High level summary​

The SRE team continues work on Cardano environment improvements and general maintenance.

Some notable recent changes, updates or improvements include:

• Cardano-parts, cardano-playground and cardano-mainnet were updated with cardano-node 10.6.4, cardano-db-sync release 13.6.0.8, pre-release 13.7.0.2, and nix was patched for security vulnerabilities GHSA-g3g9-5vj6-r3gj / CVE-2026-39860.

• The ZFS AMI module was enhanced with a configurable percentage-based ARC cache sizing option derived from the node RAM.

• Buildkite infrastructure was updated to accommodate Daedalus Linux CI support.

• A van Rossem PV11 cost model governance vote was cast on preview.

Repository Work -- Merged​

Cardano-mainnet​

cardano-mainnet PR#43:

• Bumps cardano-node to 10.6.3, and then 10.6.4 with corresponding deployments
• Bumps cardano-db-sync to 13.6.0.8 and deploys to dbsyncs
• Adjusts alerts for the remaining block producer to reflect current stake levels
• Migrates resources out of me-central-1 due to stability issues and into ap-southeast-6
• Destroys retired block producer machines and secrets
• Updates webserver and DNS resources to properly serve IOGP metadata for remaining pools that are unused and unfunded but not retired
• Adds CPU/memory usage panels and totals to cardano-node.json and cardano-node-new-tracing.json Grafana dashboards
• See the PR description for additional details

Cardano-parts​

cardano-parts PR#81:

• Bumps cardano-node release to 10.6.4, cardano-db-sync release to 13.6.0.8, and cardano-db-sync pre-release to 13.7.0.2
• Bumps nix to address security vulnerabilities GHSA-g3g9-5vj6-r3gj and CVE-2026-39860
• Extends the ZFS AMI ami.nix nixosModule with a configurable boot.zfs.zfsArcPct option for percentage-based ARC cache sizing
• Updates the AWS EC2 spec to include new machine types missing in the existing spec
• Fixes a race condition in profile-aws-ec2-ephemeral.nix where chown could fail on a disappeared ephemeral file
• Fixes a tcpTxOpt colmena module breaking change introduced in nixpkgs 25.11
• Adds CPU/memory usage panels and totals to cardano-node.json and cardano-node-new-tracing.json Grafana dashboards
• Adds non-NixOS machine handling to consistency-checking and update-ips recipes
• See the PR description for additional details

Cardano-playground​

cardano-playground PR#56:

• Bumps cardano-node to 10.6.4, cardano-db-sync to 13.6.0.8, and cardano-db-sync pre-release to 13.7.0.2 with deployments to release environments
• Extends ami.nix with configurable boot.zfs.zfsArcPct option for percentage-based ZFS ARC cache sizing
• Fixes buildkite NixOS container startup race condition with sops and repurposes a buildkite machine for a Daedalus queue
• Adds CPU/memory usage panels and totals to Grafana dashboards
• Updates cardano-book for 10.6.3 and 10.6.4 node releases
• Casts a governance vote on preview for the van Rossem PV11 cost model update with signed rationale and vote transaction
• See the PR description for additional details

Devx-ci​

devx-ci PR#154:

• This should bring hydra-tools back up to a sufficiently recent release (hydra-github-bridge to 0.2.1.0), which will make it possible to layer on other fixes on top of it (for example, recovering PostgreSQL hung connections and not crashing while reading build logs).

devx-ci PR#155:

• Adds 3 types of Oakhost Darwin machines, each with 3 available hydra build slots initially, pending further tuning
• These machines will likely be short-lived until a new hardware offering from Oakhost is available in a few months
• Adjusts number of hydra eval worker threads to 3 as 4 tends to cause semi-regular OOMs w/ 4 concurrent large evals

High level overview​

This week, the Mithril team completed production readiness preparations for circuit keys and trusted setup in the STM library. They continued work on the golden tests for the recursive SNARK circuit prototype, enhancements to witness preparation for the non-recursive prover, deterministic proof generation in golden tests, and data encoding and state transition tests for the recursive SNARK circuit prototype.

The team also completed the explorer update for Cardano blocks and transactions, the documentation of the Cardano blocks and transactions signature on the website, and the plan to sunset Cardano transaction certification. They continued work on the upgrade to Cardano node v.10.7 and on the preparation of the next distribution, 2617.

Finally, they investigated an issue with signer registration in the SNARK prover, fixed flaky end-to-end tests, and worked on supporting multiple tiers for CI tests.

