Spotify's Honk background agent merges fleet-wide code migrations: 1,500+ PRs and counting

Spotify connected a background coding agent, later built on Claude Code, to its Fleet Management platform. It opens migration pull requests across many repositories at once. Review is now the bottleneck.

Organization: Spotify
Industry: Media & Streaming
When: Nov 2025
Evidence: Company reported
Agents and tools: Claude Code Fleet Management (internal)

Reported outcome

1,500+ merged AI-generated PRs; 1,000 merged PRs took three months at first and about ten days later on.

1,500+
Merged agent PRs
3 months → ~10 days
Time for 1,000 PRs

Caveats

Stated by the company that uses the agent (blog, earnings call, interview). Not independently audited.

Figures come from Spotify's engineering blog and conference talks.
Spotify says code review, not code generation, became the bottleneck.

What the agent does

A migration owner writes one prompt that describes the change. Honk runs it on every affected repository, runs the checks, and opens a pull request in each. Repository owners review and merge.

What Spotify learned

The first agent loop had trouble with complex, multi-file changes. Things improved after the team switched to Claude Code. With generation solved, Spotify had to change review: owners can approve their own migration PRs, stale PRs get closed, and a PR inbox helps prioritize.

What to copy

Put the agent behind an existing change-at-scale system, if you have one.
Fix review before you scale generation, or PRs pile up.
Write migration prompts like specs, with clear before/after examples.

Starter prompt

Written by us, not by Spotify.

Migration: replace {old_library_call} with {new_library_call}.

Before:
{before_example}

After:
{after_example}

Apply this in the current repository only. If the pattern appears in a
form not covered by the example, leave it unchanged and list it in the
PR description under "Needs human review".
Run the build and tests. Do not open a PR if they fail.