kaiiiichen · kaiiiichen · May 5, 2026 · May 5, 2026
diff --git a/CLAUDE.md b/CLAUDE.md
@@ -8,7 +8,7 @@
 
 Personal website of Kai Chen — **Next.js 16** (App Router), **React 19**, **TypeScript**, **Tailwind CSS 4**, deployed on **Vercel**.
 
-Canonical documentation: **[README.md](README.md)** (setup, routes, APIs, env, CI, MDX, forking).
+Canonical documentation: **[README.md](README.md)** (setup, routes, APIs, env, CI, forking).
 
 ---
 
@@ -20,7 +20,7 @@ Canonical documentation: **[README.md](README.md)** (setup, routes, APIs, env, C
 | **Client polling** | `app/hooks/use-now-playing.ts` — polls every **10s**; `Cache-Control` on API allows short CDN cache |
 | **GitHub** | `GET /api/github/contributions` — GraphQL calendar + REST; `GET /api/github/stars` — star counts |
 | **Weather** | `GET /api/weather` — Open-Meteo, fixed coordinates (Berkeley), revalidated fetch |
-| **Notes** | MDX under `app/notes/**/page.mdx`; pipeline in `next.config.ts` (Webpack + `@mdx-js/loader`); components in `mdx-components.tsx` and `components/notes/` |
+| **Notes** | External Notion page linked from navigation |
 | **Observability** | Sentry via `instrumentation*.ts` + `sentry.*.config.ts` (DSN optional); Vercel Analytics / Speed Insights in root layout |
 | **Theme** | `app/components/theme-provider.tsx` + inline script in `app/layout.tsx` — default **light** when unset |
 
@@ -30,7 +30,7 @@ Canonical documentation: **[README.md](README.md)** (setup, routes, APIs, env, C
 
 ```bash
 npm install   # also sets core.hooksPath → .githooks (co-author trailer)
-npm run dev   # next dev --webpack — required for MDX parity
+npm run dev   # next dev --webpack
 npm run lint && npm run typecheck && npm run test && npm run build
 ```
 
@@ -41,13 +41,12 @@ npm run lint && npm run typecheck && npm run test && npm run build
 - [`lib/now-playing.ts`](lib/now-playing.ts) — types for Last.fm payload
 - [`lib/lastfm-now-playing-helpers.ts`](lib/lastfm-now-playing-helpers.ts) — pure helpers used by the now-playing route (tested)
 - [`app/lib/substack.ts`](app/lib/substack.ts) — RSS fetch + parse (tested)
-- [`next.config.ts`](next.config.ts) — MDX webpack rule, `withSentryConfig`
+- [`next.config.ts`](next.config.ts) — webpack config, `withSentryConfig`
 
 ---
 
 ## Conventions
 
 - **Dark mode** — support `dark:` for new UI.
-- **MDX** — do not assume Turbopack; dev/build use `--webpack`.
 - **Secrets** — never commit `.env.local` or tokens; see AGENTS.md and README.
 - **User prompts** — when the user sends copy-paste blocks, keep them as single fenced blocks when echoing back.
diff --git a/README.md b/README.md
@@ -66,16 +66,15 @@ This repository is a **[Next.js 16](https://nextjs.org/)** application using the
 7. [Routes and features](#routes-and-features)
 8. [API routes](#api-routes)
 9. [Environment variables](#environment-variables)
-10. [MDX lecture notes](#mdx-lecture-notes)
-11. [External integrations](#external-integrations)
-12. [Local development](#local-development)
-13. [Testing](#testing)
-14. [CI, Dependabot, and auto-merge](#ci-dependabot-and-auto-merge)
-15. [Git hooks](#git-hooks)
-16. [Deployment](#deployment)
-17. [Documentation map](#documentation-map)
-18. [Forking this project](#forking-this-project)
-19. [License](#license)
+10. [External integrations](#external-integrations)
+11. [Local development](#local-development)
+12. [Testing](#testing)
+13. [CI, Dependabot, and auto-merge](#ci-dependabot-and-auto-merge)
+14. [Git hooks](#git-hooks)
+15. [Deployment](#deployment)
+16. [Documentation map](#documentation-map)
+17. [Forking this project](#forking-this-project)
+18. [License](#license)
 
 ---
 
@@ -85,7 +84,7 @@ The site combines:
 
 - A **marketing-style home page** (identity, listening status, weather, **GitHub pinned repositories** via GraphQL with a static fallback, and Substack headlines).
 - **Dynamic data** from Last.fm, GitHub, Open-Meteo, and optional Supabase-backed listening history.
-- **MDX-powered notes** under `/notes` with math (KaTeX), GitHub-flavored Markdown, and syntax-highlighted code blocks — multiple course segments (UC Berkeley and SUSTech); see [MDX lecture notes](#mdx-lecture-notes).
+- **Notes** are hosted externally on Notion (via the top navigation link).
 - **Optional observability** via Sentry (client, server, edge) and Vercel Analytics / Speed Insights.
 
