…em-dash pivots

Replace the top nav bar with a hand-rolled, collapsible, searchable left
sidebar (no shadcn/Tailwind — the repo stays zero-dep; built on the existing
semantic CSS tokens). It lists the whole registry grouped by category with a
type-to-search filter, stage dots, and active-route highlighting; collapses to
an icon rail on desktop and slides over content on mobile. The old .topbar is
removed from every page; per-page cross-links (Collatz ↔ attack log, back to
index) survive as compact breadcrumb rows, and the dossier stage moves to a
crumb chip.

Add a "Submit / feedback" button in the sidebar that opens a math-context-aware
modal (Submit / Correction / Idea / Question). On a dossier it takes that
problem head-on — shown in the header and attached to the payload — and offers a
GitHub PR/issue as the durable path. It POSTs to a new server route
app/api/feedback that relays the note to Slack via chat.postMessage using a
server-only bot token (env SLACK_BOT_TOKEN + SLACK_FEEDBACK_CHANNEL; see
.env.example). This is the app's one server seam — no new deps, plain fetch;
returns 501 until the env is set. CLAUDE.md updated to reflect it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Generated via favicontools.com from noto:abacus — favicon.ico, 16/32/48/96
PNGs with light/dark 16px variants, apple-touch-icon, Android/PWA icons.
Wired into App Router metadata.icons/manifest with prefers-color-scheme
media queries; rebranded manifest.json to Math Lab.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Add attribution in three durable spots: manifest generator field, a
layout comment by the icons metadata, and a README Credits section.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…feed/theme work included

Pushes the branch so Vercel builds a preview with the Slack env vars
(Preview scope) to verify app/api/feedback end-to-end. Bundles concurrent
work-in-progress from this workspace (SEO routes, news feed, theme controls,
search filter popover) — tree typechecks and builds clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Sitemap validation found the Collatz attack-log page — a real, indexable,
HTTP-200 content page — absent because the generator maps registry entries 1:1
and skipped dossier sub-pages. Add a subPages block. 72 → 73 URLs; all 200, no
redirects, HTTPS-only, XML valid, referenced in robots.txt.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

- New CommandPalette: global ⌘K/Ctrl+K jump list over every problem plus
  nav destinations (Home, Problems by field, Collatz attack log) and actions
  (Submit/feedback, GitHub). Keyboard-driven (↑↓/↵/esc), grouped, stage badges.
- Collapsed rail: widen 60→68px, enlarge icon-buttons (mark/collapse/submit/
  GitHub to 34–40px), add a rail search button that opens the palette (search
  was hidden when collapsed), and drop RSS from the rail to declutter.
- Expanded search gains a ⌘K hint that also opens the palette.

Programmatic-SEO layer over the problem registry:

- Category hubs /problems + /problems/[category] ("open problems in
  <field>") and cross-cutting tag hubs /tags + /tags/[tag], gated to
  tags spanning >=2 problems (singletons would be thin/duplicate).
- Per-problem OG cards (next/og, no new dep) + site-wide fallback;
  math glyphs transliterated so satori needs no build-time font fetch.
- JSON-LD on every dossier (DefinedTerm + BreadcrumbList) and hub
  (ItemList); keyword-led titles via layout template + metadataBase so
  canonicals/OG resolve absolutely.
- Related-problems section wires every dossier into the hub-and-spoke
  graph (kills orphan/thin pages); server-rendered browse nav on the
  homepage gives crawlers real <a>s past the JS-only search.

All derived from lib/problems.ts via lib/seo.ts — hubs, sitemap, and
structured data follow the registry with nothing hand-maintained.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Concurrent UI/tooling tweaks left in the tree: the filter popover's stage
control becomes chip buttons (matching the category chips), and .gstack/
is gitignored.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Real shadcn components (per request), layered over the existing hand-rolled CSS:
globals.css imports only Tailwind's theme + utilities layers (no preflight), so
the legacy dossier pages are untouched; @theme inline maps the oklch tokens onto
Tailwind. Base <a> rules moved into @layer base so utilities win in components.

- components/ui/{button,badge,card,popover,switch,checkbox}: shadcn (new-york).
  Button/Badge marked 'use client' (this @radix-ui/react-slot builds createContext
  at module load, which breaks in RSC / the server-rendered feed).
- ThemeControls: single shadcn Switch (light<->dark; system = initial only).
- NewsFeed: horizontal-scroll row of shadcn Cards + Badges.
- SearchHome: funnel filter is now a shadcn Popover (Button + Checkbox chips).
- CLAUDE.md: document the new stack + the news-feed/RSS append convention.

Verified: bun run typecheck + bun run build pass; light/dark render checked.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Evergreen, high-intent content page for the very common search "I think I
solved [famous problem], now what". A calm, honest 12-step playbook: the base
rate, five-minute sanity checks, computational stress tests (Wolfram Alpha,
OEIS, SageMath/PARI/SymPy in exact arithmetic), building your own
counterexample, adversarial AI review (flaw-finders not judges), the literature
check, formalizing in Lean/Rocq/Isabelle, the classic failure modes, getting
human eyes via MathOverflow, priority/publishing, and submitting to the lab.

- HowTo + FAQPage JSON-LD for AI answer engines / rich results.
- Built on the legacy dossier classes (TOC + chapters) to match the site;
  every external tool link is real; tone is supportive, not mocking, and stays
  on the site's honesty line ("solved" means it survived all of the above).
- Wired into sitemap.ts (priority 0.8) and cross-linked from the Submit modal
  ("Think you've solved one? Read the playbook first").

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…tes it)

The inline THEME_SCRIPT toggles the `dark` class on <html> before React
hydrates, so the server/client class list differs by design — flag it so React
doesn't warn on every load.

Title-only cards read as unfinished; add back a 4-line-clamped summary and let
the title breathe, with cards stretched to a uniform height in the scroll row.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

The shadcn rebuild reintroduced the per-kind border-l-[3px] accent; remove it
and the now-dead KIND_ACCENT/FeedKind. Cards keep the plain uniform border.

Internal linking so the playbook is reachable (and flows link-equity) beyond
the sitemap:
- Generic dossier template gets a "Think you can crack this one? Read the
  playbook before you announce →" callout under §Status — one edit covers every
  registry problem, and it's suppressed on solved problems.
- Sidebar footer gets a "Solved something? Start here" link.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>