Legacy mobile appKept moving, agents since mid-2025
A ten-year-old mobile app, kept moving with agent-written pull requests.
A consumer app for Android and iOS, in production for over ten years, with a codebase of several thousand commits from about twenty contributors. Its developers now hand part of the work to agents through ProPR: more than 110 agent-written pull requests merged, about 75 of them in a single month.
This project is private. It is described here with its owner's permission, with identifying details left out.
Public record
What it is
A consumer mobile app that people have relied on for more than a decade. It ships to both app stores from one hybrid codebase, built with web technology and wrapped for Android and iOS. Ten years of releases means ten years of decisions, workarounds and platform changes layered on top of each other.
Most teams work on a codebase like this one: no empty repository, no fresh plan, and an app that must keep working for its users while it changes.
Where it started
Agent-written pull requests began in mid-2025, alongside the app's own developers, who kept working as before. The agents took a share of the backlog. The busiest stretch came in August 2026, when about 75 agent-written pull requests merged in one month.
The agents varied as the work went on, from GPT-5.6 Sol to Claude Opus and Claude Opus 5.5, and the pull requests went through the same review whichever model wrote them.
Which tasks suit an agent in an old codebase
The work started as issues, written requests that an agent turned into pull requests for a developer to read. The tasks that worked best were bounded and verifiable, and many were repetitive across many files.
- Adding whole new languages across the app.Repetitive across many files, with a clear finish line: every screen reads correctly in the new language.
- Fixing Android-version-specific layout and lifecycle bugs.Bounded to one platform version and one behaviour, and easy to confirm on the device that showed the bug.
- Dark-mode and UI polish.Visual, so the pull request can be checked by looking at the screens.
- Crash and error-handling fixes.Each starts from a stack trace that names the cause, and the same trace shows whether the fix worked.
None of these needs the agent to understand all ten years at once, only the screen, platform version or crash in front of it, and ProPR gathers that context from the repository before the agent starts.
How review keeps a production app safe
Nothing reaches the app's users until a developer merges the pull request. The agent works on its own branch and holds a read-only connection to GitHub; ProPR opens the pull request, and a person decides what happens next.
The pull request shows every line that changed, which is what makes a ten-year-old codebase safe to touch. A developer who knows the app's history reads the change. If it misses a workaround from years ago, one comment asks for the fix, and the agent answers with a follow-up commit on the same branch. When the change is right, the developer merges it, and the app's normal release process takes it from there.
If a merged change misbehaves on a device nobody tested, GitHub's Revert button on that pull request opens a new one that takes it back out, and a developer reviews that too. How review works in ProPR.
The numbers, as of 11 November 2026.
Rounded counts from the private repository, shared with the owner's permission.
What this shows for an app of your own
You do not need a new codebase to start. Pick the bounded, verifiable work, such as a new language, a platform-specific bug, a dark-mode pass or a crash with a stack trace, write it up as issues, and let the people who know the app review what the agent opens.
Your developers keep working as they always have, while the agents take the backlog nobody gets to and deliver it in the same shape, ready for the same review.
ProPR for mobile apps, and for your own server, self-host ProPR.
Two walkthroughs show the path step by step: modernise an older codebase, tests first, and build a mobile app from an empty repository.