 There is **no** `middleware.ts` (or `proxy.ts`) in this repo — every route is publicly accessible and rendered by the App Router directly.
@@ -120,15 +119,15 @@ npm run dev
 
 Open [http://localhost:3000](http://localhost:3000).
 
-**Important:** `dev` and `build` both pass **`--webpack`** to Next.js. MDX is wired through a **custom `webpack()` block** in [`next.config.ts`](next.config.ts) (`@mdx-js/loader` + remark/rehype plugins). Using Webpack for dev/build keeps MDX behavior aligned with production. Do not assume Turbopack-only behavior for `.mdx` files.
+**Important:** `dev` and `build` both pass **`--webpack`** to Next.js. Keep local and production behavior aligned.
 
 ---
 
 ## npm scripts
 
 | Script | Command | Purpose |
 | --- | --- | --- |
-| `dev` | `next dev --webpack` | Local development with Webpack (MDX-compatible). |
+| `dev` | `next dev --webpack` | Local development with Webpack. |
 | `build` | `next build --webpack` | Production bundle (also runs type checking as part of Next). |
 | `start` | `next start` | Serve the last `build` output (run `build` first). |
 | `lint` | `eslint` | ESLint across the repo ([`eslint.config.mjs`](eslint.config.mjs)). |
@@ -159,19 +158,17 @@ kaichen.dev/
 │   ├── opengraph-image.tsx       # OG image for /
 │   ├── about/                    # Bio / CV-style page + OG
 │   ├── projects/                 # Projects + GitHub heatmap + OG
-│   ├── notes/                    # Notes index, course pages, MDX note routes
 │   ├── api/                      # Route handlers (Last.fm, GitHub, weather)
 │   ├── components/               # UI: nav, cards, theme, weather, listening, GitHub heatmap, …
 │   ├── hooks/                    # e.g. use-now-playing.ts
 │   └── lib/                      # og.tsx, substack RSS, GitHub pinned repos (GraphQL)
-├── components/notes/             # MDX shortcodes: Theorem, Proof, Definition, Example, NoteBlock
 ├── lib/                          # Shared server-oriented helpers + Vitest tests
 │   ├── now-playing.ts            # Types for Last.fm payload
 │   ├── lastfm-now-playing-helpers.ts
 │   ├── weather-open-meteo.ts
 │   └── *.test.ts
-├── mdx-components.tsx            # MDX element mapping + shortcode registration
-├── next.config.ts                # MDX webpack rule + withSentryConfig
+├── mdx-components.tsx            # MDX element mapping
+├── next.config.ts                # Webpack config + withSentryConfig
 ├── instrumentation.ts            # Sentry Node/Edge registration
 ├── instrumentation-client.ts     # Sentry browser + router transition hooks
 ├── sentry.server.config.ts
@@ -201,7 +198,7 @@ kaichen.dev/
 | --- | --- |
 | Framework | Next.js **16.2** (App Router), React **19**, TypeScript **5** |
 | Styling | Tailwind CSS **4** (`@tailwindcss/postcss`), custom CSS in `app/globals.css` |
-| Content | **MDX** via `@mdx-js/loader` + `remark-gfm`, `remark-math`, `rehype-katex`, `rehype-highlight` |
+| Content | Markdown/MDX pipeline available in config for future content routes |
 | Fonts | `@fontsource/*` (Nunito, Bitter, JetBrains Mono), `geist` (sans/mono CSS variables) |
 | Data | Supabase (`@supabase/supabase-js`) — optional listening history DB writes (service role) for `/api/lastfm/now-playing` |
 | Monitoring | `@sentry/nextjs` (optional DSN), Vercel Analytics + Speed Insights |
@@ -218,9 +215,8 @@ Pinned versions are in [`package.json`](package.json).
 | `/` | Identity block, Last.fm line + card, Berkeley weather, **pinned GitHub repos** (GraphQL + fallback list), Substack RSS snippets |
 | `/about` | Education, experience, courses, volunteering |
 | `/projects` | Project cards + **GitHub contribution calendar** (client component, data from `/api/github/contributions`) |
-| `/notes` | Index of courses (see [MDX lecture notes](#mdx-lecture-notes)); links to external [SUSTech-Kai-Notes](https://github.com/kaiiiichen/SUSTech-Kai-Notes) for broader collections |
-| `/notes/...` | Nested segments per course (e.g. `cs61a`, `data100`, `cs217`, `ma121`–`ma337`); individual notes are `page.mdx` |
-**External nav (no in-app route):** the main nav includes **Blog** → [Substack](https://kaiiiichen.substack.com/); there is no `/blog` route in this repo.
+
+**External nav (no in-app route):** the main nav includes **Notes** → [Notion](https://kaichen-dev.notion.site/kaichen-dev-notion-site-357a3294e48780f3b570f2f48f1081a4?pvs=74) and **Blog** → [Substack](https://kaiiiichen.substack.com/); there is no `/notes` or `/blog` route in this repo.
 
