Agent skill

Speckit Plan

by kunstmusik in kunstmusik/blue

Execute the implementation planning workflow using the plan template to generate design artifacts.

GPL-3.0Auto-check passedDevelopment

Install Speckit Plan

skills CLI
$ npx skills add kunstmusik/blue --skill speckit-plan -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install kunstmusik/blue speckit-plan --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/kunstmusik/blue.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/speckit-plan .claude/skills/speckit-plan && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
speckit-plan
GitHub stars
154
Used in
19 other repos
Token cost
~2.1k tokens
SKILL.md length
982 words
Files
1
Skills in repo
16
Repo updated
First seen
Licence
GPL-3.0

At a glance

Execute the implementation planning workflow using the plan template to generate design artifacts.

  • Works in 2 steps: Outline & Research → Design & Contracts
  • Tasks that involve Spec-driven development
  • SKILL.md covers User Input, Pre-Execution Checks, Outline and Mandatory Post-Execution Hooks, plus 4 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Speckit Plan is an agent skill from kunstmusik/blue. Execute the implementation planning workflow using the plan template to generate design artifacts.

Its SKILL.md is about 2.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Requires spec-kit project structure with .specify/ directory

It sits in Development, covering Spec-driven development. The repository describes itself as: Blue - An Integrated Music Environment. The licence is GPL-3.0.

When your agent uses it

  • Tasks that involve Spec-driven development

Example prompts

  • “/speckit-plan”

Requirements

  • Compatibility (from SKILL.md): Requires spec-kit project structure with .specify/ directory

Workflow steps

2 steps, taken from the step headings in SKILL.md.

  1. Outline & Research
  2. Design & Contracts

What it can do on your machine

Read from SKILL.md and the folder at commit 3c32d58. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Requires spec-kit project structure with .specify/ directory

    From compatibility in the SKILL.md frontmatter.

Context cost

Speckit Plan loads about 2.1k tokens when it runs. Until then it costs about 28 tokens; SKILL.md has 982 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~28
When it runs · the whole SKILL.md, loaded when a task matches
~2.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from kunstmusik/blue at commit 3c32d58, republished under its GPL-3.0 licence (© kunstmusik). 982 words, ~2,054 tokens.

Download SKILL.mdSave it as .claude/skills/speckit-plan/SKILL.md (or your agent's skills folder).
name
speckit-plan
description
Execute the implementation planning workflow using the plan template to generate design artifacts.
compatibility
Requires spec-kit project structure with .specify/ directory
metadata.author
github-spec-kit
metadata.source
templates/commands/plan.md

User Input

text
$ARGUMENTS

You MUST consider the user input before proceeding (if not empty).

Pre-Execution Checks

Check for extension hooks (before planning):

  • Check if .specify/extensions.yml exists in the project root.
  • If it exists, read it and look for entries under the hooks.before_plan key
  • If the YAML cannot be parsed or is invalid, do not skip silently: tell the user that .specify/extensions.yml could not be read (include the parser error) and that no hooks were checked, including any mandatory (optional: false) hooks registered there, then continue normally
  • Filter out hooks where enabled is explicitly false. Treat hooks without an enabled field as enabled by default.
  • For each remaining hook, do not attempt to interpret or evaluate hook condition expressions:
    • If the hook has no condition field, or it is null/empty, treat the hook as executable
    • If the hook defines a non-empty condition, skip the hook and leave condition evaluation to the HookExecutor implementation
  • When constructing command invocations from hook command names, replace dots (.) with hyphens (-). For example, speckit.git.commit → $speckit-git-commit.
  • For each executable hook, output the following based on its optional flag:
    • Optional hook (optional: true):
      ## Extension Hooks
      
      **Optional Pre-Hook**: {extension}
      Command: `/{command}`
      Description: {description}
      
      Prompt: {prompt}
      To execute: `/{command}`
    • Mandatory hook (optional: false):
      ## Extension Hooks
      
      **Automatic Pre-Hook**: {extension}
      Executing: `/{command}`
      EXECUTE_COMMAND: {command}
      
      Wait for the result of the hook command before proceeding to the Outline.
      After emitting the block above you MUST actually invoke the hook and wait for it to finish before continuing. Run it the same way you would run the command yourself in this agent/session (the invocation may differ from the literal {command} id shown above, e.g. a skills-mode agent runs it as /skill:speckit-... or $speckit-...). Emitting the block alone does not run the hook.
  • If no hooks are registered or .specify/extensions.yml does not exist, skip silently

Outline

  1. Setup: Run .specify/scripts/bash/setup-plan.sh --json from repo root and parse JSON for FEATURE_SPEC, IMPL_PLAN, FEATURE_DIR, BRANCH. For single quotes in args like "I'm Groot", use escape syntax: e.g 'I'''m Groot' (or double-quote if possible: "I'm Groot").

