diagnose

Diagnose bugs and performance regressions through a structured reproduce-hypothesise-fix workflow.

Updated Jul 17, 2026
One-click install
npx skills add https://github.com/unnxt30/skills --skill diagnose-unnxt30
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: diagnose
Source: https://github.com/unnxt30/skills/tree/main/diagnose
Command: npx skills add https://github.com/unnxt30/skills --skill diagnose-unnxt30

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) components.

What problem does it solve? Hard bugs and performance regressions often stall because developers jump straight to guessing fixes without a reliable reproduction. This Skill enforces a disciplined diagnosis loop — build a feedback loop, reproduce, hypothesise, instrument, fix, and regression-test — so root causes are found systematically instead of by luck. ## Core Features & Use Cases - Feedback loop construction: Ten ranked strategies for building an agent-runnable pass/fail signal, from failing tests and curl scripts to headless browser runs, fuzz loops, and git bisect harnesses. - Ranked falsifiable hypotheses: Generates 3-5 hypotheses with explicit predictions before testing, avoiding single-hypothesis anchoring. - Tagged instrumentation and cleanup: Every debug log gets a unique [DEBUG-...] prefix so cleanup is a single grep, plus a post-mortem checklist covering regression tests and architectural findings. - Use Case: A user reports that an export button intermittently throws an error. The Skill guides building a deterministic repro loop (or a HITL bash script via scripts/hitl-loop.template.sh if human clicks are required), ranking hypotheses, instrumenting the code path, and landing a fix with a regression test. ## Quick Start Ask the assistant to diagnose the bug you are experiencing and describe the exact symptom, error message, or performance regression you observed.

Frequently Asked Questions about diagnose

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I debug a bug that only happens sometimes?

For non-deterministic bugs, raise the reproduction rate instead of chasing a clean repro: loop the trigger 100 times, parallelise, add stress, narrow timing windows, or inject sleeps. A 50%-flake bug is debuggable; keep increasing the rate until it is.

How to reproduce a bug that requires manual UI clicks?

Use a human-in-the-loop bash script based on scripts/hitl-loop.template.sh. The script prompts the human through each step, captures answers as KEY=VALUE output, and feeds the results back so the debugging loop stays structured.

What should I do before writing a fix for a bug?

First build a fast deterministic feedback loop that reproduces the exact symptom, then generate 3-5 ranked falsifiable hypotheses with explicit predictions. Only instrument and fix after the loop reliably demonstrates the failure the user described.

When should I not write a regression test for a bug fix?

Skip the regression test when no correct seam exists — meaning no test location exercises the real bug pattern as it occurs at the call site. A shallow test gives false confidence; instead document the missing seam as an architectural finding.

How do I debug a performance regression instead of a crash?

For performance regressions, avoid log-based probing. Establish a baseline measurement with a timing harness, profiler, or query plan, then bisect changes against that measurement. Measure first, fix second.