cherry-studio/docs/en/references/data/v2-migration-guide.md

Migration V2 (Main Process)

Architecture for the new one-shot migration from the legacy Dexie + Redux Persist stores into the SQLite schema. This module owns orchestration, data access helpers, migrator plugins, and IPC entry points used by the renderer migration window.

Directory Layout

src/main/data/migration/v2/
├── core/              # Engine + shared context
├── migrators/         # Domain-specific migrators and mappings
├── utils/             # Data source readers (Redux, Dexie, streaming JSON)
├── window/            # IPC handlers + migration window manager
└── index.ts           # Public exports for main process

Core Contracts

• core/MigrationEngine.ts coordinates all migrators in order, surfaces progress to the UI, and marks status in app_state.key = 'migration_v2_status'. It will clear new-schema tables before running and abort on any validation failure.
• core/MigrationContext.ts builds the shared context passed to every migrator:
  • sources: ConfigManager (ElectronStore), ReduxStateReader (parsed Redux Persist data), DexieFileReader (JSON exports)
  • db: current SQLite connection
  • sharedData: Map for passing cross-cutting info between migrators
  • logger: loggerService scoped to migration
• @shared/data/migration/v2/types defines stages, results, and validation stats used across main and renderer.

Migrators

• Base contract: extend migrators/BaseMigrator.ts and implement:
  • id, name, description, order (lower runs first)
  • prepare(ctx): dry-run checks, counts, and staging data; return PrepareResult
  • execute(ctx): perform inserts/updates; manage your own transactions; report progress via reportProgress
  • validate(ctx): verify counts and integrity; return ValidateResult with stats (sourceCount, targetCount, skippedCount) and any errors
• Registration: list migrators (in order) in migrators/index.ts so the engine can sort and run them.
• Current migrators (see migrators/README-<name>.md for detailed documentation):
  • PreferencesMigrator (implemented): maps ElectronStore + Redux settings to the preference table using mappings/PreferencesMappings.ts.
  • ChatMigrator (implemented): migrates topics and messages from Dexie to SQLite. See README-ChatMigrator.md.
  • AssistantMigrator, KnowledgeMigrator (placeholders): scaffolding and TODO notes for future tables.
• Conventions:
  • All logging goes through loggerService with a migrator-specific context.
  • Use MigrationContext.sources instead of accessing raw files/stores directly.
  • Use sharedData to pass IDs or lookup tables between migrators (e.g., assistant -> chat references) instead of re-reading sources.
  • Stream large Dexie exports (JSONStreamReader) and batch inserts to avoid memory spikes.
  • Count validation is mandatory; engine will fail the run if targetCount < sourceCount - skippedCount or if ValidateResult.errors is non-empty.
  • Keep migrations idempotent per run—engine clears target tables before it starts, but each migrator should tolerate retries within the same run.

Utilities

• utils/ReduxStateReader.ts: safe accessor for categorized Redux Persist data with dot-path lookup.
• utils/DexieFileReader.ts: reads exported Dexie JSON tables; can stream large tables.
• utils/JSONStreamReader.ts: streaming reader with batching, counting, and sampling helpers for very large arrays.

Window & IPC Integration

• window/MigrationIpcHandler.ts exposes IPC channels for the migration UI:
  • Receives Redux data and Dexie export path, starts the engine, and streams progress back to renderer.
  • Manages backup flow (dialogs via BackupManager) and retry/cancel/restart actions.
• window/MigrationWindowManager.ts creates the frameless migration window, handles lifecycle, and relaunch instructions after completion in production.

Implementation Checklist for New Migrators

• Add mapping definitions (if needed) under migrators/mappings/.
• Implement prepare/execute/validate with explicit counts, batch inserts, and integrity checks.
• Wire progress updates through reportProgress so UI shows per-migrator progress.
• Register the migrator in migrators/index.ts with the correct order.
• Add any new target tables to MigrationEngine.verifyAndClearNewTables once those tables exist.
• Include detailed comments for maintainability (file-level, function-level, logic blocks).
• Create/update migrators/README-<MigratorName>.md with detailed documentation including:
  • Data sources and target tables
  • Key transformations
  • Field mappings (source → target)
  • Dropped fields and rationale
  • Code quality notes