Agent skill · product strategy · addyosmani
doubt-driven-development
Subjects every non-trivial decision to a fresh-context adversarial review before it stands. Use when you want every assumption cross-examined before proceeding, when stress-testing a plan for hidden failure modes, when correctness matters more than speed, when working in unfamiliar code, when stakes are high (production auth, security-sensitive logic, a high-stakes migration, irreversible operations), or any time a confident output would be cheaper to verify now than to debug later.
Why this skill is useful
Provides a structured process for adversarial review of non-trivial decisions, enhancing correctness in complex code scenarios.
What it needs
About 10k tokens when loaded. Last updated 2026-08-06. 83,053 stars on the source repository.
What this skill does
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. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills addyosmani/doubt-driven-development