Donate change output

[cygnet3]

Since our wallet is very donation-focused, a good feature would be to suggest to users to donate the change output, rather than return it.

This has a couple of nice features:

• Stimulates donations (which is the goal of Dana)
• Excellent compatibility with the 'contacts' feature. I imagine a user having a list of donation candidates in their contact list. Then we suggest a random candidate from their donation contacts.
• Improves on-chain privacy by breaking the '1-output-1-change' heuristic

This would be a good feature to work on after the contact feature.

[yashrajd]

News (for me) but apparently "chain avoidance" is a guideline and feature Wasabi wallet already has...

[Sosthene00]

Yes I think that samourai also had some tricks to avoid change when possible but I might be misremembering. Anyway that all points out the change output being something we want to either avoid or make a donation to mislead chain analysis.

[yashrajd]

It'd figure in coin selection which might make it tricky, just a guess. A naive donate change feature should be easy though

[yashrajd]

• Excellent compatibility with the 'contacts' feature. I imagine a user having a list of donation candidates in their contact list. Then we suggest a random candidate from their donation contacts.

Hmm this could also work. But it would mean the output still exists, in which case there is no fee savings. I think the original idea was to incentivise donation by reducing fee through eliminating the change output itself.