  2. Load context: Read FEATURE_SPEC and .specify/memory/constitution.md. Load IMPL_PLAN template (already copied).

  3. Execute plan workflow: Follow the structure in IMPL_PLAN template to:

    • Fill Technical Context (mark unknowns as "NEEDS CLARIFICATION")
    • Fill Constitution Check section from constitution
    • Evaluate gates (ERROR if violations unjustified)
    • Phase 0: Generate research.md (resolve all NEEDS CLARIFICATION)
    • Phase 1: Generate data-model.md, contracts/, quickstart.md
    • Re-evaluate Constitution Check post-design

Mandatory Post-Execution Hooks

You MUST complete this section before reporting completion to the user.

Check if .specify/extensions.yml exists in the project root.

  • If it does not exist, or no hooks are registered under hooks.after_plan, skip to the Completion Report.
  • If it exists, read it and look for entries under the hooks.after_plan key.
  • If the YAML cannot be parsed or is invalid, do not skip silently: tell the user that .specify/extensions.yml could not be read (include the parser error) and that no hooks were checked, including any mandatory (optional: false) hooks registered there, then continue to the Completion Report.
  • Filter out hooks where enabled is explicitly false. Treat hooks without an enabled field as enabled by default.
  • For each remaining hook, do not attempt to interpret or evaluate hook condition expressions:
    • If the hook has no condition field, or it is null/empty, treat the hook as executable
    • If the hook defines a non-empty condition, skip the hook and leave condition evaluation to the HookExecutor implementation
  • When constructing command invocations from hook command names, replace dots (.) with hyphens (-). For example, speckit.git.commit → $speckit-git-commit.
  • For each executable hook, output the following based on its optional flag:
    • Mandatory hook (optional: false) — You MUST emit EXECUTE_COMMAND: for each mandatory hook:
      ## Extension Hooks
      
      **Automatic Hook**: {extension}
      Executing: `/{command}`
      EXECUTE_COMMAND: {command}
      After emitting the block above you MUST actually invoke the hook and wait for it to finish before continuing. Run it the same way you would run the command yourself in this agent/session (the invocation may differ from the literal {command} id shown above, e.g. a skills-mode agent runs it as /skill:speckit-... or $speckit-...). Emitting the block alone does not run the hook.
    • Optional hook (optional: true):
      ## Extension Hooks
      
      **Optional Hook**: {extension}
      Command: `/{command}`
      Description: {description}
      
      Prompt: {prompt}
      To execute: `/{command}`
Show full SKILL.md (317 more words)Show less

Completion Report

Command ends after Phase 1 design. Report branch, IMPL_PLAN path, and generated artifacts.

Phases

Phase 0: Outline & Research
  1. Extract unknowns from Technical Context above:

    • For each NEEDS CLARIFICATION → research task
    • For each dependency → best practices task
    • For each integration → patterns task
  2. Generate and dispatch research agents:

    text
    For each unknown in Technical Context:
      Task: "Research {unknown} for {feature context}"
    For each technology choice:
      Task: "Find best practices for {tech} in {domain}"
  3. Consolidate findings in research.md using format:

    • Decision: [what was chosen]
    • Rationale: [why chosen]
    • Alternatives considered: [what else evaluated]

Output: research.md with all NEEDS CLARIFICATION resolved

Phase 1: Design & Contracts

Prerequisites: research.md complete

  1. Extract entities from feature spec → data-model.md:

    • Entity name, fields, relationships
    • Validation rules from requirements
    • State transitions if applicable
  2. Define interface contracts (if project has external interfaces) → /contracts/:

    • Identify what interfaces the project exposes to users or other systems
    • Document the contract format appropriate for the project type
    • Examples: public APIs for libraries, command schemas for CLI tools, endpoints for web services, grammars for parsers, UI contracts for applications
    • Skip if project is purely internal (build scripts, one-off tools, etc.)
  3. Create quickstart validation guide → quickstart.md:

    • Document runnable validation scenarios that prove the feature works end-to-end
    • Include prerequisites, setup commands, test/run commands, and expected outcomes
    • Use links or references to contracts and data model details instead of duplicating them
    • Do not include full implementation code, model/service/controller bodies, migrations, or complete test suites
    • Keep this artifact as a validation/run guide; implementation details belong in tasks.md and the implementation phase

Output: data-model.md, /contracts/*, quickstart.md

Key rules

  • Use absolute paths for filesystem operations; use project-relative paths for references in documentation
  • ERROR on gate failures or unresolved clarifications

Done When

  • Plan workflow executed and design artifacts generated
  • Extension hooks dispatched or skipped according to the rules in Mandatory Post-Execution Hooks above
  • Completion reported to user with branch, plan path, and generated artifacts

© kunstmusik, GPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/speckit-plan of kunstmusik/blue.

