[antonis]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

isExpoFetchEnabled() checks for the expo.builtin marker on globalThis.fetch. In Expo Router apps, @expo/metro-runtime wraps fetch to support relative URLs, and before 58.0.15 the wrapper dropped that marker. The SDK then misses expo/fetch, so fetch tracing and fetch breadcrumbs stay off by default.

When the marker is missing, isExpoFetchEnabled() now also returns true if:

• globalThis.fetch has the wrapper's own marker (expo.polyfillFetchWithWindowLocation),
• the Expo SDK is 56 or later (the first SDK that installs expo/fetch), read from the native ExponentConstants.manifest (a JSON string on Android), and
• the app hasn't opted out with EXPO_PUBLIC_USE_RN_FETCH. It's read the same way as Expo's own runtime, so both resolve the same value after babel-preset-expo.

If any of these can't be determined, it returns false, which is the previous behavior.

This also applies the expo/fetch HTTP timings default from #6912 to these apps, so traceFetch: true no longer needs enableHTTPTimings: false to avoid leaking listeners.

💡 Motivation and Context

Fixes #6874

💚 How did you test it?

• Unit tests for isExpoFetchEnabled(): SDK 56/57/58, SDK 55, unknown SDK version, manifest as a JSON string and as invalid JSON, EXPO_PUBLIC_USE_RN_FETCH set to 1, true and 0.
• Expo sample:
  • Before: a traced fetch produced no http.client span and no fetch breadcrumb.
  • After: one http.client span without HTTP timings, and a fetch breadcrumb.
  • With EXPO_PUBLIC_USE_RN_FETCH=1: one http.client span from XHR and only an xhr breadcrumb (no duplicate).

📝 Checklist

• I added tests to verify changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• All tests passing.
• Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec.
• No breaking changes.

🔮 Next steps

[github-actions]

Semver Impact of This PR

⚪ None (no version bump detected)

📋 Changelog Preview

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• fix(tracing): Detect expo/fetch behind the Expo Router fetch wrapper by antonis and claude in #6965

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📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
Sentry RN	io.sentry.reactnative.sample	8.33.0 (113)	Release

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