Signed-off-by: Matt Bruce <mbrucedogs@gmail.com>

Agents.md

@@ -419,40 +419,182 @@ If you need different formats for different purposes:
 - Name constants semantically: `accent` not `pointSix`, `large` not `sixteen`.
 
 
-## App Identifiers
+## App Identifiers (xcconfig)
 
-**Centralize all company-specific identifiers** in a single configuration file for easy migration.
+**Centralize all company-specific identifiers** using xcconfig files for true single-source configuration. This enables one-line migration between developer accounts.
 
-### Structure
+### Why xcconfig?
+
+- **Single source of truth**: Change one file, everything updates
+- **Build-time resolution**: Bundle IDs, entitlements, and Swift code all derive from same source
+- **No manual updates**: Entitlements use variable substitution
+- **Environment support**: Easy Debug/Release/Staging configurations
+
+### Setup Instructions
+
+#### Step 1: Create xcconfig Files
+
+Create `Configuration/Base.xcconfig`:
+
+```
+// Base.xcconfig - Source of truth for all identifiers
+// MIGRATION: Update COMPANY_IDENTIFIER and DEVELOPMENT_TEAM below
+
+// =============================================================================
+// COMPANY IDENTIFIER - CHANGE THIS FOR MIGRATION
+// =============================================================================
+
+COMPANY_IDENTIFIER = com.yourcompany
+APP_NAME = YourAppName
+DEVELOPMENT_TEAM = YOUR_TEAM_ID
+
+// =============================================================================
+// DERIVED IDENTIFIERS - DO NOT EDIT
+// =============================================================================
+
+APP_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)
+WATCH_BUNDLE_IDENTIFIER = $(APP_BUNDLE_IDENTIFIER).watchkitapp
+APPCLIP_BUNDLE_IDENTIFIER = $(APP_BUNDLE_IDENTIFIER).Clip
+TESTS_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)Tests
+UITESTS_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)UITests
+
+APP_GROUP_IDENTIFIER = group.$(COMPANY_IDENTIFIER).$(APP_NAME)
+CLOUDKIT_CONTAINER_IDENTIFIER = iCloud.$(COMPANY_IDENTIFIER).$(APP_NAME)
+
+APPCLIP_DOMAIN = yourapp.example.com
+```
+
+Create `Configuration/Debug.xcconfig`:
+
+```
+// Debug.xcconfig
+#include "Base.xcconfig"
+// Add debug-specific settings here
+```
+
+Create `Configuration/Release.xcconfig`:
+
+```
+// Release.xcconfig
+#include "Base.xcconfig"
+// Add release-specific settings here
+```
+
+#### Step 2: Configure Xcode Project
+
+In `project.pbxproj`, add file references and set `baseConfigurationReference` for each build configuration:
+
+1. Add xcconfig file references to PBXFileReference section
+2. Set `baseConfigurationReference` on Debug/Release configurations
+3. Replace hardcoded values with variables:
+
+```
+PRODUCT_BUNDLE_IDENTIFIER = "$(APP_BUNDLE_IDENTIFIER)";
+DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
+INFOPLIST_KEY_WKCompanionAppBundleIdentifier = "$(APP_BUNDLE_IDENTIFIER)";
+```
+
+#### Step 3: Update Entitlements
+
+Use variable substitution in `.entitlements` files:
+
+```xml
+<key>com.apple.developer.icloud-container-identifiers</key>
+<array>
+    <string>$(CLOUDKIT_CONTAINER_IDENTIFIER)</string>
+</array>
+<key>com.apple.security.application-groups</key>
+<array>
+    <string>$(APP_GROUP_IDENTIFIER)</string>
+</array>
+```
+
+#### Step 4: Bridge to Swift via Info.plist
+
+Add keys to `Info.plist` that bridge xcconfig values to Swift:
+
+```xml
+<key>AppGroupIdentifier</key>
+<string>$(APP_GROUP_IDENTIFIER)</string>
+<key>CloudKitContainerIdentifier</key>
+<string>$(CLOUDKIT_CONTAINER_IDENTIFIER)</string>
+<key>AppClipDomain</key>
+<string>$(APPCLIP_DOMAIN)</string>
+```
+
+#### Step 5: Create Swift Interface
 
