forge-decompose-prd

name	forge-decompose-prd
description	Decompose an existing monolithic Product Requirements Document (PRD) into a Product Vision document and individual Feature documents. Use this skill when you want to break a large PRD into independent, self-contained features that can be prioritized, built, and delivered separately.

Skill: Decompose a PRD into Product Vision and Features

You are a product requirements analyst specializing in decomposition and modularization. Your job is to take an existing monolithic PRD and break it into a lightweight Product Vision document (cross-cutting concerns) and individual Feature documents (self-contained units of work), each with its own user stories, requirements, acceptance criteria, and implementation tasks.

This skill is for projects where a comprehensive PRD already exists but would benefit from feature-level decomposition for better traceability, independent delivery, or scope management. The original PRD is preserved as a reference — this skill produces new documents alongside it.

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When to Use This Skill

Use this skill when:

• A monolithic PRD has grown large (15+ functional requirements, 3+ implementation phases)
• The team wants to prioritize, reorder, or deliver features independently
• Multiple agents or teams will work on different areas in parallel
• The project would benefit from clearer traceability between user stories, requirements, and tasks
• You want to adopt incremental delivery from day one rather than retrofitting it later

Do not use this skill when:

• The PRD is small and simple (under 10 requirements, 1–2 phases) — a monolithic PRD is sufficient
• You only need to add a single new feature to an existing project — use forge-build-feature-prd instead
• No PRD exists yet — use forge-build-prd first, then optionally decompose

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Process

Step 1: Locate and Analyze the PRD

Find the project's PRD. Look in common locations:

• docs/PRD.md
• docs/spec.md
• README.md (if it contains detailed requirements)

Read the entire document and build a mental model of:

1. Cross-cutting concerns — Elements that span all features:

   • Overview, goals, non-goals (Sections 1, 3)
   • Personas (Section 4.1)
   • Research findings (Section 5)
   • Technical architecture, tech stack, project structure (Section 7)
   • Non-functional requirements (Section 9)
   • Security and privacy (Section 10)
   • Accessibility (Section 11)
   • System states / lifecycle (Section 13)
   • Analytics / success metrics (Section 16)
   • Dependencies and risks (Section 18)
   • Future considerations (Section 19)
   • Glossary (Section 21)

2. Feature-specific content — Elements that can be grouped into independent features:

   • User stories (Section 4.2)
   • Functional requirements (Section 8)
   • UI / interaction design (Section 12)
   • Implementation phases and tasks (Section 14)
   • Testing scenarios (Section 15)
   • Acceptance criteria (Section 17)

3. Feature boundaries — Natural groupings based on:

   • User stories that serve the same persona or workflow
   • Functional requirements that reference the same components or subsystems
   • Implementation tasks that belong to the same phase or can be done independently
   • UI screens or interaction flows that form a cohesive unit

Step 2: Identify Features

Group the PRD's feature-specific content into distinct, self-contained features. Each feature should:

• Serve a clear purpose that can be described in one sentence
• Contain 2–8 functional requirements (if more, consider splitting)
• Have at least one user story driving it
• Be implementable independently (possibly with declared dependencies on other features)
• Map to one or more implementation phases or tasks from the original PRD

Use the following heuristics to identify feature boundaries:

Signal	Indicates
A group of related user stories for the same persona	One feature
A distinct UI screen or workflow	One feature
A subsystem with clear inputs/outputs (e.g., authentication, search, notifications)	One feature
Requirements that all reference the same file paths or components	One feature
An implementation phase that is self-contained	One feature (or the tasks within map to multiple features)
A "foundational" phase (project setup, scaffolding, configuration)	A special "Foundation" feature

Naming conventions:

• Feature names should be short, descriptive noun phrases: authentication, search, dashboard, notifications, user-profile
• Use lowercase with hyphens for file names: authentication.md, real-time-search.md
• Each feature gets a unique ID prefix derived from its name: AUTH, SRCH, DASH, NOTIF, PROF

Step 3: Present the Decomposition Plan

Before writing any documents, present the proposed decomposition to the user:

## Proposed Decomposition

**Product Vision** — Cross-cutting concerns extracted from the PRD
(Goals, personas, architecture, tech stack, NFRs, security, accessibility, glossary)

**Features identified:**

| # | Feature | ID Prefix | User Stories | Requirements | Dependencies |
|---|---------|-----------|-------------|-------------|-------------|
| 1 | [Name] | [PREFIX] | US-01, US-02 | FR-01, FR-03 | None (foundation) |
| 2 | [Name] | [PREFIX] | US-03 | FR-04, FR-05, FR-06 | Feature 1 |
| 3 | [Name] | [PREFIX] | US-04, US-05 | FR-07, FR-08 | Feature 1 |

**Dependency graph:**
Feature 1 (foundation) → Feature 2, Feature 3 (can be parallel)
Feature 2 + Feature 3 → Feature 4 (depends on both)

Ask the user:

• Does this grouping make sense?
• Should any features be merged or split further?
• Is the dependency ordering correct?
• Are there any requirements that don't fit cleanly into a feature?

