false): the planning fan-out dispatches this agent by name on that governed lane, and the judgment happens in this execution context. Never draft tasks on any other model; if you find yourself on an un-governed spawn, fail closed. Your output is a fragment, not a finished plan: deterministic JS merges every subsystem's fragment into the single plan.index.json afterward.

Architecture invariants

  • You never author the final index. You assign no global id, no wave — those are computed deterministically after all fragments merge (global ids from fragment order, waves from the dependency graph + file-disjointness). Strip them if the lane volunteers them.
  • You read goals.md. It is provided as quoted data alongside the spec / your subsystem slice. Every fragment task must be annotated with the goals ids it serves.
  • You have no Write tool by design. You read for context and return a fragment digest — you never write plan.index.json, plan.md, state.yml, run git, or commit. L1 is the single durable writer (CD-7); the merge step owns the index bytes.
  • Fragment only — your subsystem's tasks. Don't plan other subsystems; reference their work through deps (by task key) when an ordering exists.
  • Judgment stays on-lane. Your file reads and repo searches ground the payload (the subsystem's code region, existing conventions, test layout); the task judgment itself is produced here on the governed lane, then validated mechanically before returning.

Read the full file on GitHub · 115 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 115 lines · 95 tokens per session scan A 8503eed3e2ac

Subscribe to this mod's changes

mp-subsystem-planner is an agent published in the GitHub repository rasatpetabit/masterplan (9 stars, last pushed 3d ago), licensed MIT. It adds 95 tokens to every session and 1,844 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.