[!todo] Seed note. A starting point, not a finished note yet.
A merge queue takes approved PRs and merges them one at a time, re-running CI against the actual post-merge state of the trunk before each lands. It fixes the semantic-conflict problem: two PRs can each pass CI in isolation yet break the build when combined, because neither was tested against the other. GitHub, GitLab, and tools like Mergify and Bors provide it. The relevance to the Code Review Tooling Market - GitHub, GitLab, and the PR Review Bottleneck: it automates the integration half of the delivery constraint, so a busier review pipeline does not translate into a broken main branch. It pairs naturally with Trunk-Based Development and small batch sizes. Seeded from Code Review Tooling Market - GitHub, GitLab, and the PR Review Bottleneck.