112 Battle-Tested Claude Code Skills — Every Bug Fix That Cost Me Hours So It Won't Cost You

AI coding assistants are powerful. They're also amnesiac.

Claude Code will help you fix a Docker SQLite WAL corruption bug at 2am. You'll figure out the root cause (you can't docker cp a SQLite DB from a running container — you need to stop writes first or copy the WAL file too). You'll fix it. Ship it. Move on.

Three days later, same project, new session. Claude Code has no memory of that fix. The same bug pattern appears. You debug it again.

After the third time this happened to me, I stopped fixing bugs and started building a system to make them unfixable.

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The Solution: Skills as Muscle Memory

Claude Code supports "skills" — markdown files that load into context when relevant patterns are detected. Think of them as institutional memory for your AI assistant.

Each skill captures:

• The problem: What goes wrong, and how it looks when it happens
• The root cause: Why it happens (not just what to do)
• The fix: Exact steps, code patches, configuration changes
• The trigger: When Claude Code should automatically apply this knowledge

Over 7 months of building a production API platform (39 services, 30+ APIs, running from an animal sanctuary in rural Japan — long story), I hit 200+ production bugs. I extracted the non-obvious ones into 112 reusable skills.

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The Categories

Docker and Deployment (12 skills)

Skill	What it fixes
docker-sqlite-wal-copy-trap	Data corruption when copying SQLite from running container
docker-ghost-container-recovery	Container name occupied but container doesn't exist
docker-small-vps-deploy-optimization	OOM kills on 2GB VPS during docker build
docker-static-asset-copy-gotcha	Static assets 404 in container but work locally
docker-compose-force-recreate-caddy-loop	Infinite restart loop with force-recreate watchdog

Database and SQLite (10 skills)

Skill	What it fixes
bun-sqlite-transaction-await-crash	Production crash from await inside db.transaction()
sqlite-check-constraint-migration	CHECK constraint failed when expanding allowed values
bun-sqlite-like-parameter-binding	Parameter binding silently fails on LIKE queries
json-to-sqlite-hybrid-migration	Safe migration from JSON file persistence to SQLite

API and Backend (15 skills)

Skill	What it fixes
hono-subrouter-auth-isolation	Auth bypass when multiple Hono sub-routers share paths
multi-provider-fallback-gateway	Single provider failures taking down the whole service
api-security-audit-methodology	Systematic security review with 30+ vulnerability patterns
hono-global-middleware-ordering	Global middleware silently not executing for sub-routes
multi-layer-proxy-timeout-chain-debugging	502/504 errors in CDN -> reverse proxy -> app chains

AI and LLM (8 skills)

Skill	What it fixes
llm-api-cost-optimization	Claude API costs spiraling out of control
ai-prompt-mastery	AI giving generic answers instead of expert-level responses
api-tool-use-upgrade-pattern	Upgrading from manual JSON parsing to proper Tool Use
llm-model-version-migration-2026	404 errors from deprecated model version strings

Frontend and UI (6 skills)

Skill	What it fixes
nextjs-common-patterns	"params is a Promise" and other Next.js 13+ gotchas
elderly-friendly-ssr-ui-optimization	Making SSR pages usable for elderly/low-vision users
template-literal-inline-js-escaping	Silent page failures from JS syntax errors in SSR scripts

Debugging and Workflow (10 skills)

Skill	What it fixes
systematic-debug	Ad-hoc debugging that wastes hours on wrong leads
code-verification-loop	Shipping code without automated verification
multi-agent-workflow-design	Identifying when to use multi-agent vs single-agent
audit-inflation-bias-prevention	AI sub-agents inflating bug reports with false positives

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Installation

One command:

curl -fsSL https://raw.githubusercontent.com/sstklen/washin-claude-skills/main/install.sh | bash

What happens:

1. Clones the skill library to ~/.claude/skills/
2. Skills are automatically available in all Claude Code sessions
3. No configuration needed

Verify it worked:

ls ~/.claude/skills/
# Should show 112 skill directories

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Before vs After: A Real Example

Scenario: You're deploying a Bun + SQLite app in Docker. You need to backup the database.

