swift-diagnostics

swift-diagnostics is a skill for Claude Code from johnrogers/claude-swift-engineering. It costs 58 tokens per session (624 once invoked), scanned A, original, MIT.

A structured set of debugging workflows for Swift and Apple-platform projects. It covers navigation problems, build and dependency failures, slow Xcode builds, memory leaks, and related debugging checks.

In plain words
What is it for?
Use it when NavigationStack behaves incorrectly, Xcode cannot resolve a package or module, builds hang or run slowly, objects are not released, or memory keeps growing.
Why use it?
It replaces trial-and-error fixes with symptom-based checks and decision paths. This makes it easier to identify whether the cause is navigation, project setup, memory management, or build performance.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the swift-engineering plugin — 17 skills, 3 commands, 11 agents shipped together

Good fit Use it when NavigationStack behaves incorrectly, Xcode cannot resolve a package or module, builds hang or run slowly, objects are not released, or memory keeps growing.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/johnrogers/claude-swift-engineering/swift-diagnostics
Install

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.

Any agent
npx skills add johnrogers/claude-swift-engineering --skill swift-diagnostics
Clone the repo
git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering

Made for: Claude Code.

Or install swift-engineering, the plugin that ships this one along with the rest of its 17 skills, 3 commands, 11 agents.

Wrote 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.

agentmods badge for swift-diagnostics

README.md
[![agentmods](https://agentmods.dev/badge/skills/johnrogers/claude-swift-engineering/swift-diagnostics.svg)](https://agentmods.dev/skills/johnrogers/claude-swift-engineering/swift-diagnostics)
Your own site
<a href="https://agentmods.dev/skills/johnrogers/claude-swift-engineering/swift-diagnostics"><img src="https://agentmods.dev/badge/skills/johnrogers/claude-swift-engineering/swift-diagnostics.svg" alt="Measured on agentmods" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 624 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00058 $0.00624
Opus 5 $0.00029 $0.00312
Sonnet 5 $0.00012 $0.00125
Haiku 4.5 $0.00006 $0.00062

Measured 8d ago against content hash 092fbdfae25e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

swift-diagnostics 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 8d 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.

plugins/swift-engineering/skills/swift-diagnostics/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Swift Diagnostics

Systematic debugging workflows for iOS/macOS development. These patterns help identify root causes in minutes rather than hours by following structured diagnostic approaches.

Reference Loading Guide

ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.

Reference Load When
Navigation NavigationStack not responding, unexpected pops, deep link failures
Build Issues SPM resolution, "No such module", dependency conflicts
Memory Retain cycles, memory growth, deinit not called
Build Performance Slow builds, Derived Data issues, Xcode hangs
Xcode Debugging LLDB commands, breakpoints, view debugging

Core Workflow

  1. Identify symptom category - Navigation, build, memory, or performance
  2. Load the relevant reference - Each has diagnostic decision trees
  3. Run mandatory first checks - Before changing any code
  4. Follow the decision tree - Reach diagnosis in 2-5 minutes
  5. Apply fix and verify - One fix at a time, test each

Key Principle

80% of "mysterious" issues stem from predictable patterns:

  • Navigation: Path state management or destination placement
  • Build: Stale caches or dependency resolution
  • Memory: Timer/observer leaks or closure captures
  • Performance: Environment problems, not code bugs

Diagnose systematically. Never guess.

Common Mistakes

  1. Skipping mandatory first checks — Jumping straight to code changes before running diagnostics (clean build, restart simulator, restart Xcode) means you'll chase ghosts. Always start with the mandatory checks.

  2. Changing multiple things at once — "Let me delete DerivedData AND restart simulator AND kill Xcode" means you can't isolate which fix actually worked. Change one variable at a time.

Read the full file on GitHub · 51 lines

Files

What ships with it

5 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.

Changes

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.

  1. 8d ago First seen · 51 lines · 58 tokens per session scan A 092fbdfae25e

Subscribe to this mod's changes

swift-diagnostics is a skill published in the GitHub repository johnrogers/claude-swift-engineering (228 stars, last pushed 7mo ago), licensed MIT. It adds 58 tokens to every session and 624 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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