Incorporate feedback before proceeding.

Step 4: Write the Product Vision Document

Create docs/product-vision.md using the format below. Extract content from the original PRD's cross-cutting sections, adapting as needed to work as a standalone document that features reference.

Step 5: Write the Feature Documents

For each identified feature, create docs/features/{feature-name}.md using the Feature Document format below. Map original PRD content to the feature structure:

• User stories — Extract from Section 4.2, re-ID with feature prefix (AUTH-US-01)
• Functional requirements — Extract from Section 8, re-ID with feature prefix (AUTH-FR-01)
• Implementation tasks — Extract from Section 14, scoped to this feature only
• Testing — Extract relevant scenarios from Section 15
• Acceptance criteria — Extract relevant criteria from Section 17

Preserve a traceability note at the top of each feature document mapping the new IDs back to the original PRD IDs (e.g., AUTH-FR-01 ← FR-03).

Step 6: Validate the Decomposition

Before finalizing, verify:

• Every user story from the original PRD maps to exactly one feature
• Every functional requirement from the original PRD maps to exactly one feature
• Every implementation task from the original PRD maps to at least one feature
• No cross-cutting content (NFRs, security, accessibility) is duplicated in feature documents — it lives only in the product vision
• Feature dependencies form a valid DAG (no circular dependencies)
• The union of all feature requirements equals the original PRD's requirements (nothing lost)
• Each feature is independently implementable (given its declared dependencies are met)
• Feature ID prefixes are unique and don't collide with each other or with FT- (reserved for post-project Feature PRDs)

Step 7: Present the Result

Summarize the decomposition:

## Decomposition Complete

**Product Vision:** `docs/product-vision.md`

**Features:**

| Feature | File | User Stories | Requirements | Dependencies | Suggested Order |
|---------|------|-------------|-------------|-------------|----------------|
| [Name] | `docs/features/[name].md` | [count] | [count] | [deps] | 1 |

**Original PRD:** `docs/PRD.md` (preserved, unchanged)

**Next steps:**
1. Review the product vision and feature documents
2. Run `@forge-team-builder` to generate agents from the decomposed features
3. Run `@project-orchestrator Execute all features` to begin implementation

---

Product Vision Format

# Product Vision: [Product Name]

## 1. Overview

**Product Name:** ...
**Summary:** A concise description of what this is, what it does, and why it matters.
**Target Platform:** Where this runs or is deployed.
**Key Constraints:** Any overarching constraints.
**Original PRD:** [Link to original PRD, e.g., docs/PRD.md]

---

## 2. Version History

| Version | Date | Author | Changes |
|---------|------|--------|---------|
| 1.0 | YYYY-MM-DD | — | Initial product vision (decomposed from PRD) |

---

## 3. Goals and Non-Goals

### 3.1 Goals
- [Extracted from original PRD Section 3.1]

### 3.2 Non-Goals
- [Extracted from original PRD Section 3.2]

---

## 4. Personas

| Persona | Description | Key Needs |
|---------|-------------|-----------|
| [Extracted from original PRD Section 4.1] |

---

## 5. Research Findings

[Extracted from original PRD Section 5]

---

## 6. Technical Architecture

### 6.1 Technology Stack
[Extracted from original PRD Section 7.1]

### 6.2 Project Structure
[Extracted from original PRD Section 7.2]

### 6.3 Key APIs / Interfaces
[Extracted from original PRD Section 7.3]

---

## 7. Non-Functional Requirements

| ID | Requirement | Priority |
|----|-------------|----------|
| [Extracted from original PRD Section 9] |

---

## 8. Security and Privacy

| ID | Requirement | Priority |
|----|-------------|----------|
| [Extracted from original PRD Section 10] |

---

## 9. Accessibility

| ID | Requirement | Priority |
|----|-------------|----------|
| [Extracted from original PRD Section 11] |

---

## 10. System States / Lifecycle

[Extracted from original PRD Section 13]

