Borrowing it
Nothing to install: this file belongs to searlsco/prove_it. 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/searlsco/prove_it/main/.claude/skills/prove-feature/SKILL.mdgit clone --depth 1 https://github.com/searlsco/prove_itWrote 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/searlsco/prove_it/prove-feature)<a href="https://agentmods.dev/skills/searlsco/prove_it/prove-feature"><img src="https://agentmods.dev/badge/skills/searlsco/prove_it/prove-feature/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/searlsco/prove_it/prove-feature"><img src="https://agentmods.dev/badge/skills/searlsco/prove_it/prove-feature.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 | $0.00081 | $0.05829 |
| Opus 5.5 | $0.00032 | $0.02332 |
| Sonnet 5.5 | $0.00016 | $0.01166 |
| Haiku 4.5 | $0.00008 | $0.00583 |
Grade A, and why
prove-feature scanned grade A with 1 finding 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 2mo 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.
Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
const { spawnSync } = require('child_process') How it starts
The opening of the file, as written. The whole thing — 613 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prove a feature works (or doesn't)
Build a throwaway project and exercise a prove_it feature through the real dispatcher pipeline. The output is a human-readable transcript the user can read to confirm the system works end-to-end.
What "prove" means — read this first
Proving a feature means watching the feature do its actual job, not just watching the dispatcher accept a config and return a decision.
If the feature is a reviewer that detects dead code, you must:
- Create a project that contains dead code → run the reviewer → see it catch the dead code
- Create a project that has no dead code → run the reviewer → see it pass clean
If the feature is a task that validates API design, you must:
- Write an API file with real design violations → see the task reject it
- Write a clean API file → see the task approve it
If the feature is a when-condition gate, you must:
- Run with the condition unmet → see the task get skipped
- Run with the condition met → see the task actually execute and produce its real output
The pattern is always the same: construct a realistic situation where the feature's logic is exercised, then observe it both succeed and fail. A test that only checks "did the dispatcher return allow/deny" without verifying the feature itself inspected the right thing and made the right call is not a proof.
The critical question
Before writing any code, answer this: "What real-world situation does this feature exist to handle, and how will I simulate that situation in a throwaway project?"
If you can't answer that, you don't understand the feature well enough to prove it yet. Stop and think harder.
Anti-patterns — do NOT do these
Plumbing-only tests. Testing that the dispatcher routes to a script and returns the script's exit code is testing prove_it's plumbing, not the feature. The feature is what the script does. You must create input that makes the script's logic actually fire.
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.
- 2mo ago First seen · 613 lines · 81 tokens per session scan A 7bc4bc2f25b2
prove-feature is a skill published in the GitHub repository searlsco/prove_it (200 stars, last pushed 1mo ago), licensed MIT. It adds 81 tokens to every session and 5,829 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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