Build number is present and incremented for each release

Both Apple and Google reject any binary whose build identifier is missing, non-integer, or less-than-or-equal to a previously shipped build for the same version string — the upload fails with ITMS-90062 on iOS or a duplicate-versionCode error on Play Console, blocking the release outright. Without a monotonically incrementing build number, TestFlight cannot route the correct artifact to internal testers, Play Console staged rollouts lose their ordering, and crash reports merge across builds so regressions become untraceable. This is an operational tripwire that delays launches by hours every time it fires.

Declare ios.buildNumber as a string and android.versionCode as an integer in app.json, then automate monotonic increments in CI so human error never ships a duplicate. Store the last-shipped build in a lockfile or release-notes table and fail the build if the new value does not exceed it.

// app.json
{
  "expo": {
    "version": "1.0.3",
    "ios": { "buildNumber": "42" },
    "android": { "versionCode": 42 }
  }
}