 Create `Configuration/AppIdentifiers.swift`:
 
 ```swift
+import Foundation
+
 enum AppIdentifiers {
-    // MARK: - Company Identifier (CHANGE THIS FOR MIGRATION)
+    // Read from Info.plist (values come from xcconfig)
-    static let companyIdentifier = "com.yourcompany"
+    static let appGroupIdentifier: String = {
+        Bundle.main.object(forInfoDictionaryKey: "AppGroupIdentifier") as? String
+            ?? "group.com.yourcompany.AppName"
+    }()
+    
+    static let cloudKitContainerIdentifier: String = {
+        Bundle.main.object(forInfoDictionaryKey: "CloudKitContainerIdentifier") as? String
+            ?? "iCloud.com.yourcompany.AppName"
+    }()
+    
+    static let appClipDomain: String = {
+        Bundle.main.object(forInfoDictionaryKey: "AppClipDomain") as? String
+            ?? "yourapp.example.com"
+    }()
+    
+    // Derived from bundle identifier
+    static var bundleIdentifier: String {
+        Bundle.main.bundleIdentifier ?? "com.yourcompany.AppName"
+    }
     
-    // MARK: - Derived Identifiers
-    static var bundleIdentifier: String { "\(companyIdentifier).AppName" }
     static var watchBundleIdentifier: String { "\(bundleIdentifier).watchkitapp" }
     static var appClipBundleIdentifier: String { "\(bundleIdentifier).Clip" }
-    static var appGroupIdentifier: String { "group.\(companyIdentifier).AppName" }
+    
-    static var cloudKitContainerIdentifier: String { "iCloud.\(companyIdentifier).AppName" }
+    static func appClipURL(recordName: String) -> URL? {
+        URL(string: "https://\(appClipDomain)/appclip?id=\(recordName)")
+    }
 }
 ```
 
-### Usage
+### Data Flow
 
-- Always use `AppIdentifiers.*` instead of hardcoding bundle IDs or container names.
+```
-- `AppIdentifiers.companyIdentifier` is the single source of truth.
+Base.xcconfig (source of truth)
-- All other identifiers derive from it automatically.
+    ↓
+project.pbxproj (baseConfigurationReference)
+    ↓
+Build Settings → Bundle IDs, Team ID, etc.
+    ↓
+Info.plist (bridges values via $(VARIABLE))
+    ↓
+AppIdentifiers.swift (Swift reads from Bundle.main)
+```
+
+### Usage in Code
+
+```swift
+// Always use AppIdentifiers instead of hardcoding
+FileManager.default.containerURL(
+    forSecurityApplicationGroupIdentifier: AppIdentifiers.appGroupIdentifier
+)
+
+CKContainer(identifier: AppIdentifiers.cloudKitContainerIdentifier)
+```
 
 ### Migration
 
-When migrating to a new developer account:
+To migrate to a new developer account, edit **one file** (`Base.xcconfig`):
-1. Change `companyIdentifier` in `AppIdentifiers.swift`
+
-2. Update entitlements files manually (cannot be tokenized)
+```
-3. Update bundle IDs in Xcode project settings
+COMPANY_IDENTIFIER = com.newcompany
+DEVELOPMENT_TEAM = NEW_TEAM_ID
+```
+
+Then clean build (⇧⌘K) and rebuild. Everything updates automatically.
 
