Alex Hunt

This commit introduces a **new capability** to the **React Native development experience** by adding a visual marker to the performance timeline. It modifies the **Fast Refresh** mechanism within `HMRClient.js` to emit a prominent "Fast Refresh ⚛︎" entry when an update completes. This **feature addition** provides developers with a clearer, vertical indication of Fast Refresh cycles in their performance tools. The change significantly improves the observability and debugging of application updates during development, making it easier to track when code changes are applied.

This commit **implements dynamic sampling for frame screenshots** within the **iOS performance tracing** system, porting an existing optimization from Android. It enhances the `RCTFrameTimingsObserver.mm` by introducing an **encoding queue** and **buffering mechanism** that uses an `encodingInProgress` atomic flag to manage screenshot encoding. This intelligent approach allows the system to **skip screenshot encoding** when the encoder is busy, while consistently emitting frame timing events. This **performance optimization** prevents truncated trace data on slower devices and significantly **reduces recording overhead**, leading to more reliable and less intrusive developer tooling for performance analysis.

This commit **enhances iOS screenshot recording** within the **DevSupport** module by **increasing the screenshot scale factor** from 0.75 to 1.0 for **frame timings observation**. This **feature enhancement** brings **iOS** screenshot fidelity to **parity with Android**, providing clearer visuals for performance analysis. However, this higher resolution significantly **increases processing overhead**, making dynamic frame sampling more critical for maintaining performance.

This commit introduces a **new feature** to the **debugger-shell** module, specifically enhancing its **Electron window management**. It **sets minimum width and height dimensions** for the debugger-shell's Electron window, preventing it from being resized to an unusable size. This change, implemented within `packages/debugger-shell/src/electron/MainInstanceEntryPoint.js` via the `handleLaunchArgs` function, improves the user experience by ensuring the debugger interface remains consistently accessible and functional.

This commit **fixes a critical stability issue** in the **JavaScript Inspector's modern tracing subsystem** where large trace events, particularly Frame Timing data containing screenshots, could exceed WebSocket message size limits and cause app crashes. It replaces the previous count-based chunking with **size-based chunking** (max 10 MiB) for `emitFrameTimings()` and `emitPerformanceTraceEvents()` within `HostTracingProfileSerializer`. To achieve this efficiently, a new `TraceEventSerializer::estimateJsonSize()` utility was introduced to approximate the serialized byte size of `folly::dynamic` values without double-serialization. This **bug fix** significantly improves the reliability of **developer tooling** by preventing crashes during performance tracing sessions involving large data.

This commit **enhances the quality of trace screenshots** within the **Android developer support tools**. It **increases the screenshot scale factor** from `0.75f` to `1.0f` in the `FrameTimingsObserver.kt` file, directly impacting the visual fidelity of debugging information. This **feature improvement** provides **higher resolution visual debugging aids** for developers, making performance traces and UI issues clearer on **Android**. The change specifically targets the screenshot functionality used during frame timing observations.

This commit introduces **dynamic sampling** for **Android frame screenshots** within the **React Native development support inspector**, specifically in `FrameTimingsObserver.kt`. This **new capability** optimizes trace data collection by limiting screenshot encoding to a single background thread and conditionally capturing images, preventing truncated traces and reducing recording overhead on slower devices. While always emitting frame timing events, it intelligently buffers the last frame to ensure settled animation states are captured, thereby improving the reliability and performance of tracing without blocking the UI.

This commit introduces **pixel diffing** to the **`RCTFrameTimingsObserver`** on **iOS**, enabling it to compare pixel hashes and avoid encoding duplicate screenshots. This **new capability** prevents unnecessary JPEG encoding and CDP transport for frames that haven't visually changed, significantly **reducing overhead** in the **DevSupport** system. By sampling pixels and using a fast FNV-1a hash, this **optimization** ensures that only visually distinct frames are processed, aligning the iOS implementation with existing Android behavior and improving the efficiency of frame timing observations.

This commit introduces a **new capability** to **iOS performance tracing** by implementing Chrome DevTools Protocol (CDP) support for the Frames track, including **screenshot capture** during a performance trace. It adds `RCTFrameTimingsObserver` to capture frame timings and visual updates, integrating it with `RCTHost` to enable this functionality when tracing starts and stops. This feature, mirroring existing Android support, captures the key window, resizes screenshots to 0.75 scale with JPEG compression, and processes them on a background thread. This significantly enhances the **debugging and performance analysis** tools available for React Native applications on iOS, providing visual context to performance bottlenecks.

This commit **updates the `debugger-frontend` package** to synchronize with the latest upstream changes from the `react-native-devtools-frontend` repository. It specifically incorporates the **formalization of the `ENABLE_TIMELINE_FRAMES` experiment**, which enhances the debugger's timeline analysis capabilities. This is a **maintenance update** and a resubmission of a previously reverted change, ensuring the React Native DevTools frontend is current. The update impacts the **debugger's timeline functionality**, potentially introducing new experimental features for analyzing frame data within the DevTools.

