doubt-driven-development

doubt-driven-development is a skill for Codex, Cursor from nota-america/forgecat-agent-profiles. It costs 67 tokens per session (3,585 once invoked), scanned A, a copy of doubt-driven-development, Apache-2.0.

A review practice that challenges important coding decisions from a fresh perspective before they are finalized.

In plain words
What is it for?
Use it to question architecture choices, branching logic, cross-module behavior, safety claims, and non-trivial code before committing it.
Why use it?
It helps uncover hidden assumptions and mistakes when code affects multiple parts of a system, security, production data, or other hard-to-reverse outcomes.

Skill for CodexCursor

Written for Codex and Cursor: runs codex exec, but also installed under .cursor/. Also seen: mentions subagents; mentions Claude Code; mentions Codex.

Good fit Use it to question architecture choices, branching logic, cross-module behavior, safety claims, and non-trivial code before committing it.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nota-america/forgecat-agent-profiles/doubt-driven-development
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add nota-america/forgecat-agent-profiles --skill doubt-driven-development
Clone the repo
git clone --depth 1 https://github.com/nota-america/forgecat-agent-profiles

Made for: Codex, Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for doubt-driven-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/nota-america/forgecat-agent-profiles/doubt-driven-development.svg)](https://agentmods.dev/skills/nota-america/forgecat-agent-profiles/doubt-driven-development)
Your own site
<a href="https://agentmods.dev/skills/nota-america/forgecat-agent-profiles/doubt-driven-development"><img src="https://agentmods.dev/badge/skills/nota-america/forgecat-agent-profiles/doubt-driven-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,585 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00067 $0.03585
Opus 5 $0.00034 $0.01792
Sonnet 5 $0.00013 $0.00717
Haiku 4.5 $0.00007 $0.00359

Measured 7d ago against content hash 59aef769adea, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

doubt-driven-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to doubt-driven-development — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

profiles/addyosmani/agent-skills/for-cursor/.cursor/skills/doubt-driven-development/SKILL.md · 244 lines

How it starts

The opening of the file, as written. The whole thing — 244 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.

Read the full file on GitHub · 244 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 244 lines · 67 tokens per session scan A 59aef769adea

Subscribe to this mod's changes

doubt-driven-development is a skill published in the GitHub repository nota-america/forgecat-agent-profiles (65 stars, last pushed today), licensed Apache-2.0. It adds 67 tokens to every session and 3,585 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to doubt-driven-development, differing in 4 lines, and is treated as a copy.