Everything an app needs to move from GitHub to Firebase without each one
reinventing the wiring.
Python:
- _config.py: FirebaseConfig.load() + firebase_client_for(app) +
mirror_client_for(app, github). One config file, read in one place.
Credential caches stay per-app (~/.config/<app>/firebase_auth.json) --
one file written by several processes is a corruption waiting to happen.
- tool/preflight_firebase.py: validates the config before any data moves.
Catches a wrong-region databaseUrl (which answers 404 with a correctUrl
body rather than an error, so it would otherwise pass every check and
break mid-migration) and confirms the uid in the ID token matches the uid
the rules pin -- sign_in() returns None and discards localId, so the uid
is decoded from the JWT.
- tool/interop_seed.py: the missing Python half of the cross-language
check. interop_check.dart asserts it can see a record written by Python,
but nothing ever wrote one, so it could only ever fail.
Dart:
- firebase_config.dart: the same config shape, kept free of dart:io so it
works on web and Android, where the file does not exist at all and
credentials belong in flutter_secure_storage.
- PersistedSyncStateStore: the revision cache, persisted. Without it a
phone forgets every peer revision on each cold start and re-downloads
everything -- the exact traffic the revision scheme exists to avoid, and
what the free-tier headroom depends on.
Verified live against the real database: preflight passes all five checks,
the Dart smoke test passes end to end, and Python <-> Dart interop is OK.
Python 226 tests at 100% branch coverage; Dart 218 tests, both new files
at 100% line coverage.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SJ9sxEw3ymzXNjL7SHNpJc
