field notes
Short notes from real engineering work: one decision, one incident, one reversal at a time. Each one names the shape of the problem, the tension that made it hard, the decision, and what it cost. The internals stay out — the codename is the hint.
If you have five minutes rather than an afternoon: the three case studies condense this material to one problem, one decision and what the decision cost. The notes below are the record those studies cite — and the projects the codenames belong to are on the front page.
A quality filter had been in place since the archive was assembled, and it was simple: keep a value only if it does not differ from the last value kept by more than a declared bound. That filter carries an assumption nobody had written down…
Before a measurement is allowed to mean anything, two questions have to be answered, and both are about the input rather than the result. Does the decision set reproduce exactly as it was recorded, and what does the platform not give you.
method
Not a changelog entry and not a repository summary. One decision, one incident, one reversal, or one hard-won invariant — the thing an engineer would tell you at a whiteboard.
Prefer records with dates and root causes? Those are on incidents. Live numbers are on stats.