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 JordanCoin/codingskills --skill yagnigit clone --depth 1 https://github.com/JordanCoin/codingskillsWrote 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/jordancoin/codingskills/yagni)<a href="https://agentmods.dev/skills/jordancoin/codingskills/yagni"><img src="https://agentmods.dev/badge/skills/jordancoin/codingskills/yagni/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/jordancoin/codingskills/yagni"><img src="https://agentmods.dev/badge/skills/jordancoin/codingskills/yagni.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 | $0.00065 | $0.01040 |
| Opus 5 | $0.00032 | $0.00520 |
| Sonnet 5 | $0.00013 | $0.00208 |
| Haiku 4.5 | $0.00006 | $0.00104 |
Grade A, and why
yagni 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 8d 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 — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
YAGNI — You Aren't Gonna Need It
Before Applying
If .agents/stack-context.md exists, read it first. Apply this principle using idiomatic patterns for the detected stack. For framework-specific details, use context7 MCP or web search — don't guess.
Principle
Do not build for hypothetical future requirements. Build what is needed now, and refactor when actual requirements emerge.
Why This Matters in Production
Speculative code is the #1 source of accidental complexity. Every abstraction, configuration option, or extension point you add "just in case" has a real cost: it must be understood, tested, maintained, and debugged. Unused code paths are the most dangerous — they rot silently, give false confidence in test coverage, and create surface area for bugs.
Premature generalization is worse than duplication. Duplication is obvious and easy to fix later. A wrong abstraction is painful to undo because other code grows to depend on it.
Rules
- Solve the problem in front of you. If you have one use case, write code for one use case. Not two. Not "what if later."
- Three strikes, then abstract. The first time you write something, just write it. The second time, note the duplication. The third time, extract the pattern — now you have enough data to design the right abstraction.
- Delete speculative code paths. If a feature flag has never been toggled, a configuration option has never been changed, or a parameter has never been passed anything other than the default — remove it.
- Don't build plugin systems for one plugin. Interfaces, registries, and extension points are justified only when you have multiple concrete implementations today.
- Prototype when uncertain. If you aren't sure whether something will be needed, spike it in a branch. Don't merge speculative infrastructure into main.
Anti-Patterns
- Adding parameters "for flexibility" that only ever receive one value
- Building an event system when you have two components that could just call each other
- Creating abstract base classes with a single concrete implementation
- Writing configuration files for values that never change
- Adding database columns "we might need later"
- Implementing caching before measuring whether there's a performance problem
- Building a microservice when a function call would suffice
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.
- 8d ago First seen · 90 lines · 65 tokens per session scan A c2176588a2e3
yagni is a skill published in the GitHub repository JordanCoin/codingskills (7 stars, last pushed 6mo ago), licensed MIT. It adds 65 tokens to every session and 1,040 once invoked, about $0.0003 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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