Claude/investigate digibyte issue - Fix: getmininginfo difficulty

[JaredTate]

Fix: getmininginfo difficulty field always returns Groestl difficulty (Issue #346)

Summary

Fixes #346 - The difficulty field in getmininginfo RPC was returning a frozen/incorrect value because it was always querying Groestl's difficulty instead of the current mining algorithm's difficulty.

Problem Description

In DigiByte v8.26.1, users reported that the difficulty field in the getmininginfo RPC method displays a frozen value that doesn't update correctly. The difficulties field (plural) works as expected, but the singular difficulty field was broken.

Root Cause

During the Bitcoin Core v26.2 merge, the GetDifficulty() call in getmininginfo lost the algorithm parameter.

In v8.22.2 (working):

obj.pushKV("difficulty", (double)GetDifficulty(tip, NULL, miningAlgo));

In v8.26.1 (broken):

obj.pushKV("difficulty", (double)GetDifficulty(tip));

Since DigiByte's GetDifficulty() function signature is:

double GetDifficulty(const CBlockIndex* tip = NULL, const CBlockIndex* blockindex = nullptr, int algo = 2);

When called with only one parameter, algo defaults to 2 (ALGO_GROESTL), causing it to always return Groestl's difficulty regardless of the user's configured mining algorithm.

Changes Made

• File: src/rpc/mining.cpp
• Line 526: Restored the miningAlgo parameter to the GetDifficulty() call
• Change: GetDifficulty(tip) → GetDifficulty(tip, nullptr, miningAlgo)

Testing

This fix ensures that:

1. The difficulty field returns the difficulty for the current mining algorithm (as set by -miningalgo)
2. Behavior matches DigiByte v8.22.2
3. The field updates correctly as blocks arrive for different algorithms

Test commands:

# Test with different algorithms
digibyted -miningalgo=sha256d
digibyte-cli getmininginfo | jq '.difficulty'

digibyted -miningalgo=scrypt
digibyte-cli getmininginfo | jq '.difficulty'

# Verify difficulty matches the corresponding value in difficulties object
digibyte-cli getmininginfo | jq '{difficulty, difficulties}'

Impact

• Severity: Medium - Affects mining operations and monitoring
• Affected versions: DigiByte v8.26.0, v8.26.1
• Scope: Users running any algorithm other than Groestl see incorrect difficulty values

Additional Context

This is a regression introduced during the Bitcoin Core v26.2 merge. It highlights the importance of preserving DigiByte-specific multi-algorithm functionality when integrating upstream Bitcoin changes. The difficulties field was unaffected because it explicitly iterates through all algorithms with the correct parameters.

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Repository: DigiByte-Core/digibyte
Branch: claude/investigate-digibyte-issue-018eRW2M8brZzweTZpj1e89B
Target: develop
Commit: c6f3663

Create PR Link:

https://github.com/DigiByte-Core/digibyte/compare/develop...claude/investigate-digibyte-issue-018eRW2M8brZzweTZpj1e89B?expand=1

[gto90]

ACK

[ycagel]

cACK