charon-fan/prd-planner

PRD Planner

A PRD creation skill that uses persistent file-based planning to maintain coherent thinking and avoid "left-brain vs right-brain" context switching issues.

When This Skill Activates

This skill activates when you:

• Explicitly say "PRD", "prd", "create a PRD", or "产品需求文档"
• Say "product requirements document" or "产品需求"
• Mention "write a PRD for..."
• Say "PRD planning" or "PRD 设计"

If user says "design solution" or "architecture design" without mentioning PRD, use architecting-solutions instead.

The Core Philosophy

"PRD creation should be traceable, coherent, and persistent - not scattered across context switches."

This skill combines:

• PRD methodology (from architecting-solutions)
• File-based persistence (from planning-with-files)

To create a single, coherent PRD creation workflow that doesn't lose context.

4-File Pattern for PRD Creation

For every PRD project, create FOUR files:

Pick a SCOPE (short, unique, kebab-case slug) and use it as a prefix for all files.

docs/{scope}-prd-notes.md     → Store research, requirements, findings, options
docs/{scope}-prd-task-plan.md → Track PRD creation phases and progress
docs/{scope}-prd.md           → Product requirements (what & why)
docs/{scope}-tech.md          → Technical design (how)

File Purposes

| File | Purpose | Audience | Updated When | |------|---------|----------|--------------| | {scope}-prd-notes.md | Raw research, requirements, architecture options (A/B/C) | Self + reviewers | New information gathered | | {scope}-prd-task-plan.md | Track progress, phases, checkboxes, timestamps | PM + dev lead | Each phase completion | | {scope}-prd.md | Product requirements (what & why), user flows | PM + stakeholders + devs | After requirements are clear | | {scope}-tech.md | Technical design (API, data flow, implementation) | Developers + architects | After architecture is decided |

Workflow

┌─────────────────────────────────────────────────────────────────┐
│                     PRD Creation Workflow                       │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  1. Initialize → Create 4 files with template                   │
│  2. Requirements → Gather to {scope}-prd-notes.md               │
│  2.5 Edge Cases → Scan codebase, infer patterns, ask smartly    │
│  3. Analysis → Research best practices, save to notes           │
│  4. Design → Propose architecture options (A/B/C), save to notes │
│  5. PRD → Write product requirements to {scope}-prd.md          │
│  6. Tech → Write technical design to {scope}-tech.md            │
│  7. Validate → Review with user, finalize                       │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘
                    ↓
           All thinking persisted to files
                    ↓
              No context switching

Step 1: Initialize

Create the four files with templates:

{scope}-prd-task-plan.md

# PRD Task Plan: {Feature Name}

## Goal
Create a PRD and technical design for {feature description}.

## Owner
{User name/role}

## Phases
- [x] Phase 1: Initialize files ✓
- [ ] Phase 2: Gather requirements (CURRENT)
- [ ] Phase 3: Research & analysis
- [ ] Phase 4: Design solution
- [ ] Phase 5: Write PRD
- [ ] Phase 6: Write technical design
- [ ] Phase 7: Validate & finalize

## Status
**Currently in Phase 2** - Gathering requirements from user

## Progress Log
- {timestamp} - Phase 1 complete: Files initialized

{scope}-prd-notes.md

# PRD Notes: {Feature Name}

## Raw Requirements
(Add user requirements as they emerge)

## Constraints
(Add technical, business, time constraints)

## Inferred Patterns (from codebase)

| Edge Case | Source | Pattern Applied |
|-----------|--------|-----------------|
| (Filled after Step 2.5 codebase scan) | | |

## Edge Cases

### Auto-handled (following codebase patterns)
- (Filled after Step 2.5 analysis)

### Confirmed by User
- (Filled after user confirms edge case decisions)

### Open Questions
- (Track questions to ask user)

## Research Findings
(Add research on best practices, similar solutions)

## Architecture Options

- Option A: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

- Option B: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

- Option C: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

**Selected**: Option {X}

{scope}-prd.md

# PRD: {Feature Name}

> Status: DRAFT
> Last updated: {timestamp}

## Table of Contents
- [Problem Statement](#problem-statement)
- [Goals and Non-Goals](#goals-and-non-goals)
- [Success Criteria](#success-criteria)
- [Scope](#scope)
- [Requirements](#requirements)
- [User Flows](#user-flows)
- [Implementation Plan](#implementation-plan)

---

## Problem Statement
_To be filled after requirements gathering_

## Goals and Non-Goals
### Goals
- {Specific achievable outcomes}

### Non-Goals
- {Explicit exclusions}

## Success Criteria
_To be filled with measurable criteria_

## Scope
### In Scope
- {Specific items included}

### Out of Scope
- {Specific items excluded}

... (rest of PRD sections)

{scope}-tech.md

# Technical Design: {Feature Name}

> Status: DRAFT
> Last updated: {timestamp}

## Overview
{High-level technical approach}

## Key Components
{List major components and their responsibilities}

## API Design
{API signatures, request/response formats}

## Data Flow
{How data flows through the system}

## Implementation Details
{Specific implementation notes}

## Migration Plan
{If applicable, how to migrate from existing system}

Step 2: Gather Requirements

Ask clarifying questions and save responses to {scope}-prd-notes.md:

Core Questions to Ask

1. Problem: What problem are we solving?
2. Users: Who will use this?
3. Success: How do we know it's successful?
4. Constraints: Any technical/time/budget constraints?