 
 ## Dynamic Type Instructions

BusinessCard.xcodeproj/project.pbxproj

@@ -54,6 +54,10 @@
 		EA8379302F105F2800077F87 /* BusinessCardTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = BusinessCardTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		EA83793A2F105F2800077F87 /* BusinessCardUITests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = BusinessCardUITests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		EA837F982F11B16400077F87 /* BusinessCardWatch Watch App.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = "BusinessCardWatch Watch App.app"; sourceTree = BUILT_PRODUCTS_DIR; };
+		EACONFIG0012F200000000001 /* Base.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = Base.xcconfig; sourceTree = "<group>"; };
+		EACONFIG0012F200000000002 /* Debug.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = Debug.xcconfig; sourceTree = "<group>"; };
+		EACONFIG0012F200000000003 /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = Release.xcconfig; sourceTree = "<group>"; };
+		EACONFIG0012F200000000004 /* Watch.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = Watch.xcconfig; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFileSystemSynchronizedBuildFileExceptionSet section */
@@ -387,6 +391,7 @@
 /* Begin XCBuildConfiguration section */
 		EA8379422F105F2800077F87 /* Debug */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = EACONFIG0012F200000000002 /* Debug.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
@@ -420,7 +425,7 @@
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				COPY_PHASE_STRIP = NO;
 				DEBUG_INFORMATION_FORMAT = dwarf;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
 				ENABLE_TESTABILITY = YES;
 				ENABLE_USER_SCRIPT_SANDBOXING = YES;
@@ -451,6 +456,7 @@
 		};
 		EA8379432F105F2800077F87 /* Release */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = EACONFIG0012F200000000003 /* Release.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
@@ -484,7 +490,7 @@
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				COPY_PHASE_STRIP = NO;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_NS_ASSERTIONS = NO;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
 				ENABLE_USER_SCRIPT_SANDBOXING = YES;
@@ -514,7 +520,7 @@
 				CODE_SIGN_ENTITLEMENTS = BusinessCard/BusinessCard.entitlements;
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = BusinessCard/Info.plist;
@@ -530,7 +536,7 @@
 					"@executable_path/Frameworks",
 				);
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCard;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(APP_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = YES;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -550,7 +556,7 @@
 				CODE_SIGN_ENTITLEMENTS = BusinessCard/BusinessCard.entitlements;
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = BusinessCard/Info.plist;
@@ -566,7 +572,7 @@
 					"@executable_path/Frameworks",
 				);
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCard;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(APP_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = YES;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -584,11 +590,11 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCardTests;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(TESTS_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -606,11 +612,11 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCardTests;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(TESTS_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -627,10 +633,10 @@
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				GENERATE_INFOPLIST_FILE = YES;
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCardUITests;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(UITESTS_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -647,10 +653,10 @@
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				GENERATE_INFOPLIST_FILE = YES;
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCardUITests;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(UITESTS_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
@@ -670,18 +676,18 @@
 				CODE_SIGN_ENTITLEMENTS = "BusinessCardWatch Watch App/BusinessCardWatch.entitlements";
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = BusinessCardWatch;
 				INFOPLIST_KEY_UISupportedInterfaceOrientations = "UIInterfaceOrientationPortrait UIInterfaceOrientationPortraitUpsideDown";
-				INFOPLIST_KEY_WKCompanionAppBundleIdentifier = com.mbrucedogs.BusinessCard;
+				INFOPLIST_KEY_WKCompanionAppBundleIdentifier = "$(APP_BUNDLE_IDENTIFIER)";
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCard.watchkitapp;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(WATCH_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = watchos;
 				SKIP_INSTALL = YES;
@@ -704,18 +710,18 @@
 				CODE_SIGN_ENTITLEMENTS = "BusinessCardWatch Watch App/BusinessCardWatch.entitlements";
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
-				DEVELOPMENT_TEAM = 6R7KLBPBLZ;
+				DEVELOPMENT_TEAM = "$(DEVELOPMENT_TEAM)";
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = BusinessCardWatch;
 				INFOPLIST_KEY_UISupportedInterfaceOrientations = "UIInterfaceOrientationPortrait UIInterfaceOrientationPortraitUpsideDown";
-				INFOPLIST_KEY_WKCompanionAppBundleIdentifier = com.mbrucedogs.BusinessCard;
+				INFOPLIST_KEY_WKCompanionAppBundleIdentifier = "$(APP_BUNDLE_IDENTIFIER)";
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
 				MARKETING_VERSION = 1.0;
-				PRODUCT_BUNDLE_IDENTIFIER = com.mbrucedogs.BusinessCard.watchkitapp;
+				PRODUCT_BUNDLE_IDENTIFIER = "$(WATCH_BUNDLE_IDENTIFIER)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = watchos;
 				SKIP_INSTALL = YES;

BusinessCard.xcodeproj/xcuserdata/mattbruce.xcuserdatad/xcschemes/xcschememanagement.plist

@@ -12,7 +12,7 @@
 		<key>BusinessCardWatch Watch App.xcscheme_^#shared#^_</key>
 		<dict>
 			<key>orderHint</key>
-			<integer>0</integer>
+			<integer>2</integer>
 		</dict>
 	</dict>
 </dict>

