change(chain): raise ZIP 317 block production weight_ratio_cap from 4 to 10

[aphelionz]

Motivation

Widen the ZIP 317 block production "priority lane": with the cap at 4, any transaction paying more than 4x its conventional fee gets no additional selection weight. Raising the cap to 10 lets fee-based prioritization follow an easy-to-explain powers-of-10 model, as a companion to zcash/zips#1352 (lowering the marginal fee to 1000 zatoshis).

Discussed with the Zebra team on Discord beforehand.

Solution

Raise BLOCK_PRODUCTION_WEIGHT_RATIO_CAP (weight_ratio_cap in ZIP 317) from 4 to 10.

Tests

Existing zebra-chain zip317 tests pass; no test depends on the cap value. The cap only bounds conventional_fee_weight_ratio, which is used for weighted-random block template construction and mempool metrics.

Specifications & References

• ZIP 317: block production
• Add draft-aphelionz-marginal-fee: Reduce Marginal Fee to 1000 Zatoshis zcash/zips#1352

AI Disclosure

• AI tools were used: Claude Code (change and PR description)

PR Checklist

• The PR title follows conventional commits format: type(scope): description
• The PR follows the contribution guidelines.
• This change was discussed in an issue or with the team beforehand.
• The solution is tested.
• The documentation and changelogs are up to date.

[conradoplg]

IMO this is blocked on getting this change accepted into the ZIP

[arya2]

This seems like a trivial change that we can re-open or replace when needed, please open an issue first next time, see:

PRs are welcome, but every PR requires human review time. To make that time count:

Start with an issue. Check the issue tracker for existing issues or create a new one describing what you want to change and why. Wait for a team member to respond before writing code — an issue with no team acknowledgment does not count as prior discussion.

https://github.com/ZcashFoundation/zebra/blob/main/CONTRIBUTING.md#pull-requests

[arya2]

Bumping the weight ratio cap from 4 to 10 in Zebra was discussed in advance, sorry for closing this.

I agree we should ideally update the ZIP first.