[Core] 8 - Verify migrations and backup restore

[KacperKozak]

What to build

Create shared upgrade fixtures for every production-supported DB upgrade path and verify real Android-to-iOS and iOS-to-Android backup/restore behavior. Derive supported versions from current migration and restore contracts.

Part 8 of the approved cross-platform persistence reliability plan. Android and iOS remain separate native implementations with shared observable contracts. Local planning document: docs/persistence-reliability-plan.md; this issue is self-contained. Type: AFK.

Likely files

• modules/vescape-core/ios/telemetry/DatabaseBackupManager.swift - production behavior or caller to inspect
• modules/vescape-core/ios/telemetry/TelemetryMigrationTests.swift - existing verification seam
• modules/vescape-core/android/src/main/java/expo/modules/vescapecore/telemetry/DatabaseBackupManager.kt - production behavior or caller to inspect
• modules/vescape-core/android/src/test/java/expo/modules/vescapecore/telemetry/TelemetryBoardIdMigrationTest.kt - existing verification seam
• modules/vescape-core/ios/telemetry/TelemetryDatabase.swift - production behavior or caller to inspect

Implementation hints

Keep Room on Android and GRDB on iOS. Native owns durable truth; JS renders state and sends intents. Follow bidirectional @parity links and preserve bridge payloads. Custom SQL is allowed for migrations and aggregate updates with real DB tests. Use existing error UI and avoid a generic persistence/recovery framework. Diagnostics transport follows ADR 0031; Sentry handles errors independently of local event persistence. Use bun commands and appropriate scoped verification.

Acceptance criteria

• Real migrations preserve expected rides, Boards, settings, Favorites and other durable values across both runners.
• Exercise actual backup/restore validation and migrations, including both cross-platform directions, not just queries on prepared final schemas.
• Invalid/unsupported restores fail explicitly without replacing valid current data; no new support cutoff or automatic destructive reset.
• Keep raw schema and driver differences explicit; fixture coverage catches missing platform migration implementations.

Blocked by

• [Core] 7 - Cover remaining persistence contracts #467

Related

• [Core] 1 - Test recording across hosts #461
• [Core] 2 - Surface recording storage failures #462
• [Core] 3 - Protect Board and settings saves #463
• [Core] 4 - Protect Favorite storage operations #464
• [Core] 5 - Protect Tune and alert storage #465
• [Core] 6 - Surface history read failures #466
• [Core] 7 - Cover remaining persistence contracts #467
• [Core] 9 - Gate releases on storage contracts #469

[KacperKozak]

Implemented in 463580b on persistence-reliability.