Better Harness is an open-source platform for studying and improving how coding agents work on tasks, using written harnesses, controlled tests, and evidence from projects and sessions. Coding teams use it to identify workflow problems and turn them into prioritized improvements and verifiable next steps. Its catalogue entries extend coding-agent workflows for supported hosts such as Claude Code, Codex, Cursor, and others.
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.
npx agentmods add skills/qoderai/better-harness/better-harnessnpx skills add QoderAI/better-harness --skill better-harnessgit clone --depth 1 https://github.com/QoderAI/better-harnessWrote 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.
[](https://agentmods.dev/skills/qoderai/better-harness/better-harness)<a href="https://agentmods.dev/skills/qoderai/better-harness/better-harness"><img src="https://agentmods.dev/badge/skills/qoderai/better-harness/better-harness.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00053 | $0.02546 |
| Opus 5 | $0.00026 | $0.01273 |
| Sonnet 5 | $0.00011 | $0.00509 |
| Haiku 4.5 | $0.00005 | $0.00255 |
Grade A, and why
better-harness 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 216 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Better Harness
Review the coding-agent system: context, execution, control, feedback, and learning; keep Sessions, project, and Agent assets independent.
Step 1: Resolve Scope and Collect the Evidence Bundle
Route:
<better-harness-fix-output>: Finding-bound Fix.- No callback plus leading
fix,repair, or\u4fee\u590d: Manual Direct Fix. - Review/evaluation/reporting or mixed review-and-fix: Step 1.
Resolve the Skill path, <better-harness-root> as ../.., a supported <node>,
and <cli> as <node> <better-harness-root>/scripts/better-harness.mjs. Stop if
any owner is missing; never select another cache or runtime by search order.
Resolve absolute target, decision, acceptance boundary, risks, locale (request language by default), output mode, provider, and depth. Quick uses three items and 7 days; normal uses five and 30 days. Default Qoder/Cursor to durable Canvas and other rendering hosts to HTML. Providers without REPORT_RENDERING proceed only inline or no-files and must not create HTML, Markdown, or Canvas output. Keep providers separate. Use the current one unless project-wide review explicitly authorizes multiple supported providers. Qoder project Memory title metadata is part of the selected workspace baseline. Memory bodies, Codex Memory, Qoder global Memory, user-home, raw Session, installed-plugin, marketplace, and historical-insight access require explicit scope.
Before delegation, collect one versioned evidence bundle per authorized provider:
<cli> harness evidence-bundle --platform <provider> --workspace <target> --cwd <effective-cwd> --language <locale> --depth <quick|normal> --since <window-start> --until <window-end> --format json [--include-memories] [--include-user-home] [--canvas-out <run-dir>/canvas.json]
Use --canvas-out only for Qoder/Cursor durable reports. For Qoder, keep the
default project Memory-title scan; --include-user-home
widens it to authorized global Memory/config and other user assets. For Codex,
Memory metadata requires --include-memories; user/global or installed-Plugin
metadata requires --include-user-home. Apply both when both scopes are
authorized. Neither flag authorizes Memory bodies.
What ships with it
12 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.
- references/agent-customize.md 6.8 KB
- references/asset-demand-reconciliation.md 3.8 KB
- references/finding-bound-fix.md 7.3 KB
- references/findings-review.md 6.6 KB
- references/manual-direct-fix.md 1.7 KB
- references/project-harness.md 5.3 KB
- references/report-source-review.md 2.4 KB
- references/session-evidence.md 4.9 KB
- references/session-repeated-workflows.md 4.8 KB
- references/support-bootstrap.md 2.9 KB
- references/support-operationalize.md 2.3 KB
- references/support-optimize.md 2.5 KB
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.
- 6d ago First seen · 216 lines · 53 tokens per session scan A f5ebdb715e19
better-harness is a skill published in the GitHub repository QoderAI/better-harness (2,168 stars, last pushed yesterday), licensed MIT. It adds 53 tokens to every session and 2,546 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.
Other skills, from other repositories
capability-recommender
Use when the need is read-only capability design only: skills, hooks, MCP servers, subagents, plugins, scripts, or CI/headless automation. For cross-surface workbench bootstrap or repair, use harness-builder.
agent-instructions-maintainer
Use when durable agent instructions need audit or repair only: AGENTS.md, CLAUDE.md, .claude.md, .claude.local.md, canonical rules/.mdc, or Cursor rule mirrors. For cross-surface workbench bootstrap or repair, use harness-builder.
implement
用于在一个 scoped active slice 上做最小代码或文档改动。触发条件：用户请求/Spec/Executable Plan 已清楚，工作面和验证路径足够明确。不要在需求、active slice、根因或工作面不清时使用；局部检查只是反馈，ready 只能交给 verify。.
plan
用于把已批准 Spec 或足够明确的非平凡请求转成 Executable Plan。触发条件：需要 active slice、planning surface、验证路径、能力缺口或 commit unit。不要在需求/验证策略不清时使用；先回 brainstorm。项目工作面不清时转 harness-builder。.
diagnose
用于把 build/test/lint/typecheck/CI 或运行时失败诊断成可复现 root cause。触发条件：命令红、行为坏、flaky 或本地/CI 不一致且根因未知。不要在 RED->GREEN 的已知失败或根因已清楚时使用；修复前必须先复现和验证单一假设。.
find-skills
Use this helper to discover reusable agent skills for a clear task or capability gap. Trigger it when the user asks how to do X, find a skill, or extend agent capabilities. Do not install or adopt a skill just because it is related; project adoption belongs to harness-builder.