Low level overview​

Features​

• Completed the issue Prepare production readiness for circuit keys and trusted setup in STM #3165
• Completed the issue Update explorer for Cardano Blocks and Transactions #3079
• Completed the issue Document Cardano Blocks and Transactions signature in website #3101
• Completed the issue Prepare plan to sunset Cardano transaction signed entity type #3158
• Worked on the issue Add golden tests for recursive SNARK circuit prototype #3125
• Worked on the issue Enhance preparation of witness for the non-recursive prover in STM #3178
• Worked on the issue Deterministic proof generation in golden tests #3164
• Worked on the issue Add data encoding and state transition tests for recursive SNARK circuit prototype #3191

Protocol maintenance​

• Completed the issue Update client test in CI to check blocks and transactions #3159
• Completed the issue Create Cardano node upgrade runbook #1197
• Worked on the issue Upgrade to Cardano 10.7 #2894
• Worked on the issue Release 2617 distribution #2967
• Worked on the issue SNARK aggregator certification stopped on dev-follower-preview #3183
• Worked on the issue End to end tests are flaky #3205
• Worked on the issue Support multiple tiers for tests in CI #3206
• Worked on the issue Nightly tests are flaky #3210

High level summary​

The Plutus team has recently made a number of significant improvements to the UPLC executable, including:

• support for hex-encoded scripts as input (#7655).
• support for blueprint JSON as input, with the ability to optimize all scripts it contains (#7685).
• the ability to certify optimizations and generate a certifier report for each optimized validator (#7692).
• a number of flags to give users control over optimization behavior (#7682).
• allow evaluating a script using user-supplied input before and after optimization (#7695).

The UPLC executable is included with every Plutus release. While it supports a range of use cases, its most immediately useful feature for most developers is script optimization. Preliminary testing suggests that applying these optimizations to recent mainnet scripts yields, on average, a 10% reduction in execution cost and a 2% reduction in script size.

We are currently working on user documentation for the UPLC executable.

Low level summary​

Key Pull Requests Merged​

• Allow the uplc executable to take cbor-hex
• Allow blueprint as input and output for the uplc executable
• Certifier can now report execution costs before/after each pass
• Allow optimisation options to be configured in uplc executable
• UPLC executable: enable eval during optimisation

High level summary​

• Leios prototype development (Treasury Funding Initiative 4: Ouroboros Leios Implementation):
  • Fixed an "impossible!" crash in the Leios prototype's fetch decision logic (#1996).
  • Added cumulative transaction bytes to the ledger state and exposed them as a Prometheus metric, giving operators a direct measure of throughput on the proto-devnet (#1988, cardano-node#6536).
  • Added a confirmed-transaction throughput panel to the proto-devnet dashboard (ouroboros-leios#859).
  • Hardened the prototype's test suite around endorser-block inclusion, making it easier to extend to upcoming features such as voting (#1971).
  • Started aligning the prototype with the original Leios design by migrating the endorser-block announcement and certification flag from the Ledger Block into the Praos Header (ouroboros-leios#837).
  • Investigating a performance bug observed during the March demo, where the time between forging and storing an endorser block can stretch to minutes and disrupt protocol operation (ouroboros-leios#844).
  • Nick Frisby shared a work-in-progress snapshot of his SQLite latency investigation from March, which informs Leios-related storage work (ouroboros-leios#863).
  • Posted the logbook update from the 2026-04-09 Consensus Office Hours (ouroboros-leios#854).
• Peras protocol development (Treasury Funding Initiative 17: Maintenance and Support):
  • Defined sensible default values for PerasParams, simplifying configuration for downstream users (#1998).
• Documentation (Treasury Funding Initiative 17: Maintenance and Support):
  • Added an explanation page describing the data flow between consensus components (#1955).
  • Published a first iteration of an explanation page covering the Ouroboros Praos consensus protocol (#1960).
  • Removed leftover documentation stubs and cleaned up the sidebar on the consensus website (#1956).
• Releases and integration (Treasury Funding Initiative 17: Maintenance and Support):
  • Released ouroboros-consensus-3.0.1.0 (#1987).
  • Bumped the node's consensus dependency to 3.0.1, propagating recent consensus improvements to cardano-node (cardano-node#6533).
  • Re-landed the rework of snapshotFromIS, part of ongoing improvements to ledger snapshotting (#1992).

High level summary​

These were our main areas of focus last period on the Ledger project:

Maintenance​

We worked really hard in order to prepare Ledger for the cardano-node-10.7.0 release that had all of the bug fixes and features needed for the upcoming van Rossem Hard Fork into protocol version 11. Furthermore, we prepared Ledger for a subsequent cardano-node-10.7.1 release that had some of the performance issues resolved, which were identified in the Ledger component of 10.7.0 release.

