Collaborator or Assistant? How AI Coding Agents Partition Work Across Pull Request Lifecycles
This program is tentative and subject to change.
AI coding agents can now open branches, write code, and submit pull requests (PRs). Despite these advancements, we still know little about how agents and humans share responsibilities across the full PR lifecycle. This study analyzes 29,585 PRs from five AI coding tools: OpenAI, Copilot, Devin, Cursor, and Claude Code. Using an Initiator × Approver taxonomy with 6 interaction scenarios, the analysis distinguishes between the PR initiator and the entity with authority to merge it. The observed patterns fall along a Collaborator–Assistant spectrum. In Collaborator tools (Cursor, Devin, Copilot), agents typically initiate PRs that are subsequently reviewed by humans. In contrast, with Assistant tools (OpenAI, Claude), humans initiate most PRs, and a significant proportion are merged without a recorded review step. Across all tools, operational agency and governance authority diverge: agents initiate over 96% of Collaborator PRs, yet less than 0.1% of merges are authorized by agents or automation without explicit human approval. Detailed analysis of all 54 automation‑authorized merges highlights a measurement boundary: event logs indicate who executed the merge, but not who made the decision. This work introduces a lifecycle taxonomy and per‑tool state machines and provides a replication package to support future research on the interplay between automation, oversight, and governance in PR workflows.