Our upload keystore is PKCS12 (verified from its DER header, 0x30 0x82 —
JKS would start 0xFEEDFEED). That format has nowhere to store a key password
distinct from the store password, and keytool enforces the two being equal,
so requiring a separate OSTP_KEY_PASSWORD meant configuring a secret whose
only possible correct value was a copy of another one.
Falls back to the store password when unset; an explicit value still takes
precedence for the legacy JKS format, where the two can genuinely differ.
Published APKs could never be updated over - users hit "App not installed" or
"unable to parse the package" and had to uninstall first. The cause was not the
version code (verified: local.properties carries flutter.versionCode=23 and
gha.ps1 bumps pubspec's build number every release, so it increments correctly).
It was the signing key: app/build.gradle.kts still had the stock Flutter
template TODO and pointed the release build type at signingConfigs["debug"].
Android identifies an app by applicationId + signing key and refuses to update
across a key change, and the debug keystore is generated per machine - on
ephemeral CI runners that means every single published build was signed with a
different random key.
Release builds now take their key from android/key.properties or the
OSTP_KEYSTORE_* environment variables, falling back to debug (with a loud
warning) only so local `flutter build apk --release` keeps working. CI
materialises the keystore from repository secrets, refuses to build at all if
the secret is absent, and re-verifies the finished APK is not debug-signed
rather than ever shipping an un-updatable build again.
NOTE: existing installs are signed with a now-unreproducible random key, so
users must uninstall once more for THIS release. Every update after it works.