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sdd-spec

Write specifications with requirements and scenarios (delta specs for changes). Trigger: When the orchestrator launches you to write or update specs for a change.

Packaged view

This page reorganizes the original catalog entry around fit, installability, and workflow context first. The original raw source lives below.

Stars
1,535
Hot score
99
Updated
March 20, 2026
Overall rating
C4.0
Composite score
4.0
Best-practice grade
B80.4

Install command

npx @skill-hub/cli install gentleman-programming-gentleman-dots-sdd-spec

Repository

Gentleman-Programming/Gentleman.Dots

Skill path: GentlemanClaude/skills/sdd-spec

Write specifications with requirements and scenarios (delta specs for changes). Trigger: When the orchestrator launches you to write or update specs for a change.

Open repository

Best for

Primary workflow: Ship Full Stack.

Technical facets: Full Stack.

Target audience: everyone.

License: MIT.

Original source

Catalog source: SkillHub Club.

Repository owner: Gentleman-Programming.

This is still a mirrored public skill entry. Review the repository before installing into production workflows.

What it helps with

  • Install sdd-spec into Claude Code, Codex CLI, Gemini CLI, or OpenCode workflows
  • Review https://github.com/Gentleman-Programming/Gentleman.Dots before adding sdd-spec to shared team environments
  • Use sdd-spec for development workflows

Works across

Claude CodeCodex CLIGemini CLIOpenCode

Favorites: 0.

Sub-skills: 0.

Aggregator: No.

Original source / Raw SKILL.md

---
name: sdd-spec
description: >
  Write specifications with requirements and scenarios (delta specs for changes).
  Trigger: When the orchestrator launches you to write or update specs for a change.
license: MIT
metadata:
  author: gentleman-programming
  version: "2.0"
---

## Purpose

You are a sub-agent responsible for writing SPECIFICATIONS. You take the proposal and produce delta specs — structured requirements and scenarios that describe what's being ADDED, MODIFIED, or REMOVED from the system's behavior.

## What You Receive

From the orchestrator:
- Change name
- Artifact store mode (`engram | openspec | hybrid | none`)

## Execution and Persistence Contract

Read and follow `skills/_shared/persistence-contract.md` for mode resolution rules.

- If mode is `engram`:

  **CRITICAL: `mem_search` returns 300-char PREVIEWS, not full content. You MUST call `mem_get_observation(id)` for EVERY artifact. If you skip this, you will work with incomplete data and produce wrong specs.**

  **STEP A — SEARCH** (get IDs only — content is truncated):
  1. `mem_search(query: "sdd/{change-name}/proposal", project: "{project}")` → save ID

  **STEP B — RETRIEVE FULL CONTENT** (mandatory):
  2. `mem_get_observation(id: {proposal_id})` → full proposal content (REQUIRED)

  **DO NOT use search previews as source material.**

  If specs span multiple domains, concatenate into a single artifact with domain headers.

  **Save your artifact**:
  ```
  mem_save(
    title: "sdd/{change-name}/spec",
    topic_key: "sdd/{change-name}/spec",
    type: "architecture",
    project: "{project}",
    content: "{your full spec markdown — all domains concatenated}"
  )
  ```
  `topic_key` enables upserts — saving again updates, not duplicates.

  (See `skills/_shared/engram-convention.md` for full naming conventions.)
- If mode is `openspec`: Read and follow `skills/_shared/openspec-convention.md`.
- If mode is `hybrid`: Follow BOTH conventions — persist to Engram (single concatenated artifact) AND write domain files to filesystem.
- If mode is `none`: Return result only. Never create or modify project files.

## What to Do

### Step 1: Load Skill Registry

**Do this FIRST, before any other work.**

1. Try engram first: `mem_search(query: "skill-registry", project: "{project}")` → if found, `mem_get_observation(id)` for the full registry
2. If engram not available or not found: read `.atl/skill-registry.md` from the project root
3. If neither exists: proceed without skills (not an error)

From the registry, identify and read any skills whose triggers match your task. Also read any project convention files listed in the registry.

### Step 2: Identify Affected Domains

From the proposal's "Affected Areas", determine which spec domains are touched. Group changes by domain (e.g., `auth/`, `payments/`, `ui/`).

### Step 3: Read Existing Specs

**IF mode is `openspec` or `hybrid`:** If `openspec/specs/{domain}/spec.md` exists, read it to understand CURRENT behavior. Your delta specs describe CHANGES to this behavior.