Open the folder on GitHubat commit 3c32d58

Used in 19 other repositories

We found 21 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 19 other GitHub owners. This page covers the copy in kunstmusik/blue, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Speckit Plan next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Speckit Plan compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Speckit Plan this skillkunstmusik/blue15419 repos~2.1kAutomated safety check: PassGPL-3.0
OpenSpec Bulk Change ArchiverFission-AI/OpenSpec72k2 repos~5.6kAutomated safety check: PassMIT
Speckit ConstitutionWeihanLi/WeihanLi.Common24212 repos~2.1kAutomated safety check: PassApache-2.0
Review Spdzhu1090093659/spec_driven_develop987—~1.5kAutomated safety check: PassMIT
React Router RFC Implementerremix-run/react-router57k—~2.3kAutomated safety check: PassMIT
Ss SpecSerial-Studio/Serial-Studio7.2k—~766Automated safety check: PassCustom licence

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More from kunstmusik/blue

All 16 skills in this repo
  • Speckit Specify

    kunstmusik/blue

    Create or update the feature specification from a natural language feature description.

    154 GitHub starsUsed in 19 repos~4.7k tokens
    Auto-check passed
  • Speckit Tasks

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    Generate an actionable, dependency-ordered tasks.md for the feature based on available design artifacts.

    154 GitHub starsUsed in 19 repos~3k tokens
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  • Speckit Analyze

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    Perform a non-destructive cross-artifact consistency and quality analysis across spec.md, plan.md, and tasks.md after task generation.

    154 GitHub starsUsed in 18 repos~3k tokens
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  • Karpathy Coder

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    A skill your agent uses when writing, reviewing, or committing code to enforce Karpathy's 4 coding principles — surface assumptions before coding, keep it simple, make surgical changes, define…

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  • Speckit Clarify

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    Identify underspecified areas in the current feature spec by asking up to 5 highly targeted clarification questions and encoding answers back into the spec.

    154 GitHub starsUsed in 18 repos~4.9k tokens
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  • Speckit Taskstoissues

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    Convert existing tasks into actionable, dependency-ordered GitHub issues for the feature based on available design artifacts.

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Categories

Questions about Speckit Plan

What does Speckit Plan do?

Execute the implementation planning workflow using the plan template to generate design artifacts. Speckit Plan is an agent skill from kunstmusik/blue. Execute the implementation planning workflow using the plan template to generate design artifacts.

When should I use Speckit Plan?

Speckit Plan fits situations like: tasks that involve Spec-driven development.

How do I install Speckit Plan in Claude Code?

Run `npx skills add kunstmusik/blue --skill speckit-plan -a claude-code`. Or copy the skill folder (.agents/skills/speckit-plan in kunstmusik/blue) into .claude/skills/speckit-plan in your project. Claude Code loads it when a task matches its description.

How do I install Speckit Plan in Codex?

Run `npx skills add kunstmusik/blue --skill speckit-plan -a codex`. Or copy the skill folder (.agents/skills/speckit-plan in kunstmusik/blue) into .agents/skills/speckit-plan in your project. Codex loads it when a task matches its description.

Can I use Speckit Plan in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add kunstmusik/blue --skill speckit-plan -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/speckit-plan, .gemini/skills/speckit-plan, .github/skills/speckit-plan and .opencode/skills/speckit-plan in your project.

What does Speckit Plan need to run?

SKILL.md names no scripts, command-line tools or credentials: Speckit Plan is instructions for the agent only. Compatibility (from SKILL.md): Requires spec-kit project structure with .specify/ directory.

Does Speckit Plan access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Speckit Plan safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Speckit Plan use?

Speckit Plan is published under the GPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Speckit Plan use?

About 2.1k tokens (SKILL.md is roughly 8.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Speckit Plan?

Skills that share tags, products or a category with Speckit Plan: OpenSpec Bulk Change Archiver (Fission-AI/OpenSpec, 72k stars), Speckit Constitution (WeihanLi/WeihanLi.Common, 242 stars), Review Spd (zhu1090093659/spec_driven_develop, 987 stars) and React Router RFC Implementer (remix-run/react-router, 57k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Speckit Plan?

kunstmusik (a GitHub user) maintains it in kunstmusik/blue, which has 154 GitHub stars. The repository holds 16 skills in this directory. The repository was last updated on October 8, 2026.

Source: kunstmusik/blue on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.