 **Open Graph:** several routes ship `opengraph-image` route handlers for social previews. Set [`metadataBase`](https://nextjs.org/docs/app/api-reference/functions/generate-metadata#metadatabase) in `app/layout.tsx` if you see build warnings about resolving OG image URLs.
 
@@ -274,20 +270,6 @@ CI does not need any real Supabase keys to build — every Supabase client in th
 
 ---
 
-## MDX lecture notes
-
-- Notes are **route segments** with `page.mdx` files (e.g. `app/notes/cs61a/scheme-quote/page.mdx`), not a separate `content/` directory.
-- The index at [`/notes`](app/notes/page.tsx) lists courses by code (examples: **CS61A**, **Data 100**, **CS217**, **MA121**–**MA337**). Each course has a `page.tsx` hub and nested folders for individual notes.
-- Shared layout: [`app/notes/layout.tsx`](app/notes/layout.tsx) (imports KaTeX CSS, width/padding).
-- MDX components and typography are centralized in [`mdx-components.tsx`](mdx-components.tsx).
-- Custom shortcodes (Theorem, Definition, Proof, Example, NoteBlock) live in [`components/notes/`](components/notes/) and are registered globally for MDX.
-- Metadata in MDX files often uses `export const metadata = { title, description }` (Next.js metadata), not always YAML frontmatter.
-- Large PDFs or archives for a course may live under `public/notes/...` and be linked from MDX; keep binary paths in sync if you move files.
-
-To add a new course: add a card on the notes index, create `app/notes/<slug>/page.tsx` plus note folders with `page.mdx`, match existing note headers (breadcrumb, title block) for visual consistency, and run `npm run build` to validate the MDX pipeline.
-
----
-
 ## External integrations
 
 | Service | Use in this repo |
@@ -306,14 +288,12 @@ To add a new course: add a card on the notes index, create `app/notes/<slug>/pag
 ## Local development
 
 - **Node 20**, **npm install** then **`npm run dev`**.
-- If MDX fails to compile, confirm you did not remove the `--webpack` flag from scripts.
 - **Supabase:** only `/api/lastfm/now-playing` uses Supabase (service role) for the optional listening history. The site builds and serves every page without any Supabase env set; the route just falls back to live Last.fm + in-memory cache when the DB is unreachable.
 
 ### Common issues
 
 | Symptom | Things to check |
 | --- | --- |
-| MDX differs between dev and prod | Ensure both use Webpack (`--webpack`). |
 | GitHub widgets empty | `GITHUB_TOKEN` set and not expired; API rate limits. |
 | "Recently played" never persists across deploys | `NEXT_PUBLIC_SUPABASE_URL` / `SUPABASE_SERVICE_ROLE_KEY` set; tables `listening_history` / `listening_stats` exist with the expected columns. |
 | Sentry noisy locally | DSN unset disables reporting; or lower sample rate in `instrumentation-client.ts`. |

diff --git a/app/components/nav.tsx b/app/components/nav.tsx
@@ -10,7 +10,11 @@ const WAVE_SVG = `url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/s
 const NAV_LINKS = [
   { href: "/about", label: "About", external: false },
   { href: "/projects", label: "Projects", external: false },
-  { href: "/notes", label: "Notes", external: false },
+  {
+    href: "https://kaichen-dev.notion.site/kaichen-dev-notion-site-357a3294e48780f3b570f2f48f1081a4?pvs=74",
+    label: "Notes",
+    external: true,
+  },
   { href: "https://kaiiiichen.substack.com/", label: "Blog", external: true },
 ];
 

diff --git a/app/lib/github-pinned.ts b/app/lib/github-pinned.ts
@@ -15,13 +15,6 @@ const FALLBACK_PINNED: PinnedProject[] = [
     repo: "kaiiiichen/kaichen.dev",
     stack: ["Next.js", "TypeScript", "Tailwind"],
   },
-  {
-    name: "SUSTech-Kai-Notes",
-    desc: "Open lecture notes for 20+ math and CS courses.",
-    href: "https://github.com/kaiiiichen/SUSTech-Kai-Notes",
-    repo: "kaiiiichen/SUSTech-Kai-Notes",
-    stack: ["LaTeX"],
-  },
   {
     name: "SudoSodoku",
     desc: "Terminal-style Sudoku for iOS. Minimalist, focus-driven.",

diff --git a/app/notes/cs217/dsaa/page.mdx b/app/notes/cs217/dsaa/page.mdx
diff --git a/app/notes/cs217/page.tsx b/app/notes/cs217/page.tsx