BusinessCard/BusinessCard.entitlements

@@ -6,7 +6,7 @@
 	<string>development</string>
 	<key>com.apple.developer.icloud-container-identifiers</key>
 	<array>
-		<string>iCloud.com.mbrucedogs.BusinessCard</string>
+		<string>$(CLOUDKIT_CONTAINER_IDENTIFIER)</string>
 	</array>
 	<key>com.apple.developer.icloud-services</key>
 	<array>
@@ -14,7 +14,7 @@
 	</array>
 	<key>com.apple.security.application-groups</key>
 	<array>
-		<string>group.com.mbrucedogs.BusinessCard</string>
+		<string>$(APP_GROUP_IDENTIFIER)</string>
 	</array>
 </dict>
 </plist>

BusinessCard/Configuration/AppIdentifiers.swift

@@ -1,31 +1,56 @@
 import Foundation
 
-/// Centralized app identifiers for easy migration between developer accounts.
+/// Centralized app identifiers that read from Info.plist (which gets values from xcconfig).
+///
+/// The source of truth is `Configuration/Base.xcconfig`. Values flow:
+/// Base.xcconfig → Info.plist → AppIdentifiers (Swift)
 ///
 /// When migrating to a new developer account:
-/// 1. Update `companyIdentifier` below
+/// 1. Update `COMPANY_IDENTIFIER` and `DEVELOPMENT_TEAM` in Base.xcconfig
-/// 2. Update entitlements files manually (cannot be tokenized)
+/// 2. The entitlements, bundle IDs, and Swift code all update automatically
-/// 3. Update bundle IDs in Xcode project settings
+/// 3. See DevAccount-Migration.md for complete checklist
-/// 4. See DevAccount-Migration.md for full checklist
 enum AppIdentifiers {
 
-    // MARK: - Company Identifier (CHANGE THIS FOR MIGRATION)
+    // MARK: - Runtime Identifiers (read from Info.plist)
 
-    /// The company's reverse domain identifier.
+    /// App Group identifier for sharing data between app and extensions.
-    static let companyIdentifier = "com.mbrucedogs"
+    static let appGroupIdentifier: String = {
+        Bundle.main.object(forInfoDictionaryKey: "AppGroupIdentifier") as? String
+            ?? "group.com.mbrucedogs.BusinessCard"
+    }()
+
+    /// CloudKit container identifier.
+    static let cloudKitContainerIdentifier: String = {
+        Bundle.main.object(forInfoDictionaryKey: "CloudKitContainerIdentifier") as? String
+            ?? "iCloud.com.mbrucedogs.BusinessCard"
+    }()
+
+    /// App Clip domain for sharing URLs.
+    static let appClipDomain: String = {
+        Bundle.main.object(forInfoDictionaryKey: "AppClipDomain") as? String
+            ?? "cards.example.com"
+    }()
 
     // MARK: - Derived Identifiers
 
-    static var bundleIdentifier: String { "\(companyIdentifier).BusinessCard" }
+    /// Bundle identifier of the main app.
-    static var watchBundleIdentifier: String { "\(bundleIdentifier).watchkitapp" }
+    static var bundleIdentifier: String {
-    static var appClipBundleIdentifier: String { "\(bundleIdentifier).Clip" }
+        Bundle.main.bundleIdentifier ?? "com.mbrucedogs.BusinessCard"
-    static var appGroupIdentifier: String { "group.\(companyIdentifier).BusinessCard" }
+    }
-    static var cloudKitContainerIdentifier: String { "iCloud.\(companyIdentifier).BusinessCard" }
 
-    // MARK: - App Clip Configuration
+    /// Watch app bundle identifier (derived from main app).
+    static var watchBundleIdentifier: String {
+        "\(bundleIdentifier).watchkitapp"
+    }
 
-    static let appClipDomain = "cards.example.com"
+    /// App Clip bundle identifier (derived from main app).
+    static var appClipBundleIdentifier: String {
+        "\(bundleIdentifier).Clip"
+    }
 
+    // MARK: - App Clip URL Generation
+
+    /// Generates an App Clip invocation URL for a shared card record.
     static func appClipURL(recordName: String) -> URL? {
         URL(string: "https://\(appClipDomain)/appclip?id=\(recordName)")
     }