Without the skill:

You run docker cp container:/app/data.db ./backup.db. It works. But the backup is silently corrupted — SQLite was mid-write, and the WAL file wasn't copied. You don't discover this until you try to restore from backup in an emergency. 2-4 hours of debugging. Panic.

With docker-sqlite-wal-copy-trap skill:

Claude Code recognizes the pattern the moment you mention copying a SQLite DB from a container. It immediately warns you about the WAL trap and provides the correct approach:

# Stop writes first, or copy all three files:
docker cp container:/app/data.db ./backup.db
docker cp container:/app/data.db-wal ./backup.db-wal
docker cp container:/app/data.db-shm ./backup.db-shm

Problem solved in seconds. Not hours. And it never happens again, across any project.

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Skill Format

Every skill follows this structure:

skill-name/
  SKILL.md       # The skill content

Here's what a real skill looks like (abbreviated):

---
name: docker-sqlite-wal-copy-trap
category: Docker & Deployment
trigger: "copying SQLite from Docker container"
---

# Fix: Docker SQLite WAL Copy Trap

## The Problem
`docker cp container:/app/data.db ./backup.db` produces a
silently corrupted copy. No error, no warning — just missing
recent data.

## Root Cause
SQLite uses WAL (Write-Ahead Log). The .db file alone is
incomplete. You must also copy .db-wal and .db-shm, or
checkpoint the WAL first.

## The Fix
Option A — Copy all three files:
  docker cp container:/app/data.db ./backup.db
  docker cp container:/app/data.db-wal ./backup.db-wal
  docker cp container:/app/data.db-shm ./backup.db-shm

Option B — Checkpoint first:
  sqlite3 /app/data.db "PRAGMA wal_checkpoint(TRUNCATE);"
  Then copy the single .db file.

Each skill is under 500 lines. Claude Code loads relevant skills into context automatically when it detects matching patterns.

A Note on Stack Compatibility

Most of these skills come from a specific stack: Bun + Hono + SQLite + Docker on a Linux VPS. If that's your stack, almost everything applies directly.

If you use a different stack, here's what still works universally:

• Debugging and Workflow skills (10 skills) — stack-agnostic problem-solving patterns
• AI and LLM skills (8 skills) — applicable to any Claude Code project
• Docker skills (12 skills) — useful for any Dockerized app, not just Bun/Hono
• API patterns (many of the 15 skills) — timeout chains, auth isolation, security audits work regardless of framework

Stack-specific skills (Bun SQLite quirks, Hono sub-router bugs) are clearly named — if you don't use Bun or Hono, you'll know which ones to skip.

Want to contribute your own? Fork the repo, add your skill following the format, and open a PR. Every production bug you've solved is a skill waiting to be shared.

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The Philosophy

Skills aren't just bug fixes. They encode a principle:

If the same problem happens three times, stop fixing it. Change the system so it can't happen again.

These 112 skills represent 7 months of production pain at an animal sanctuary in Japan, distilled into patterns that any Claude Code user can benefit from. Your worst production bugs become your AI's best skills.

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GitHub: github.com/sstklen/washin-claude-skills

Install:

curl -fsSL https://raw.githubusercontent.com/sstklen/washin-claude-skills/main/install.sh | bash

Full backstory: Zero Engineer — Animal Sanctuary to Production Platform

Comments

[Vic Chen]

The "amnesiac" framing is exactly right. The pattern that has clicked for me: treat every non-trivial debugging session as scar tissue worth encoding. I keep a LESSONS.md in each project. When the same issue resurfaces 3 months later in a fresh Claude session, I paste the relevant entry. The model context window becomes your institutional memory proxy. Curious how you organize your 112 - project-level or as a global library across repos?