# Expo's Exact: a cross-platform app runtime built for AI agents to build, run and test

Canonical: https://theagenticweekly.com/news/expo-exact-agent-native-cross-platform-runtime · Evidence: Reported · First seen: 2026-11-11 00:30 UTC · Source published: 2026-11-02 01:29 UTC · Brief published: 2026-11-11 06:09 UTC · Updated: 2026-11-11 06:09 UTC · Author: Agentic Weekly

> Exact, an MIT-licensed project in Expo's GitHub organization created on Nov 2, 2026, says it lets you "Write an app once" and run it natively on the web, macOS, iOS and Linux. Agents drive every host through ten operations; the README says it is pre-1.0 and "changes daily."

## What changed

- Exact is a cross-platform runtime: the interface is written in Contract, a small declarative language, and data logic in TypeScript or Rust. The compiler turns the interface into a plan that runs on the web over a roughly 20 KB runtime driving the real DOM.
- On macOS, iOS and Linux a Rust runner executes the same plan with a Rust layout kernel using CSS rules, drawing with AppKit, UIKit or a GPU painter. The README says there is no webview and no JavaScript bridge in the UI.
- Agents get ten operations that work the same on every host (tree, screenshot, tap, type, state, layout, logs, clock, prefer, perf) through one script, scripts/agent.mjs. The README notes the predecessor's agent API had grown to eighty wire names.
- The agent controls the clock: nothing moves between operations, so tests advance time with commands like clock +60000 instead of sleeping. An app.test.contract test file runs unchanged on any host.
- The README's tracked budgets include 100 ms p50 cold start to first interactive frame and 100 ms p50 edit-to-present dev restart. It reports a fresh agent built a tested to-do list app on three platforms in about 57 minutes in an Oct 4 run.
- Status: pre-1.0 with no API stability, backwards compatibility or migration guide by design. The repo had 2,361 GitHub stars when we checked, nine days after it was created.

## In the source's words

> "There is no webview and no JavaScript bridge in the UI, and no app JavaScript runs before the first pixel."
> (expo/exact README, https://github.com/expo/exact)

## What we have not verified

- We did not build or run an Exact app; performance budgets and the 57-minute agent run are the README's own claims.
- The README does not state that Exact is an official Expo product or give a roadmap; we only confirmed the repository sits in the expo GitHub organization.
- Android and Windows support are not described in the parts of the README we read.
- The star count is a snapshot from the GitHub API on Nov 11, 2026.

## Timeline

- Source published: 2026-11-02 01:29 UTC
- First seen by our watcher: 2026-11-11 00:30 UTC (via GitHub new repos: topic ai-agents)
- Brief published: 2026-11-11 06:09 UTC

## Sources

- [GitHub: expo/exact README](https://github.com/expo/exact) (primary source) (fetched 2026-11-11)

## Related

- [All news briefs](https://theagenticweekly.com/news)
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## How to cite

Agentic Weekly, "Expo's Exact: a cross-platform app runtime built for AI agents to build, run and test", published 2026-11-11 06:09 UTC, https://theagenticweekly.com/news/expo-exact-agent-native-cross-platform-runtime