Show estimated read time in the viewer bar

[sjmiller609]

Summary

Adds an estimated read time to the /d/:slug chrome bar, alongside the other page-independent controls (theme toggle, bookmark, comments, history).

• lib/docs/reading-time.ts — estimateReadMinutes(html): masks comments/script/style/template/noscript/svg, runs the existing htmlToText, counts word tokens at 200 wpm and CJK characters at 500/min (they have no spaces to tokenize on), rounds up. Returns 0 when the doc has no prose so an image-only doc doesn't claim "1 min read".
• Computed at SSR in app/d/[slug]/page.tsx next to extractSections and passed to the shell — a pure function of the stored HTML, nothing stored, no client recompute (an inline edit changes it on the next load, same as the title and section list).
• Rendered as a muted N min read before the theme toggle, inheriting --jh-bar-muted so it themes in light and dark. Hidden below 768px, where the bar is already tight.

Testing

• npm test — 168 passing, including 6 new cases for estimateReadMinutes (wpm rounding, non-prose blocks and comments ignored, entities decoded, CJK, zero-prose docs).
• npm run build clean, tsc --noEmit clean.
• Verified in a local dev server against a seeded doc: a 1000-word doc shows "6 min read", a short doc "1 min read".

---

Note

Low Risk
Display-only SSR derivation from stored HTML with no auth or persistence changes; behavior is covered by new unit tests.

Overview
The document viewer chrome bar now shows an estimated read time (N min read) before the theme toggle, using muted bar styling and a tooltip. It is omitted when the estimate is 0 (no readable prose) and hidden below 768px so the tight mobile bar stays usable.

lib/docs/reading-time.ts introduces estimateReadMinutes(html): strip comments and non-prose blocks (including svg), convert with existing htmlToText, count word tokens at 200 wpm and CJK characters at 500/min, round up. app/d/[slug]/page.tsx computes this at SSR next to extractSections and passes readMinutes into CommentsShell. No persistence or client recompute—edits update the label on the next load like the title.

Vitest covers rounding, empty/non-prose docs, ignored markup, entities, and CJK.

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Project	Deployment	Actions	Updated (UTC)
justhtml	Ready	Preview	Jul 31, 2026 3:11pm