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March 2023

ยท 6 min read
Franco Testagrossa
Sasha Bogicevic
Sebastian Nagel

This report summarizes the work on Hydra since February 2023. It serves as preparation for the monthly review meeting (slides/recording) , where the team updates major project stakeholders on recent developments to gather their feedback on proposed plans.


The project saw one release this month and several items on our roadmap were updated.

Released version 0.9.0โ€‹

  • This release brought in on-chain and off-chain changes that are now also fully reflected in our specification.

  • We managed to decrease the costs of our plutus scripts by using a new error code framework and made also the head script a reference script.

  • The mutation test suite is improved. Now, if tests fail they show the correct reason.

  • The contestation deadline is now pushed out by each contesting party, so the contestation period parameter can be chosen irrespective of number of parties.

  • Added a tutorial contributed by @perturbing.

  • Full release notes and list of delivered features

The latest roadmap, with many items marked as idea.

Notable roadmap updatesโ€‹

  • Now that 0.9.0 is released, the focus is on mainnet compatiblity. The next planned version 0.10.0 will be the first hydra-node to be mainnet compatible.

  • Also prioritized API configurability #380 higher and planned it into 0.10.0 as more users were requesting this.

  • We aim for several more 0.x.0 versions to incorporate user-requested features before reaching a 1.0.0, which will be a fully maintained release where features can be considered stable and won't be removed without appropriate deprecation cycles.

  • Marked multiple features as ๐Ÿ’ญ idea, meaning they are up for discussion. Many have been on the roadmap for a long time without user demand or input, while other ideas are incubating as github idea discussion. We are planning to convert these idea issues to GitHub discussions as these provide better dicussion tools and allow to gauge interest in topics. In turn, by cleaning up we provide more room for the most popular ideas to be planned onto the roadmap in a more timely manner.

  • In short, if you want to see some feature added, show your support on the corresponding idea discussion.

  • The ๐Ÿ’ฌ feature items remaining are the currently identifed "must-haves" or too vague to remove ๐Ÿ”ด red items.

The roadmap without idea items.


Issues and pull requests closed since last report

This month, the team worked on the following:

  • Making Hydra mainnet compatible. Besides making it technically possible to run on mainnet, this is about safeguarding our users and preventing them from shooting themselves in the foot with a mainnet gun. That is why we limited the amount of ada you can commit to a head on mainnet. Our smoke tests should be running on mainnet also so we made sure to return the leftover funds back to our faucet. There was also work on our CI that enables running the tests on mainnet using a dedicated github runner.

  • Improving the Hydra UX. We noticed a possible pitfall when restarting the hydra-node using different parameters than in the persisted state. Now, the node would prevent this kind of misconfiguration.

  • Optimize the on-chain scripts. Reduced the cost of opening/closing a Head by reducing size of scripts via error codes #748 and also having the head script as a reference only #701).

    The mutation test also got improved by making all cases expect the corresponding error codes #705 and new golden test suite ensures the script hashes don't change accidentally.

    Furthermore, we addressed a problem discovered in our property tests #724 by preventing committing outputs with reference scripts to a Head #766. This is still a documented known issue, but a workaround is available.


  • Team workshop in Austria. Meetup of core contributors in Feldkirch, Austria for retrospective, grooming and discussions on future plans for Hydra. Part of the agenda was also a presentation of Hydra to members of the Cardano Foundation and a meeting with builders from the Cardano community.

    The highlight, though was the common effort of going the last mile to open a head on mainnet for the monthly review meeting! ๐ŸŽ‰

    We demonstrated our good old hydraw application on that Hydra head and we saw thousands of pixels painted by hundreds of users (no detailed metrics).

  • Next step in Hydra for Payments. Also announced in the monthly meeting was the next phase on the Hydra for Payments project. The scope of this will be to extend hydra-pay and build a mobile payment channels app that makes direct use of it - working title: HydraNow.


The monthly review meeting for March was conducted on 2023-03-27 via Google Meet - slides/recording.

This month was very important for the project and culminated in the first demonstration of a Hydra Head on mainnet! The demo was well received and we received positive feedback in the meeting, on following twitter announcements and on the published recording on youtube. Inspired by this, we saw multiple people offer to help and collaborate on communicating, educating and ultimately spreading the love. The invitation via the new discord category worked well - we had about 40 community members in the call - and we will continue with this workflow. Make sure to follow the Hydra #announcements on the IOG Technical discord server.

While being mainnet compatible is a major milestone for the project, there are still many known issues, shortcomings and requested features. The roadmap changes this month should make it clear that we are serious about the latter - Hydra will only reach 1.0.0 if it is used by an application on mainnet. Hence, we will focus on adding features required for payments, voting, auctions, ... and eventually, your use case.

Hydra Head is ready to be used on mainnet. Are you ready to use it?