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 moeru-ai/auv --skill m13-domain-errorgit clone --depth 1 https://github.com/moeru-ai/auvWrote 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/moeru-ai/auv/m13-domain-error)<a href="https://agentmods.dev/skills/moeru-ai/auv/m13-domain-error"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m13-domain-error/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/moeru-ai/auv/m13-domain-error"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m13-domain-error.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00095 | $0.01169 |
| Opus 5 | $0.00048 | $0.00584 |
| Sonnet 5 | $0.00019 | $0.00234 |
| Haiku 4.5 | $0.00010 | $0.00117 |
Grade A, and why
m13-domain-error 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 10d 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 — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Domain Error Strategy
Layer 2: Design Choices
Core Question
Who needs to handle this error, and how should they recover?
Before designing error types:
- Is this user-facing or internal?
- Is recovery possible?
- What context is needed for debugging?
Error Categorization
| Error Type | Audience | Recovery | Example |
|---|---|---|---|
| User-facing | End users | Guide action | InvalidEmail, NotFound |
| Internal | Developers | Debug info | DatabaseError, ParseError |
| System | Ops/SRE | Monitor/alert | ConnectionTimeout, RateLimited |
| Transient | Automation | Retry | NetworkError, ServiceUnavailable |
| Permanent | Human | Investigate | ConfigInvalid, DataCorrupted |
Thinking Prompt
Before designing error types:
-
Who sees this error?
- End user → friendly message, actionable
- Developer → detailed, debuggable
- Ops → structured, alertable
-
Can we recover?
- Transient → retry with backoff
- Degradable → fallback value
- Permanent → fail fast, alert
-
What context is needed?
- Call chain → anyhow::Context
- Request ID → structured logging
- Input data → error payload
Trace Up ↑
To domain constraints (Layer 3):
"How should I handle payment failures?"
↑ Ask: What are the business rules for retries?
↑ Check: domain-fintech (transaction requirements)
↑ Check: SLA (availability requirements)
| Question | Trace To | Ask |
|---|---|---|
| Retry policy | domain-* | What's acceptable latency for retry? |
| User experience | domain-* | What message should users see? |
| Compliance | domain-* | What must be logged for audit? |
Trace Down ↓
To implementation (Layer 1):
"Need typed errors"
↓ m06-error-handling: thiserror for library
↓ m04-zero-cost: Error enum design
"Need error context"
↓ m06-error-handling: anyhow::Context
↓ Logging: tracing with fields
"Need retry logic"
↓ m07-concurrency: async retry patterns
↓ Crates: tokio-retry, backoff
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.
- 10d ago First seen · 181 lines · 95 tokens per session scan A 8b20e875534e
m13-domain-error is a skill published in the GitHub repository moeru-ai/auv (27 stars, last pushed yesterday), licensed Apache-2.0. It adds 95 tokens to every session and 1,169 once invoked, about $0.0005 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 2026-08-30.
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