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CarlosWilliamsR
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sdd-spec

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

Updated Aug 25, 2026
Search Tags:#specification#requirements#spec-driven development#openspec#delta spec#given when then#rfc 2119
One-click install
npx skills add https://github.com/CarlosWilliamsR/SketchOS --skill sdd-spec-carloswilliamsr
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: sdd-spec
Source: https://github.com/CarlosWilliamsR/SketchOS/tree/main/.config/opencode/skills/sdd-spec
Command: npx skills add https://github.com/CarlosWilliamsR/SketchOS --skill sdd-spec-carloswilliamsr

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Translating a change proposal into precise, testable specifications is error-prone: requirements get lost, modified requirements lose scenarios at archive time, and specs drift into implementation detail. This Skill standardizes the spec-writing phase of a spec-driven development (SDD) workflow by producing structured delta specs. ## Core Features & Use Cases - Delta Spec Generation: Produces ADDED, MODIFIED, REMOVED, and RENAMED requirement sections per affected domain, or full specs for new domains. - Strict Format Enforcement: Every requirement uses RFC 2119 keywords (MUST, SHALL, SHOULD, MAY) and at least one Given/When/Then scenario covering happy paths and edge cases. - Multi-Mode Persistence: Supports engram, openspec, hybrid, and none artifact store modes, reading the proposal's Capabilities section to map domains to spec files. - Use Case: An orchestrator launches spec work for a change named "add-oauth-login"; the sub-agent reads the proposal, writes delta specs for the auth domain under openspec/changes/add-oauth-login/specs/, and returns a coverage summary ready for the design phase. ## Quick Start Delegate to the sdd-spec sub-agent with the change name and artifact store mode to generate delta specifications from the existing proposal.

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 spec-driven development change?▼

Read the proposal's Capabilities section to identify affected domains, then write ADDED, MODIFIED, REMOVED, or RENAMED requirement sections per domain. Each requirement uses RFC 2119 keywords and at least one Given/When/Then scenario.

What is the difference between ADDED and MODIFIED requirements in a delta spec?▼

Use ADDED when introducing new behavior without changing existing requirements. Use MODIFIED when altering an existing requirement, and copy the entire original requirement block with all scenarios before editing, since the archive step replaces the old block entirely.

Why do MODIFIED requirements lose scenarios at archive time?▼

The archive step replaces the requirement in the main spec with your MODIFIED block. If the block is partial, any scenarios you did not copy are permanently lost, so always paste the full original requirement before editing.

Does the spec phase support different artifact storage modes?▼

Yes, it supports engram, openspec, hybrid, and none modes. Engram persists a single concatenated artifact, openspec writes domain files to the filesystem, hybrid does both, and none returns the result without creating files.

What format must scenarios follow in SDD specifications?▼

Every scenario uses Given/When/Then format with preconditions, actions, and expected outcomes, kept to 3-5 lines. Each requirement needs at least one scenario, and specs should cover both happy paths and edge cases.

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