Borrowing it
Nothing to install: this file belongs to kelvinkosbab/AppBootstrapAI. 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/kelvinkosbab/AppBootstrapAI/main/.claude/skills/swift-error-handling-pro/SKILL.mdgit clone --depth 1 https://github.com/kelvinkosbab/AppBootstrapAIWrote 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/kelvinkosbab/appbootstrapai/swift-error-handling-pro)<a href="https://agentmods.dev/skills/kelvinkosbab/appbootstrapai/swift-error-handling-pro"><img src="https://agentmods.dev/badge/skills/kelvinkosbab/appbootstrapai/swift-error-handling-pro/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/kelvinkosbab/appbootstrapai/swift-error-handling-pro"><img src="https://agentmods.dev/badge/skills/kelvinkosbab/appbootstrapai/swift-error-handling-pro.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 | $0.00044 | $0.00780 |
| Opus 5 | $0.00022 | $0.00390 |
| Sonnet 5 | $0.00009 | $0.00156 |
| Haiku 4.5 | $0.00004 | $0.00078 |
Grade A, and why
swift-error-handling-pro 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 — 95 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Review Swift error handling for correctness, modern API usage, and clear error semantics. Report only genuine problems - do not nitpick or invent issues.
Review process:
- Check error type definitions for
LocalizedError,Equatable, andSendableconformance usingreferences/error-types.md. - Evaluate whether typed throws (Swift 6.0+) would clarify the API using
references/typed-throws.md. - Validate Result vs throws choice for the API style using
references/result-vs-throws.md. - Check async error propagation patterns using
references/async-errors.md. - Flag swallowed errors (catch blocks that ignore errors silently).
If doing a partial review, load only the relevant reference files.
Core Instructions
- Target Swift 6.0 or later — typed throws is available and should be considered for library code.
- Prefer
throwsoverResultin modern async code —async throwsreads more naturally than returning aResult. - Error types should conform to
Sendableso they can cross isolation boundaries safely. - Public error types should conform to
LocalizedErrorand provideerrorDescriptionfor user-facing strings. - Never use
try!ortry?to silence errors that could meaningfully be handled or surfaced. - Avoid
catch { }blocks that swallow the error — at minimum, log it. - Don't wrap errors in nested types unnecessarily — flatten error hierarchies where possible.
Output Format
Organize findings by file. For each issue:
- State the file and relevant line(s).
- Name the rule being violated.
- Show a brief before/after code fix.
Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.
Example output:
Sources/Storage/FileStoreError.swift
Line 12: Public error type should conform to LocalizedError for user-facing strings.
// Before
public enum FileStoreError: Error {
case readFailed
case writeFailed
}
// After
public enum FileStoreError: LocalizedError {
case readFailed
case writeFailed
public var errorDescription: String? {
switch self {
case .readFailed: "Failed to read from disk."
case .writeFailed: "Failed to write to disk."
}
}
}
What ships with it
4 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 · 95 lines · 44 tokens per session scan A 3bef2111db81
swift-error-handling-pro is a skill published in the GitHub repository kelvinkosbab/AppBootstrapAI (5 stars, last pushed 19d ago), licensed MIT. It adds 44 tokens to every session and 780 once invoked, about $0.0002 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 2026-08-31.
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