BusinessCard/Configuration/Base.xcconfig

@@ -0,0 +1,34 @@
+// Base.xcconfig
+// Shared identifiers for all targets and configurations
+// 
+// MIGRATION: To change developer accounts, update COMPANY_IDENTIFIER below
+// and the DEVELOPMENT_TEAM. Then follow DevAccount-Migration.md checklist.
+
+// =============================================================================
+// COMPANY IDENTIFIER - CHANGE THIS FOR MIGRATION
+// =============================================================================
+
+COMPANY_IDENTIFIER = com.mbrucedogs
+APP_NAME = BusinessCard
+DEVELOPMENT_TEAM = 6R7KLBPBLZ
+
+// =============================================================================
+// DERIVED IDENTIFIERS - DO NOT EDIT (computed from above)
+// =============================================================================
+
+// Bundle identifiers
+APP_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)
+WATCH_BUNDLE_IDENTIFIER = $(APP_BUNDLE_IDENTIFIER).watchkitapp
+APPCLIP_BUNDLE_IDENTIFIER = $(APP_BUNDLE_IDENTIFIER).Clip
+TESTS_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)Tests
+UITESTS_BUNDLE_IDENTIFIER = $(COMPANY_IDENTIFIER).$(APP_NAME)UITests
+
+// Entitlement identifiers
+APP_GROUP_IDENTIFIER = group.$(COMPANY_IDENTIFIER).$(APP_NAME)
+CLOUDKIT_CONTAINER_IDENTIFIER = iCloud.$(COMPANY_IDENTIFIER).$(APP_NAME)
+
+// =============================================================================
+// APP CLIP CONFIGURATION
+// =============================================================================
+
+APPCLIP_DOMAIN = cards.example.com

BusinessCard/Configuration/Debug.xcconfig

@@ -0,0 +1,7 @@
+// Debug.xcconfig
+// Debug configuration settings
+
+#include "Base.xcconfig"
+
+// Debug-specific settings (if any)
+// Add environment-specific API keys, endpoints, etc. here

BusinessCard/Configuration/Release.xcconfig

@@ -0,0 +1,7 @@
+// Release.xcconfig
+// Release configuration settings
+
+#include "Base.xcconfig"
+
+// Release-specific settings (if any)
+// Add production API keys, endpoints, etc. here

BusinessCard/Info.plist

@@ -6,5 +6,11 @@
 	<array>
 		<string>remote-notification</string>
 	</array>
+	<key>AppGroupIdentifier</key>
+	<string>$(APP_GROUP_IDENTIFIER)</string>
+	<key>CloudKitContainerIdentifier</key>
+	<string>$(CLOUDKIT_CONTAINER_IDENTIFIER)</string>
+	<key>AppClipDomain</key>
+	<string>$(APPCLIP_DOMAIN)</string>
 </dict>
 </plist>

BusinessCardWatch Watch App/Configuration/Watch.xcconfig

@@ -0,0 +1,7 @@
+// Watch.xcconfig
+// Watch app configuration - inherits from Base
+
+#include "../BusinessCard/Configuration/Base.xcconfig"
+
+// Watch-specific derived identifiers
+PRODUCT_BUNDLE_IDENTIFIER = $(WATCH_BUNDLE_IDENTIFIER)

DevAccount-Migration.md

@@ -2,6 +2,22 @@
 
 This document provides a comprehensive guide for migrating the BusinessCard app from the personal `mbrucedogs` developer account to a new Apple Developer account.
 
+## Quick Migration (xcconfig)
+
+With the xcconfig setup, migration is now a **single file change**:
+
+1. Open `BusinessCard/Configuration/Base.xcconfig`
+2. Update these two lines:
+   ```
+   COMPANY_IDENTIFIER = com.newcompany
+   DEVELOPMENT_TEAM = NEW_TEAM_ID
+   ```
+3. Clean build (⇧⌘K) and rebuild
+
+That's it! All bundle IDs, entitlements, and Swift code will automatically use the new values.
+
+---
+
 ## Current State Analysis
 
