Explanation built and opened.

- **file**
  - `/tmp/2026-07-11-skim-eval-example-explanation.html`
  - 58KB, self-contained HTML+CSS+JS
- **target commit**
  - `1c80ad4` "use eval example to improve"
  - 13 files, +492/−33
- **sections**
  - Background → deep (Skim contracts, anatomy, eval harness, improvement loop) + narrow (3 pre-commit gaps)
  - Intuition → specimen + 4 diseases, two-surfaces-one-tree trick, 7-child violation
  - Code → 5 groups: specimen · 3rd linter shape · 3 new checks · per-container runner prompts · rules/skill/ext alignment
  - Quiz → 5 interactive MCQs with feedback + live score
- **diagrams**
  - 6 reusable HTML families: reply anatomy · eval dataflow · improvement loop · two-forms-one-tree · structure tree · commit thread
  - no ASCII; code in `<pre>` with `white-space:pre`
- **verified**
  - 19 pre blocks, 0 raw brackets, tags balanced
  - matches repo: gold = `bodyKind:markdown`, 4 anchors, 18 lines; 14/14 tests pass

Want deeper dive on any one group, or a darker theme variant?