mirror of
https://github.com/kuhyx/todo-app.git
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Krzysztof kuhy Rudnicki
80e86157ee
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019KwUCPESvE5CjCtmUFz8xQ
45 lines
2.2 KiB
Markdown
45 lines
2.2 KiB
Markdown
# Migration: `sqlite_crdt` → shared `crdt_sync`
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todo's note storage and sync were moved off `sqlite_crdt` onto the shared
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[`crdt_sync`](https://github.com/kuhyx/utils/tree/main/crdt_sync_dart) library
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(pinned tag `crdt_sync_dart-v0.3.0`), so every companion app now syncs through
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one library.
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## What changed
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- **Storage:** `NoteRepository` is backed by `crdt_sync`'s `LogStore` (a
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`Log = Map<String, Record>` persisted as JSON). Each `Note` is stored *as* a
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`Record` (per-field last-writer-wins + a sticky tombstone), so the on-disk
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log **is** the sync wire format — no separate adapter. Filtering/sorting run
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in Dart over the in-memory log.
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- **Sync:** `SyncService` pushes each device's `Log` to
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`todo-sync/notes/<nodeId>.json` in `kuhyx/syncs` (new dir; the old
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`changesets/` format is incompatible, so it's a clean cutover). It uses
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`crdt_sync`'s `GitHubClient` + `logToJson`/`logFromJson`.
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- **Client:** todo's local `lib/sync/github_client.dart` was deleted; it now
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uses `crdt_sync`'s `GitHubClient` (which gained `canAccessRepo()` +
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`deleteFile()` in v0.3.0). `putFileText` self-resolves the file sha, so the
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old SHA-tracking is gone.
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## The one-time on-device migration
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`NoteRepository.open()` migrates a pre-existing `sqlite_crdt` DB into the log on
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first launch, guarded by a persisted `crdt.migratedFromSqlite` flag. Verified
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on-device: a real 27-note backlog (+5 tombstones) migrated intact.
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`sqlite_crdt` is **retained as a dependency** only to read that legacy DB during
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migration — the old `todo.db` is left untouched as a safety net. Remove the dep
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in a later cleanup once every device is known-migrated.
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## Surprises / non-obvious decisions
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- **Seed HLCs from each note's `updatedAt`, not "now".** Two devices migrate
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independently; stamping migration-time "now" would let per-field LWW resolve
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a pre-cutover edit arbitrarily. Seeding from `updatedAt` keeps
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last-real-edit-wins across the cutover.
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- **Reuse the legacy `sqlite_crdt` node id** (persisted in prefs) so a device
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keeps its `devices/<id>` identity and devices still converge.
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- **`watchNotes`/`watchCount` seed in `onListen`**, not lazily in an `async*`
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body — otherwise a write between `listen()` and the first generator tick
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swallows the initial snapshot.
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