High level summary​

• Leios prototype development (Treasury Funding Initiative 4: Ouroboros Leios Implementation):
  • Split the Leios database into two files, one for data a node can still roll back, and one for data that is settled. A certified Endorser Block moves from the first file to the second in the background. An operator can put the two files on different disks, and give the busier file the faster disk. The same change adds garbage collection in small steps: one thread marks the rows a node no longer needs, and a second thread deletes them in paced batches, so the deletion does not hold up the rest of the node (#2261, for ouroboros-leios#969).
  • Adapted the prototype node to the two file layout, and published the size of each part as a node metric (cardano-node#6656). Added a dashboard that shows how many Endorser Blocks and transactions sit in each part, and updated the devnet configuration to match (ouroboros-leios#1054).
  • db-synthesizer now builds a Leios chain instead of a chain of empty blocks. It fills each block with transactions, puts what does not fit into an Endorser Block, and votes on each announced Endorser Block so that a later block can certify it. It also stores each Endorser Block it forges, which an earlier version dropped. The other database tools now have a Leios chain to work on (#2241, #2283).
  • db-truncater now handles a Leios chain. After it cuts the chain back to a chosen slot, it cuts the Leios database back to the same slot, drops the transactions that no Endorser Block refers to, and shrinks the file (#2262, for ouroboros-leios#1023).
  • Moved block forging out of the node kernel into a module of its own, and split it into named steps. The behaviour does not change. The new shape makes the forging path easier to follow, easier to instrument, and easier to reuse from the database tools (#2281).
• Maintenance and support (Treasury Funding Initiative 17: Maintenance and Support):
  • Dropped support for node-to-client protocol versions below v23. Version 23 shipped with node 10.7.0 in March 2026, and every client we checked already offers it. The older versions kept legacy code alive in the consensus layer (#2265).

High level summary​

This update spans four weeks, so it covers a larger than usual body of work. The headline item is that Dijkstra's batch validation now executes Plutus scripts from sub-transactions and accounts for their execution budgets. Previously it skipped Plutus execution for sub-transactions, so spending validators and minting policies inside a sub-transaction were not enforced and their ExUnits were left out of transaction and block limits and of script fees; that gap is now closed, and sub-transaction budgets count toward limits and fees. Alongside this, withdrawals handling in the ENTITIES rule was reworked to implement the full set of responsibilities from the specification, covering the network and existence checks, the legacy-mode full-drain and per-account sub-aggregate cap, and the non-legacy pre-batch existence check and batch-wide aggregate cap over the top transaction together with all of its sub-transactions. This moved the batch withdrawal checks out of UTXO and into ENTITIES, and was accompanied by conservation of value in legacy mode and by SUBUTXO/SUBUTXOW predicate failures.

A second major thread was the Plutus V4 context: we implemented the TxInfo translation for protocol version 4, redid the PlutusPurpose translation, made further TxInfo improvements, fixed the Dijkstra cost model injection, and bumped plutus-ledger-api to at least 1.68.

Progress continued on the Dijkstra era rules and on Leios. A POOL rule was added for Dijkstra, an EMax /= 0 well-formedness check was introduced, the stake calculation was made consistent by moving SNAP to the end of the EPOCH, and account balance intervals are now enforced. On the Leios side, the Leios protocol parameters were added to the Dijkstra era and the leios_certificate signer set is now size-constrained. We also removed the hardforkConwayMoveWithdrawalsAndDRepChecksToLedgerRule transition flag and the WithdrawalsNotInRewardsCERTS failure, finishing the migration of those withdrawal and DRep checks into the ledger rule.

The rest of the work spanned serialisation, more abstract interfaces, conformance, and releasing. On serialisation we adjusted transaction serialisation in the block body, made the OutputVRF decoder more resilient, removed a guard from the IndividualPoolStake codecs, and improved the custom PParamUpdate encoding. The move toward era-parametric interfaces continued with an era parameter on StakePoolParams, forcing of the Shelley initial-funds injection result, and ToJSON/FromJSON instances for EraTxOut and for TxBody/Tx across all eras. On testing we landed two formal-ledger-specification updates (one enabling the corresponding tests), conformance for the Dijkstra EPOCH rule and for starting account balance intervals, the Shelley Pool Imp tests in Dijkstra conformance, an era-generic Conway CERTS test, and a fix for a produced vs. consumed conformance failure. Finally, we updated to crypton == 1.1 (replacing memory with ram), hardened the branch-history CI job, and landed two rounds of backports of fixes for node 11.1.1.

