[DRAFT] Expose AssumeUTXO Load Snapshot Functionality To The GUI

[D33r-Gee]

based on the QML PR 424. For evaluation purposes only!

GUI Integration for UTXO Snapshot Loading

Overview

This PR adds initial GUI support for loading a UTXO snapshot, building on Bitcoin Core's assumeutxo infrastructure.

What This PR Does

1. Adds a basic GUI interface for loading UTXO snapshots via the Options Dialog panel
2. Provides visual confirmation of snapshot activation
3. Adds a snapshot progress notification bar accessible via a handler

Implementation Details

Core Components Modified

1. Node Interface (src/node/interfaces.cpp)

• Implements snapshotLoad() based on the loadtxoutset RPC

2. QT Integration (src/qt/optionsdialog.cpp)

• Manages snapshot loading state and progress
• makes use of a worker class to manage snapshot metadata (src/qt/snapshotmodel.cpp)
• Provides progress updates via a progress bar

Key Design Decisions

2. Extensibility

• Interface designed to accommodate future assumeutxo changes
• Error handling framework in place

Testing Instructions

1. Build
2. Launch Bitcoin Core GUI (bitcoin-qt)
3. Navigate to Settings -> Options
4. Click Load Snapshot button
5. Follow pop-up instructions
6. Test with sample snapshot:

https://bitcoin-snapshots.jaonoctus.dev/ (No affiliation with the maintainer of this site. As always "Don't trust! Verify!")

POC Ubuntu Screenshots `signet`

Launch bitcoin-qt on signet

Navigate to Settings -> Options

Click the "Load Snapshot..." button

Navigate to where your snapshot file is. The snapshot was downloaded from here

Click "Yes"

Wait for the snapshot to load and for this pop-up to appear and click "Ok"

Verify the "chain_snapshot" directory is present in your datadir

Expected Behavior

• File selection dialog works
• Success/failure state properly displayed
• Node becomes usable while background validation continues

Notes for Reviewers

• This is a POC so all feedback is welcomed
• I am not a designer so please feel free to chime in if there's a more elegant way to achieve this

This is a work in progress - feedback welcome on the approach and implementation details.

[DrahtBot]

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Reviews

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Type	Reviewers
Concept ACK	Sjors

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #bitcoin/bitcoin/34495 (Replace boost signals with minimal compatible implementation by theuni)
• #bitcoin/bitcoin/34038 (logging: replace -loglevel with -trace, various API improvements by ajtowns)
• #bitcoin/bitcoin/33117 (Interfaces: Expose UTXO Snapshot Loading and Add Progress Notifications by D33r-Gee)
• #bitcoin/bitcoin/32297 (bitcoin-cli: Add -ipcconnect option by ryanofsky)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

LLM Linter (✨ experimental)

Possible places where named args for integral literals may be used (e.g. func(x, /*named_arg=*/0) in C++, and func(x, named_arg=0) in Python):

• QProgressDialog(tr("Loading snapshot..."), tr("Cancel"), 0, 100, this) in src/qt/optionsdialog.cpp

^{2026-02-25 17:47:14}

[D33r-Gee]

friendly ping @Sjors

[Sjors]

Concept ACK

Although I'm not sure how much effort we should put into maintaining the current GUI codebase (if it's going to be replaced with QML eventually), this particular feature is high on my wish list. And the code changes here seem very simple. So I'm happy to test and review it.

---

The first commit which touches the node interface should eventually be PR'd to bitcoin/bitcoin. But let's wait with that until this PR has enough concept ACK and some initial review.

[luke-jr]

Seems like this would be more appropriate for the first-run intro page?

[D33r-Gee]

Seems like this would be more appropriate for the first-run intro page?

yep that's a great idea! I will update soon.

[Sjors]

I'm a bit confused about the relation between this and bitcoin/bitcoin#33117. I would suggest rebasing 60f676a on that branch for clarity.

---

Managed to load the most recent testnet4 snapshot at height 90,000! (after I rebased)

The file dialog was a bit unresponsive, but that's fine since this is just PoC. I like the progress bar.

[D33r-Gee]

I'm a bit confused about the relation between this and bitcoin/bitcoin#33117. I would suggest rebasing 60f676a on that branch for clarity.

Will rebase shortly with the changes from bitcoin/bitcoin#33117

Managed to load the most recent testnet4 snapshot at height 90,000! (after I rebased)

WooHoo!

The file dialog was a bit unresponsive, but that's fine since this is just PoC. I like the progress bar.

Hmmm... will look into that... does the dialog hang?

[Sjors]

The dialog wouldn't respond to me clicking on a file or folder. But then after a minute or so it worked again.

[D33r-Gee]

With 82a3969 it updates the interface methods to match bitcoin/bitcoin#33117
It also adds a load snapshot button during the intro and seamless loading if a proper path has been selected (from @luke-jr suggestion)
Also adds the use of threads to make sure there's no hanging or UI blocking when the load snapshot button is used in the options dialog (hopefully addressing @Sjors experience).
looking for any feedback on the approach and code implementation.

[D33r-Gee]

With 6e5582f updated the validation section of the snapshot load progress notification to batch progress updates for every 100,000 coins processed (and upon completion).

This optimization reduces the overhead of signaling the GUI on every single coin while ensuring the interface remains responsive and provides smooth feedback during the UTXO snapshot population process.

Additionally, I've rebased the branch on upstream/master and resolved the conflicts in

src/qt/bitcoin.cpp