> Markdown version of [/events/world-congress-2026-north-america/sessions/1773-how-ai-agents](https://www.wearedevelopers.com/events/world-congress-2026-north-america/sessions/1773-how-ai-agents). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md).

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# How AI Agents Tripled Our Test Coverage on a 1.8M-Line iOS Codebase


- **Event:** World Congress 2026 North America

## Description

Duolingo's iOS app has nearly 1.8M executable lines and, until recently, test coverage that lagged far behind. We built an autonomous pipeline that writes unit tests and gets them to a merged state. Scheduled Temporal workflows pick untested code, Claude Code agents open real pull requests, and a lifecycle manager monitors CI, self-heals failures, runs AI review, and merges. Humans act only as final reviewers. The pipeline has merged over 85,000 lines of test code and tripled unit-test coverage of our MVVM components. This talk walks through the architecture, the guardrails that keep agent-written code trustworthy, the failure modes we hit, and how we are using the same skeleton for additional migrations across the company. You will walk away with a concrete blueprint for agents that ship code in a large production codebase.

## Speaker

### [Kush Agrawal](https://www.wearedevelopers.com/@kush-agrawal)

Staff Software Engineer, Platform


## Related talks at this congress

- [Agents Can't Iterate Against Tests That Lie](https://www.wearedevelopers.com/events/world-congress-2026-north-america/sessions/1700-agents-can-t-iterate) — Rocky Warren
- [When Agents Became Users: Rearchitecting Identity and Permissions for AI at Scale](https://www.wearedevelopers.com/events/world-congress-2026-north-america/sessions/1713-when-agents-became) — Yoav Gal, Dor Cohen
- [Closing the Visibility Gap: Lessons from Safety Critical Agentic Systems](https://www.wearedevelopers.com/events/world-congress-2026-north-america/sessions/1408-closing-the) — Vivek Pandit
- [AI-Powered Incident Triage: How We Built GenAI Agents with MCPs to Automate On-Call Workflows](https://www.wearedevelopers.com/events/world-congress-2026-north-america/sessions/1682-ai-powered-incident) — Prakshal Doshi

## Watch remotely

Can’t make it to San José? Watch this session live with Pro. You also get:

- All full videos, bookmarks, and playlists
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[See pricing](https://www.wearedevelopers.com/pricing)

## Links

- [Get tickets](https://www.wearedevelopers.com/world-congress-north-america/tickets)