aedificium — a personal learning notebook + lexicon, Claude-native

A card-grid UI on http://localhost:8788 for notes, definitions (a lexicon), and PDFs, with a chat pane bridged to Claude Code via MCP. Math renders first-class (KaTeX). Everything on disk is plain markdown, auto-committed to git, and (optionally) auto-pushed to GitHub.

This is the open-source template. Fork it, clone your fork next to a sibling scriptorium/ code lab, and start writing.

What you get

• Card grid + reader — notes on the left, chat with Claude on the right.

• First-class math — $e^{i\pi}+1=0$ inline, $$…$$ display, KaTeX server-side. Renders in the card grid and in the reader.

• Lexicon — one definition per file (lexicon/eigenvalue.md), rendered as a dictionary entry with headword + synonyms + domain label.

• PDF library — drop a PDF into pdfs/; a sidecar discussion card appears automatically. No embedded viewer — the browser's native one is better. Deep-link into pages with #page=N.

• Chat is Claude Code — you type in the browser, Claude answers, and your current card selection travels along as context (refs=…).

• Wiki-links — [[slug]] in any note becomes a click-to-open link in the reader, with /note/<slug> deep-links via the History API.

• Git-native — writes auto-commit (debounced ~3 s) and, if origin is set, auto-push. LFS pre-configured for PDFs so GitHub handles large binaries cleanly.

Prerequisites

Developed and tested on macOS (arm64). Linux should work with the equivalent package installs.

• bun — the JavaScript runtime the server uses. brew install oven-sh/bun/bun.

• git-lfs — for PDFs. brew install git-lfs.

• Claude Code — the CLI the chat pane talks to. This is what makes the notebook interactive.

Setup

# Fork on GitHub first, then:
git clone git@github.com:clausd/aedificium.git
cd aedificium
bun install
git lfs install

Launching

One flag matters and it is easy to miss. Claude Code needs --dangerously-load-development-channels server:aedificium for the browser → Claude direction of the channel to work. Without it, the reply / commit_chat tools still work (Claude → browser), but nothing you type into the chat pane reaches Claude. Silence looks like a bug and isn't.

claude --dangerously-load-development-channels server:aedificium

Claude Code will spawn bun server.ts automatically (per .mcp.json). Then open http://localhost:8788.

Consider aliasing:

alias claude-aed='claude --dangerously-load-development-channels server:aedificium'

The "don't nohup bun" rule

Do not start bun yourself with nohup / disown. If you do, bun becomes an orphan process detached from Claude Code's MCP stdio pipe — the browser still works, but Claude loses reply and commit_chat, and no future Claude Code session can bind port 8788 either (the orphan is holding it).

If you need to pick up a server.ts change:

kill $(lsof -tiTCP:8788 -sTCP:LISTEN)   # or just kill the pid you see
# then exit + re-enter Claude Code; the harness respawns a fresh bun child.

Layout

notes/                  YYYY-MM-DD-HHMM-slug.md — free-form notes
lexicon/                <slug>.md — one term per file, dictionary style
pdfs/                   PDFs + auto-generated sidecar .md discussion cards
assets/                 pasted / dropped images referenced from cards
files/                  misc non-PDF uploads
archive/                archived cards (preserves original subdir)
data/chat.jsonl         durable chat transcript (tracked + searchable)

server.ts               the Bun app (single file, ~2500 lines)
CLAUDE.md               the design doc + Claude Code project instructions
.mcp.json               MCP config (Claude Code reads this to spawn bun)
.gitattributes          LFS routing for *.pdf

Conventions in one page

• Card kinds are inferred, not declared: files in notes/ are notes, files in lexicon/ are lexicon entries, PDFs get sidecar cards.

• Math: $x$ inline (dollars hug content), $$…$$ display. See CLAUDE.md for edge cases.

• Machine tags in the body: #area:calculus, #see:other-slug, or a bare #question. The UI hides them from the prose and renders them as chips.

• Wiki-links: [[some-slug]] (optionally [[some-slug|display text]]) resolve server-side and open in the reader.

Full spec: CLAUDE.md.

Optional — the sibling code lab

If you want a companion Python repo for models, notebooks, and figures, use scriptorium-template as a sibling checkout:

your-workspace/
  aedificium/          # this repo
  scriptorium/         # from scriptorium-template

The scriptorium aedificium.py bridge lets notebook cells render aedificium prose inline and save matplotlib figures directly into aedificium/assets/. Set AEDIFICIUM_DIR (in scriptorium) or AED_SCRIPTORIUM_DIR (here) if the two aren't siblings.

GitHub setup

Push to GitHub as usual once you have LFS installed locally:

git remote set-url origin git@github.com:clausd/aedificium.git
git push -u origin main

Auto-push runs after each auto-commit (5 s debounce). Disable with AED_NO_PUSH=1. GitHub LFS free tier is 1 GB storage / 1 GB bandwidth per month per account — comfortably enough for a personal PDF library up to a few hundred papers.

Environment knobs

Troubleshooting

• "I type in the chat pane and nothing happens." Almost always the missing --dangerously-load-development-channels server:aedificium flag. Restart Claude Code with it.

• "Claude says the reply tool is unavailable." Bun got orphaned. Kill the process on port 8788, exit and re-enter Claude Code.

• "git push refuses a PDF (exceeds 100 MB)." LFS wasn't active when the PDF was added. Run git lfs install, then git lfs migrate import --include="*.pdf" --everything, then git push --force-with-lease (only safe when you're the sole clone).

• "Auto-commit stopped." Check bun's stderr. Most common cause is a merge conflict on data/chat.jsonl between machines — the conflict is usually the union of the two sides (chat.jsonl is append-only).

License

MIT. Adapt freely — the point is that you own your notebook.

Credits

Original concept, architecture, and implementation by Claus Dahl. The two-repo split (prose ↔ code) is inspired by the way medieval scriptoria fed monastic libraries — hence the names.