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name: feature-brainstorm description: Multi-phase brainstorming for complex feature implementations using parallel sub-tasks. Use when the user asks to brainstorm, design, or plan a complex feature, wants to explore implementation approaches, or needs architectural analysis before coding. Triggers on phrases like "brainstorm feature", "design implementation", "explore approaches", "plan architecture", or "how should we implement".

Feature Brainstorm

A structured three-phase approach to brainstorming complex feature implementations using parallel Sonnet sub-tasks for exploration, validation, and feasibility assessment.

Overview

CopyPhase 1: EXPLORE    → Launch parallel sub-tasks to analyze codebase
Phase 2: VALIDATE   → Launch parallel sub-tasks to research and validate ideas
Phase 3: ASSESS     → Launch parallel sub-tasks to evaluate feasibility and create proposals

Before Starting

1. Confirm the feature scope with the user
2. Identify the codebase location (ask if not provided)
3. Create a working directory: mkdir -p /home/claude/brainstorm-sessions

Phase 1: Exploration

Launch 3-5 parallel sub-tasks using Sonnet to explore the codebase from different angles.

Sub-task prompt template:

CopyYou are exploring a codebase to understand how to implement: [FEATURE]

Your specific focus: [EXPLORATION_ANGLE]

Codebase location: [PATH]

Instructions:
1. Explore relevant files using view and bash tools
2. Document key findings in /home/claude/brainstorm-sessions/explore-[ANGLE].md
3. Note: existing patterns, relevant abstractions, potential integration points, dependencies

Keep findings concise and actionable.

Exploration angles to assign:

• Architecture: Overall structure, module boundaries, data flow patterns
• Similar features: Existing features with comparable patterns
• Data layer: Models, schemas, database interactions, state management
• API surface: Endpoints, interfaces, contracts that would be affected
• Testing patterns: How similar features are tested, test infrastructure

Example sub-task launch:

Copyclaude --model claude-sonnet-4-20250514 --print \
  "You are exploring a codebase to understand how to implement: user authentication with OAuth.
   Your specific focus: Architecture - overall structure and module boundaries.
   Codebase location: /path/to/repo

   Explore relevant files and document findings in /home/claude/brainstorm-sessions/explore-architecture.md"

After all exploration sub-tasks complete, synthesize findings:

Copycat /home/claude/brainstorm-sessions/explore-*.md > /home/claude/brainstorm-sessions/exploration-summary.md

Phase 2: Validation

Based on exploration findings, launch 3-4 parallel sub-tasks to validate ideas and perform research.

Sub-task prompt template:

CopyYou are validating an implementation approach for: [FEATURE]

Exploration context:
[PASTE KEY FINDINGS FROM PHASE 1]

Your validation focus: [VALIDATION_ANGLE]

Instructions:
1. Research best practices using web search if needed
2. Validate against codebase patterns in [PATH]
3. Document findings in /home/claude/brainstorm-sessions/validate-[ANGLE].md
4. Flag any concerns, risks, or open questions

Be critical - identify potential problems early.

Validation angles to assign:

• Pattern alignment: Does the approach fit existing codebase patterns?
• Technical research: Best practices, library options, security considerations
• Edge cases: Error handling, failure modes, boundary conditions
• Performance: Scalability concerns, potential bottlenecks
• Dependencies: Impact on existing code, breaking changes

After validation sub-tasks complete:

Copycat /home/claude/brainstorm-sessions/validate-*.md > /home/claude/brainstorm-sessions/validation-summary.md

Phase 3: Assessment

Launch 2-3 parallel sub-tasks to assess feasibility and create concrete proposals.

Sub-task prompt template:

CopyYou are creating an implementation proposal for: [FEATURE]

Context:
- Exploration findings: [SUMMARY]
- Validation results: [SUMMARY]

Your assessment focus: [ASSESSMENT_ANGLE]

Instructions:
1. Create a concrete implementation proposal
2. Estimate effort and complexity
3. Identify prerequisites and blockers
4. Document in /home/claude/brainstorm-sessions/assess-[ANGLE].md

Output format:
## Approach Summary
## Implementation Steps
## Effort Estimate (T-shirt size + reasoning)
## Risks and Mitigations
## Prerequisites

Assessment angles to assign:

• MVP approach: Minimum viable implementation, fastest path
• Robust approach: Production-ready, handles edge cases
• Alternative approach: Different architecture or pattern (if applicable)

After assessment sub-tasks complete:

Copycat /home/claude/brainstorm-sessions/assess-*.md > /home/claude/brainstorm-sessions/assessment-summary.md

Synthesis

After all phases, create a final brainstorm report:

1. Read all summary files
2. Create /home/claude/brainstorm-sessions/[FEATURE]-brainstorm-report.md with:
   • Executive summary
   • Recommended approach with justification
   • Alternative approaches considered
   • Key risks and mitigations
   • Suggested next steps
   • Open questions for user

Present the report to the user and discuss.

Sub-task Management

Launching sub-tasks:

Copy# Run in background, capture output
claude --model claude-sonnet-4-20250514 --print "[PROMPT]" > output.md 2>&1 &

Waiting for completion:

Copywait  # Wait for all background jobs

Checking results:

Copyls -la /home/claude/brainstorm-sessions/

Customization

Adjust the number and focus of sub-tasks based on:

• Small feature: 2-3 sub-tasks per phase
• Medium feature: 3-4 sub-tasks per phase
• Large/complex feature: 4-5 sub-tasks per phase

Skip phases if appropriate:

• Skip Phase 2 if the implementation is straightforward
• Combine Phase 2 and 3 for well-understood patterns