CAP Process and Lifecycle

The Core Advancement Proposal (CAP) process is the formal governance pathway for modifying the Stellar protocol. It governs changes to the Stellar Core node software, the underlying consensus mechanism, and the transaction processing rules that all validators must follow. For protocol engineers and node operators, the CAP lifecycle is not merely a documentation standard; it is the primary signal for upcoming mandatory upgrades, breaking changes to the XDR transaction format, and new ledger header protocol versions that require coordinated activation to prevent network divergence.

A CAP progresses through a defined sequence of states—starting as a draft, moving through a review and consensus-building phase, and culminating in a validator vote to upgrade the network. The process is shepherded by a CAP Champion, who is responsible for building technical consensus, while the Stellar Development Foundation (SDF) often plays a coordinating role in shepherding proposals to implementation in Stellar Core. The final activation gate is a validator-led vote using the setoption operation to upgrade the protocolVersion, making the change binding on all compliant nodes. Understanding this lifecycle is critical for anticipating when compatibility testing, integration updates, and operational changes must be completed.

For builders and operators, the CAP process is the leading indicator of protocol-level risk. A CAP that introduces a new transaction envelope format or modifies the Soroban host environment's resource pricing directly impacts wallet SDKs, exchange integrations, and smart contract deployment costs. Monitoring the CAP pipeline allows teams to perform proactive impact assessments, participate in technical discussions before a change is locked in, and prepare their infrastructure for testnet and mainnet activation. Chainscore Labs supports this readiness by providing protocol impact assessments, upgrade compatibility reviews, and integration testing for teams that need to act on a CAP before it reaches the validator voting stage.

The Core Advancement Proposal (CAP) process is the formal mechanism for evolving the Stellar protocol. It governs how changes to the Stellar Core codebase, the Soroban smart contract environment, and the underlying XDR transaction schema are proposed, debated, and ultimately adopted by the network's validators. Understanding this lifecycle is critical for node operators and protocol engineers who must anticipate breaking changes, schedule mandatory upgrades, and ensure compatibility before a new protocol version is signaled in the ledger header.

A CAP begins as a draft championed by a community member or a Stellar Development Foundation (SDF) engineer. The proposal must precisely define the motivation, technical specification, and rationale for the change. The lifecycle progresses through distinct states—Draft, Proposed, Accepted, Final, and Rejected—with each transition requiring a consensus-driven decision by the CAP Core Team, a group of protocol stewards. For protocol-level changes that alter consensus rules or transaction validity, the final step is a validator vote to upgrade the network. This is not a simple software release; validators must coordinate to set the upgrade flag in the ledger header, triggering a synchronous protocol version bump across the network.

The operational impact of a CAP is determined by its type. A change to the transaction envelope format or a new operation type requires SDK and wallet developers to update their XDR parsing and transaction construction logic. A Soroban environment upgrade, such as a change to the WASM metering model or host function costs, directly impacts smart contract execution costs and may require developers to re-benchmark their contracts. Node operators must monitor the lifecycle closely: once a CAP reaches 'Final' status and is included in a Stellar Core release, the window for testing and integration begins. Failure to upgrade before the validator vote deadline results in ledger divergence and an effective loss of consensus participation. Chainscore Labs provides upgrade readiness reviews and integration impact assessments to help teams navigate this critical window without disrupting their services.