Low level summary​

Features​

• PR-5983 - Implement TxInfo translation for PV4
• PR-6017 - shelley: force the initial-funds injection result
• PR-6031 - Add EMax /= 0 as well formed check to Dijkstra era
• PR-6012 - Conservation of value in legacy mode
• PR-5888 - Constrain the size of leios_certificate signers
• PR-6033 - Make OutputVRF decoder more resilient
• PR-5986 - Make stake calculation consistent in dijkstra by moving SNAP to the end of the EPOCH
• PR-5985 - Adjust transaction serialization in BlockBody
• PR-6001 - Enforce (starting_)account_balance_intervals
• PR-6002 - Add Leios protocol parameters to DijkstraEra
• PR-6041 - Remove hardforkConwayMoveWithdrawalsAndDRepChecksToLedgerRule and WithdrawalsNotInRewardsCERTS
• PR-6040 - Add era parameter to StakePoolParams
• PR-6046 - Bump plutus-ledger-api to >=1.68
• PR-5855 - Add ToJSON/FromJSON instances for EraTxOut
• PR-6038 - Redo PlutusPurpose translation
• PR-6030 - Fix CostModels injection for Dijkstra
• PR-6051 - TxInfo improvements
• PR-6029 - Add POOL rule for Dijkstra
• PR-5997 - Withdrawals rework in ENTITIES
• PR-6071 - Execute Plutus scripts from sub-transactions and count their ExUnits
• PR-6070 - Improve versatility of custom PParamUpdate encoding
• PR-6042 - Remove guard from IndividualPoolStake codecs
• PR-6076 - Add ToJSON/FromJSON instances for TxBody l and Tx l in all eras

Testing​

• PR-6019 - Improve tests in UtxoSpec
• PR-6022 - Update formal-ledger-specification
• PR-5995 - Update formal-ledger-specification and enable tests
• PR-6024 - Enable Shelley Imp tests for Pool in conformance (Dijkstra)
• PR-5842 - Add a submitFailingSubsetTx helper
• PR-6009 - Make Conway CERTS test era-generic
• PR-6056 - Conformance for EPOCH rule in Dijkstra
• PR-6044 - Conformance for starting account balance intervals
• PR-6034 - SUBUTXOW predicate failures
• PR-6055 - SUBUTXO predicate failures
• PR-6074 - Fix conformance failure in produced vs. consumed

Infrastructure and releasing​

• PR-6014 - Make the branch-history CI job more robust
• PR-5999 - Update to crypton == 1.1 and replace memory package with ram
• PR-6025 - Backport of fixes for node 11.1.1
• PR-6028 - Backport of fixes for node 11.1.1 - take 2
• PR-6032 - Add changelog for cardano-ledger-shelley-1.19.0.1 backport

High level overview​

This week, the Mithril team completed the missing IVC off-circuit checks, the property-based tests for the IVC pure helpers, the caching of the circuit keys with the reuse of the SNARK prover setups, and the enhancements of the end-to-end tests for the IVC SNARK. They continued implementing the circuit verification key whitelist/revoke mechanism and supporting an IVC follower aggregator joining the network at any time. They also started implementing the Relation trait for the IVC circuit and adding a Proof of Bound Possession for the SNARK verification keys.

The team completed the IPFS support in the end-to-end tests, the test infrastructure for IPFS nodes, and the summary of the IPFS PoC. They also started adding a certificate chain cache committed after chain verification in the client library.

Finally, they kept upgrading to Cardano node 11.1, reduced the aggregator compile time, and kept investigating the blocks and transactions verification failure on the testing-preview network.