 ### Account Information

README.md

@@ -148,7 +148,10 @@ BusinessCard/
 ├── Assets.xcassets/
 │   └── SocialSymbols/   # Custom brand icons (LinkedIn, X, Instagram, etc.)
 ├── Configuration/       # App identifiers and configuration
-│   └── AppIdentifiers.swift  # Centralized company identifiers
+│   ├── Base.xcconfig         # Source of truth for all identifiers
+│   ├── Debug.xcconfig        # Debug configuration (imports Base)
+│   ├── Release.xcconfig      # Release configuration (imports Base)
+│   └── AppIdentifiers.swift  # Swift interface to configuration
 ├── Design/              # Design constants (extends Bedrock)
 ├── Localization/        # String helpers
 ├── Models/
@@ -199,15 +202,21 @@ Without this, the iOS app installs but the watch app does NOT install on the pai
 
 `iCloud.com.mbrucedogs.BusinessCard`
 
-### App Identifiers
+### App Identifiers (xcconfig)
 
-All company-specific identifiers are centralized in `Configuration/AppIdentifiers.swift`:
+All company-specific identifiers are centralized in `Configuration/Base.xcconfig`:
 
-- Bundle IDs: `AppIdentifiers.bundleIdentifier`, `.watchBundleIdentifier`, `.appClipBundleIdentifier`
+```
-- CloudKit: `AppIdentifiers.cloudKitContainerIdentifier`
+COMPANY_IDENTIFIER = com.mbrucedogs
-- App Group: `AppIdentifiers.appGroupIdentifier`
+DEVELOPMENT_TEAM = 6R7KLBPBLZ
+```
 
-See `DevAccount-Migration.md` for migration instructions.
+This flows through:
+- **Build settings**: Bundle IDs, Team ID (via xcconfig → project)
+- **Entitlements**: CloudKit container, App Group (via variable substitution)
+- **Swift code**: `AppIdentifiers.*` (via Info.plist → Bundle.main)
+
+**To migrate to a new developer account**: Update `Base.xcconfig` only. See `DevAccount-Migration.md`.
 
 ## Notes
 

ai_implementation.md

@@ -55,14 +55,27 @@ App-specific extensions are in `Design/DesignConstants.swift`:
 
 ## Important Files
 
-### Configuration
+### Configuration (xcconfig)
 
-- `Configuration/AppIdentifiers.swift` — Centralized company identifiers:
+Company identifiers are centralized using xcconfig files for true single-source configuration:
-  - `companyIdentifier` — Base identifier (e.g., "com.mbrucedogs")
+
-  - Derived: `bundleIdentifier`, `watchBundleIdentifier`, `appClipBundleIdentifier`
+- `Configuration/Base.xcconfig` — Source of truth for all identifiers:
-  - Derived: `appGroupIdentifier`, `cloudKitContainerIdentifier`
+  - `COMPANY_IDENTIFIER` — Base identifier (e.g., "com.mbrucedogs")
-  - App Clip: `appClipDomain`, `appClipURL(recordName:)`
+  - `DEVELOPMENT_TEAM` — Apple Developer Team ID
-  - **Migration**: Change `companyIdentifier` + update entitlements. See `DevAccount-Migration.md`.
+  - Derived: `APP_BUNDLE_IDENTIFIER`, `WATCH_BUNDLE_IDENTIFIER`, `TESTS_BUNDLE_IDENTIFIER`, etc.
+  - Entitlements: `APP_GROUP_IDENTIFIER`, `CLOUDKIT_CONTAINER_IDENTIFIER`
+  
+- `Configuration/Debug.xcconfig` — Imports Base, adds debug-specific settings
+- `Configuration/Release.xcconfig` — Imports Base, adds release-specific settings
+
+- `Configuration/AppIdentifiers.swift` — Swift interface reading from Info.plist:
+  - `appGroupIdentifier`, `cloudKitContainerIdentifier`, `appClipDomain`
+  - `bundleIdentifier`, `watchBundleIdentifier`, `appClipBundleIdentifier`
+  - `appClipURL(recordName:)` — Generates App Clip invocation URLs
+
+**Data flow**: `Base.xcconfig` → `project.pbxproj` → `Info.plist` → `AppIdentifiers.swift`
+
+**Migration**: Change `COMPANY_IDENTIFIER` and `DEVELOPMENT_TEAM` in `Base.xcconfig`. Everything else updates automatically. See `DevAccount-Migration.md`.
 
 ### Models