plan-feature

A command for creating a detailed implementation plan for an Archon feature. Archon is the software project whose packages, interfaces, and workflows the plan examines.

In plain words
What is it for?
Use it before implementation to investigate the codebase, identify files and packages involved, coordinate research, and save a plan for the execute command.
Why use it?
It turns a feature request into defined goals, affected code, boundaries, interfaces, and checks for deciding whether the work is complete.

Command for Claude Code

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 commands/coleam00/archon/plan-feature
Clone the repo
git clone --depth 1 https://github.com/coleam00/Archon

Made for: Claude Code.

Per session 10 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,290 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00010 $0.01290
Opus 5 $0.00005 $0.00645
Sonnet 5 $0.00002 $0.00258
Haiku 4.5 $0.00001 $0.00129

Measured 3d ago against content hash 2d824ce16c7f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan-feature scanned grade A with 1 finding 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

5. Manual test: {specific curl command or UI steps to verify the feature}
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.claude/commands/plan-feature.md · 171 lines

How it starts

The opening of the file, as written. The whole thing — 171 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plan Feature: Comprehensive Archon Implementation Planning

Objective

Produce a detailed, actionable implementation plan for: $ARGUMENTS

The plan will be saved to .claude/archon/plans/{kebab-case-name}.md and is designed to be consumed by the /execute command.


Phase 1: Feature Understanding

Restate the feature request in your own words. Identify:

  1. Problem being solved — What user pain point or capability gap does this address?
  2. Success criteria — What does "done" look like? How will we verify it works?
  3. Scope boundaries — What is explicitly in scope vs. out of scope?
  4. Package impact — Which of the 8 packages are affected? (paths, git, isolation, workflows, core, adapters, server, web)
  5. Interface changes — Does this touch IPlatformAdapter, IAgentProvider, IDatabase, or IWorkflowStore? New interfaces needed?

Phase 2: Codebase Intelligence

Use subagents to perform targeted codebase research in parallel. Spawn separate subagents for:

Subagent A — Affected package deep-dive: Read all relevant source files in the affected packages. Map the current data flow. Identify every file that will need to change.

Subagent B — Interface and type contracts: Read packages/core/src/types/ and relevant index.ts exports. Understand what interfaces exist and how they're consumed across packages.

Subagent C — Test patterns: Find existing test files similar to the area of change:

find packages/ -name "*.test.ts" | head -30

Read 2-3 representative test files to understand mocking patterns, assertion style, and mock.module() isolation requirements per package.

Subagent D — Related prior work:

git log --oneline --all | head -20

Read recent commits touching relevant files to understand change patterns.

Synthesize findings: current state, gaps, constraints.


Phase 3: External Research (if needed)

If the feature involves external APIs, new libraries, or unfamiliar patterns, use web search to research:

Read the full file on GitHub · 171 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 · 171 lines · 10 tokens per session scan A 2d824ce16c7f

Subscribe to this mod's changes

plan-feature is a command published in the GitHub repository coleam00/Archon (23,339 stars, last pushed yesterday), licensed MIT. It adds 10 tokens to every session and 1,290 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.