1. Account/Contract Merge

• Merge Overview:
  • Casper currently tracks Accounts and Contracts as separate record types, which are about 80% identical but have distinct fields and behaviors. Condor merges these into one entity record called AddressableEntity, simplifying the code base and removing arbitrary behavioral restrictions.
  • Migration:
    • Existing Account and Contract records will migrate upon on-chain interaction (e.g., sending transactions, native transfers).
    • New “accounts” and “contracts” will create an AddressableEntity record.
    • PublicKey/AccountHash associations for existing Account records remain and function with the corresponding AddressableEntity.
  • Named Keys:
    • Previously embedded in Account and Contract records, named keys are now a top-level concern stored directly in global state. This improves scalability and reduces gas cost volatility.
    • Entry points for smart contracts also transition to top-level storage in global state, similarly to named keys.
  • Action Items:
    • Off-chain logic retrieving Account or Contract records for processing, storage, indexing, etc., must be updated to use the AddressableEntity record structure.

2. Fee Elimination

• New Features:
  • Condor introduces configurable fee, refund, and pricing strategies, initially rolling out in “NoFee” mode. This mode places a balance hold on the paying purse instead of transferring tokens used for gas.
  • A configurable interval determines how long a balance hold remains. The available balance equals the actual balance minus non-expired holds.
  • Query Balance:
    • Off-chain logic can continue using the query_balance endpoint for available balance or the new query_balance_details RPC endpoint for detailed balance information.
  • Action Items:
    • Existing implementations generally do not need changes.
    • Platforms with automated funding should consider the new behavior for optimal scheduling strategies.

3. Dynamic Pricing

• Gas Price Changes:
  • Condor introduces a configurable gas price multiplier based on block consumption. Gas price adjusts at the end of each era based on average block usage, increasing or decreasing by 1 within set thresholds.
  • Configuration:
    • Minimum and maximum gas prices and adjustment thresholds are configurable.
    • The current gas price is included in the block header for easy discovery.
  • Action Items:
    • Plan for potential cost increases during high network usage.
    • Transactions can specify a maximum gas price using the gas_tolerance field.

4. Transaction Types

• Transition to Transaction Model:
  • The Deploy structure is deprecated; Condor introduces a Transaction model, supporting more advanced features.
  • Existing Deploys will continue to be accepted and executed if compatible, but eventual full transition to the Transaction model is recommended.
  • Action Items:
    • Determine if existing off-chain systems remain compatible with the legacy Deploy model.
    • Consider upgrading to the Transaction model for new features and efficiencies.

5. Block Restructure

• Changes to Block Structure:
  • Block records are modified to accommodate more types of Transactions and surface previously embedded information. New blocks will use the new format; historical blocks retain their original format.
  • Action Items:
    • Client software must be upgraded to parse new blocks while retaining the ability to handle historical blocks.

6. Contract Level Events

• New Feature:
  • Smart contracts can define message topics and emit messages as contract-level events, maintaining identity and exact ordering in interactions.
  • Action Items:
    • Existing systems do not need changes.
    • Smart contracts using dictionaries for events should consider migrating to the new system for better security and support.

7. Zug Consensus Protocol

• New Consensus Protocol:
  • Zug Consensus Protocol replaces Highway on the Casper network. Private/hybrid networks can choose between Highway or Zug.
  • Action Items: None.

8. Server-Sent Event (SSE) Endpoint Changes

• Event Stream Changes:
  • Structural changes to Block records and the transition from Deploy to Transaction model, as well as the addition of contract-level events, result in breaking changes to the event stream.
  • Changes include:
    • DeployProcessed becomes TransactionProcessed.
    • DeployExpired becomes TransactionExpired.
    • Verbs and behavioral semantics remain the same.
  • Action Items:
    • Update software and SDKs to handle the new event stream post-Condor.

For more details, you can refer to the following resources:

• Contract-level Messages
• Zug Consensus Protocol Design
• Zug Consensus Protocol Theory

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