openspec-sync-specs

openspec-sync-specs is a skill for Claude Code, Codex from alphacornutum/layercake. It costs 38 tokens per session (1,367 once invoked), scanned A, a copy of openspec-sync-specs, MIT.

A procedure for applying changes from a delta specification to the main specifications in an OpenSpec repository. A delta specification describes proposed changes, while the main specifications hold the current requirements.

In plain words
What is it for?
Updating main OpenSpec requirements from a named change, reviewing available changes, and applying scenarios or other requirement updates.
Why use it?
It helps merge changes into existing requirements without simply copying an entire document. It also explains how to select the correct registered repository when needed.

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/alphacornutum/layercake/openspec-sync-specs
Any agent
npx skills add alphacornutum/layercake --skill openspec-sync-specs
Clone the repo
git clone --depth 1 https://github.com/alphacornutum/layercake

Made for: Claude Code, Codex.

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 openspec-sync-specs

README.md
[![agentmods](https://agentmods.dev/badge/skills/alphacornutum/layercake/openspec-sync-specs.svg)](https://agentmods.dev/skills/alphacornutum/layercake/openspec-sync-specs)
Your own site
<a href="https://agentmods.dev/skills/alphacornutum/layercake/openspec-sync-specs"><img src="https://agentmods.dev/badge/skills/alphacornutum/layercake/openspec-sync-specs.svg" alt="Measured on agentmods" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,367 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 78% 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 $0.00038 $0.01367
Opus 5 $0.00019 $0.00683
Sonnet 5 $0.00008 $0.00273
Haiku 4.5 $0.00004 $0.00137

Measured 4d ago against content hash 44ef7617aa61, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openspec-sync-specs 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 4d 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.

Origin

This is a copy

78% identical to openspec-sync-specs — 65 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.

.ai/src/skills/openspec-sync-specs/SKILL.md · 169 lines

How it starts

The opening of the file, as written. The whole thing — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Sync delta specs from a change to main specs.

This is an agent-driven operation - you will read delta specs and directly edit main specs to apply the changes. This allows intelligent merging (e.g., adding a scenario without copying the entire requirement).

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). 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: Optionally specify a change name. If omitted, check if it can be inferred from conversation context. If vague or ambiguous you MUST prompt for available changes.

Steps

  1. If no change name provided, prompt for selection

    Run openspec list --json to get available changes. Use the AskUserQuestion tool to let the user select.

    Show changes that have delta specs (under specs/ directory).

    IMPORTANT: Do NOT guess or auto-select a change. Always let the user choose.

  2. Resolve change context

    Run:

    openspec status --change "<name>" --json
    
  3. Find delta specs

    Use artifactPaths.specs.existingOutputPaths from the status JSON as the list of delta spec files.

    Each delta spec file contains sections like:

    • ## ADDED Requirements - New requirements to add
    • ## MODIFIED Requirements - Changes to existing requirements
    • ## REMOVED Requirements - Requirements to remove
    • ## RENAMED Requirements - Requirements to rename (FROM:/TO: format)

    If no delta specs found, inform user and stop.

  4. For each delta spec, apply changes to main specs

    For each repo-local capability delta spec path returned by the CLI:

    a. Read the delta spec to understand the intended changes

    b. Read the main spec at openspec/specs/<capability>/spec.md (may not exist yet)

    c. Apply changes intelligently:

    ADDED Requirements:

    • If requirement doesn't exist in main spec → add it
    • If requirement already exists → update it to match (treat as implicit MODIFIED)

    MODIFIED Requirements:

    • Find the requirement in main spec
    • Apply the changes - this can be:
      • Adding new scenarios (don't need to copy existing ones)
      • Modifying existing scenarios
      • Changing the requirement description
    • Preserve scenarios/content not mentioned in the delta

    REMOVED Requirements:

    • Remove the entire requirement block from main spec

    RENAMED Requirements:

    • Find the FROM requirement, rename to TO

    d. Create new main spec if capability doesn't exist yet:

    • Create openspec/specs/<capability>/spec.md
    • Add Purpose section (can be brief, mark as TBD)
    • Add Requirements section with the ADDED requirements
  5. Update ARCHITECTURE.md

    After main specs are updated, read root ARCHITECTURE.md and refresh it when the sync changes system shape:

    • Capability map (openspec/specs/ ↔ MCP tools ↔ src/ packages)
    • Layers, dependency direction, runtime flow, or design constraints
    • New/removed/renamed tools or host protocol implications from the delta

    Prefer a precise update over leaving the map stale. If the sync is requirements-only with no architectural impact, leave the file unchanged and note that in the summary.

  6. Show summary

    After applying all changes, summarize:

    • Which capabilities were updated
    • What changes were made (requirements added/modified/removed/renamed)
    • Whether ARCHITECTURE.md was updated or reviewed unchanged

Delta Spec Format Reference

## ADDED Requirements

### Requirement: New Feature

The system SHALL do something new.

#### Scenario: Basic case

- **WHEN** user does X
- **THEN** system does Y

## MODIFIED Requirements

### Requirement: Existing Feature

#### Scenario: New scenario to add

- **WHEN** user does A
- **THEN** system does B

## REMOVED Requirements

### Requirement: Deprecated Feature

## RENAMED Requirements

- FROM: `### Requirement: Old Name`
- TO: `### Requirement: New Name`

Read the full file on GitHub · 169 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. 4d ago First seen · 169 lines · 38 tokens per session scan A 44ef7617aa61

Subscribe to this mod's changes

openspec-sync-specs is a skill published in the GitHub repository alphacornutum/layercake (0 stars, last pushed 1mo ago), licensed MIT. It adds 38 tokens to every session and 1,367 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 78% identical to openspec-sync-specs, differing in 65 lines, and is treated as a copy.

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