Things I broke, debugged, or got curious about — written down before I forget how I actually understood them.
None of this starts from a textbook. It starts from something I'm actually using and not fully understanding yet — then I work backward, or just get curious and follow it. Some of this is depth-first understanding. Some of it is system design concepts and interview cheatsheets — condensed for recall speed, not depth.
Some of it:
- Auth started with JWT because that's what I had at work. Working backward led to the older schemes, then forward again to JWE.
- Indexes started with "add an index, query gets faster" — working backward led to how data sits on disk, which I still don't fully have.
- Timeseries started because I use Mongo's TSDB feature and got curious why it's structured differently.
- Idempotency started from Kafka — producer-side vs consumer-side idempotency are not the same problem.
So this repo is not "implemented and mastered." It's closer to: here's the depth I've reached on this, going backward from what I use. Some docs are near-complete. Some stop at "I understand the shape of it, not the internals yet".
Two rules for anything that goes in here:
- If I can't explain it without jargon, I don't understand it yet.
- Say what I actually know, not what sounds complete.
Every doc (Mostly) here follows a similar map:
- Mental Model — the one image/analogy that makes the rest click
- Historical Evolution — why it exists, what it replaced
- What Broke — the failure that forced the idea into existence
- Core Mechanism — how it actually works, no hand-waving
- Tradeoffs — what you give up to get it
- Production Usage — where I've actually seen or used it (if I haven't, well thats on me)
- Common Failure Modes — how it breaks, and how that looks in practice
- Practical Guidelines — when to reach for it, when not to
- One-line Principle — the takeaway if you remember nothing else
So six months from now I don't have to relearn this from scratch.