Test a predicted future mainline
Merge trains verify cumulative states such as A, A+B and A+B+C before any of them reaches main.
Trade-off: Speculative checks consume CI and later checks may need to restart.
Tool / Merge queue
Mergify Parallel Queue
Dependency-aware parallel merges and speculative verification.
The summary describes what the project says it does; inclusion is not an endorsement.
Approaches it illustrates
Declare the boundaries of independence
Scope-aware queues allow separate areas to move concurrently while still ordering overlapping work.
Trade-off: Scope maps can miss dependencies that cross a module boundary.