OpenAI's Codex now runs an iOS development loop without leaving the agent environment. The Build iOS Apps plugin gives Codex the ability to view a live streaming simulator via Serve-sim, open SwiftUI previews through Sentry's SnapshotPreviews library, and hot reload code edits in real time.
This matters because the feedback loop between writing code and seeing it run on a simulated device has historically required context switches across Xcode, simulators, and separate tooling. Collapsing that into a single agent environment changes how Codex can autonomously iterate on UI code, not just generate it.
The technical stack here is worth examining closely. Serve-sim by Evan Bacon streams the simulator over a browser interface. SnapshotPreviews by Sentry extracts SwiftUI component previews without a full build. Both are open source. Read the original to see how these pieces connect inside the Codex plugin architecture.
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