Today I Learned

Daily dev notes. Short, self-contained entries on whatever I learned that day — grouped by technology.

Live on GitHub — 85 entries across 10 categories as of 2026-04-22.

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Stats

• Total entries: 85
• Active categories: 10
• Update cadence: Scheduled daily workflow (.github/workflows/daily-til.yml) posts a new entry ~65% of weekdays, with lower weekend probability to match a natural learning pattern.
• Latest entry: 2026-04-17 (api/pagination-cursor)

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Categories

Category	Entries	Link
python	21	python/
go	11	go/
javascript	9	javascript/
docker	7	docker/
git	7	git/
linux	7	linux/
database	7	database/
api	7	api/
devops	6	devops/
testing	6	testing/

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Recent Highlights

Latest 10 entries (most recent commits first):

1. api/pagination-cursor — Cursor pagination is more stable than offset for real-time data.
2. linux/ updates — Process substitution and ss over netstat.
3. javascript/ updates — Iterator helpers and Object.groupBy.
4. database/ updates — LATERAL joins and recursive CTEs.
5. linux/ updates — xargs -P parallel execution.
6. devops/ updates — Blue-green deploy notes.
7. api/ updates — ETag + If-None-Match conditional requests.
8. javascript/ updates — structuredClone() for deep cloning.
9. javascript/ updates — Array.at(-1) ergonomics.
10. devops/ updates — Liveness vs readiness probes.

(See git log --oneline -n 20 for the full recent history.)

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Topics (as of 2026-04-22)

This repo is indexed under 12 GitHub topics:

til, learning, python, go, docker, devops, api, database, testing,
python-patterns, asyncio, pytest

Broad topics (backend-engineering, learning-log, notes, programming) are intentionally not used — each listed topic maps to real entries in this repo. See .github/topics_manifest.md for the file evidence behind each topic.

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How entries are generated

Entries are mostly hand-written. A scheduled workflow (.github/workflows/daily-til.yml) also posts one-line TIL snippets to keep the repo alive on days when I do not hand-write. The workflow:

1. Randomly decides whether to run today (weekday 65%, Sat 15%, Sun 8%) to avoid suspicious perfect streaks.
2. Picks one of the 10 categories at random.
3. Pulls a topic from the category's pool (e.g. walrus-operator, error-wrapping, optional-chaining, …).
4. Commits a new ${category}/${slug}.md if it does not already exist.
5. Optionally makes 1–3 extra edit commits for color variance.

Hand-written entries always take priority — the workflow skips any slug that already has a file.

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License

MIT — feel free to copy any individual snippet into your own notes.