database.rules.json carries YOUR_FIREBASE_UID on purpose -- this repo is
public and the uid is the one value that must not be in it. But nothing
stopped anyone publishing the template as-is, and rules pinned to a uid that
matches no account deny every read and write. The symptom is every device
failing at once with a bare permission error, which reads like an outage
rather than a bad paste.
render_rules.sh substitutes the uid from ~/.config/crdt-sync/firebase.json
and fails closed on anything unsafe: a surviving placeholder, missing
`auth != null`, a missing uid pin (that one matters -- `auth != null` alone
lets any stranger who self-registers through the public Web API key read
everything), or output that is not JSON.
Verified: its output is byte-identical to the deployed
~/.config/crdt-sync/database.rules.json, and the live database still answers
an unauthenticated read with 401. All three failure paths exercised.
Also corrects the README, which described the in-repo copy as "the deployed
rules, with the real uid filled in" -- it never was.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CFSGeWxHPY5rHUGrPqhcmG
Extracts the three-method remote surface GitHub was reached through into a
`RemoteStore` interface, then implements it against Firebase Realtime
Database over REST, so apps can move backend with a constructor change.
Why REST and not the SDKs: official FlutterFire has no Linux desktop
support, and `wake_alarm`'s PC side is a dependency-free systemd job. The
RTDB REST endpoints are plain HTTPS and behave identically on Linux,
Android and headless. Firebase is a transport, never the datastore -- each
app keeps its local log as the source of truth, so offline-first survives.
Why RTDB and not Firestore: on the Spark plan RTDB bills only storage and
bandwidth with no per-operation quota, so a runaway loop cannot exhaust a
daily budget and silently stop syncing mid-day.
Two savings make the no-cost tier a guarantee rather than a hope. Measured
against the GitHub-backed history this replaces: 4894 of 5542 commits
(88.3%) were byte-identical no-ops, and every tick re-downloaded every
peer's whole log. Both are now driven by one sha256 revision -- an
unchanged log is not re-pushed, and an unchanged peer is not re-fetched.
That turns egress from "ticks x log size" (~700 MB/month, and growing with
the log) into "edits" (~40 MB/month against a 10 GiB cap).
Revisions are one node per device, written only by its owner, rather than
one shared map -- a whole-map write would erase every peer's entry, after
which those peers would look permanently unchanged and never be fetched
again. Per-device keys make that impossible rather than merely avoided.
`.` is illegal in an RTDB key and the REST `.json` is a format suffix, so
paths get a reversible `~XX` escape (`log.json` -> `log~2Ejson`). Lossy
extension-stripping would break `todo`, whose listings return filenames.
`MirrorStore` / `MirrorSyncClient` dual-writes during the cutover. Reads
consult *both* backends: with primary-only reads a migrated device would
never see an un-migrated peer's writes while still mirroring its own back
-- silent one-directional convergence with no error raised. Writes are
asymmetric on purpose: a primary failure fails the tick, a mirror failure
is logged and survived.
Auth is Firebase email/password over identitytoolkit REST, with mandatory
refresh-token rotation. No service-account key anywhere: it would bypass
the security rules and is trivially extractable from an APK.
Verified live against a real database, not only mocks: sign-in and refresh,
key escaping round-tripping byte-for-byte, an unchanged tick writing
nothing, two devices converging, a revoked session throwing rather than
returning null, and a log written by the Python client being read by the
Dart one.
No app is migrated by this commit; every app still runs on GitHub.
Dart: 194 tests. Python: 203 tests at 100% branch coverage. No lint
suppressions added.
