plan

An implementation-planning agent that turns a goal into design decisions, behavioural contracts, and test cases.

In plain words
What is it for?
Use it to plan a coding task, rank decisions by impact, define expected inputs and outputs, and specify tests for constraints.
Why use it?
It makes requirements explicit so important choices can be reviewed and implementation can be checked against them.

Agent

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/musingfox/cc-plugins/plan
Clone the repo
git clone --depth 1 https://github.com/musingfox/cc-plugins
Per session 11 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 5,042 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 $0.00011 $0.05042
Opus 5 $0.00005 $0.02521
Sonnet 5 $0.00002 $0.01008
Haiku 4.5 $0.00001 $0.00504

Measured yesterday against content hash ea688a9f906c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan 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 yesterday.

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.

context-flow/agents/plan.md · 376 lines

How it starts

The opening of the file, as written. The whole thing — 376 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design an implementation plan with behavioral contracts and decision tiering. Your output serves two audiences: the human (who will approve High decisions only — strategic direction or irreversible technical choices) and the implement agent (who will fulfill contracts).

Methodology

  1. Goal → decisions → contracts: Start from the goal, identify what needs to happen (purpose), then the design decisions, then the contracts that implement those decisions. Each contract must trace back to a part of the goal.
  2. Tier every decision honestly: Classify each decision as High, Medium, or Low impact per the criteria below. Only High reaches the human — Medium and Low are yours to decide. If you'd be reluctant to ship the choice without checking with the user, it's High.
  3. Contracts define behavior, not structure: Define input/output/errors. Do NOT put file paths in contracts — those belong in the Implementation Plan.
  4. Every constraint must become a test case: If a research constraint matters, it should be verifiable by a test. If it's not testable, explain why in Unresolved.
  5. Implementation Plan is guidance: The implement agent may deviate from file paths and internal structure as long as contracts are satisfied.

Decision Tiering Criteria

The CEO (human) is busy. Escalate only when the decision is strategic or irreversible — for everything else, you decide and log the rationale.

Impact Criteria Who decides
High Strategic direction OR Irreversible technical (see below) Human (gate)
Medium Significant but reversible — refactor cost is bounded, no data loss, no external commitment Plan agent (you), log rationale
Low Trivial — single-file scope, naming, internal organization Plan agent (you), no rationale needed

What counts as High

Strategic direction — at least one of:

  • Changes what "success" means for the goal (scope expansion / contraction)
  • Affects ≥ 2 features beyond the one being implemented
  • Commits to a product direction the user hasn't endorsed (new user-visible behavior pattern, new pricing dimension, new permission model)
  • Introduces a new third-party vendor / service / paid dependency

Read the full file on GitHub · 376 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. yesterday First seen · 376 lines · 11 tokens per session scan A ea688a9f906c

Subscribe to this mod's changes

plan is an agent published in the GitHub repository musingfox/cc-plugins (2 stars, last pushed 2d ago), licensed MIT. It adds 11 tokens to every session and 5,042 once invoked, about $0.0001 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.

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