deep-plan

deep-plan is a skill for Claude Code from EthanSei/skills. It costs 98 tokens per session (3,108 once invoked), scanned A, original, MIT.

An architecture-planning review that asks several specialists to examine a proposed software design from different angles, such as security, data, speed, and maintainability. It then combines their trade-offs into an implementation-ready plan.

In plain words
What is it for?
Use it for substantial planning or architecture questions, such as designing APIs, data storage, or a larger system structure. It is intended for deliberate design work rather than small feature additions.
Why use it?
It helps expose design problems and competing priorities before code is written. This reduces the risk of committing to an architecture that works in one area but causes problems elsewhere.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents.

Good fit Use it for substantial planning or architecture questions, such as designing APIs, data storage, or a larger system structure. It is intended for deliberate design work rather than small feature additions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ethansei/skills/deep-plan
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.

Any agent
npx skills add EthanSei/skills --skill deep-plan
Clone the repo
git clone --depth 1 https://github.com/EthanSei/skills

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for deep-plan

README.md
[![agentmods](https://agentmods.dev/badge/skills/ethansei/skills/deep-plan/github.svg)](https://agentmods.dev/skills/ethansei/skills/deep-plan)
Your own site
<a href="https://agentmods.dev/skills/ethansei/skills/deep-plan"><img src="https://agentmods.dev/badge/skills/ethansei/skills/deep-plan/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for deep-plan

Your own site · 80×15
<a href="https://agentmods.dev/skills/ethansei/skills/deep-plan"><img src="https://agentmods.dev/badge/skills/ethansei/skills/deep-plan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 98 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,108 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00098 $0.03108
Opus 5.5 $0.00039 $0.01243
Sonnet 5.5 $0.00020 $0.00622
Haiku 4.5 $0.00010 $0.00311

Measured 2mo ago against content hash 4b8a29fca8b8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

deep-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 2mo 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.

skills/deep-plan/SKILL.md · 301 lines

How it starts

The opening of the file, as written. The whole thing — 301 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Deep Plan

Multi-perspective architecture planning. Spawns specialist agents for different quality-attribute concerns that evaluate trade-offs before you write code.

When This Skill Activates

Trigger on architecture and planning requests:

  • User says: "plan", "architect", "design", "how should I architect..."
  • User asks: "deep plan", "plan the architecture", "technical design"
  • User wants pre-implementation architecture evaluation

Do NOT activate on every task. This is for deliberate architecture planning, not quick feature additions. Simple features don't need a 6-agent swarm.

Phase 1: Context Gathering

Before spawning agents, establish scope:

  1. Check for deep-research artifact: Scan recent conversation context for the structured JSON artifact from deep-research (contains task, tech_stack, approaches, findings, verdict). Validate the artifact has at minimum: task, tech_stack, and at least one approach with a summary. If any required field is missing or empty, treat as if no artifact was found and fall through to step 2. If valid, use it as primary input — skip step 2 and use the recommended approach as the starting architecture to evaluate.
  2. If no artifact: Gather context manually:
    • Run git rev-parse --show-toplevel for {repo_root}
    • Check for package manifests to identify {tech_stack}. If no manifests are found, infer tech_stack from primary file extensions (.py, .ts, .go, etc.) or ask the user. Never pass an empty tech_stack to planning agents.
    • Ask the user what they're building and what constraints matter most
    • Read existing code in the affected area to understand current architecture
  3. speak-memory: If .speak-memory/index.md exists and an active story matches, read it for context. Skip if .speak-memory/ does not exist.
  4. Frame the architecture: State what is being planned:
    • Feature/System: What is being designed
    • Scope: Which components, modules, or layers are affected
    • Constraints: Performance targets, security requirements, compatibility needs
    • Starting approach: From deep-research artifact, or from user description
  5. Set scope budget: "Budget: 5 planning specialists + 1 trade-off arbiter = 6 agent calls." Present to user:

Read the full file on GitHub · 301 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2mo ago First seen · 301 lines · 98 tokens per session scan A 4b8a29fca8b8

Subscribe to this mod's changes

deep-plan is a skill published in the GitHub repository EthanSei/skills (2 stars, last pushed 8mo ago), licensed MIT. It adds 98 tokens to every session and 3,108 once invoked, about $0.0004 per session on Opus 5.5. 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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