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sdd-spec

Writes delta specifications with RFC 2119 requirements and Given/When/Then scenarios.

Updated Apr 4, 2026
Search Tags:#requirements#sdd#spec-driven development#openspec#delta specs#given when then#rfc 2119
One-click install
npx skills add https://github.com/juanjo-zurich/juarvis-v4 --skill sdd-spec-juanjo-zurich
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: sdd-spec
Source: https://github.com/juanjo-zurich/juarvis-v4/tree/main/plugins/sdd/skills/sdd-spec
Command: npx skills add https://github.com/juanjo-zurich/juarvis-v4 --skill sdd-spec-juanjo-zurich

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Translating a change proposal into precise, testable specifications is error-prone and often skipped. This Skill acts as a sub-agent that converts a proposal into structured delta specs describing exactly what behavior is ADDED, MODIFIED, or REMOVED, so downstream design and task phases have a reliable contract. ## Core Features & Use Cases - Delta Spec Generation: Produces ADDED/MODIFIED/REMOVED requirement sections when specs already exist, or full specs for new domains. - Standardized Format: Enforces RFC 2119 keywords (MUST, SHALL, SHOULD, MAY) and Given/When/Then scenarios that are directly testable. - Multi-Backend Persistence: Saves artifacts to Engram memory, OpenSpec filesystem files, both (hybrid), or returns results only, based on the artifact store mode. - Use Case: After an orchestrator creates a proposal for a new authentication change, this Skill reads the proposal, groups changes by domain, and writes testable spec scenarios ready for the design and tasks phases. ## Quick Start Ask the orchestrator to launch the spec writer for your change proposal so it produces delta specs with requirements and scenarios for each affected domain.

Frequently Asked Questions about sdd-spec

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I write delta specs for a software change?▼

Delta specs describe changes relative to existing behavior using ADDED, MODIFIED, and REMOVED requirement sections. Each requirement uses RFC 2119 keywords and includes at least one Given/When/Then scenario covering happy paths and edge cases.

What is the difference between a delta spec and a full spec?▼

A delta spec documents only changes to an existing domain's behavior, while a full spec is written when no spec exists yet for that domain. The Skill checks for existing specs and chooses the correct format automatically.

How does the spec agent store artifacts in Engram vs OpenSpec?▼

In engram mode it saves one concatenated artifact via mem_save with a topic_key for upserts. In openspec mode it writes spec.md files under openspec/changes/{change-name}/specs/{domain}/, and hybrid mode does both.

Why must scenarios use Given/When/Then format?▼

Given/When/Then makes every requirement directly testable, so an automated test can be written from each scenario. The Skill requires at least one scenario per requirement, covering both happy paths and edge cases.

Can specs include implementation details?▼

No. Specs describe WHAT the system must do, not HOW it is built. Implementation details belong in the design phase, which runs after specs are written.

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