Add focused XCFramework slice builds

AGENTS.md

@@ -25,6 +25,17 @@ This project is in active development and contains multiple Swift packages with
 # Generates module interfaces for library evolution
 ```
 
+### Build a Local XCFramework Slice
+
+Use the slice helper for a faster iPhone Simulator arm64 Release build:
+
+```bash
+# Build the OpenSwiftUICore XCFramework slice.
+Scripts/build_xcframework_slice.sh osuicore
+# Build the OpenSwiftUI XCFramework slice and its Core dependency.
+Scripts/build_xcframework_slice.sh osui
+```
+
 ### Environment Variables
 The build system uses many environment variables for configuration:
 - `OPENSWIFTUI_BUILD_FOR_DARWIN_PLATFORM`: Build for Darwin platforms (default: true on macOS)

Scripts/build_xcframework.sh

@@ -28,6 +28,7 @@ SDKS=()
 SDK_ARCHS=()
 DEBUG_MODE=false
 RUN_TUIST_INSTALL=true
+CLEAN_DERIVED_DATA=true
 EXPLICIT_FRAMEWORK_NAMES=false
 FRAMEWORK_NAMES=()
 
@@ -51,6 +52,7 @@ Options:
   --debug                 Keep release metadata and copy dSYMs.
   --compute               Build OpenAttributeGraphShims with the Compute source backend.
   --skip-tuist-install    Skip tuist install.
+  --keep-derived-data     Reuse DerivedData from a previous build.
   --framework <name>      Build one framework. May be passed multiple times.
   --help                  Show this help.
 USAGE
@@ -92,6 +94,10 @@ while [[ $# -gt 0 ]]; do
             RUN_TUIST_INSTALL=false
             shift
             ;;
+        --keep-derived-data)
+            CLEAN_DERIVED_DATA=false
+            shift
+            ;;
         --framework)
             EXPLICIT_FRAMEWORK_NAMES=true
             FRAMEWORK_NAMES+=("$2")
@@ -543,7 +549,11 @@ copy_debug_symbols() {
     done
 }
 
-rm -rf "$DERIVED_DATA_PATH"
+if [ "$CLEAN_DERIVED_DATA" = true ]; then
+    rm -rf "$DERIVED_DATA_PATH"
+else
+    echo "Reusing DerivedData at $DERIVED_DATA_PATH"
+fi
 mkdir -p "$PROJECT_BUILD_DIR"
 
 for scheme in "${FRAMEWORK_NAMES[@]}"; do

Scripts/build_xcframework_slice.sh

@@ -0,0 +1,162 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd -P)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+
+KEEP_DERIVED_DATA=true
+SKIP_TUIST_INSTALL=false
+FRAMEWORK_NAMES=()
+
+# Rough planning estimates for a recent Apple Silicon Mac with dependencies
+# already installed. These are not benchmarks: Xcode/Swift versions, thermal
+# state, local/remote compilation caches, and the changed module all matter.
+#
+#                             Clean build      Warm no-change build
+#   OpenSwiftUICore           ~3-8 minutes     ~10-60 seconds
+#   OpenSwiftUI (plus Core)   ~5-12 minutes    ~20-90 seconds
+#
+# A Release source change, especially in OpenSwiftUICore, can invalidate most of
+# the target and bring a nominally warm build close to the clean-build range.
+print_usage() {
+    cat <<'USAGE'
+Usage: Scripts/build_xcframework_slice.sh [options] [osuicore|osui ...]
+
+Build a single-architecture Release XCFramework for local binary comparison.
+The default target is OpenSwiftUICore.
+
+Typical timing on a recent Apple Silicon Mac (rough planning estimates):
+  OpenSwiftUICore           clean ~3-8 min;  warm no-change ~10-60 sec
+  OpenSwiftUI (plus Core)   clean ~5-12 min; warm no-change ~20-90 sec
+A Release source change can make a warm build approach the clean-build range.
+
+Options:
+  --clean                 Discard DerivedData before building.
+  --skip-tuist-install    Skip tuist install.
+  --help                  Show this help.
+
+Targets:
+  osuicore, OpenSwiftUICore   Build OpenSwiftUICore.
