Context

Every chapter folder now has a link-page.md Colab index — a bilingual table of one-click Colab badges generated from the git-tracked notebooks. Coverage: 40_linear_algebra_1 / 60_linear_algebra_2 (earlier) plus 00_introduction, 10_root_finding, 15_optimization, 20_probability, 28_interpolation, 30_num_int, 35_sympy, 50_ode, tutorial (added 2026年06月01日, commit d3c2ea79).

But nothing points to them. The README's folder table lists topics, not the indexes, so a visitor has to already know the files exist. (Left standalone for now per the 2026年06月01日 decision.)

Proposed (deferred)

1. Surface the link-pages from the README — e.g. make each folder name in the README chapter table link to its link-page.md, or add a short "per-chapter Colab index" line. A draft of this was tried earlier and reverted pending a decision.
2. Optionally, a single top-level index page (or README section) listing all chapters' link-pages.

Maintenance note (worth pairing with the above)

The link-pages are currently hand-generated (glob git-tracked notebooks → first H1 as title → Colab badge table). They will go stale on renumber / add / remove. Promoting the inline generator used for the 2026年06月01日 batch into a committed utils/gen_link_pages.py — runnable in pre-commit or CI — would keep them in sync. Notes for that script:

• Use git-tracked notebooks only (the batch initially swept in untracked scratch like ODE examples * / eca wk06 sample; exclude those).
• Title from the notebook's first H1, <br> → /.
• link-page.md is the ONE place hard file links are acceptable (regenerated from actual files), so it does not conflict with the concept-name cross-reference rule used elsewhere.

Parked from the 2026年06月01日 session.