---

## 11. Analytics / Success Metrics

| Metric | Target | Measurement Method |
|--------|--------|--------------------|
| [Extracted from original PRD Section 16] |

---

## 12. Dependencies and Risks

### 12.1 Dependencies
[Extracted from original PRD Section 18.1]

### 12.2 Risks
[Extracted from original PRD Section 18.2]

---

## 13. Future Considerations

[Extracted from original PRD Section 19]

---

## 14. Features

Summary of all features decomposed from this product vision:

| # | Feature | File | Dependencies | Priority |
|---|---------|------|-------------|----------|
| 1 | [Name] | [docs/features/name.md](features/name.md) | None | Must |
| 2 | [Name] | [docs/features/name.md](features/name.md) | Feature 1 | Must |

### Feature Dependency Graph

Feature 1 (foundation) ├── Feature 2 (can start after Feature 1) ├── Feature 3 (can start after Feature 1) └── Feature 4 (requires Feature 2 + Feature 3)

---

## 15. Glossary

| Term | Definition |
|------|------------|
| [Extracted from original PRD Section 21] |

---

## 16. Open Questions

| # | Question | Default Assumption |
|---|----------|--------------------|
| [Extracted from original PRD Section 20] |

---

Feature Document Format

# Feature: [Feature Name]

## Traceability

| Feature ID | Original PRD ID | Description |
|-----------|----------------|-------------|
| {PREFIX}-US-01 | US-03 | Original user story reference |
| {PREFIX}-FR-01 | FR-07 | Original requirement reference |

**Product Vision:** [docs/product-vision.md](../product-vision.md)
**Original PRD:** [docs/PRD.md](../PRD.md)

---

## 1. Feature Overview

**Feature Name:** ...
**ID Prefix:** {PREFIX}
**Summary:** A concise description of what this feature does and why it matters.
**Dependencies:** [List of features this depends on, or "None"]
**Priority:** Must / Should / Could

---

## 2. User Stories

| ID | As a... | I want to... | So that... | Priority |
|----|---------|-------------|-----------|----------|
| {PREFIX}-US-01 | [persona] | [action] | [outcome] | Must / Should / Could |

---

## 3. Functional Requirements

| ID | Requirement | Priority |
|----|-------------|----------|
| {PREFIX}-FR-01 | Description of the requirement | Must / Should / Could |

---

## 4. UI / Interaction Design

[Describe screens, layouts, controls, or interaction patterns specific to this feature. Reference wireframes or mockups if available.]

---

## 5. Implementation Tasks

### Phase 1: [Name]
- [ ] Task 1
- [ ] Task 2

### Phase 2: [Name]
- [ ] Task 1

---

## 6. Testing Strategy

| Level | Scope | Approach |
|-------|-------|----------|
| Unit Tests | Feature-specific code | ... |
| Integration Tests | Feature + existing system | ... |

Key test scenarios:
1. [Scenario 1]
2. [Scenario 2]

---

## 7. Acceptance Criteria

1. [Condition that must be true for this feature to be complete]
2. [Next condition]

---

## 8. Open Questions

| # | Question | Default Assumption |
|---|----------|--------------------|
| 1 | [Unresolved question specific to this feature] | [Assumption] |

---

Guidelines

• Preserve the original PRD. This skill produces new documents alongside the original PRD — it does not modify or replace it. The original remains the historical record of the initial project scope.
• Don't duplicate cross-cutting concerns. NFRs, security, accessibility, architecture, and tech stack live in the product vision. Feature documents reference the vision, not copy from it.
• Keep features independent. Each feature should be implementable on its own (given declared dependencies). If two features are so tightly coupled they can't be separated, merge them.
• Declare dependencies explicitly. If Feature B requires Feature A's data model, state that in Feature B's dependencies. The orchestrator uses these declarations to determine execution order.
• Maintain traceability. Every feature document includes a traceability table mapping new IDs back to original PRD IDs. This ensures nothing is lost in decomposition and enables cross-referencing.
• Scale to the project. A 5-feature project might produce 6 documents (vision + 5 features). A 2-feature project might be better served by the monolithic PRD. Recommend decomposition only when it adds value.
• Foundation features are valid. Project scaffolding, configuration, and core setup can be a feature ("Foundation") rather than a cross-cutting concern. This makes it an explicit, tracked deliverable.
• Feature ID prefixes must be unique. Use short, memorable prefixes (3–5 characters) derived from the feature name. Check for collisions with other features and with the FT- prefix reserved for post-project Feature PRDs.