diff --git a/README.md b/README.md
index fc1c11d..6b339d8 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,10 @@ Backgammon Galaxy control. Defaults to 3:00 + 12s.
 
 Plain HTML, CSS and JavaScript. No frameworks, no fonts, no images, no network.
 
+There's an Android package too, in `android/` — a WebView around the same
+`public_html/`, so the two can't drift. It declares no permissions at all. See
+[RELEASING.md](RELEASING.md) for how to cut a new version for F-Droid.
+
 ## Getting it onto your phone
 
 Chrome will only offer a real install over HTTPS, so the file needs a host.
diff --git a/RELEASING.md b/RELEASING.md
new file mode 100644
index 0000000..4b4587d
--- /dev/null
+++ b/RELEASING.md
@@ -0,0 +1,116 @@
+# Releasing a new version
+
+The clock lives in two places: the web app in `public_html/`, which you host
+yourself, and the Android app on F-Droid, which is built from a git tag.
+
+**Everything F-Droid needs comes from a tag in this repository.** After the first
+release was accepted there is nothing to do in F-Droid's own repo — their bot
+watches the tags here and writes the build entry itself. Don't open a merge
+request against `fdroiddata` for a new version.
+
+Worked example below bumps 1.0 to 1.1. Substitute your own numbers.
+
+## 1. Make the change
+
+Both versions share one copy of the app. Edit `public_html/index.html` and the
+Android build picks it up automatically — the Gradle build reads `public_html/`
+directly rather than keeping a second copy, so the two can't drift.
+
+If you changed anything visible, bump the service worker cache or installed web
+users will keep the old page:
+
+```
+# public_html/sw.js
+const CACHE = "bgclock-v18";     # any new value; it only has to differ
+```
+
+## 2. Bump the version
+
+In `android/app/build.gradle.kts`:
+
+```kotlin
+versionCode = 2          // an integer, +1 every release, never reused
+versionName = "1.1"      // what people see
+```
+
+`versionCode` is what Android uses to decide one version is newer than another.
+It must go up every single release, even for a one-character fix.
+
+## 3. Write the changelog
+
+A new file named after the **versionCode**, not the version name:
+
+```
+fastlane/metadata/android/en-US/changelogs/2.txt
+```
+
+Maximum 500 characters. This is what shows up in F-Droid's "What's New".
+
+## 4. Build it and put it on your phone
+
+```bash
+export ANDROID_HOME="$HOME/Android/Sdk"     # already in ~/.bashrc
+cd android
+./gradlew assembleDebug
+adb install -r app/build/outputs/apk/debug/app-debug.apk
+./gradlew --stop                            # the daemon holds ~500 MB otherwise
+```
+
+Play a real game before tagging. Worth checking specifically: start a match,
+make some moves, force-quit from the task switcher and reopen — everything
+should come back, paused. That is the check that proves the app's storage is
+working, and it fails silently rather than loudly.
+
+## 5. Commit, tag, push
+
+```bash
+git add -A
+git commit -m "…"
+git tag -a v1.1 -m "Backgammon Clock 1.1"
+git push
+git push origin v1.1
+```
+
+**The tag must keep the `v` prefix.** F-Droid's `checkupdates` takes the tag name
+verbatim as the commit to build, so `v1.1` here means `commit: v1.1` in their
+metadata. A tag named `1.1` would break the automation.
+
+Never move or delete a tag that has been pushed — F-Droid may already have built
+it. If a release is wrong, bump the version and release again.
+
+## 6. Wait
+
+Their bot notices the new tag, adds a build entry, and the build server picks it
+up on its next cycle. Expect a day or two. Nothing to do.
+
+## Deploying the web version
+
+Separate from all of the above, and manual: upload the six files in
+`public_html/` — `index.html`, `manifest.webmanifest`, `sw.js`, `icon-192.png`,
+`icon-512.png`, `icon-maskable-512.png` — to the web host. `README.md` and
+`RELEASING.md` stay out of it; they live in the repo root for that reason.
+
+## If the screenshots need redoing
+
+`fastlane/metadata/android/en-US/images/phoneScreenshots/` holds five shots at
+1170×2532. They are generated from `public_html/index.html` itself with headless
+Chromium, not taken on a phone, so they can be regenerated exactly. Two traps if
+you do it by hand:
+
+- The capture lands whenever the virtual-time budget runs out, not when your
+  script finishes — so freeze the render loop (`requestAnimationFrame = () => 0`)
+  once the frame you want is on screen.
+- CSS transitions don't advance under `--virtual-time-budget`, so a panel caught
+  mid-transition photographs in its *old* colour. Disable transitions in the
+  screenshot build.
+
+## Reference
+
+- App ID: `nl.hansdezwart.bgclock` — fixed forever; changing it makes a new app.
+- F-Droid listing text: `fastlane/metadata/android/en-US/` (title ≤50 chars,
+  summary ≤80, description ≤4000, changelog ≤500). Only these HTML tags work in
+  the description: `b big blockquote br cite em i li ol small strike strong sub
+  sup tt u ul`.
+- The original submission: https://gitlab.com/fdroid/fdroiddata/-/merge_requests/45478
+- F-Droid signs the APK with their key, not yours. Reproducible builds were
+  declined at submission and can't be enabled later for this app ID.