Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
17 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
TLS Handshake Failure: Connection Reset Debugging Guide
A practical guide for diagnosing and fixing TLS handshake failures that manifest as connection resets, covering packet-level analysis, cipher mismatches, and server-side issues.
OpenTelemetry Metrics Not Exporting: A Field Guide
A direct, actionable guide for debugging OpenTelemetry metrics that fail to export. Covers collector configuration, SDK timing, and common silent failures.
Astro Component Hydration Not Working: Debugging Missing Client-Side Interactivity
A debugging guide for Astro components that fail to hydrate: symptoms, root causes, diagnosis steps, and fixes for missing client-side interactivity.
Debugging TypeScript Module Augmentation When It Silently Fails
A direct guide to diagnosing why your TypeScript module augmentation doesn't take effect, covering ambient module declarations, import side effects, and module resolution quirks.
Postgres Sequence Gaps in SERIAL ID: Why They Happen and How to Stop Panicking
A no-fluff guide to understanding why Postgres serial IDs have gaps, how to identify the cause, and when to actually worry.
CSS Modules Class Not Found: Why Your Imported Styles Object Returns Undefined
When a CSS Modules class import resolves to undefined at runtime, the root cause is almost always a misconfiguration in your build pipeline. This guide walks through the five real reasons it happens and how to fix each one.
Long-form thinking on debugging habits, observability, and the systems around the bug.
How to Reproduce a Flaky Test: From CI Logs to Reliable Failure
A practical guide to turning intermittent test failures into reliably reproducible bugs, with techniques ranging from loop testing to thread sanitizers.
Property-Based Testing: Finding the Off-by-One That Lived in Production for 18 Months
A concrete story of how switching from example-based tests to property-based tests caught a timing bug that had survived code review, QA, and 18 months of production traffic.
How We Reduced End-to-End Test Flakiness by 80% with Deterministic Seeding
After months of chasing intermittent failures in our CI pipeline, we implemented a three-part strategy — deterministic seeding, isolated state per test, and a structured retry budget — that cut flaky end-to-end test failures by 80%.
Snapshot Testing: The 5 Hidden Failure Modes That Will Break Your CI
Snapshot tests seem like a safety net, but they often hide real bugs, bloat diffs, and silently break your CI. Here are the five failure modes I've seen in production and how to fix them.
Testing Async Code: Avoiding Flakiness and False Positives in JavaScript
Async testing is full of traps: unhandled rejections, race conditions, and tests that pass when they shouldn't. Here's how to write reliable async tests in JavaScript.
Testing Error Handling Code Paths: A Practical Approach
Error handling code is often the least tested and most brittle. Here's how to cover those paths with fault injection, mocks, and chaos engineering.