Flake Axis Bisection
Locates the condition a known-flaky test actually depends on by holding the test constant and varying one axis at a time (isolation, execution order, worker count, viewport, network latency, repetition depth), recording a pass/fail count per variation, and testing whether the gap between two conditions exceeds sampling noise. Covers choosing the run count N from the failure rate you need to detect, binomial confidence intervals on a measured reproduction rate, a two-proportion comparison rule, what a zero-failure result does and does not prove, and the resource-collision walk (DB row, DB schema, file path, port, env var, module state, inode, cookie jar) used once parallelism is implicated. Use when a specific test is already known to fail intermittently, reading its source has not explained why, and a decision about what to change must rest on measurement rather than on a plausible-sounding guess.
Security AStatic scan found no risk patternsHow grading works ›
From the source SKILL.md
A non-deterministic test is one that "sometimes pass[es] and sometimes fail[s], without any noticeable change in the code, tests, or environment" ([Fowler, Eradicating Non-Determinism in Tests](https://martinfowler.com/articles/nonDeterminism.html)). That definition is the problem in a nutshell: nothing visible changed, so inspection has nothing to grip. This skill is the experiment that manufactures a visible change. Pick one condition, move it, and see whether the failure rate moves with it.
What this skill does
Flake Axis Bisection is a community-contributed Claude Code skill in the testing sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/flake-axis-bisection/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when a specific test is already known to fail intermittently, reading its source has not explained why, and a decision about what to change must rest on measurement rather than on a plausible-sounding guess.
Who uses this skill
The Flake Axis Bisection Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 158,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
How to install
Free
Manual install (2 steps)
mkdir -p ~/.claude/skills/flake-axis-bisection
curl -L https://claudskills.com/skills/flake-axis-bisection/SKILL.md \
-o ~/.claude/skills/flake-axis-bisection/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/flake-axis-bisection/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/flake-axis-bisection/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\flake-axis-bisection\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Telegram
📱 Install from your phone or desktop Telegram
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
Pro
One-click install via the desktop app
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
Pro
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
Frequently asked questions
How do I install the Flake Axis Bisection Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy
SKILL.md from the source repository to
~/.claude/skills/flake-axis-bisection/SKILL.md and restart Claude Code. Both flows are detailed at
claudskills.com/install/.
What does the Flake Axis Bisection skill do?
Locates the condition a known-flaky test actually depends on by holding the test constant and varying one axis at a time (isolation, execution order, worker count, viewport, network latency, repetition depth), recording a pass/fail count per variation, and testing whether the gap between two conditions exceeds sampling noise. Covers choosing the run count N from the failure rate you need to detect, binomial confidence intervals on a measured reproduction rate, a two-proportion comparison rule, what a zero-failure result does and does not prove, and the resource-collision walk (DB row, DB schema, file path, port, env var, module state, inode, cookie jar) used once parallelism is implicated. Use when a specific test is already known to fail intermittently, reading its source has not explained why, and a decision about what to change must rest on measurement rather than on a plausible-sounding guess.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Flake Axis Bisection skill?
Use Flake Axis Bisection when your Claude Code task falls under the Engineering category — specifically in the testing area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Flake Axis Bisection" or describe the task and let Claude pick). Browse related skills at
/category/engineering/.
What is a Claude Code skill and how does the Flake Axis Bisection skill fit in?
A Claude Code skill is a
SKILL.md file that lives under
~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Flake Axis Bisection is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at
/learn/what-is-a-claude-skill/.
Attribution & license
Cite this skill
If you reference this skill in a blog post, paper, or documentation, you can cite it as:
APA
testland. (2026). Flake Axis Bisection [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/flake-axis-bisection/
BibTeX
@misc{flake-axis-bisection-2026,
author = {testland},
title = {Flake Axis Bisection [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/flake-axis-bisection/}
}Embed this skill
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Security scan
Grade A · scanned 2026-07-23 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
- ✓ Prompt injection
- ✓ Data exfiltration
- ✓ Supply chain
- ✓ Reverse shell
- ✓ Credentials
- ✓ Execution
- ✓ Filesystem
- ✓ Persistence
- ✓ Obfuscation
- ✓ Network
Show this grade on your repo (click to copy):
[](https://claudskills.com/skills/flake-axis-bisection/#security)
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