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.
npx skills add mycelium-hq/ai-brain-starter --skill doubt-driven-developmentgit clone --depth 1 https://github.com/mycelium-hq/ai-brain-starterWrote 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.
[](https://agentmods.dev/skills/mycelium-hq/ai-brain-starter/doubt-driven-development)<a href="https://agentmods.dev/skills/mycelium-hq/ai-brain-starter/doubt-driven-development"><img src="https://agentmods.dev/badge/skills/mycelium-hq/ai-brain-starter/doubt-driven-development/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mycelium-hq/ai-brain-starter/doubt-driven-development"><img src="https://agentmods.dev/badge/skills/mycelium-hq/ai-brain-starter/doubt-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00104 | $0.03577 |
| Opus 5.5 | $0.00042 | $0.01431 |
| Sonnet 5.5 | $0.00021 | $0.00715 |
| Haiku 4.5 | $0.00010 | $0.00358 |
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 1mo 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.
This is a copy
89% identical to doubt-driven-development — 36 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.
How it starts
The opening of the file, as written. The whole thing — 246 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Doubt-Driven Development
Cherry-picked from addyosmani/agent-skills (MIT) 2026-05-26. Adapted to this substrate.
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 post-PR review. Post-PR 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) can spawn a fresh-context reviewer.
- Do NOT add this skill to a subagent's
skills:frontmatter. A subagent that follows Step 3 would spawn another subagent, which Claude Code blocks by construction (subagents cannot spawn subagents). - If you find yourself applying this skill inside a subagent context: 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. Flag the result as degraded and prefer escalation whenever the user is reachable.
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.
- 1mo ago First seen · 246 lines · 104 tokens per session scan A 16eecbed1ff1
doubt-driven-development is a skill published in the GitHub repository mycelium-hq/ai-brain-starter (48 stars, last pushed today), licensed MIT. It adds 104 tokens to every session and 3,577 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 89% identical to doubt-driven-development, differing in 36 lines, and is treated as a copy.
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