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 m06-error-handlinggit 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/m06-error-handling)<a href="https://agentmods.dev/skills/moeru-ai/auv/m06-error-handling"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m06-error-handling/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/m06-error-handling"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m06-error-handling.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 | $0.00061 | $0.01150 |
| Opus 5 | $0.00030 | $0.00575 |
| Sonnet 5 | $0.00012 | $0.00230 |
| Haiku 4.5 | $0.00006 | $0.00115 |
Grade A, and why
m06-error-handling 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 — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Error Handling
Layer 1: Language Mechanics
Core Question
Is this failure expected or a bug?
Before choosing error handling strategy:
- Can this fail in normal operation?
- Who should handle this failure?
- What context does the caller need?
Error → Design Question
| Pattern | Don't Just Say | Ask Instead |
|---|---|---|
| unwrap panics | "Use ?" | Is None/Err actually possible here? |
| Type mismatch on ? | "Use anyhow" | Are error types designed correctly? |
| Lost error context | "Add .context()" | What does the caller need to know? |
| Too many error variants | "Use Box" | Is error granularity right? |
Thinking Prompt
Before handling an error:
-
What kind of failure is this?
- Expected → Result<T, E>
- Absence normal → Option
- Bug/invariant → panic!
- Unrecoverable → panic!
-
Who handles this?
- Caller → propagate with ?
- Current function → match/if-let
- User → friendly error message
- Programmer → panic with message
-
What context is needed?
- Type of error → thiserror variants
- Call chain → anyhow::Context
- Debug info → anyhow or tracing
Trace Up ↑
When error strategy is unclear:
"Should I return Result or Option?"
↑ Ask: Is absence/failure normal or exceptional?
↑ Check: m09-domain (what does domain say?)
↑ Check: domain-* (error handling requirements)
| Situation | Trace To | Question |
|---|---|---|
| Too many unwraps | m09-domain | Is the data model right? |
| Error context design | m13-domain-error | What recovery is needed? |
| Library vs app errors | m11-ecosystem | Who are the consumers? |
Trace Down ↓
From design to implementation:
"Expected failure, library code"
↓ Use: thiserror for typed errors
"Expected failure, application code"
↓ Use: anyhow for ergonomic errors
"Absence is normal (find, get, lookup)"
↓ Use: Option<T>
"Bug or invariant violation"
↓ Use: panic!, assert!, unreachable!
"Need to propagate with context"
↓ Use: .context("what was happening")
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 167 lines · 61 tokens per session scan A 9760e9433bfa
m06-error-handling is a skill published in the GitHub repository moeru-ai/auv (27 stars, last pushed yesterday), licensed Apache-2.0. It adds 61 tokens to every session and 1,150 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 2026-08-30.
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