diff --git a/CLAUDE.md b/CLAUDE.md
index ad011be..2c24119 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -2,6 +2,7 @@
 
 Personal static photo gallery with Atom feed and upload API. Single-user.
 No database, no framework — just a Go binary that watches a directory and regenerates a static site.
+An Android app in `android/` posts to the same upload API.
 
 ## Architecture
 
@@ -9,7 +10,8 @@ No database, no framework — just a Go binary that watches a directory and rege
 content/          # images + .toml sidecars (source of truth)
 public/           # generated output (served by nginx / --serve flag)
 templates/        # embedded HTML templates
-static/           # embedded CSS
+static/           # embedded CSS + JS
+android/          # Kotlin/Compose uploader app, own flake
 ```
 
 The binary does three things at once:
@@ -17,13 +19,15 @@ The binary does three things at once:
 - Serves a multipart upload API at `POST /upload`
 - In dev mode (`--serve`), also serves `public/` as static files
 
-In production nginx sits in front: serves `public/` directly, proxies `/upload` to localhost, htpasswd on the upload endpoint.
+Routes: `GET /upload` (HTML upload form), `POST /upload` (multipart), `GET /health`.
+
+In production nginx sits in front: serves `public/` directly, proxies `/upload` to localhost, htpasswd on the upload endpoint. Note `/health` is **not** proxied — nginx only forwards `location /upload`, so anything outside the box can only reach `/upload`.
 
 ## Stack
 
 - **Go** — stdlib + `BurntSushi/toml`, `fsnotify/fsnotify`, `golang.org/x/image`
 - **Templates** — `html/template`, embedded via `embed.FS`
-- **Images** — centre-crop to square, Catmull-Rom resize to 600×600 JPEG thumbnails
+- **Images** — three renditions per photo: original copy, 600×600 centre-cropped square thumbnail, and a 1600px-longest-side "medium" for the detail page. Catmull-Rom resize. Outputs are skipped when newer than the source.
 - **Feed** — Atom (`encoding/xml`)
 - **NixOS** — `flake.nix` + `module.nix`, exports `nixosModules.default`
 
@@ -34,15 +38,36 @@ caption = "Tempelhof at sunrise"
 date    = "2026-06-14"
 ```
 
-Missing sidecar → filename as caption, today as date.
+Missing sidecar → filename as caption, today as date. Photos sort newest first by that date.
 
 ## Design
 
 - Gruvbox dark hard colour scheme
-- Vollkorn (serif) for headings and captions
-- Manjari for Malayalam text (bio line)
-- 3-column square grid → 2-column on mobile
-- Single photo page with sidebar
+- Crimson Pro (serif) for headings and captions — configurable via `-serif-family` / `-fonts-url`
+- Manjari for Malayalam text (bio line), via `-ml-family`
+- 3-column square grid → 2-column on mobile, 60 photos per page (`/`, `/page/2/`, …)
+- Single photo page with sidebar and newer/older navigation
+
+### Photo page navigation
+
+`static/photo-nav.js` handles arrow keys and touch swipe. Both read their
+destinations from the `[data-nav="newer"]` / `[data-nav="older"]` anchors the
+template renders, so a photo with no sibling in that direction has nothing to
+find and the gesture rubber-bands. If the script fails to load the links still
+work.
+
+Swipe left → older, right → newer, matching ArrowRight/ArrowLeft. Constraints
+worth knowing before touching it:
+
+- Swipes starting within 24px of a screen edge are ignored — that strip is the browser's own back-gesture.
+- Only `pointerType === "touch"`, so desktop drag-to-save is untouched.
+- Axis locks once after 10px so vertical drags stay scrolls; `touch-action: pan-y` tells the compositor the same.
+- The image is wrapped in an `<a>` to the full-size original, so the click trailing a swipe is suppressed or it opens a new tab.
+- `EXIT_MS` in the JS must stay in sync with the transition duration in `style.css`.
+
+Anything added under `static/` is embedded and copied to `public/static/`
+automatically — `assets.go` embeds the whole directory and `copyStatic()` walks
+every entry, so new CSS/JS needs no generator change.
 
 ## Running locally
 
@@ -54,6 +79,20 @@ go run . --serve
 # upload:  http://localhost:8080/upload
 ```
 
+## Android app
+
+Kotlin + Jetpack Compose uploader: pick or share a photo, add caption and date, post. Credentials (HTTP Basic) are sealed with an Android Keystore AES-GCM key. See `android/README.md` for the detail.
+
+Its own flake, deliberately separate from the root one so NixOS consumers of `nixosModules.default` don't pull the Android SDK into their lock:
+
+```bash
+cd android
+nix develop
+./gradlew assembleRelease   # app/build/outputs/apk/release/app-release.apk
+```
+
+The server needs no changes to serve it — every gap (slug collisions, EXIF, HEIC, size caps) is closed client-side. Release builds need `android/keystore.properties`; without it the signing config is skipped and only debug builds work.
+
 ## NixOS module usage
 
 ```nix
@@ -86,12 +125,19 @@ nix build          # succeeds
 | File | Purpose |
 |---|---|
 | `main.go` | Flags, wires generator + watcher + server |
-| `generator.go` | Scans content dir, renders HTML + Atom feed, generates thumbs |
+| `generator.go` | Scans content dir, renders HTML + Atom feed, generates thumbs/mediums |
 | `server.go` | Upload API + optional static file serving |
 | `watcher.go` | fsnotify watcher with 500ms debounce |
 | `assets.go` | `//go:embed` for templates and static |
+| `templates/photo.html` | Single photo page, neighbour links and prefetch |
+| `static/photo-nav.js` | Arrow-key and swipe navigation |
 | `module.nix` | NixOS module (systemd service, tmpfiles, nginx vhost) |
 | `flake.nix` | `buildGoModule` package + devShell + nixosModules |
+| `android/flake.nix` | Android SDK dev shell (separate from the root flake) |
+
+## Gotchas
+
+- `.gitignore` patterns here must be anchored. An unanchored `photogallery` also matches the Kotlin package directory `android/app/src/main/java/ws/inflo/photogallery/` and silently swallows every source file in it.
 
 ## What's not done yet
 
@@ -99,3 +145,5 @@ nix build          # succeeds
 - Multi-image upload
 - Delete/edit via UI
 - Any auth beyond nginx htpasswd
+- The Android app has never been run on real hardware
+- Photo-page swipe has never been tested on a real touchscreen; the iOS Safari edge-gesture interaction is the untested part