Feature Brainstorm

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

Overview

Phase 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:

You 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:

claude --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:

cat /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:

You 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:

cat /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:

You 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:

cat /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:

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

Waiting for completion:

wait  # Wait for all background jobs

Checking results:

ls -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