Blog · page 6
Notes on engineering, design, and everything in between.
What technical debt interest actually looks like
Debt is not ugly code; it is the extra cost every future change pays. The test is measurable: files touched per edit, test runtime, places that must change together.
Time zones and DST: store UTC, or daylight saving will bite
A DST day has 23 or 25 hours, and local times near the switch may not exist or may happen twice. Storing UTC timestamps and converting at display is the only model that holds.
Turning an AI search into a tree you can page through
Visualising a search is not mainly about drawing the tree. The data has to be real, the panel must not shove the board around, and it must load only for people who click the button.
Unicode normalization: why two identical-looking strings differ
An e-acute can be one code point or a base letter plus a combining mark. Normalize to NFC before comparing, storing or indexing, or duplicates quietly slip through.
URL encoding: spaces, plus signs and double encoding
A plus is a space in the query string and a literal plus in the path; the two positions encode the same character differently; encoding twice yields a plausible value that never matches.
Four places Chinese chess rules go wrong
Horse-leg blocking, elephant-eye blocking, cannon screens and the flying-general rule. Splitting move generation into a geometry layer and a legality layer removes most of the mistakes.