M13 Domain Error

What it does

When your agent uses it

• Designing domain error handling
• Tasks that involve Error handling

Example prompts

• “/m13-domain-error”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

1. 1Who sees this error?
2. 2Can we recover?
3. 3What context is needed?

What it can do on your machine

Read from SKILL.md and the folder at commit eed457f. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are rust).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

M13 Domain Error loads about 1.2k tokens when it runs. Until then it costs about 97 tokens; SKILL.md has 301 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~97

When it runs · the whole SKILL.md, loaded when a task matches

~1.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from fjrevoredo/mini-diarium at commit eed457f, republished under its MIT licence (© fjrevoredo). 301 words, ~1,203 tokens.

name

m13-domain-error

description

Use when designing domain error handling. Keywords: domain error, error categorization, recovery strategy, retry, fallback, domain error hierarchy, user-facing vs internal errors, error code design, circuit breaker, graceful degradation, resilience, error context, backoff, retry with backoff, error recovery, transient vs permanent error, 领域错误, 错误分类, 恢复策略, 重试, 熔断器, 优雅降级

user-invocable

false

"How should I handle payment failures?"
    ↑ Ask: What are the business rules for retries?
    ↑ Check: domain-fintech (transaction requirements)
    ↑ Check: SLA (availability requirements)

"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

#[derive(thiserror::Error, Debug)]
pub enum AppError {
    // User-facing
    #[error("Invalid input: {0}")]
    Validation(String),

    // Transient (retryable)
    #[error("Service temporarily unavailable")]
    ServiceUnavailable(#[source] reqwest::Error),

    // Internal (log details, show generic)
    #[error("Internal error")]
    Internal(#[source] anyhow::Error),
}

impl AppError {
    pub fn is_retryable(&self) -> bool {
        matches!(self, Self::ServiceUnavailable(_))
    }
}

use tokio_retry::{Retry, strategy::ExponentialBackoff};

async fn with_retry<F, T, E>(f: F) -> Result<T, E>
where
    F: Fn() -> impl Future<Output = Result<T, E>>,
    E: std::fmt::Debug,
{
    let strategy = ExponentialBackoff::from_millis(100)
        .max_delay(Duration::from_secs(10))
        .take(5);

    Retry::spawn(strategy, || f()).await
}

© fjrevoredo, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/m13-domain-error of fjrevoredo/mini-diarium.

Open the folder on GitHubat commit eed457f

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in fjrevoredo/mini-diarium, which our catalogue first saw on October 7, 2026.

• NeverSight/learn-skills.devdata/skills-md/actionbook/rust-skills/m13-domain-error