Stellar Core developers discussed replacing the variable rent balance system with a fixed expiration ledger approach for state expiration. The new model simplifies user experience and downstream system integration by storing a single expiration ledger per entry instead of periodically deducting variable rent fees.
In this technical discussion, Garen from Stellar Core presented a major proposal to shift from a variable rent balance model to a fixed expiration ledger system for managing state expiration on Soroban. The rent balance approach charged variable fees each ledger based on bucket list size, creating unpredictable entry lifetimes and complex downstream system requirements. The expiration ledger model instead locks in a rent fee at creation time and stores a single expiration ledger value, making lifetimes predictable and simplifying integration for systems like Horizon. Key tradeoffs discussed include preventing exploits through maximum lifetime caps, handling auto-bumps for shared resources like contract WASM, and managing edge cases like entry resizing. The team debated whether to expose configuration flags for auto-bump behavior and whether contract data should default to auto-bumping, ultimately leaning toward simpler defaults with potential future configurability.