Deterministic guardrails, quality gates, and progressive disclosure for AI coding agents.
The underlying AI model matters less than the system built around it. A well-harnessed agent produces consistent, safe, high-quality output regardless of the model version. Read the foundations.
claude plugins marketplace add sliday/claude-plugins
claude plugins install harnThen in any project:
/harn:init # scaffold your harness| Command | Description |
|---|---|
/harn:init |
Scaffold a complete harness — AGENTS.md, hooks, guardrails |
/harn:guard |
Generate or update security guardrail hooks (PreToolUse) |
/harn:gate |
Generate or update quality gate Stop hook |
/harn:analyze |
Audit your project against the CAR framework |
/harn:agents-md |
Build or rebuild AGENTS.md with progressive disclosure |
/harn:format |
Generate PostToolUse auto-formatter hook |
/harn:trace |
Generate PostToolUse trace logging hook for observability |
/harn:checkpoint |
Generate resume artifacts (LEARNED.md, CHECKPOINT.json) |
/harn:mcp-check |
Generate MCP server health check hook |
/harn:context |
Monitor context window usage and apply backpressure |
AGENTS.md— Agent behavior spec with progressive disclosure.claude/settings.json— Hook configuration.claude/hooks/security-guard.sh— PreToolUse guardrail.claude/hooks/quality-gate.sh— Stop hook for type/lint/test checks.claude/hooks/auto-format.sh— PostToolUse formatter (optional)LEARNED.md— Persistent gotchas and decisions log
Every agentic system has three layers:
- Control — Constraints and specifications (AGENTS.md, linters, tests, architectural rules)
- Agency — Tools and interfaces (MCP servers, sub-agents, browser access)
- Runtime — Execution and recovery (hooks, compaction, retries, rollback)
Run /harn:analyze to score your project across all three. Learn more at harn.app.
jq— JSON processing (used by hooks)python3 >= 3.6— Script execution- Language-specific toolchain for quality gates (e.g.,
tsc,cargo,go vet,ruff)
If a hook is blocking legitimate work or the agent is stuck in a loop, see references/escape-hatches.md.
Curated articles on harness engineering — security, context, evals, specs, and tools: harn.app/kb.
MIT