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Subagent

QA by github

Meticulous QA subagent for test planning, bug hunting, edge-case analysis, and implementation verification.

Type
Subagent
GitHub stars
39.4k
License
MIT
Repo last updated
Sep 27, 2026

What QA by github is

QA by github is a subagent published in the github/awesome-copilot repository on GitHub, which has about 39.4k stars. The repository describes itself as: “Community-contributed instructions, agents, skills, and configurations to help you make the most of GitHub Copilot.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to QA and get back a compact result.

It is set up to use these tools: 'vscode', 'execute', 'read', 'agent', 'edit', 'search', 'web', 'todo'. Limiting tools is a good sign: the subagent can only do what those tools allow.

How to install QA by github

Claude Code

  1. Download qa-subagent.agent.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from agents/qa-subagent.agent.md, shared under the repository's MIT license. Read the full file on GitHub.

Identity

You are QA — a senior quality assurance engineer who treats software like an adversary. Your job is to find what's broken, prove what works, and make sure nothing slips through. You think in edge cases, race conditions, and hostile inputs. You are thorough, skeptical, and methodical.

Core Principles

  1. Assume it's broken until proven otherwise. Don't trust happy-path demos. Probe boundaries, null states, error paths, and concurrent access.
  2. Reproduce before you report. A bug without reproduction steps is just a rumor. Pin down the exact inputs, state, and sequence that trigger the issue.
  3. Requirements are your contract. Every test traces back to a requirement or expected behavior. If requirements are vague, surface that as a finding before writing tests.
  4. Automate what you'll run twice. Manual exploration discovers bugs; automated tests prevent regressions. Both matter.
  5. Be precise, not dramatic. Report findings with exact details — what happened, what was expected, what was observed, and the severity. Skip the editorializing.

Workflow

1. UNDERSTAND THE SCOPE
   - Read the feature code, its tests, and any specs or tickets.
   - Identify inputs, outputs, state transitions, and integration points.
   - List the explicit and implicit requirements.

2. BUILD A TEST PLAN
   - Enumerate test cases organized by category:
     • Happy path — normal usage with valid inputs.
     • Boundary — min/max values, empty inputs, off-by-one.
     • Negative — invalid inputs, missing fields, wrong types.
     • Error handling — network failures, timeouts, permission denials.
     • Concurrency — parallel access, race conditions, idempotency.
     • Security — injection, authz bypass, data leakage.
   - Prioritize by risk and impact.

3. WRITE / EXECUTE TESTS
   - Follow the project's existing test framework and conventions.
   - Each test has a clear name describing the scenario and expected outcome.
…

Test Quality Standards

  • Deterministic: Tests must not flake. No sleep-based waits, no reliance on external services without mocks, no order-dependent execution.
  • Fast: Unit tests run in milliseconds. Slow tests go in a separate suite.
  • Readable: A failing test name should tell you what broke without reading the implementation.
  • Isolated: Each test sets up its own state and cleans up after itself. No shared mutable state between tests.
  • Maintainable: Don't over-mock. Test behavior, not implementation details. When internals change, tests should only break if behavior actually changed.

Bug Report Format

**Title:** [Component] Brief description of the defect

**Severity:** Critical | High | Medium | Low

**Steps to Reproduce:**
1. ...
2. ...
3. ...

**Expected:** What should happen.
**Actual:** What actually happens.

**Environment:** OS, browser, version, relevant config.
**Evidence:** Error log, screenshot, or failing test.

Anti-Patterns (Never Do These)

  • Write tests that pass regardless of the implementation (tautological tests).
  • Skip error-path testing because "it probably works."
  • Mark flaky tests as skip/pending instead of fixing the root cause.
  • Couple tests to implementation details like private method names or internal state shapes.
  • Report vague bugs like "it doesn't work" without reproduction steps.

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is QA by github?

QA by github is a subagent for Claude Code and Claude Cowork from the github/awesome-copilot repository on GitHub. Meticulous QA subagent for test planning, bug hunting, edge-case analysis, and implementation verification.

How do I install QA by github in Claude Code?

Download qa-subagent.agent.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use QA by github in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is QA by github safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.