A diff is a pile of files in alphabetical order. But that's not how you understand a change — you follow it: where data enters, how it's transformed, where it lands. Loupe does that reordering for you:

• Data-flow order, not file order. The engine groups the change into clusters and lays them out so you read entry points → core logic → edges.
• One symbol-card at a time. A focused card per changed function/type. Keyboard-first: Space to pass, ←/→ to move. No 4,000-line scroll.
• Grounded AI, not vibes. Threads run an agentic, read-only Claude scoped to the repo — it reads the real definitions and callers, not just the diff snippet.

• 🧭 Data-flow review — clusters + flow ordering so a PR reads as a story.
• 🃏 Symbol cards — one changed function/type per card, split before/after diff.
• 💬 Inline threads — drag to select lines, ask a question; the answer is codebase-aware (reads definitions/callers across the repo). Pick Sonnet or Haiku per thread. Threads persist with the review.
• 🔗 Jump links — when an answer references another changed symbol, it's a click away.
• 🧠 Editor handoff — ⌘-click any diff line to open the whole project at that file:line in IntelliJ IDEA or VS Code.
• ⌨️ loupe CLI — loupe <path> [base] [target] from a terminal or an AI skill; the app opens and starts the review (and remembers it in recents).
• 🔎 Fast project switching — branch picker with live search; recent projects.
• 🔍 ⌘ + scroll to zoom the code; adaptive font that fits the change.
• ✅ Approve the PR — when a review ends all-pass, approve the GitHub PR straight from the summary screen (delegated to your gh CLI; explicit two-step confirm).
• 🗄️ SHA-cached — re-opening an unchanged range is instant (no AI re-spend).

• macOS 11 (Big Sur) or later — universal build (Apple Silicon + Intel).
• Claude Code CLI installed and on your PATH — Loupe shells out to claude for all AI work.
• A Claude setup-token: run claude setup-token and paste it into Loupe once (stored locally on your Mac, chmod 600, never logged).
• (optional) the GitHub CLI (gh), signed in (gh auth login) — only needed to approve a PR from the summary screen.

Loupe makes no network calls of its own — every AI request goes through your claude CLI with your token.

Homebrew (recommended)

brew install --cask JiwonKKang/loupe/loupe

To update: brew upgrade --cask loupe.

Or grab the DMG from Releases → drag Loupe.app to /Applications.

The build is ad-hoc signed (no paid Apple Developer cert). The Homebrew cask strips the quarantine flag for you. If you install the DMG by hand and Gatekeeper complains: xattr -dr com.apple.quarantine /Applications/Loupe.app.

1. Launch Loupe → paste your claude setup-token.
2. Top-left menu → Browse to a git repo → pick base and target branches → Open review.
3. Walk the cards: Space pass · ←/→ move · ⌘E jump back to the previous card.
4. Drag across lines on a card to open an inline thread and ask away.
5. ⌘-click a line to open it in your editor; the bottom bar's logo picks IntelliJ / VS Code.

Installed alongside the app by the Homebrew cask.

loupe                                   # current dir, auto base/target
loupe ~/code/myproject main feature/x   # explicit

It resolves the range and opens the app straight into the review.

git 3-dot diff (base...target)
        │
        ▼
tree-sitter symbol extraction        → one card per changed function / type
        │
        ▼
AI clustering + flow ordering (Claude Sonnet)   ┐
per-cluster labels (Claude Haiku, in parallel)  ┘ → data-flow ordered review
        │
        ▼
SHA cache (SQLite)  → unchanged range = instant, 0 AI calls

Inline threads run a separate agentic, read-only Claude (Read/Grep/Glob/LS only; no writes, no shell) confined to the repo, so answers are grounded in the real code.

Adding a language is mostly wiring up its tree-sitter grammar — PRs welcome.

• Tauri 2 shell · React 19 (plain JS) front-end
• Rust engine: git2 (diff), tree-sitter (symbols), rusqlite (cache)
• AI via the claude CLI (Claude Code) — Sonnet for structure, Haiku for labels

git clone https://github.com/JiwonKKang/loupe
cd loupe
npm install
npm run tauri dev        # run
npm run tauri build      # produce a universal .dmg / .app

Requires Node, Rust, and the Tauri prerequisites.

• Your token is stored only on your Mac (~/Library/Application Support/com.jiwon.loupe/), 0600, and passed to the claude child process via env — never on a command line, never logged.
• The app itself opens no network connections; AI traffic is the claude CLI on your machine.

Issues and PRs welcome — language grammars, editor integrations, and UI polish especially.

MIT © 강지원 (Jiwon Kang)