Merge queues build up after parallel implementation
Several agents working in parallel produce several PRs. Integrating results one at a time creates a queue: a verified change can wait before it becomes available to the team.
Running CI for each PR repeats builds and tests. As PRs accumulate, integration waiting time and repeated runs consume resources after implementation has finished.
Group verified PRs into a single CI run
In the October 14, 2026 release, Merge Train groups verified PRs into one CI run before applying them to main, reducing the merge queue and CI costs.
Merge Train groups PRs that have passed verification. Task verification comes before the CI run that integrates those changes together.
The single CI run covers grouped integration; each task retains its verification step.
Reduce waiting and repeated runs together
Integrating verified results as a group lets ready work move forward together instead of waiting for individual turns.
For workflows that run CI for each PR’s integration, grouping reduces repeated runs. The release notes provide no measured savings rates.
When parallel work waits for integration, track how quickly verified results reach the shared branch alongside implementation speed.
When to use it
Consider Merge Train in these situations:
- Several agents work in parallel on one project: examine the stage where their verified PRs wait for integration.
- An improvement effort spans several PRs: consider a flow that integrates the verified results together.
- Merge waiting and repeated CI become a burden: address ready PRs' waiting time and the CI runs used for integration together.
Start with several verified PRs. Keep their status distinct from work still undergoing checks.
Connect it to integration in the closed loop
The closed loop connects assignment, verification, review, and merging within a mission. Merge Train handles grouped integration after the divided work has been verified.
Risk-based independent testers use a separate AI tester to verify important changes, including counterexamples. Use independent testers for verification and Merge Train for integrating the verified PRs.
The Marblo CI preview in Part 1 covers local verification and signed receipts. Merge Train groups verified PRs into a single CI run in this release.
In this series
- Marblo Build Notes 1 — The Closed Loop Release
- Marblo Build Notes 2 — Completing a Mission with the Closed Loop
- Marblo Build Notes 3 — Agent Mosaic
- Marblo Build Notes 4 — Orchebrain
- Marblo Build Notes 5 — Web Tabs
- Marblo Build Notes 6 — Merge Train
- Marblo Build Notes 7 — Multiple AI Accounts
- Marblo Build Notes 8 — Risk-Based Independent Testers
- Marblo Build Notes 9 — Telegram Conversations with the Orchestrator