Section edit pens, cursor-driven piecewise scroll sync, URL-following editor.

Anchored h1/h2s carry data-line (markdown source line, top-level
headings only) and h2s get dimmed section pens that open the page
editor at that section. Editor scroll sync is now piecewise-linear
keyed on those anchors: the page follows the cursor (fractional,
wrap-aware, fixed window anchor; editor scroll no longer drives it),
the editor follows page scroll with a progress-based viewport anchor,
so document ends line up exactly in both directions. The editor always
follows the URL — fetch-navigation retargets it — with unsaved text
stashed per path for the session and restored on return. Banner pen
removed (the tab stays in the shell); top-right order is now
analytics, site settings, login/logout.

docs/backend.md

@@ -18,7 +18,7 @@ msgspec Structs for the kanta database. See `docs/content-model.md` for the full
 
 ## `markdown.py`
 
-markdown-it-py renderer (html passthrough + attrs, footnote, deflist, tasklists, admon, gfm_autolink, sub/superscript plugins; typographer + breaks on). In bodies with at least three in-body h1/h2 headings, each gets a slug id (`python-slugify`, mirroring the editor's `slugify.js` — unicode folds to ASCII, separators become single hyphens) unless the author set `{#id}`, and their text is wrapped in a self-link (`a.anchor`) so section links are copyable; the first in-body h1 is the article title — when the markdown has no h1, `render(title=...)` injects it as `# {title}` so implicit and explicit titles take the same path — it gets no id and doesn't count toward the three, its self-link is `href=""` (scroll to top); shorter articles stay anchor-free, h3+ is never navigable, and duplicates get `-2`/`-3` suffixes. Custom image rule: relative srcs resolve against the page path; an image standing alone in its paragraph becomes a figure (captioned when titled), while inline-with-text images and raw `<img>` HTML stay plain. A `{dates}` line expands to the article's published/updated dateline (`p.dateline`, from `Node.created`/`modified`; left literal in previews of unsaved pages).
+markdown-it-py renderer (html passthrough + attrs, footnote, deflist, tasklists, admon, gfm_autolink, sub/superscript plugins; typographer + breaks on). In bodies with at least three top-level h1/h2 headings (nested ones, e.g. inside `::: aside`, never participate), each gets a slug id (`python-slugify`, mirroring the editor's `slugify.js` — unicode folds to ASCII, separators become single hyphens) unless the author set `{#id}`, and their text is wrapped in a self-link (`a.anchor`) so section links are copyable; anchored headings also carry `data-line` with their markdown source line (the page editor's section pens and piecewise scroll sync key off it); the first in-body h1 is the article title — when the markdown has no h1, `render(title=...)` injects it as `# {title}` so implicit and explicit titles take the same path — it gets no id and doesn't count toward the three, its self-link is `href=""` (scroll to top); shorter articles stay anchor-free, h3+ is never navigable, and duplicates get `-2`/`-3` suffixes. Custom image rule: relative srcs resolve against the page path; an image standing alone in its paragraph becomes a figure (captioned when titled), while inline-with-text images and raw `<img>` HTML stay plain. A `{dates}` line expands to the article's published/updated dateline (`p.dateline`, from `Node.created`/`modified`; left literal in previews of unsaved pages).
 
 `render()` returns a `Rendered(html, multicol)`: the article content segmented for the column layout (there is no wrapper div — segments and bare blocks are direct `<article>` children) — h1/h2 headings, `.wide` blocks and margin-breakout blocks (`.margin`, `::: aside`) stand bare, the runs between them become `<div class="colseg">` (plus `.cols` on segments with enough text, `::: nocols` opting out), and `multicol` flags bodies long enough to columnize (visible-text thresholds, code excluded). `views.py` puts the class on the article; pagerite.css takes it from there (at most two columns, the left-margin breakout, all viewport adaptation).