/brainstorm — Clarify Goals Before Planning

Purpose: Separate WHAT from HOW. Explore the problem space before committing to a solution.

Four phases:

1. Assess clarity — Is the goal specific enough?
2. Understand idea — What problem, who benefits, what exists?
3. Explore approaches — Generate options, compare tradeoffs, adversarial critique
4. Capture design — Write structured output for /plan

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Quick Start

/brainstorm "add user authentication"     # full 4-phase process
/brainstorm                                # prompts for goal

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Execution Steps

Phase 1: Assess Clarity

If the user provided a goal string, evaluate it. Otherwise prompt for one.

Use AskUserQuestion with options to gauge clarity:

• clear — Goal is specific and actionable (e.g., "add JWT auth to the API")
• vague — Goal exists but needs narrowing (e.g., "improve security")
• exploring — No firm goal yet, just a direction (e.g., "something with auth")

If vague or exploring, ask follow-up questions to sharpen the goal before proceeding. Do NOT move to Phase 2 until you have a concrete problem statement (one sentence, testable).

Phase 2: Understand the Idea

Answer these questions (use codebase exploration as needed):

1. What problem does this solve? — State the pain point in concrete terms.
2. Who benefits? — End users, developers, operators, CI pipeline?
3. What exists today? — Current state, prior art in the codebase, adjacent systems.
4. What constraints matter? — Performance, compatibility, security, timeline.

Summarize findings before moving on. If anything is unclear, ask the user.

Phase 3: Explore Approaches

Generate 2-3 distinct approaches. For each:

• Name — Short label (e.g., "JWT middleware", "OAuth proxy", "Session cookies")
• How it works — 2-3 sentences
• Pros — What it gets right
• Cons — What it gets wrong or defers
• Effort — Rough scope (small / medium / large)

Phase 3b: Adversarial Critique

Before asking the user to choose, stress-test each approach:

For each approach, answer these red team questions (read references/red-team-checklist.md):

1. What breaks first? — Under load, edge cases, or adversarial input
2. What's the hidden cost? — Maintenance burden, technical debt, learning curve
3. What assumption is wrong? — The unstated belief that makes this approach seem good
4. Who disagrees? — What would a senior engineer with the opposite preference say?

Mark any approach that fails 2+ red team questions as HIGH RISK in the comparison.

If all approaches fail 2+ questions, generate a 4th "hybrid" approach addressing the weaknesses.

Present the comparison and use AskUserQuestion to let the user pick an approach or request a hybrid.

Phase 4: Capture Design

Generate a date slug: YYYY-MM-DD-<goal-slug> (lowercase, hyphens, no spaces).

Write the output file to .agents/brainstorm/YYYY-MM-DD-<slug>.md:

---
id: brainstorm-YYYY-MM-DD-<goal-slug>
type: brainstorm
date: YYYY-MM-DD
---
# Brainstorm: <Goal>
## Problem Statement
## Approaches Considered
## Selected Approach
## Open Questions
## Next Step: /plan

All five sections must be populated. The "Next Step" section should contain a concrete /plan invocation suggestion with the selected approach as context.

Create the .agents/brainstorm/ directory if it does not exist.

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Termination

Phase 4 output written = done. No further phases, no loops.

Validation

After writing the output file, verify:

1. File exists at the expected path
2. All 5 sections (Problem Statement, Approaches Considered, Selected Approach, Open Questions, Next Step: /plan) are present and non-empty

Report the file path to the user.

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Examples

Example 1: Specific goal

User: /brainstorm "add rate limiting to the API"

Phase 1: Goal is clear — add rate limiting to the API.
Phase 2: Problem is uncontrolled request volume causing timeouts.
         Benefits operators and end users. No rate limiting exists today.
Phase 3: Three approaches — token bucket middleware, API gateway,
         per-route decorators. User picks token bucket.
Phase 4: Writes .agents/brainstorm/2026-02-17-rate-limiting.md

Example 2: Vague goal

User: /brainstorm "improve performance"

Phase 1: Goal is vague. Asks: "Which part? API response times,
         build speed, database queries, or something else?"
         User says: "API response times on the search endpoint."
Phase 2: Investigates search endpoint, finds N+1 queries.
Phase 3: Approaches — query optimization, caching layer, pagination.
Phase 4: Writes .agents/brainstorm/2026-02-17-search-performance.md

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Troubleshooting

Problem	Cause	Solution
Brainstorm loops in Phase 1 without advancing	Goal remains too vague after follow-up questions	Provide a concrete, testable problem statement (e.g., "reduce API search latency below 200ms" instead of "improve performance").
Output file missing one or more required sections	Phase 4 was interrupted or the skill terminated early	Re-run /brainstorm with the same goal; verify all 5 sections (Problem Statement, Approaches Considered, Selected Approach, Open Questions, Next Step: /plan) are present in the output.
.agents/brainstorm/ directory not created	The skill could not create the directory (permissions or path issue)	Manually create it with mkdir -p .agents/brainstorm and re-run.
/plan invocation in "Next Step" section is generic or incomplete	The selected approach was not specific enough to generate a concrete plan command	Edit the output file to refine the selected approach, then craft a /plan invocation that includes the approach name and key constraints.
Brainstorm produces only one approach in Phase 3	The problem space is narrow or the goal is overly constrained	Widen the goal slightly or explicitly ask for alternative approaches (e.g., "consider a caching approach and a query optimization approach").

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See Also

• skills/plan/SKILL.md — Decompose the selected approach into actionable issues

Reference Documents

• references/red-team-checklist.md — Adversarial critique template for Phase 3b