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 agentmods add skills/junmystery/agent-guidance-python/doubt-driven-developmentnpx skills add JunMystery/Agent-Guidance-Python --skill doubt-driven-developmentgit clone --depth 1 https://github.com/JunMystery/Agent-Guidance-PythonWhat 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 | $0.00067 | $0.03585 |
| Opus 5 | $0.00034 | $0.01792 |
| Sonnet 5 | $0.00013 | $0.00717 |
| Haiku 4.5 | $0.00007 | $0.00359 |
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 yesterday.
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
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.
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 byreferences/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.
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.
- yesterday First seen · 244 lines · 67 tokens per session scan A 59aef769adea
doubt-driven-development is a skill published in the GitHub repository JunMystery/Agent-Guidance-Python (2 stars, last pushed 1mo ago), licensed MIT. 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.
Other skills, from other repositories
common-feedback-reporter
Pre-write audit for skill violations: checks planned code against loaded skill anti-patterns before any file write. Use when writing Flutter/Dart/TS code or editing SKILL.md files with active project skills. Load as composite; on auto-fixed violation, also load +common/common-learning-log.
common-exploit-verification
Enforce "No Exploit, No Report" policy with PoC construction standards, false-positive filtering, and evidence collection per vulnerability class across backend, frontend, and mobile. Use when validating security findings, constructing exploit proofs, filtering false positives, or writing pentest findings.
common-session-retrospective
Analyze conversation corrections to detect skill gaps and prepare targeted skill-library maintenance tasks. Use after any session with user corrections, rework, or retrospective requests. After finding correction loops, also load +common/common-learning-log to persist mistake entries to AGENTSLEARNING.md.
common-store-changelog
Generate user-facing release notes for the App Store and Google Play from git history (App Store <=4000 chars, Google Play <=500). Use when generating release notes, app store changelog, play store release, or "what's new" text for a mobile app.
common-code-review
Conduct high-quality, persona-driven code reviews. Use when reviewing PRs, critiquing code quality, or analyzing changes for team feedback.
common-workflow-writing
Rules for writing concise, token-efficient workflow and skill files. Prevents over-building that requires costly optimization passes. Use when creating or editing workflow files, SKILL.md files, or new skill definitions.