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 a code review. Code 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 this 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
• 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.

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.

If you have access to a subagent tool, use it to spawn a fresh-context reviewer with the adversarial prompt above. If subagents are not available, rewrite ARTIFACT + CONTRACT as a fresh self-prompt with a hard mental separator from your prior reasoning, and walk Steps 1–5. Flag the result as degraded since you carry your own context.

Step 4: RECONCILE — Fold findings back

The reviewer's output is data, not verdict. You are still the orchestrator. Re-read the artifact text against each finding before classifying — rubber-stamping the reviewer is the same failure mode as ignoring it.

For each finding, classify in this precedence order (first matching class wins):

1. Contract misread — reviewer flagged something specifically because the CONTRACT you provided was unclear or incomplete. Fix the contract first, re-classify on the next cycle.
2. Valid + actionable — real issue requiring a change to the artifact. Change it, re-loop.
3. Valid trade-off — issue is real but cost of fixing exceeds cost of accepting. Document the trade-off explicitly so the user sees it.
4. Noise — reviewer flagged something that's actually correct under context the reviewer didn't have. Note it, move on, and ask: would adding that context to the contract have prevented the false flag?

A fresh reviewer can be wrong because it lacks context. Don't defer just because it's "fresh."

Step 5: STOP — Bounded loop, not recursion

Stop when:

• Next iteration returns only trivial or already-considered findings, or
• 3 cycles completed (escalate to user, don't grind a fourth alone), or
• User explicitly says "ship it"

If after 3 cycles the reviewer still surfaces substantive issues, the artifact may not be ready. Surface this to the user — three unresolved cycles is information about the artifact, not a reason to keep looping.

If 3 cycles is "obviously insufficient" because the artifact is large: the artifact is too big — return to Step 2 and decompose. Do not lift the bound.

Interaction with Other Skills

• `test-driven-development`: TDD's RED step is doubt made concrete — a failing test is a disproof attempt. When TDD applies, that failing test is the doubt step for behavioral claims.
• `systematic-debugging`: when the reviewer surfaces a real failure mode, drop into debugging to localize and fix.
• `verification-before-completion`: complementary. Verification checks evidence after implementation; doubt-driven checks decisions during implementation.

Common Rationalizations

Red Flags

• Spawning a reviewer for a one-line rename or formatting change
• Treating reviewer output as authoritative without re-reading the artifact text
• Looping >3 cycles without escalating to the user
• Prompting the reviewer with "is this good?" instead of "find issues"
• Skipping doubt under time pressure on a high-stakes decision
• Doubt theater: across 2 or more cycles where the reviewer surfaced substantive findings, zero findings were classified as actionable. You are validating, not doubting. Stop and escalate.
• Doubting only after committing — that's a post-hoc review, not doubt-driven development
• Stripping the contract from the reviewer's input
• Passing the CLAIM to the reviewer (biases toward agreement)

Verification

After applying doubt-driven development:

• [ ] Every non-trivial decision (per the definition above) was named explicitly as a CLAIM before standing
• [ ] At least one fresh-context review per non-trivial artifact (a failing test produced by TDD's RED step satisfies this for behavioral claims)
• [ ] The reviewer received ARTIFACT + CONTRACT — NOT the CLAIM, NOT your reasoning
• [ ] The reviewer's prompt was adversarial ("find issues"), not validating ("is it good")
• [ ] Findings were classified against the artifact text (not rubber-stamped) using the precedence: contract misread / actionable / trade-off / noise
• [ ] A stop condition was met (trivial findings, 3 cycles, or user override)
• [ ] If the skill ran in degraded mode (no subagent), the result was flagged as degraded