sdd-spec

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:

  Read dependencies (two-step — search returns truncated previews):

  1. mem_search(query: "sdd/{change-name}/proposal", project: "{project}") → get observation ID
  2. mem_get_observation(id: {id from step 1}) → full proposal content (REQUIRED)

  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 openspec/specs/{domain}/spec.md exists, read it to understand CURRENT behavior. Your delta specs describe CHANGES to this behavior.

Step 4: Write Delta Specs

Create specs inside the change folder:

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

Delta Spec Format

# 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):

# {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:

## 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