Summary

Add a deterministic offline integration test covering the complete wallet creation and SQLite persistence lifecycle.

The repository has constructor-focused wallet tests, fixture-based persistence tests, and broad sync canaries. It does not have a focused test that creates a wallet against a fresh SQLite database, persists newly revealed derivation state, fully reopens the wallet, and verifies that state was retained.

Scope

• Add a focused test under test/integration.
• Create deterministic receive and change descriptors.
• Create a wallet using a fresh temporary SQLite database.
• Reveal external and internal addresses and persist the wallet.
• Dispose the original wallet and persister before reopening the database.
• Reload the wallet with a new persister.
• Verify the network, zero balance, address scripts, and derivation indexes survive the reopen.
• Clean up temporary SQLite files reliably across supported platforms.
• Run offline in the normal test suite without environment variables.

Out of scope

• Electrum or Esplora synchronization.
• Changes to production wallet APIs.
• Demo app behavior or UI tests.
• New test-only dependencies.

Acceptance criteria

• A wallet is created against a previously nonexistent SQLite path.
• External and internal derivation state is persisted and restored.
• The original wallet and persister are disposed before reload.
• Assertions are deterministic and do not depend on a live network.
• Temporary resources are cleaned up on macOS, Linux, and Windows.
• The focused test and the complete Dart test suite pass.