openspec-propose

A planning workflow for describing a proposed software change and producing a proposal, design, specification updates, and implementation tasks.

In plain words
What is it for?
Use it to prepare a complete, reviewable plan for a new feature or other change. Implementation starts later through a separate workflow.
Why use it?
It turns a rough request into a structured plan without changing project code, so the work can be reviewed before implementation begins.

Skill for Claude CodeCodex

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 skills/fission-ai/openspec/openspec-propose
Any agent
npx skills add Fission-AI/OpenSpec --skill openspec-propose
Clone the repo
git clone --depth 1 https://github.com/Fission-AI/OpenSpec

Made for: Claude Code, Codex.

Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,442 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 84% copy Near-identical to another mod 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 $0.00047 $0.02442
Opus 5 $0.00023 $0.01221
Sonnet 5 $0.00009 $0.00488
Haiku 4.5 $0.00005 $0.00244

Measured yesterday against content hash c0537ce31111, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openspec-propose 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.

Origin

This is a copy

84% identical to openspec-ff-change — 64 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/openspec-propose/SKILL.md · 149 lines

How it starts

The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Propose a new change - create the change and generate all artifacts in one step.

Planning boundary: This workflow creates planning artifacts only. The user request that selected or triggered this workflow authorizes planning only, even if it asks to build or fix something. Do not edit project code. After the planning artifacts are complete, stop. Do not start implementation in the same response, even if the initial request asks for it. Wait for a new user request after the artifacts are presented; then start the apply workflow.

I'll create a change with the artifacts your schema defines. With the default spec-driven schema that is:

  • proposal.md (what & why)
  • specs/<capability-path>/spec.md (what the system must do - a delta, not the main spec)
  • design.md (how)
  • tasks.md (implementation steps)

<capability-path> is the spec directory relative to specs/ (for example, user-auth or identity/user-auth). Preserve an existing capability's full path and follow the project's established organization for new capabilities.

When the user is ready to implement, they must start the apply workflow explicitly.


Store selection: If the user names a store (a store is a standalone OpenSpec repo registered on this machine) or the work lives in one, run openspec store list --json to discover registered store ids, then pass --store <id> on the commands that read or write specs and changes (new change, status, instructions, list, show, validate, archive, doctor, context, schemas, view). Once selected, treat --store <id> as sticky for the rest of the workflow. Every unscoped example of those commands below is shorthand: before running it, append the flag. For example, run openspec status --change "<name>" --json --store "<id>", not the unscoped form shown below. Other commands do not take the flag. Hints printed by commands already carry the flag; keep it on follow-ups. Without a store, commands act on the nearest local openspec/ root.

Input: The user's request should include a change name (kebab-case) OR a description of what they want to build.

Steps

  1. Understand the request and clarify material ambiguity

    If no clear input is provided, ask the user (open-ended, no preset options):

    "What change do you want to work on? Describe what you want to build or fix."

    From their description, derive a kebab-case name (e.g., "add user authentication" → add-user-auth).

    IMPORTANT: Do NOT proceed without understanding what the user wants to build.

    If the request contains ambiguity that would materially affect scope, externally observable behavior, compatibility, or acceptance criteria, ask the user before creating the change. For minor details, make a reasonable assumption and record it in the planning artifacts.

  2. Determine the workflow schema

    Use the configured default schema unless the user explicitly requests a different workflow.

    Use a different schema only if the user:

    • Explicitly requests a specific schema by name → use --schema <schema-name>
    • Asks to "show workflows" or asks "what workflows" exist → resolve the authoritative root by running openspec context --json from the current working directory. If the user explicitly selected a registered store, use openspec context --json --store "<store-id>". Then run openspec schemas --json with its working directory set to the returned root.path and let them choose. This preserves roots selected by a local store: pointer or the global defaultStore; when a registered store was explicitly selected, append --store "<store-id>" to openspec schemas --json as well. If context reports only no_openspec_root, run openspec schemas --json from the current working directory instead. Do not use this fallback for invalid or unavailable stores.

    Otherwise, omit --schema to preserve the configured default.

  3. Create the change directory

    Choose one schema form below. If a registered store is selected, append --store "<store-id>" to that command and each later OpenSpec command shown below that accepts --store.

Read the full file on GitHub · 149 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 · 149 lines · 47 tokens per session scan A c0537ce31111

Subscribe to this mod's changes

openspec-propose is a skill published in the GitHub repository Fission-AI/OpenSpec (66,714 stars, last pushed 3d ago), licensed MIT. It adds 47 tokens to every session and 2,442 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 84% identical to openspec-ff-change, differing in 64 lines, and is treated as a copy.