Rnn Codebase Agent Skill

React Native Navigation Codebase

Architecture Overview

RNN has three layers that mirror each other:

JS/TS (src/)  →  TurboModule bridge  →  iOS native (ios/)
                                     →  Android native (android/)

A navigation command (e.g. push) flows:

• Navigation.push() → Commands.ts → processing pipeline → NativeCommandsSender.ts
• TurboModule: RNNTurboModule (iOS) / NavigationTurboModule.kt (Android)
• iOS: RNNCommandsHandler → RNNViewControllerFactory → UIKit controllers
• Android: Navigator → LayoutFactory → View-based controllers (no Fragments)

Read ARCHITECTURE.md for the full overview.

Key Cross-Layer Mappings

Layout Types → Native Controllers

| JS Layout Type | iOS Controller | Android Controller |

|----------------|---------------|-------------------|

| component | RNNComponentViewController | ComponentViewController |

| stack | RNNStackController (UINavigationController) | StackController |

| bottomTabs | RNNBottomTabsController (UITabBarController) | BottomTabsController |

| sideMenu | RNNSideMenuViewController (MMDrawerController) | SideMenuController (DrawerLayout) |

| topTabs | RNNTopTabsViewController | TopTabsController (ViewPager) |

| splitView | RNNSplitViewController | N/A (iOS only) |

| externalComponent | RNNExternalViewController | ExternalComponentViewController |

Options → Presenters

Each controller type has a Presenter that applies options to views:

| iOS Controller | iOS Presenter | Android Presenter |

|----------------|--------------|-------------------|

| RNNComponentViewController | RNNComponentPresenter | ComponentPresenter |

| RNNStackController | RNNStackPresenter + TopBarPresenter | StackPresenter |

| RNNBottomTabsController | RNNBottomTabsPresenter | BottomTabsPresenter |

| RNNSideMenuViewController | RNNSideMenuPresenter | SideMenuPresenter |

Events (same names both platforms)

| Event | Trigger |

|-------|---------|

| RNN.ComponentDidAppear | Screen becomes visible |

| RNN.ComponentDidDisappear | Screen hidden |

| RNN.NavigationButtonPressed | TopBar button tap |

| RNN.BottomTabSelected | Tab changed |

| RNN.ModalDismissed | Modal dismissed |

| RNN.ScreenPopped | Screen popped from stack |

| RNN.CommandCompleted | Any command finished |

Where to Find Things

By task: "I need to fix/change X"

| Task | JS File(s) | iOS File(s) | Android File(s) |

|------|-----------|------------|----------------|

| Command execution | src/commands/Commands.ts | ios/RNNCommandsHandler.mm | react/NavigationTurboModule.kt |

| Layout creation | src/commands/LayoutTreeParser.ts | ios/RNNViewControllerFactory.mm | options/LayoutFactory.java |

| Options processing | src/commands/OptionsProcessor.ts | ios/RNNNavigationOptions.mm | options/Options.java |

| Options application | — | ios/*Presenter.mm | viewcontrollers/*Presenter.java |

| TopBar | src/interfaces/Options.ts (TopBarOptions) | ios/TopBarPresenter.mm, ios/RNNUIBarButtonItem.mm | views/stack/topbar/ |

| Bottom tabs | src/interfaces/Options.ts (BottomTabsOptions) | ios/RNNBottomTabsPresenter.mm | viewcontrollers/bottomtabs/ |

| Modals | src/commands/Commands.ts | ios/RNNModalManager.mm | viewcontrollers/modal/ModalStack.java |

| Overlays | src/commands/Commands.ts | ios/RNNOverlayManager.mm | viewcontrollers/overlay/OverlayManager.kt |

| Animations | src/interfaces/Options.ts (AnimationOptions) | ios/ScreenAnimationController.mm | viewcontrollers/stack/StackAnimator.kt |

| React view rendering | — | ios/RNNReactView.mm | react/ReactView.java |

| Events to JS | src/adapters/NativeEventsReceiver.ts | ios/RNNEventEmitter.mm | react/events/EventEmitter.java |

| Component registration | src/components/ComponentRegistry.ts | — | — |

By directory

• src/ — JS public API, commands, processing pipeline. See src/ARCHITECTURE.md
• ios/ — All Obj-C/C++ native code. See ios/ARCHITECTURE.md
• ios/TurboModules/ — New architecture entry points (RNNTurboModule, RNNTurboManager, RNNTurboCommandsHandler)
• android/src/main/java/com/reactnativenavigation/ — All Java/Kotlin native code. See android/ARCHITECTURE.md
• playground/ — Demo app for development and E2E tests
• playground/src/screens/ — Test screens exercising every feature
• playground/e2e/ — Detox E2E tests

Options Resolution Order

Options are applied in ascending priority:

• Default options (from Navigation.setDefaultOptions()) — lowest priority
• Static options (from component class or Navigation.registerComponent)
• Options passed in the layout call (e.g. push, setRoot)
• mergeOptions() — runtime override, highest priority

JS Processing Pipeline (exact order)

API layout → OptionsCrawler.crawl() → LayoutProcessor.process()
  → LayoutTreeParser.parse() → LayoutTreeCrawler.crawl()
  → OptionsProcessor (colors, assets, custom) → NativeCommandsSender

iOS Patterns

• All controllers conform to RNNLayoutProtocol
• RNNBasePresenter subclasses apply options — applyOptionsOnInit:, applyOptions:, mergeOptions:resolvedOptions:
• Commands run on main thread (RCTExecuteOnMainQueue)
• React views: RNNReactView wraps RCTSurfaceHostingView (new arch)
• Overlays use separate UIWindow instances (RNNOverlayWindow)
• RNNReactComponentRegistry caches React component instances

Android Patterns

• View-based, NOT Fragment-based
• All commands dispatched via UiThread.post()
• ViewController<T extends ViewGroup> is the base — createView() is abstract
• ParentController extends ChildController extends ViewController
• Bottom tabs use AHBottomNavigation library
• Three root layouts in NavigationActivity: rootLayout, modalsLayout, overlaysLayout
• Tab attachment modes: Together, OnSwitchToTab, AfterInitialTab

Development Workflow

Playground app

• yarn start — Metro bundler
• yarn xcode — Open iOS project
• yarn studio — Open Android project
• yarn pod-install — Install iOS pods

Testing

• yarn test-js — Jest unit tests
• yarn test-unit-ios — iOS native unit tests (XCTest)
• yarn test-unit-android — Android native unit tests (JUnit + Robolectric)
• yarn test-e2e-ios-ci / yarn test-e2e-android-ci — Detox E2E tests

Building

• yarn prepare — Builds src/ → lib/ (ESM + types)
• Codegen config: rnnavigation in package.json

Common Gotchas

• iOS uses UIKit subclasses (UINavigationController, UITabBarController); Android uses custom View hierarchy
• splitView is iOS-only
• Side menu: iOS uses MMDrawerController (3rd party); Android uses DrawerLayout (native)
• Options that exist in JS types may not be implemented on both platforms — check the presenter
• passProps are stored in JS Store, not sent to native (cleared before bridge crossing)
• The lib/ folder is generated — never edit it, edit src/ instead