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Hard Fork

Rolling Agenda & Working Notes

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Agenda

Date: Tuesday 16 December 2026

Proposed intra-era scope and community feedback

Draft: Update policy to include alternative node implementations and Midnight�

Ratify proposed naming of the intra-era hard fork�
Readiness list and Submission criteria�
Timings on testnet forks�
Timing of Plutus cost model update after hard fork, considering other parameter changes around similar times�
Requests for next session agenda and the date of the next meeting

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Communication Channels

All messages, notes and updates from the Hard Fork Working Group will be replicated/broadcasted in these channels:

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Key Stakeholders

‘A hard fork requires the whole ecosystem, not just a few’ - however key stakeholders listed for note and ease

Hard fork working group coordination: Bosko Majdanac, Matt Davis

Anyone not here who you think should be!

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Hard Fork Working Group Purpose

The working group is focussed on the facilitation of Cardano upgrades and oversee and coordinate issues relating to hard forks. Reporting status and progress to the Technical Steering Committee (TSC), the wider Intersect membership and back to hard fork proposers, collaborators and the ecosystem.

The working group aspires to have representation from all stakeholders required to enable a hard fork; from builders, stake-pool-operators, exchanges and the broader community,

‘A hard fork requires the whole ecosystem, not just a few’.

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Backup Slides

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Agenda

Date: Tuesday 02 December 2026

Introduction

Impact assessment, IOE SMEs to talk through proposed changes
Aid clarity & understanding
Early challenges and risks
Anything missed, the CIP069 issue from Plomin

Readiness & Submission lists - feedback required

Naming - Tradition to name after a pillar and champion of the community and ecosystem

Requests for next session agenda

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Technical Changes

Summary

These changes focus on validation improvements, security enhancements, governance fixes, and significant Plutus performance and capability upgrades. The Plutus changes add powerful new primitives and enable all builtins across all Plutus versions, which increases what developers can build with V1 and V2 scripts.

Key Highlights:

Plutus: All built-in functions now available in V1/V2/V3, new Array and Value types, advanced cryptographic primitives, and performance improvements via case expressions
Ledger: VRF key uniqueness enforcement, improved governance validation, better error reporting, and script validation fixes

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Technical Changes - Plutus Features

Plutus Features

Enable All Built-in Functions and Language Features Across All Plutus Versions

Makes all built-in functions available to PlutusV1, V2, and V3
Previously, some builtins like serialiseData, verifyEcdsaSecp256k1Signature, and verifySchnorrSecp256k1Signature were only available in V2/V3
Enables sums-of-products across all Plutus ledger language versions
Increases the power and capabilities of PlutusV1 and V2 scripts

case Expressions for Built-in Types

GitHub Issue: #6602
Adds the ability to use case expressions on built-in types (Bool, Integer, Data) in UPLC
Performance improvements:

More efficient boolean matching (compared to current IfThenElse builtin)
More efficient integer matching (eliminates repeated IfThenElse and EqualsInteger calls)
Faster data processing (addresses one of the most pressing UPLC performance issues)

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Technical Changes -New Plutus Builtin & Types

New Plutus Builtins and Types (Protocol Version 11 Additions):

CIP-138: Plutus Core Builtin Type - Array

Introduces native Array type to Plutus Core
Improves data structure efficiency for on-chain scripts

CIP-153: Plutus Core Builtin Type - MaryEraValue

Adds native Value type for more efficient on-chain value operations
Reduces costs for scripts that work extensively with multi-asset values

CIP-109: Modular Exponentiation Built-in for Plutus Core

Adds efficient modular exponentiation primitive
Critical for cryptographic operations on-chain

CIP-132: New Plutus Builtin dropList

Adds efficient list manipulation primitive
Improves performance for list operations in scripts

CIP-133: Plutus Support for Multi-Scalar Multiplication over BLS12-381

Enables advanced cryptographic operations
Critical for zero-knowledge proofs and other advanced cryptographic protocols

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Technical Changes -Ledger Features

Ledger Features

Revert BabbageNonDisjointRefInputs check for PlutusV1/V2

GitHub Issue: #5009
Changes validation rules for PlutusV1 and PlutusV2 scripts regarding reference inputs
Addresses a predicate check that was causing issues with PlutusV1/V2 script validation

Constitutional Committee Voting Restriction

GitHub Issue: #5022
Converts the Constitutional Committee voting restriction from a mempool sanitizer into a proper ledger predicate failure
Makes governance validation more explicit and part of the ledger rules rather than just mempool filtering

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Technical Changes -Ledger Features cont.

VRF Key Uniqueness Enforcement

GitHub Issues: #5159, #5252
Prevents different stake pools from using the same VRF (Verifiable Random Function) key
Security Impact: Improves stake pool security and prevents potential attack vectors where malicious actors could reuse VRF keys

Non-Matching Withdrawals Predicate

GitHub Issue: #4640
Adds a new predicate failure for transactions with non-matching withdrawals
Improves transaction validation and provides clearer error reporting for withdrawal mismatches

Enhanced Protocol Parameter Hash Mismatch Reporting

GitHub Issue: #4517
Improves the PPViewHashesDontMatch error to include the expected hash data
Better debugging and error diagnostics for protocol parameter mismatches