learn: retrospective learnings

[peco-engineer-bot]

Rolling retrospective learnings

This PR accumulates one dated section of learnings per day (from merged PRs and engineer-bot author runs) until it is merged; merging it starts a fresh one. The bot never writes the canonical log directly.

Latest update 2026-09-05: 1 new learning(s) since 2026-09-04T17:26:13Z.

[peco-review-bot]

✅ No issues identified by the review bot.

[peco-review-bot]

✅ No issues identified by the review bot.

[peco-review-bot]

✅ No issues identified by the review bot.

[peco-review-bot]

✅ No issues identified by the review bot.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[peco-review-bot]

✅ No issues identified by the review bot.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[peco-review-bot]

✅ No issues identified by the review bot.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[peco-review-bot]

✅ No issues identified by the review bot.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[peco-review-bot]

✅ No issues identified by the review bot.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[peco-review-bot]

Verdict: 1 Nit

Looks good — this PR only appends dated retrospective learning entries to .claude/knowledge/learning-log.md; no executable code changes, so nothing to check for correctness/security/tests. One cosmetic nit: the "No learnings have been recorded yet" placeholder line is now stale since entries follow it.

Other findings

• ⚪ Nit — The intro placeholder paragraph ("No learnings have been recorded yet — the first retrospective PR will append the initial dated section below.") is now stale: several dated sections follow it. Consider removing or rewording the placeholder now that entries exist, so the header no longer contradicts the body. Purely cosmetic — the retrospective flow appends below it as designed.