/doubt-driven-development

name: doubt-driven-development
description: Subjects every non-trivial decision to a fresh-context adversarial review before it stands. Use when correctness matters more than speed, when working in unfamiliar code, when stakes are high (production, security-sensitive logic, irreversible operations), or any time a confident output would be cheaper to verify now than to debug later.
source_repo: "addyosmani/agent-skills"
source_url: "https://github.com/addyosmani/agent-skills"
source_license: "MIT"
origin: aggregated
language: en

Doubt-Driven Development

Overview

A confident answer is not a correct one. Long sessions accumulate context that quietly turns assumptions into "facts" without anyone noticing. Doubt-driven development is the discipline of materializing a fresh-context reviewer — biased to **disprove**, not approve — before any non-trivial output stands.

This is not `/review`. `/review` is a verdict on a finished artifact. This is an in-flight posture: non-trivial decisions get cross-examined while course-correction is still cheap.

When to Use

A decision is **non-trivial** when at least one of these is true:

• It introduces or modifies branching logic
• It crosses a module or service boundary
• It asserts a property the type system or compiler cannot verify (thread safety, idempotence, ordering, invariants)
• Its correctness depends on context the future reader cannot see
• Its blast radius is irreversible (production deploy, data migration, public API change)

Apply the skill when:

• About to make an architectural decision under uncertainty
• About to commit non-trivial code
• About to claim a non-obvious fact ("this is safe", "this scales", "this matches the spec")
• Working in code you don't fully understand

**When NOT to use:**

• Mechanical operations (renaming, formatting, file moves)
• Following a clear, unambiguous user instruction
• Reading or summarizing existing code
• One-line changes with obvious correctness
• Pure tooling operations (running tests, listing files)
• The user has explicitly asked for speed over verification

If you doubt every keystroke, you ship nothing. The skill applies only to non-trivial decisions as defined above.

Loading Constraints

This skill is designed for the **main-session orchestrator**, where Step 3 (DOUBT, detailed below) can spawn a fresh-context reviewer.

• **Do NOT add this skill to a persona's `skills:` frontmatter.** A persona that follows Step 3 would spawn another persona — the orchestration anti-pattern explicitly forbidden by `references/orchestration-patterns.md` ("personas do not invoke other personas").
• **If you find yourself applying this skill from inside a subagent context** (where Claude Code prevents nested subagent spawn): the preferred path is to surface to the user that doubt-driven cannot run nested and let the main session handle it. As a last resort only, a degraded self-questioning fallback exists — rewrite ARTIFACT + CONTRACT as a fresh self-prompt with a hard mental separator from your prior reasoning, and walk Steps 1–5. This is **not fresh-context review** (you carry your own context with you), so flag the result as degraded and prefer escalation whenever the user is reachable.

The Process

Copy this checklist when applying the skill:

Doubt cycle:
- [ ] Step 1: CLAIM — wrote the claim + why-it-matters
- [ ] Step 2: EXTRACT — isolated artifact + contract, stripped reasoning
- [ ] Step 3: DOUBT — invoked fresh-context reviewer with adversarial prompt
- [ ] Step 4: RECONCILE — classified every finding against the artifact text
- [ ] Step 5: STOP — met stop condition (trivial findings, 3 cycles, or user override)

Step 1: CLAIM — Surface what stands

Name the decision in two or three lines:

CLAIM: "The new caching layer is thread-safe under the
        read-heavy workload described in the spec."
WHY THIS MATTERS: a race here corrupts user data and is
                  hard to detect in QA.

If you can't write the claim that compactly, you have a vibe, not a decision. Surface it before scrutinizing it.

Step 2: EXTRACT — Smallest reviewable unit

A fresh-context reviewer needs the **artifact** and the **contract**, not the journey.

• Code: the diff or the function — not the whole file
• Decision: the proposal in 3–5 sentences plus the constraints it has to satisfy
• Assertion: the claim plus the evidence that supposedly supports it (kept distinct from the Step 1 CLAIM block, which is the orchestrator's hypothesis under scrutiny)

Strip your reasoning. If you hand over conclusions, you'll get back validation of your conclusions. The unit must be small enough that a reviewer can hold it in mind in one read — if it's a 500-line PR, decompose first.

Step 3: DOUBT — Invoke the fresh-context reviewer

The reviewer's prompt **must be adversarial**. Framing decides the answer.

Adversarial review. Find what is wrong with this artifact.
Assume the author is overconfident. Look for:
- Unstated assumptions
- Edge cases not handled
- Hidden coupling or shared state
- Ways the contract could be violated
- Existing conventions this might break
- Failure modes under unexpected input

Do NOT validate. Do NOT summarize. Find issues, or state
explicitly that you cannot find any after thorough examination.

ARTIFACT: <paste artifact>
CONTRACT: <paste contract>

**Pass ARTIFACT + CONTRACT only. Do NOT pass the CLAIM.** Handing the reviewer your conclusion biases it toward agreement. The reviewer must independently determine whether the artifact satisfies the contract.

In Claude Code, the role-based reviewers in `agents/` start with isolated context by design and are usable here — see `agents/` for the roster and per-domain match.

**The adversarial prompt above takes precedence over the persona's default response shape.** Personas like `code-reviewer` are written to produce balanced verdicts with both strengths and weaknesses; doubt-driven needs issues-only