+  osui, OpenSwiftUI           Build OpenSwiftUI.
+
+Examples:
+  Scripts/build_xcframework_slice.sh
+  Scripts/build_xcframework_slice.sh osui
+  Scripts/build_xcframework_slice.sh --clean osuicore osui
+USAGE
+}
+
+format_duration() {
+    local total_seconds="$1"
+    printf '%02d:%02d:%02d' \
+        "$((total_seconds / 3600))" \
+        "$(((total_seconds % 3600) / 60))" \
+        "$((total_seconds % 60))"
+}
+
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --help|-h)
+            print_usage
+            exit 0
+            ;;
+        --clean)
+            KEEP_DERIVED_DATA=false
+            shift
+            ;;
+        --skip-tuist-install)
+            SKIP_TUIST_INSTALL=true
+            shift
+            ;;
+        osuicore|OpenSwiftUICore)
+            FRAMEWORK_NAMES+=("OpenSwiftUICore")
+            shift
+            ;;
+        osui|OpenSwiftUI)
+            FRAMEWORK_NAMES+=("OpenSwiftUI")
+            shift
+            ;;
+        *)
+            echo "Error: Unknown argument: $1" >&2
+            print_usage >&2
+            exit 64
+            ;;
+    esac
+done
+
+if [ ${#FRAMEWORK_NAMES[@]} -eq 0 ]; then
+    FRAMEWORK_NAMES=("OpenSwiftUICore")
+fi
+
+build_args=(
+    --compute
+    --sdk iphonesimulator
+    --archs arm64
+)
+
+if [ "$KEEP_DERIVED_DATA" = true ]; then
+    build_args+=(--keep-derived-data)
+fi
+
+if [ "$SKIP_TUIST_INSTALL" = true ]; then
+    build_args+=(--skip-tuist-install)
+fi
+
+for framework_name in "${FRAMEWORK_NAMES[@]}"; do
+    build_args+=(--framework "$framework_name")
+done
+
+project_build_dir="${PROJECT_BUILD_DIR:-"$PROJECT_ROOT/build"}"
+if [[ "$project_build_dir" != /* ]]; then
+    project_build_dir="$PROJECT_ROOT/$project_build_dir"
+fi
+derived_data_path="$project_build_dir/DerivedData"
+
+if [ "$KEEP_DERIVED_DATA" = false ]; then
+    cache_state="cold (--clean requested)"
+elif [ -d "$derived_data_path" ]; then
+    cache_state="warm (reusing existing DerivedData)"
+else
+    cache_state="cold (no existing DerivedData)"
+fi
+
+display_command=(Scripts/build_xcframework.sh "${build_args[@]}")
+printf -v command_line '%q ' "${display_command[@]}"
+command_line="${command_line% }"
+
+started_at="$(date '+%Y-%m-%dT%H:%M:%S%z')"
+started_seconds=$SECONDS
+
+echo "Local XCFramework build started"
+echo "  Started:       $started_at"
+echo "  Cache state:   $cache_state"
+echo "  Frameworks:    ${FRAMEWORK_NAMES[*]}"
+echo "  Configuration: Release"
+echo "  Backend:       Compute"
+echo "  SDK:           iphonesimulator"
+echo "  Architectures: arm64"
+echo "  DerivedData:   $derived_data_path"
+echo "  Command:       $command_line"
+echo
+
+if "$SCRIPT_DIR/build_xcframework.sh" "${build_args[@]}"; then
+    build_status=0
+    result="succeeded"
+else
+    build_status=$?
+    result="failed (exit $build_status)"
+fi
+
+elapsed_seconds=$((SECONDS - started_seconds))
+finished_at="$(date '+%Y-%m-%dT%H:%M:%S%z')"
+
+echo
+echo "Local XCFramework build $result"
+echo "  Finished:          $finished_at"
+echo "  Elapsed:           $(format_duration "$elapsed_seconds")"
+echo "  Cache state:       $cache_state"
+echo "  Frameworks:        ${FRAMEWORK_NAMES[*]}"
+echo "  Completed command: $command_line"
+
+exit "$build_status"