ECC: The Plugin That Makes Your AI Coding Agent Actually Good

If you use Claude Code, Cursor, Codex, or any AI coding harness day-to-day, you've probably hit the ceiling: the agent is smart but forgets context, makes the same mistakes twice, and needs hand-holding on your project's conventions. That's what ECC was built to fix.

ECC (originally "Everything Claude Code") is an open-source agent harness performance system — 188K+ GitHub stars, Anthropic Hackathon winner, actively maintained.

What It Does

ECC installs as a plugin and gives your AI agent a complete operating system:

Skills — 232 reusable workflow units covering TypeScript, Python, Go, Java, Kotlin, C++, Rust, and more. TDD, security review, documentation lookup, cost-aware LLM pipelines, even PM workflows.

Agents — 60 specialized subagents to delegate to: Planner, Architect, TDD Guide, Security Reviewer, E2E Runner, Refactor Cleaner, Chief of Staff.

Memory + Hooks — Lifecycle hooks that automatically save and restore context across sessions. Your agent picks up where it left off.

Security (AgentShield) — /security-scan runs 1,282 tests and 102 rules. Attack vectors, sandboxing, sanitization — all checked.

Cross-Harness — One config, works across Claude Code, Cursor, Codex, OpenCode, Gemini, Zed, and GitHub Copilot.

How It Works

ECC hooks into your agent's session lifecycle. On start, it loads your project memory, active rules, and relevant skills into context. During a session, you invoke skills via slash commands — /ecc:plan, /ecc:security-scan, /ecc:tdd, and so on. On session end, hooks summarize what happened and persist learnings. Over time, the agent builds up a working model of your codebase and conventions — it stops being stateless.

Where to Use It

It's most valuable when you're doing serious, repeated work in a codebase: kicking off a new feature, running a security audit before a release, doing a refactoring sprint, or coordinating across multiple services. If you only talk to your AI agent once in a while, ECC is overkill. If it's part of your daily workflow, it pays back fast.

Get It

Two commands in Claude Code:

/plugin marketplace add https://github.com/affaan-m/ECC
/plugin install ecc@ecc

Then copy the rules you need:

mkdir -p ~/.claude/rules/ecc
cp -R rules/common ~/.claude/rules/ecc/
cp -R rules/typescript ~/.claude/rules/ecc/

That's it — 60 agents and 232 skills, ready to go.