An entire module was missing from the APK. The app died with
ClassNotFoundException for app.echo_lot.protocol.EnrollmentLink while the
build was green, the module's jar was correct, and :app:dependencies
listed it on debugRuntimeClasspath — its code simply never reached AGP's
intermediates.
The cause was a poisoned Gradle build cache entry, which is why nothing
obvious fixed it: clean, rm -rf */build and --rerun-tasks all leave the
build cache alone. Only --no-build-cache did. Every app build made in this
session shipped without core-protocol, so enrolment, sign-in and upload
would all have crashed identically; several hours of "the tap does
nothing" were this, misread as a UI problem.
CLAUDE.md now carries the symptom, the fix, and the verification —
grepping the dex for a string literal only that module defines, because
grepping for a class *name* proves nothing: callers carry the name as a
reference whether or not the class is packaged. That false check is what
let me believe an earlier rebuild had fixed it.
Also: the enrolment dialog compared the stored endpoint against the link's
public URL, so re-enrolling with the same server announced itself as a
move to a different one. Those are deliberately different strings now that
discovery exists; the comparison uses the public name on both sides.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
