QML Snapshot Load

[D33r-Gee]

This is an re-opened PR based on #424 and #449. It's an alternate to #485 that uses a different /bitcoin branch instead of a patch.

UTXO Snapshot Loading

Overview

This PR enables loading UTXO snapshots both during and after the initial onboarding process.

What This PR Does

1. Adds a basic GUI interface for loading UTXO snapshots via the Connection Settings panel
2. Enables snapshot selection during onboarding, with loading when headers are synced
3. Implements non-blocking snapshot loading via QT Thread
4. Provides visual confirmation of snapshot activation
5. Adds a snapshot progress notifications accessible via a handler

Implementation Details

Core Components Modified

1. CPP Backend (qml/models/nodemodel.cpp)

• Manages snapshot loading state and progress
• Uses Qt's thread system to prevent UI blocking
• Provides progress updates via Qt signals
• Adds support for storing snapshot file path during onboarding
• Implements automatic snapshot loading once headers are synced

2. UI Components (qml/components/SnapshotLoadSettings.qml, src/qml/components/ConnectionSettings.qml)

• File selection dialog with onboarding awareness
• Snapshot verification status
• Progress tracking and visualization
• Updated visibility conditions to enable loading during onboarding

3. Snapshot Qml Model (qml/models/snapshotqml.cpp)

• Introduces a worker class to manage snapshot metadata

Key Design Decisions

1. Onboarding Integration

• Allows users to select snapshot during setup
• Delayed loading until headers are synced
• Proper state handling between onboarding and regular modes

Testing Instructions

1. Build
2. Launch Bitcoin Core QML GUI
3. Navigate to Connection Settings
4. Test with different snapshots:

mainnet: magnet:?xt=urn:btih:559bd78170502971e15e97d7572e4c824f033492&dn=utxo-880000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969

alternatively, you can use the following link to download the mainnet snapshot: https://bitcoin-snapshots.jaonoctus.dev/

signet: https://drive.google.com/file/d/1VJeeGQncrs4xZhh6kU5IwkyatXVM4SOm/view?usp=sharing

7. Test onboarding flow:

   • Select a snapshot file during initial setup
   • Verify it loads automatically after headers sync

8. Verify (see screenshots below):

   • "Snapshot Loaded" confirmation appears
   • For errors, check debug.log for [snapshot]

Ubuntu 22.04 Screenshots

Expected Behavior

• File selection dialog works
• Node becomes usable while background validation continues
• When selected during onboarding, snapshot loads after headers sync

Success/failure state properly displayed

feedback welcome on the approach and implementation details.