feat(spm): B1 flavor architecture — per-config linking + RN-owned embed, no pin

Flavored prebuilt binaries (React, hermes-engine, ReactNativeDependencies)
leave the SwiftPM package graph. The generated ReactNative package vends only
headers-only products (ReactHeaders / ReactNativeHeaders /
ReactNativeDependenciesHeaders); both flavors' framework trees are staged at
add/update time and a per-configuration RN_SPM_FLAVOR build setting selects
one at build time via sdk-conditional link settings; embedding + codesign is
an RN-owned script phase with declared per-config outputs. A Debug/Release
configuration switch is green and flavor-correct on the FIRST build, both
directions, with zero user action.

The flavor pin, swap sandwich, hard-fail + converge, and OBJROOT cache
surgery are deleted (swap-flavor.js and its test suites removed; --flavor
gone from the CLI surface). New flavored-frameworks.js owns staging and
module-map relocation.

Verified: 448 spm unit tests green; Expo E2E on 0.87.0-nightly-20260710-b1test
(existing app + Swift source packages + precompiled frameworks via the
flavoredFrameworks contract): repeated CLI + GUI config flips green and
nm-flavor-correct first build every time, codesign --deep --strict clean,
SwiftOnoneSupport structurally moot, clean migration from the previous
architecture. Untested there: custom configuration names, device/Archive.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: chrfalch

packages/react-native/react-native.config.js

@@ -124,10 +124,6 @@ const spmCommand /*: Command */ = {
       description:
         'React Native version (e.g. 0.80.0). Defaults to the version in node_modules/react-native/package.json.',
     },
-    {
-      name: '--flavor <string>',
-      description: 'Artifact flavor: debug or release.',
-    },
     {
       name: '--yes',
       description: 'Skip the dirty-pbxproj confirmation prompt.',
@@ -152,8 +148,7 @@ const spmCommand /*: Command */ = {
     {
       name: '--artifacts <path>',
       description:
-        '[advanced] Local artifact source: a .xcframework file (used directly, ' +
-        'no download) or a directory (cache dir to read/download into).',
+        '[advanced] Local artifact root containing complete debug/ and release/ slots.',
     },
     {
       name: '--download <string>',
@@ -172,7 +167,6 @@ const spmCommand /*: Command */ = {
     }
     const stringOpts /*: Array<[string, string]> */ = [
       ['version', '--version'],
-      ['flavor', '--flavor'],
       ['productName', '--product-name'],
       ['xcodeproj', '--xcodeproj'],
       ['artifacts', '--artifacts'],

packages/react-native/scripts/codegen/templates/Package.swift.spm-template

@@ -12,14 +12,15 @@
 
 import PackageDescription
 
-// React headers need NO search paths: React/react namespaces come from the
-// React binaryTarget (auto -F; headers + module map inside the framework),
+// React headers need NO search paths: the React module comes from the
+// invariant ReactHeaders Clang target,
 // every other RN namespace from the ReactNativeHeaders binaryTarget
 // (pure-RN), the third-party deps namespaces (folly/glog/boost/...) from the
 // ReactNativeDependenciesHeaders sidecar, and the per-app generated headers
 // from the ReactAppHeaders target below — all auto-served by SPM through
 // product/target dependencies.
 let headersDep: [Target.Dependency] = [
+    .product(name: "ReactHeaders", package: "ReactNative"),
     .product(name: "ReactNativeHeaders", package: "ReactNative"),
     .product(name: "ReactNativeDependenciesHeaders", package: "ReactNative"),
     "ReactAppHeaders",
@@ -45,10 +46,7 @@ let package = Package(
     targets: [
         .target(
             name: "ReactCodegen",
-            dependencies: [
-                .product(name: "ReactNative", package: "ReactNative"),
-                .product(name: "ReactNativeDependencies", package: "ReactNative"),
-            ] + headersDep,
+            dependencies: headersDep,
             path: "ReactCodegen",
             exclude: ["ReactCodegen.podspec"],
             publicHeadersPath: ".",