Low level overview​

Features​

• Completed the issue Add missing IVC off-circuit checks #3381
• Completed the issue Add property-based tests for the IVC pure helpers #3469
• Completed the issue Cache the circuit keys and reuse the SNARK prover setups #3424
• Completed the issue Enhance end-to-end tests for IVC SNARK #3390
• Completed the issue Implement IPFS in the end to end tests #3460
• Completed the issue Prepare summary for IPFS PoC #3519
• Worked on the issue Implement circuit verification key whitelist/revoke mechanism #3148
• Worked on the issue Support an IVC follower aggregator joining the network at any time #3446
• Worked on the issue Implement Relation trait for the IVC circuit #3428
• Worked on the issue Add a SNARK verification key Proof of Bound Possession #3537
• Worked on the issue Add a certificate chain cache committed after chain verification in the client library #3520

Protocol maintenance​

• Completed the issue Implement test infrastructure for IPFS nodes #3461
• Completed the issue Reduce the aggregator compile time #3538
• Completed the issue Publication to doc.rs failed for distribution 2630 #3507
• Worked on the issue Upgrade to Cardano 11.1 #3346
• Worked on the issue Blocks and transaction verification fails on testing-preview #3526

High level overview​

This week, the Mithril team completed the behavior tests for the IVC wiring, the harmonization of the recursive and non-recursive SNARK implementations in STM, and the STM README with recursive and non-recursive examples. They continued adding the missing IVC off-circuit checks, implementing the circuit verification key whitelist/revoke mechanism, and supporting an IVC follower aggregator joining the network at any time. They also started adding property-based tests for the IVC pure helpers.

The team completed the adaptation of the documentation for the on-chain configuration parameters. They also completed the IPFS file downloader of the client and started implementing the IPFS support in the end-to-end tests.

Finally, they kept upgrading to Cardano node 11.1, started fixing the failed publication of the distribution 2630 to docs.rs, and started investigating the blocks and transactions verification failure on the testing-preview network.

Low level overview​

Features​

• Completed the issue Add behavior tests for the IVC wiring #3465
• Completed the issue Harmonize the recursive and non-recursive SNARK implementations in STM #3421
• Completed the issue Adapt documentation for on-chain configuration parameters #3398
• Completed the issue Implement an IpfsFileDownloader in the client #3459
• Completed the issue Update STM README with recursive/non-recursive examples #3385
• Worked on the issue Add missing IVC off-circuit checks #3381
• Worked on the issue Implement circuit verification key whitelist/revoke mechanism #3148
• Worked on the issue Support an IVC follower aggregator joining the network at any time #3446
• Worked on the issue Add property-based tests for the IVC pure helpers #3469
• Worked on the issue Implement IPFS in the end to end tests #3460

Protocol maintenance​

• Worked on the issue Upgrade to Cardano 11.1 #3346
• Worked on the issue Publication to doc.rs failed for distribution 2630 #3507
• Worked on the issue Blocks and transaction verification fails on testing-preview #3526

High level summary​

Casing on Data has been merged: case on a Data.Constr value now dispatches directly on the constructor tag, which, combined with the recently added dropList, significantly reduces the cost of consuming Data-encoded values. This is a Plutus V4 feature, and we are also working on specifying casing on built-in types in the Plutus Core specification.

Work on the Value builtins (CIP-0168) continues: the keepPolicies and dropPolicies builtins have been added, the cost model for policies has been merged, and the cost models for keepPolicies and dropPolicies are in progress. Like the other new builtins, these are gated behind a future protocol version and cannot be used on-chain until Dijkstra.

On the Plutus V4 ScriptContext front, we are implementing a different encoding for product types using List instead of Constr, which makes them cheaper to decode. We are also improving the usability of the certifier in the uplc and plc tools.

Key Pull Requests Merged​

• Add Data.Constr casing to Case
• Add keepPolicies and dropPolicies builtins (CIP-0168)
• Cost model for policies (CIP-0168)
• Remove deferred builtin applications from the specification

Pull Requests In Progress​

• Builtin Pattern Matching (CIP-0194)
• Specify casing on built-in types
• Cost model for keepPolicies (CIP-0168)
• Cost model for dropPolicies (CIP-0168)
• Encode single constructor ledger types using Data.List
• Improve uplc/plc certifier usability
• Compile BuiltinData transparently in the plugin