Save each answer to {scope}-prd-notes.md under appropriate section.

Always update {scope}-prd-task-plan.md after gathering info:

- [x] Phase 2: Gather requirements ✓
- [ ] Phase 2.5: Edge case analysis (CURRENT)
- [ ] Phase 3: Research & analysis

Step 2.5: Context-Aware Edge Case Analysis

Before asking users about edge cases, scan the codebase first to infer existing patterns. This reduces redundant questions and ensures consistency with the project.

Detailed reference: See references/edge-case-analysis.md for full scanning commands and output formats.

Quick Process

1. Scan codebase for existing patterns (delete strategy, error handling, empty states, pagination)
2. Identify requirement type (CRUD, State Workflow, Async, Data Display, Form, File)
3. Generate smart assumptions - patterns found in code don't need user confirmation
4. Ask only when needed - no precedent, multiple patterns, or business decision required

When to Ask Users

| Condition | Action | |-----------|--------| | Pattern exists in codebase | Auto-apply, no question needed | | No precedent found | Ask user with options | | Multiple conflicting patterns | Ask user to choose | | Business rule required | Ask user |

Output to Notes File

Update {scope}-prd-notes.md with:

## Inferred Patterns (from codebase)
| Edge Case | Source | Pattern Applied |
|-----------|--------|-----------------|
| Delete | `src/models/User.ts:45` | Soft delete |

## Edge Cases
### Auto-handled (following codebase patterns)
- Empty list → Use existing EmptyState component

### Confirmed by User
- Concurrent edit: Last write wins (confirmed {date})

Update task plan:

- [x] Phase 2.5: Edge case analysis ✓
- [ ] Phase 3: Research & analysis (CURRENT)

Step 3: Research & Analysis

Research best practices and save to {scope}-prd-notes.md:

# Search for similar implementations
grep -r "keyword" packages/ --include="*.ts"

# Search web for best practices
web search "best practices for {feature}"

Save findings to {scope}-prd-notes.md → Research Findings section.

Step 4: Design Solution

Propose architecture with trade-offs, save to {scope}-prd-notes.md:

## Architecture Options

- Option A: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

- Option B: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

- Option C: {Description}
  - Pros: {Advantages}
  - Cons: {Disadvantages}

**Selected**: Option {X} - because {reason}

Step 5: Write PRD

Read {scope}-prd-notes.md and synthesize into polished PRD:

1. Read {scope}-prd-notes.md to understand:
   - Requirements gathered
   - Research findings
   - Architecture decision (which option was selected)

2. Write {scope}-prd.md with:
   - Clear problem statement
   - Goals and Non-Goals (explicit exclusions)
   - Measurable success criteria (specific numbers/timings)
   - Scope (In Scope / Out of Scope)
   - Functional requirements
   - Non-functional requirements
   - User flows
   - Implementation plan (high level)

3. Reference tech doc: "See {scope}-tech.md for technical design"

Step 6: Write Technical Design

1. Read {scope}-prd-notes.md for selected architecture option

2. Write {scope}-tech.md with:
   - Overview (technical approach summary)
   - Key Components (what pieces, responsibilities)
   - API Design (signatures, contracts)
   - Data Flow (how data moves through system)
   - Implementation Details (specific notes)
   - Migration Plan (if applicable)

Step 7: Validate & Finalize

Review with user:

1. Present PRD summary
2. Ask for feedback
3. Incorporate changes
4. Mark Phase 7 complete

Important Rules

| Rule | Bad | Good | |------|-----|------| | Use Files | Keep in memory | Save to {scope}-prd-notes.md | | Update Plan | Move on without update | Update task-plan.md with checkbox | | Read Before Decide | Decide from memory | Read notes first | | Separate Docs | Mix PRD + Tech | PRD for "what", Tech for "how" | | Include Options | Jump to solution | Document 2-3 options with pros/cons |

Phase Transitions

Update {scope}-prd-task-plan.md after each phase with checkbox ✓ and timestamp.

Completing a PRD

Mark all phases complete, set status to "✅ COMPLETE", log final deliverables.

File Cleanup (Optional)

After PRD is complete:

• Keep {scope}-prd-notes.md for reference (shows decision process)
• Archive {scope}-prd-task-plan.md or delete
• Final outputs are {scope}-prd.md and {scope}-tech.md

Quick Start Template

# PRD Task Plan: {Feature}

## Goal
Create PRD and technical design for {description}

## Phases
- [ ] Initialize 4 files
- [ ] Gather requirements
- [ ] Research & analysis
- [ ] Design solution (A/B/C options)
- [ ] Write PRD
- [ ] Write technical design
- [ ] Validate & finalize

## Status
Phase 1: Initializing files

Why This Works

| Problem | Solution | |---------|----------| | Context switching | All thinking in files, read anytime | | Lost requirements | Saved to {scope}-prd-notes.md immediately | | Inconsistent PRDs | Same process, same structure | | "Left brain vs right brain" | One coherent workflow | | Re-explaining context | Files contain full context | | Mixed concerns | PRD (product) separate from Tech (implementation) | | Hidden decisions | Architecture options A/B/C documented |

References

• planning-with-files - File-based planning methodology
• architecting-solutions - PRD creation best practices
• Edge case scanning: references/edge-case-analysis.md

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Auto-Trigger (Automation)

When this skill completes, automatically trigger:

1. self-improving-agent (background) - Extract patterns
2. session-logger (auto) - Save session context