supabase / supabase-flutter / 36978546799

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fix(supabase): replace an already streamed row on a realtime insert (#1908)

Fixes
[SDK-2000](https://linear.app/supabase/issue/SDK-2000/stream-builder-duplicates-rows-when-an-insert-lands-just-after-a).

`stream(primaryKey:)` appended every realtime insert without checking
the primary key. After a reconnect, the stream refetches the rows over
PostgREST. When a row is inserted around that time, the refetch can
already return it before its insert event arrives, and the event then
added the row a second time. The database has one row, but the stream
shows two until the next refetch.

This showed up in the flutter-chat example while adding attachments
(https://github.com/supabase-community/flutter-chat/pull/17). The file
picker sends the app to the background, and the message is inserted a
few seconds after the resume, so the sender saw every file message
twice.

An insert is now handled like an update: it replaces the row with the
same primary key, and is appended when there is none.

## Testing

- New `test/stream_insert_test.dart` built on `MockRealtimeTransport`
and `MockSupabaseHttpClient`. An insert event for a row the fetch
already returned now leaves one copy, and failed with two copies before
the fix. An insert of a new row is still appended.
- `stream_integration_test.dart` passes against the local stack, along
with `mock_test.dart`, `stream_filter_test.dart` and
`typed_table_schema_test.dart`.
- `dart analyze` and `dcm analyze` find no issues.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Prevented duplicate rows in streamed data when an insert arrives after
a reconnect refetch. Matching rows are now updated, while inserts with
new IDs are added as usual.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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