app/libs/Peergos.jar is not checked in. It is built from the web-ui submodule, which in turn builds the peergos submodule nested inside it, and then stripped of the entries Android can't use (see prepare-jar.sh).

A normal build produces it automatically, so a fresh clone only needs:

./gradlew assembleDebug

To drive it explicitly:

./gradlew peergosJar        # build it from the commit web-ui is pinned to
./gradlew updatePeergosJar  # fast-forward web-ui to upstream first, then rebuild
./gradlew initWebUi         # just check out the submodules
./gradlew updateWebUi       # just fast-forward web-ui to upstream

The jar records the web-ui commit it came from in its manifest, so the slow ant build is skipped whenever the existing jar already matches the submodule's HEAD. After updatePeergosJar, commit the new web-ui submodule pointer.

ant, and a JDK 25 or newer for the server build (it needs the final java.lang.foreign API) - separate from the JDK 21 Gradle and AGP run on. Gradle finds it automatically if it is in a standard location; otherwise point at it with -Ppeergos.jdk=/path/to/jdk or PEERGOS_JDK in the environment.