We've also identified and fixed a few bugs, most of which were in CDDL specification. This was largely thanks to the recently integrated tool AntiGen, that we developed specifically for creating negative property tests for Ledger serialization.

Besides bug fixes, we've added quite a few nice optimizations, which do result in noticeable speed up in chain validation and replay.

Some very nice improvements were implemented for the Ledger API used by Consensus, which will result in clearer and safer boundaries between those two components.

CIP-118 - Nested Transactions:​

Two more major Ledger rules UTXO and UTXOW were defined for processing transactions in the Dijkstra era that now take sub-transactions into consideration.

CIP-165 - Canonical Ledger State:​

Fixes were applied to canonical ledger state representation for the Constitutional Committee

Low level summary​

Features​

• PR-5654 - Normalize StakeRefPtr addresses better and improve UTxO decoding
• PR-5647 - Change B constructor of Metadatum from ByteString to ByteArray
• PR-5655 - Add ToJSON/FromJSON instances for NonEmptyMap and NonEmptySet
• PR-5630 - Remove distinct_bytes hack, make CDDL reflect reality in previous eras
• PR-5560 - *EraBlockHeader typeclasses deprecating BHeaderView
• PR-5658 - Optimize Text byte length check in metadata and other places
• PR-5632 - Forecast API
• PR-5671 - Remove NoThunks instances for predicate failures and ContextError types
• PR-5635 - ScriptPurpose aware memoization of TxInfo
• PR-5676 - Remove state update from UTXOS
• PR-5641 - Avoid unnecessary computation of PlutusWithContext
• PR-5672 - Make ContextError constructors from Alonzo to Dijkstra era lazy
• PR-5614 - SUBUTXO implementation
• PR-5668 - SUBUTXOW fixes
• PR-5704 - Backport: revert ConwayAccountState type unrolling
• PR-5697 - Remove 5 redundant NativeScript era ~ Timelock era constraints (#5319)
• PR-5665 - Fix metadatum decoder and chain_code CDDL
• PR-5681 - Add/refactor committee-related canonical namespaces
• PR-5725 - Revert decoders to a more efficient implementation
• PR-5716 - Move applyTick into its own ApplyTick typeclass
• PR-5719 - Add protocol version validation to createInitialState
• PR-5729 - Fix ConwayAccountState overhead
• PR-5727 - Add storable instances

Testing​

• PR-5656 - Translate all transaction building examples in our test files to use Lens interface.
• PR-5609 - Adequate conformance to Version restriction
• PR-5667 - Fix Proposal generation to generate HardForkInitiation with bounded major version
• PR-5695 - Update formal-ledger-specifications and re-enable tests
• PR-5529 - Add simpleRewards reproducer from cardano-db-sync and migrate TwoPools example to an ImpTest
• PR-5715 - Bump cuddle to 1.5.0.0

Infrastructure and releasing​

• PR-5653 - Add cabal-gild and shellcheck as part of the pre-commit hook in our Nix devShell.
• PR-5648 - Changelog for cardano-node-10.7
• PR-5657 - Migrate scripts to cardano-ledger-release-tool
• PR-5599 - Enable ghc 9.14 to be used for tests in CI and locally
• PR-5677 - Bump requests from 2.32.4 to 2.33.0 in /doc
• PR-5675 - Add nixfmt in our Github CI checks
• PR-5670 - Add CHANGELOG and cabal file updater skill
• PR-5691 - Bump pygments from 2.19.1 to 2.20.0 in /doc
• PR-5702 - Update contribution policy to note how contributions should be vetted
• PR-5703 - Add a CI workflow for checking nix hashes
• PR-5708 - Bump the actions group with 3 updates
• PR-5709 - Update slack-github-action configuration for v2 onward
• PR-5712 - Fix missed version bump for allegra package
• PR-5713 - Stop running bump-changelogs on release branches
• PR-5666 - Refactor transaction and transaction body of examples in Test.CardanoLedger.<era>.Examples.hs.
• PR-5717 - claude: improve changelog update skill
• PR-5710 - Update microlens dependency
• PR-5726 - Update ghc-9.12 on CI and Nix to ghc-9.12.4, and cabal-3.16 to cabal-3.16.1.0
• PR-5728 - Backport of fixes for cardano-node-10.7.1
• PR-5741 - Fix nix build failure in plutus-preprocessor
• PR-5721 - Leios: Make the (leios enhanced) block decoding backwards compatible