**IF mode is `engram`:** Existing specs were already retrieved from Engram in the Persistence Contract. Skip filesystem reads.

**IF mode is `none`:** Skip — no existing specs to read.

### Step 4: Write Delta Specs

**IF mode is `openspec` or `hybrid`:** Create specs inside the change folder:

```
openspec/changes/{change-name}/
├── proposal.md              ← (already exists)
└── specs/
    └── {domain}/
        └── spec.md          ← Delta spec
```

**IF mode is `engram` or `none`:** Do NOT create any `openspec/` directories or files. Compose the spec content in memory — you will persist it in Step 5.

#### Delta Spec Format

```markdown
# Delta for {Domain}

## ADDED Requirements

### Requirement: {Requirement Name}

{Description using RFC 2119 keywords: MUST, SHALL, SHOULD, MAY}

The system {MUST/SHALL/SHOULD} {do something specific}.

#### Scenario: {Happy path scenario}

- GIVEN {precondition}
- WHEN {action}
- THEN {expected outcome}
- AND {additional outcome, if any}

#### Scenario: {Edge case scenario}

- GIVEN {precondition}
- WHEN {action}
- THEN {expected outcome}

## MODIFIED Requirements

### Requirement: {Existing Requirement Name}

{New description — replaces the existing one}
(Previously: {what it was before})

#### Scenario: {Updated scenario}

- GIVEN {updated precondition}
- WHEN {updated action}
- THEN {updated outcome}

## REMOVED Requirements

### Requirement: {Requirement Being Removed}

(Reason: {why this requirement is being deprecated/removed})
```

#### For NEW Specs (No Existing Spec)

If this is a completely new domain, create a FULL spec (not a delta):

```markdown
# {Domain} Specification

## Purpose

{High-level description of this spec's domain.}

## Requirements

### Requirement: {Name}

The system {MUST/SHALL/SHOULD} {behavior}.

#### Scenario: {Name}

- GIVEN {precondition}
- WHEN {action}
- THEN {outcome}
```

### Step 5: Persist Artifact

**This step is MANDATORY — do NOT skip it.**

If mode is `engram`:
```
mem_save(
  title: "sdd/{change-name}/spec",
  topic_key: "sdd/{change-name}/spec",
  type: "architecture",
  project: "{project}",
  content: "{your full spec markdown from Step 4 — all domains concatenated}"
)
```

If mode is `openspec` or `hybrid`: the file was already written in Step 4.

If mode is `hybrid`: also call `mem_save` as above (write to BOTH backends).

If you skip this step, the next phase (sdd-tasks) will NOT be able to find your specs and the pipeline BREAKS.

### Step 6: Return Summary

Return to the orchestrator:

```markdown
## Specs Created

**Change**: {change-name}

### Specs Written
| Domain | Type | Requirements | Scenarios |
|--------|------|-------------|-----------|
| {domain} | Delta/New | {N added, M modified, K removed} | {total scenarios} |

### Coverage
- Happy paths: {covered/missing}
- Edge cases: {covered/missing}
- Error states: {covered/missing}

### Next Step
Ready for design (sdd-design). If design already exists, ready for tasks (sdd-tasks).
```

## Rules

- ALWAYS use Given/When/Then format for scenarios
- ALWAYS use RFC 2119 keywords (MUST, SHALL, SHOULD, MAY) for requirement strength
- If existing specs exist, write DELTA specs (ADDED/MODIFIED/REMOVED sections)
- If NO existing specs exist for the domain, write a FULL spec
- Every requirement MUST have at least ONE scenario
- Include both happy path AND edge case scenarios
- Keep scenarios TESTABLE — someone should be able to write an automated test from each one
- DO NOT include implementation details in specs — specs describe WHAT, not HOW
- Apply any `rules.specs` from `openspec/config.yaml`
- Return a structured envelope with: `status`, `executive_summary`, `detailed_report` (optional), `artifacts`, `next_recommended`, and `risks`

## RFC 2119 Keywords Quick Reference

| Keyword | Meaning |
|---------|---------|
| **MUST / SHALL** | Absolute requirement |
| **MUST NOT / SHALL NOT** | Absolute prohibition |
| **SHOULD** | Recommended, but exceptions may exist with justification |
| **SHOULD NOT** | Not recommended, but may be acceptable with justification |
| **MAY** | Optional |
sdd-spec | SkillHub