This commit **updates** the **React Native debugger frontend** to a newer version, incorporating recent changes from its upstream `react-native-devtools-frontend` repository. This **maintenance update** specifically formalizes the `ENABLE_TIMELINE_FRAMES` experiment, which is expected to introduce new or improved **timeline profiling capabilities** for React Native applications. The `packages/debugger-frontend/BUILD_INFO` file is updated to reflect the new Git revision, ensuring the debugger uses the latest upstream features and fixes.

This commit introduces a new **feature flag**, `fuseboxFrameRecordingEnabled`, across **React Native's Android, C++, and JavaScript layers**. This **refactoring** replaces the previous `globalThis.enableTimelineFrames` mechanism with a more robust, backend-gated system for **controlling frame recording** in the DevTools CDP backend. The `FrameTimingsObserver` initialization in the **Android runtime** is now gated by this flag, enabling safer iteration and per-app rollout of this **developer tooling** functionality. This change improves **maintenance** and provides more granular control over a critical **performance profiling** feature.

This commit **refactors** the **Android FrameTimings** screenshot capture and serialization process to **optimize memory usage and JNI transfer efficiency**. Instead of immediately Base64 encoding screenshots upon capture, the system now stores them as raw binary `ByteArray` or `std::vector<uint8_t>` within the `FrameTimingSequence` data structure. The Base64 encoding is deferred until the trace event is generated by `TraceEventGenerator`, significantly **reducing the size of the trace buffer** and eliminating costly string copies during JNI communication. This internal change improves performance within the **JS Inspector Modern tracing** subsystem without altering the final trace event format.

This commit **restores** the `unstable_onHostTargetAdded` listener callback within the `addPage` function in `packages/react-native/ReactCommon/jsinspector-modern/InspectorInterfaces.cpp`. This **bug fix** addresses an accidental removal, ensuring that the **InspectorInterfaces** module correctly notifies listeners when a new page is added. The restoration is critical for the proper functioning of the **`fuseboxAssertSingleHostState` feature** in the React Native DevTools frontend, which relies on these notifications to maintain host state integrity.

This commit **fixes a bug** in the **CI/CD workflow** by correcting conditional expressions within the `.github/workflows/test-all.yml` file. Previously, `test-all` jobs for Android and iOS were not reliably executing outside of Pull Requests due to a missing `== 'true'` specifier in their conditional logic. This **maintenance change** ensures that these critical **integration tests** now run as intended on branches like `main`, allowing the project to **catch rare integration-conflict failures** at the appropriate commit. The fix improves the robustness and coverage of the automated testing pipeline.

Add error when running build script after prepack (#55914)

This commit **refactors** the internal C++ codebase by **relocating** the `base64Encode` utility function. Previously vendored, this function is now moved to `ReactCommon/react/utils/Base64.h` to establish a common, reusable location for base64 encoding logic. This **internal architectural improvement** allows other C++ packages within `ReactCommon` to easily access and reuse the `base64Encode` functionality. The `jsinspector-modern` module is updated to reflect this new path, demonstrating the immediate benefit of improved code organization and reusability across the project's C++ components.

This commit **restores request body previews** within **React Native DevTools for Android**, specifically for network requests handled by `ProgressRequestBody` that previously displayed "[Preview unavailable]". It introduces a new utility function, `NetworkEventUtil.getRequestBodyPreview`, to safely generate these previews by checking for one-shot bodies and truncating content, thereby preventing a known runtime crash with `FormData` uploads. The `NetworkingModule`'s `onCreateRequest` method is updated to utilize this new function, ensuring previews are available in debug builds. This **feature restoration** significantly enhances the **debugging experience** for network requests on Android while maintaining stability against previous crash scenarios.

This commit **refactors** the **React Native Android networking module** by updating the signature of `NetworkEventUtil.onCreateRequest` and removing legacy `onCreateRequest` and `onResponseReceived` overloads. This **internal API cleanup** effectively "de-OkHttp-s" the `NetworkEventUtil` to reduce specific network library dependencies. The `NetworkingModule` is updated to reflect these changes, ensuring continued functionality while simplifying the underlying network event handling. This work improves maintainability and prepares the module for future architectural evolutions without affecting external consumers.

This commit introduces a **robust mocking strategy** for the `DefaultToolLauncher` within the **`dev-middleware` package** to prevent unintended debugger shell and browser launches during tests. It **fixes a critical testing bug** where real tool launches caused unwanted side effects and flakiness, likely introduced by a previous change. A new mock implementation for `DefaultToolLauncher` is added, and runtime checks are integrated into `DefaultToolLauncher.js` to **enforce that its methods are always mocked in test environments**, significantly improving test stability and developer experience. This ensures that `launchDebuggerAppWindow` and `launchDebuggerShell` are properly stubbed across the test suite.