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/nwiizo/cargo-coupling/mutantsnpx skills add nwiizo/cargo-coupling --skill mutantsgit clone --depth 1 https://github.com/nwiizo/cargo-couplingWrote 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/nwiizo/cargo-coupling/mutants)<a href="https://agentmods.dev/skills/nwiizo/cargo-coupling/mutants"><img src="https://agentmods.dev/badge/skills/nwiizo/cargo-coupling/mutants.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 | $0.00000 | $0.00517 |
| Opus 5 | $0.00000 | $0.00259 |
| Sonnet 5 | $0.00000 | $0.00103 |
| Haiku 4.5 | $0.00000 | $0.00052 |
Grade A, and why
mutants 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 4d 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.
What it actually says
Mutation Testing
Run cargo-mutants, analyze missed mutants, write tests for new code, verify fixes.
Workflow
- Run: Scope to changed files or specified targets
- Analyze: Focus on new/changed code missed mutants (ignore pre-existing)
- Fix: Add tests for missed mutants in new code
- Verify: Re-run on fixed functions to confirm 0 missed
Commands
# Scoped to specific files (recommended for incremental work)
cargo mutants --no-shuffle -j4 -f src/config.rs -f src/volatility.rs
# Scoped to specific functions
cargo mutants --no-shuffle -j4 -F "function_name"
# Full run (slow, 1000+ mutants)
cargo mutants --no-shuffle -j4 -- --lib
# Check results
cat mutants.out/missed.txt | grep "target_file.rs"
cat mutants.out/caught.txt | wc -l
Options
| Option | Description |
|---|---|
-f <FILE> |
Limit to specific source file |
-F <PATTERN> |
Filter by function name pattern |
-E <PATTERN> |
Exclude by function name |
-j <N> |
Parallel jobs (default: auto) |
--no-shuffle |
Deterministic ordering |
-- --lib |
Only run library tests |
Result Interpretation
| Result | Meaning | Action |
|---|---|---|
| caught | Test detected mutation | None (good) |
| missed | Test didn't detect | Add/improve test |
| unviable | Compile error from mutation | Ignore |
| timeout | Test too slow | Optimize or skip |
Triage Strategy
- Pre-existing missed mutants in
main.rs(CLI entry point): low priority, hard to unit test - Output formatting functions (
report.rs,cli_output.rs): low priority unless logic-heavy - Business logic (
config.rs,balance.rs,analyzer.rs): high priority - New code: always fix missed mutants before release
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.
- 4d ago First seen · 63 lines · 0 tokens per session scan A a79bd33529d8
mutants is a skill published in the GitHub repository nwiizo/cargo-coupling (96 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 517 tokens. 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 2026-09-01.
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