What modelharness runs automatically, and when. A hook is a command Claude Code fires at a fixed moment, without you asking for it.
Claude Code
> /plugin marketplace add vitaliikapliuk/modelharness> /plugin install modelharness@modelharness
Cursor
Cursor also runs Claude Code hooks from .claude/settings.json, so copy these hooks there to use them in Cursor.
What fires, and when
SessionStart
Fires once when a session begins, and again after a context compaction. It is where a plugin sets up its environment, or restores state the compaction dropped.
startup|resume|clear|compact"${CLAUDE_PLUGIN_ROOT}/hooks/session-start.sh"Where it lives
#!/usr/bin/env bash
# SessionStart hook: stdout is appended to Claude's context at session start.
set -euo pipefail
DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
cat "${DIR}/../core/modelharness-core.md"
Read the script before you install anything that runs on your machine. This is the one part of a plugin that acts without being asked.
Make every model cheaper or better. Measured on four Claude models — none got worse. What it actually is: a zero-config Claude Code plugin.
Stars on GitHub
A development methodology for coding agents that makes the agent brainstorm before building, follow plans, run parallel work and finish branches in a disciplined way. You get fewer skipped steps and more consistent results from your coding assistant.
@obraA Claude Code plugin with skills for auditing a whole repo, reviewing a change, listing deferred shortcut comments, and showing measured savings and a quick command reference.
@dietrichgebertWalks a software change from a written spec through design, testing, code review, CI/CD, and release, applying the matching engineering skill at each stage. Useful for developers using Claude Code on full development workflows.
@addyosmaniPersistent file-based planning for AI coding agents on long-running, multi-step tasks. It keeps task_plan.md, findings.md and progress.md on disk, so work can resume after /clear or context compaction.
@othmanadiA spec-driven development workflow for Claude Code that guides a project through planning, phases, milestone audits and fixes. Includes skills to generate tests from UAT criteria and to audit completed work.
@open-gsdChinese-language skill pack for Claude Code that adds workflow guidance for brainstorming, TDD, debugging, and code review, plus Chinese conventions for commits, documentation, and domestic Git platforms like Gitee and Coding.net.
@jnmetacodeGives Claude Code semantic search, dependency graph and architecture context over a codebase, so an AI assistant can explore and understand a project's code. Includes skills for indexing a project and managing its file watching.
@giancarloerraA lightweight code search engine that uses AST-based semantic search with local embeddings and incremental indexing. It helps Claude Code users find code faster and more efficiently.
@cocoindex-io