Brainstorm

Brainstorm — Tournament Solution Exploration

Why this gate exists

Three biases to defeat:

• First-solution lock-in: commits to first reasonable solution → local optimum
• Convergence bias: asked "any better way?", says "no" to stop sooner
• Dimensional collapse: compares on 1 dimension (usually "simple"), ignores others

Brainstorm enforces:

• Multiple candidates (min 2 standard, min 3 high-stakes)
• Multi-dimensional comparison
• Adversarial challenges
• Honest recommendation with trade-offs

When to fire

Mandatory:

• High-stakes lane (always, ≥3 options)
• User invokes /brainstorm

Conditional (standard):

• Multiple viable paths exist
• User mentions "X or Y" trade-off
• CONTEXT.md suggests recurring decision space

Skip:

• Trivial lane
• Solution genuinely obvious (state reasoning before skipping)
• User: "no brainstorm, just do A"

Process — 3 phases

Phase 1 — Frame

1.1 Restate problem. Use Align artifact if exists; else restate.

1.2 Identify 3-5 evaluation dimensions. See references/evaluation-dimensions.md for catalog by task type.

1.3 Separate constraints vs assumptions:

• Constraints (MUST hold): regulation, hard requirements
• Assumptions (may not hold): challengeable in Round 3

Phase 2 — Tournament loop

2.1 Generate A1 — first reasonable solution.

## Solution A1: <Name>

**Approach:** <1-2 sentence description>

**Implementation sketch:**
- <Step 1>
- <Step 2>

**Self-assessment:**
| Dimension | Score | Notes |
|---|---|---|
| ... | ... | ... |

**Weaknesses (be honest):**
- <Weakness 1 — most important>

2.2 Adversarial Challenge 1 — beat the weakness.

"What solution beats A1 on its WEAKEST dimension?"

No meaningful alternative → state so, may stop with note.

2.3 Generate A2 + head-to-head.

## Solution A2: <Name>

**Targets A1's weakness:** <which weakness, explicit>

**Head-to-head A1 vs A2:**
| Dimension | A1 | A2 | Winner |
|---|---|---|---|
| ... | ... | ... | ... |

**Champion:** A<N>
**Reasoning:** <why champion wins overall>

2.4 Adversarial Challenge 2 — different paradigm.

After 2 solutions: "DIFFERENT PARADIGM entirely?"

Paradigm shifts: sync↔async, pull↔push, imperative↔declarative, server↔client, in-house↔managed, additive↔subtractive, reactive↔proactive, centralized↔distributed, stateful↔stateless.

Paradigm shift available → generate A3.

2.5 Generate A3 + compare. Same template. Update champion.

2.6 Adversarial Challenge 3 — question assumptions.

After 3 solutions: "What CONSTRAINT did I ASSUME that doesn't actually hold?"

Meta-challenge. Often reveals breakthrough (e.g., "must use Postgres" → actually have TigerBeetle).

2.7 Stop conditions.

Stop when ALL:

• ≥ minimum (2 standard, 3 high-stakes)
• AND any of:
  • 5 solutions reached (hard cap)
  • New option adds no new dimension/paradigm
  • Honest "no meaningful alternative"

Don't stop to save effort. Don't continue to seem thorough.

Phase 3 — Synthesis

3.1 Comparison matrix — concrete values, not ✅/❌.

| Dimension | A1: Batch | A2: Parallel | A3: CDC | A4: TigerBeetle |
|---|---|---|---|---|
| Throughput | 5k/sec | 15k/sec | 10k/sec | 50k+/sec |
| Latency p95 | 200ms | 50ms | 100ms | 5ms |
| Ops complexity | Low | Medium | High | High (new tech) |
| Consistency | Strong | Eventual | Eventual | Strong (ledger) |
| Time to ship | 1 week | 2 weeks | 3 days | 3 weeks |

3.2 Agent recommendation.

## Recommendation: A<N> — <Name>

**Why:** <2-3 sentences>

**What we gain:**
- <Concrete benefit 1>

**What we sacrifice (honest):**
- <Concrete trade-off 1>

**Confidence:** High | Moderate | Low

**Caveats:**
- <Uncertainty 1>
- <When to revisit this decision>

3.3 Present to user. Options:

1. Accept recommendation → Plan
2. Pick different option → Plan with that choice
3. Reject all → Align gate missed requirement, loop back

Phase 4 (high-stakes only) — ADR

Auto-generate ADR at docs/adr/NNNN-<decision>.md. See doc 05 brainstorm.md §"Phase 4" for full template.

Anti-patterns

Don't:

• Generate A1, A2 in same paradigm (cosmetic difference)
• Skip self-critique to commit faster
• Hide weaknesses of recommended option
• Stop at 2 when 3rd paradigm exists
• Vague matrix (✅/❌ only, no concrete values)
• Fake decisive recommendation when tie

Do:

• Force paradigm shift at A3
• Question assumptions at A4
• Concrete numbers in matrix
• Acknowledge close calls
• Save rejected alternatives in ADR (institutional memory)

Output artifacts

Acceptance tests

• T1 (high-stakes ≥3): "Migrate monolith to microservices?" → ≥3 options, ≥5 dimensions, recommendation has trade-offs
• T2 (standard skip): "Add @Valid annotation" → not fired (obvious)
• T3 (standard fire): "Refactor PaymentService to be more testable" → fires, ≥2 options
• T4 (close call): "Redis vs Memcached for session?" → "close call" if genuinely close
• T5 (ADR): After T1 → docs/adr/NNNN-microservices-decision.md exists with 4 options + rationale + consequences

Integration

• Auto-fire from triage when TRIAGE_LANE=high-stakes (after Align)
• Auto-fire from Align when multiple paths detected (standard lane)
• Manual: /brainstorm
• Output → Plan gate (chosen solution) + ADR (high-stakes only)

Related

• references/evaluation-dimensions.md — dimension catalog by task type
• references/adversarial-challenges.md — challenge question library
• references/presentation-template.md — recommendation format
• references/paradigm-shifts.md — paradigm-shift examples
• examples/architecture-decision.md — full worked example
• examples/refactor-approach.md — refactor brainstorm example
• examples/library-selection.md — library choice example
• skills/align/SKILL.md — runs before Brainstorm
• commands/brainstorm.md — entry point
• commands/plan.md — consumes Brainstorm output