self-consistency

AI-consumed reference. Optimized for Claude to read during execution. Human-readable explanation: see docs/architecture/HIERARCHICAL_PLANNING.md or docs/getting-started/ depending on topic.

Self-Consistency

For ambiguous design decisions with multiple plausible answers. Generate multiple independent paths, take the majority.

Governed by: rules/workflow/self-consistency.md (when / why)

When NOT to Use

Single-answer tasks (file rename, typo)
Quick/Standard complexity — cost doesn't pay back
User said must do: / just do: / no discussion
Budget already >85% of session limit

The Protocol

Step 1 — Frame the decision

Write the decision as a question with ≥2 possible answers:

"Should the API use REST or GraphQL?" "Monolith, modular monolith, or microservices?" "Redis for cache vs in-memory LRU?"

If the question has only one sensible answer, skip SC.

Step 2 — Generate N = 3 paths

For each path, reason from scratch in an isolated context:

Path 1:
  - Consider user scale (est. 10K DAU for this product)
  - Consider team size (2 backend devs)
  - Consider infra (already on Fly.io, no k8s expertise)
  → Answer: Modular monolith

Path 2:
  - Consider dev velocity (team ships weekly)
  - Consider deploy complexity (monorepo, single deploy)
  - Consider failure domains (single point of failure OK at this scale)
  → Answer: Modular monolith

Path 3:
  - Consider future scale (could hit 100K DAU in 12mo)
  - Consider hiring plan (doubling team in 6mo)
  - Consider isolation needs (auth service is security-critical)
  → Answer: Microservices (start with auth as separate service)

Each path should use different starting considerations — don't copy-paste one reasoning with cosmetic changes.

Step 3 — Extract answers, count votes

Answers: [modular monolith, modular monolith, microservices]
Votes:   modular monolith: 2 | microservices: 1
Winner:  modular monolith (2/3 majority)

Step 4 — Report

If clear majority (2/3 or 3/3):

Decision: Modular monolith (2/3 paths agreed)

Both winning paths cited scale (10K DAU), team size (2 devs), and existing Fly.io infra. The dissenting path optimized for 12-month scale which is speculative.

Flagging dissent: if hiring doubles and we hit 100K DAU fast, consider extracting auth service as a Phase 2 refactor.

If no majority (1/1/1 with 3 different answers):

Paths disagreed — pausing to ask.

Path 1 → REST (simplicity) Path 2 → GraphQL (client flexibility) Path 3 → tRPC (end-to-end types)

Which constraint matters most to you: simplicity, client flexibility, or type safety across client/server?

Per rules/core/no-assumption.md — when paths disagree, ask rather than pick.

Anti-Patterns

Cosmetic paths — same reasoning with word swaps. Don't. Each path must start from different considerations.
Forcing consensus — if paths disagree, don't pick silently. Ask.
N > 3 — diminishing returns. 3 catches most issues; 5+ is expensive and rarely changes the answer.
Using SC for non-trade-offs — if the answer is obvious, skip this. SC costs 3× tokens.

Output Format

## Decision: [Answer]
**Votes:** [X/N paths]
**Majority reasoning:** [1-2 sentence summary of why the winning paths agreed]
**Dissent:** [if any — what the losing path(s) prioritized]
**Flag for Phase 5:** [any follow-up action implied by dissent]

Tie-Ins

rules/workflow/self-consistency.md — policy
rules/workflow/tree-of-thoughts.md — for branching exploration (different technique)
rules/core/no-assumption.md — when to escalate to user
skills/chain-of-verification/SKILL.md — verify the SC winner's facts