Borrowing it
Nothing to install: this file belongs to Geeksfino/ai-dev-playbook. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Geeksfino/ai-dev-playbook/main/CLAUDE.mdgit clone --depth 1 https://github.com/Geeksfino/ai-dev-playbookWrote 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/instructions/geeksfino/ai-dev-playbook/claude-md)<a href="https://agentmods.dev/instructions/geeksfino/ai-dev-playbook/claude-md"><img src="https://agentmods.dev/badge/instructions/geeksfino/ai-dev-playbook/claude-md.svg" alt="Measured on agentmods" 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 | $0.01159 | $0.01159 |
| Opus 5 | $0.00580 | $0.00580 |
| Sonnet 5 | $0.00232 | $0.00232 |
| Haiku 4.5 | $0.00116 | $0.00116 |
Grade A, and why
ai-dev-playbook CLAUDE.md 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.
How it starts
The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
LLMs make the same mistakes repeatedly. These rules exist to prevent them.
1. Read Before You Write
Before writing anything:
- Read the files you're about to modify. Not skim. Read.
- Find how similar things are done elsewhere and follow that pattern.
- Check existing imports — don't introduce a library the project doesn't use.
- Look at test files to understand expected behavior, not assumed behavior.
If you don't see a pattern for something, ask: "I don't see a pattern for X — should I follow Y or do something different?"
2. Think Before You Code
State your assumptions. If the task is ambiguous, say what you're assuming before you start. "I'm assuming JWT auth with httpOnly cookies — let me know if you want something different." Guessing silently wastes hours.
Name the tradeoffs. "This trades memory for speed and introduces cache invalidation." Say it before writing 200 lines.
Present options briefly when they exist. Two, maybe three. With a recommendation. Not five.
If something is confusing, stop. Say what's confusing and ask. Don't fill confusion with plausible-sounding code.
3. Simplicity
Write the minimum code that solves this specific problem right now.
- No premature abstraction. One email type needed? Write
send_welcome_email(user), not anEmailServicewith a strategy pattern. - No speculative error handling. Only handle errors that can actually occur.
- No unnecessary configurability. Hardcode things until there's a real reason not to.
- No dead flexibility. Interfaces with one implementation, abstract classes with one child — these cost cognitive overhead and provide nothing until a second case exists.
Test: if someone asks "why is this abstracted?" and the answer is "in case we need to…" — revert it.
4. Surgical Changes
Your diff should be as small as possible.
- Don't touch what you weren't asked to touch — not variable names, not comments, not import order.
- Match the existing style exactly: quotes, casing, semicolons, indentation.
- Clean up after yourself only: remove imports/variables/functions made unused by your change. Leave pre-existing dead code alone.
- Don't reformat. Don't run a linter on a file that wasn't formatted with that linter.
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.
- 7d ago First seen · 91 lines · 1,159 tokens per session scan A 9ec0b5edc919
ai-dev-playbook CLAUDE.md is an instructions file published in the GitHub repository Geeksfino/ai-dev-playbook (2 stars, last pushed 29d ago), licensed MIT. It adds 1,159 tokens to every session, about $0.0058 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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