iOS: Share Extension (share to Noo) via an App Group inbox

ShareExtension target copies shared files into group.dev.ayushya.noo and
leaves a manifest; the app consumes it on launch/activation through the
existing share_intent channel into the destination picker. Extension is
embedded before Flutter's script phases; versions follow FLUTTER_BUILD_*.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.claude/context/server.md

@@ -817,9 +817,10 @@ files, 15 for folders), keeping the existing reshare bit, plus Remove access.
 The five `dev.ayushya.noo/*` channels (`share_intent`, `pick_intent`,
 `upload_service`, `download_service`, `sync_service`, plus their status
 `EventChannel`s) were written for Android in Kotlin. iOS implements
-`upload_service` (+ its status stream) and `download_service` so far
+`upload_service` (+ its status stream), `download_service` and
-(`ios/Runner/Native/`, see below); for the other three there's no handler, so
+`share_intent` so far (`ios/Runner/Native/` + `ios/ShareExtension/`, see
-calls throw `MissingPluginException`. `lib/services/native_channel.dart`
+below); for `pick_intent` and `sync_service` there's no handler, so calls
+throw `MissingPluginException`. `lib/services/native_channel.dart`
 makes that safe until each one is built in Swift:
 
 - `invokeIfAvailable` - a missing implementation returns null. For cold-start
@@ -871,5 +872,39 @@ iOS. `OfflineController` and `localSyncedFilePath` both go through it.
   ios/Runner.xcworkspace -scheme Runner -destination 'platform=iOS
   Simulator,id=<udid>'`).
 
-Not built on iOS yet: Share Extension (needs an App Group), the picker
+### iOS Share Extension (`ios/ShareExtension/`, `ios/Shared/`)
-(File Provider), and sync (`BGTaskScheduler`) - see the iOS handoff notes.
+
+"Share to Noo" from any app's share sheet. An extension can't pick a
+destination, hold a session, or launch its host app, so it only *hands off*:
+
+1. `ShareViewController` (extension) copies each shared file
+   (`NSItemProvider.loadFileRepresentation`, public.item) into the App Group
+   container (`group.dev.ayushya.noo`) under `SharedInbox/<batch>/`, appends
+   them to `SharedInbox/pending.json`, and posts a local notification ("Open
+   Noo to choose where to upload N files") since it can't open the app.
+2. The app reads that manifest through `SharedInbox.consume` - once on cold
+   start via `share_intent.getInitialShare`, and whenever it becomes active
+   (`UIApplication.didBecomeActiveNotification`) via the `share_intent/new`
+   event stream - and from there it's the same Dart flow as an Android
+   share: `main.dart`'s `_handleSharedFiles` -> `ShareUploadView` ->
+   `UploadService`. The `file://` URI points into the App Group container;
+   `TransferManager.startUpload` deletes that copy once it has staged it.
+3. `ios/Shared/SharedInbox.swift` is compiled into both targets (manifest
+   read/append/consume under an `NSFileCoordinator`, entries whose file is
+   gone are dropped, each share is delivered once) and unit-tested in
+   `RunnerTests`.
+
+Both targets carry `group.dev.ayushya.noo` in their `.entitlements`
+(`Runner/Runner.entitlements`, `ShareExtension/ShareExtension.entitlements`);
+the extension's bundle id is `dev.ayushya.noo.ShareExtension`, and its
+version/build come from the same `FLUTTER_BUILD_NAME`/`FLUTTER_BUILD_NUMBER`
+xcconfig as the app (iOS rejects a mismatch). The extension is embedded via an
+"Embed Foundation Extensions" phase placed *before* Flutter's script phases
+(after them Xcode reports a dependency cycle). The simulator honours the App
+Group without a signing team; a real device needs a team that owns the group
+id and both bundle ids registered. To try it without the share sheet, put a
+file and a `pending.json` in the simulator's group container
+(`xcrun simctl get_app_container <udid> dev.ayushya.noo groups`) and launch.
+
+Not built on iOS yet: the picker (File Provider) and sync
+(`BGTaskScheduler`) - see the iOS handoff notes.

ios/Runner.xcodeproj/project.pbxproj

@@ -8,16 +8,21 @@
 
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
+		223784E5DAE5A653F0F61771 /* ShareExtension.appex in Embed Foundation Extensions */ = {isa = PBXBuildFile; fileRef = 405A5408F4071B4D12F08B21 /* ShareExtension.appex */; settings = {ATTRIBUTES = (RemoveHeadersOnCopy, ); }; };
 		331C808B294A63AB00263BE5 /* RunnerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 331C807B294A618700263BE5 /* RunnerTests.swift */; };
+		33B3C3BED4C1F26439DD6825 /* SharedInbox.swift in Sources */ = {isa = PBXBuildFile; fileRef = 836D37F2376AFCE0EFDD30A7 /* SharedInbox.swift */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
 		5694337ECF8D3ADD3695CBCD /* NativeServices.swift in Sources */ = {isa = PBXBuildFile; fileRef = 901C0CDB4FB819302E2A7563 /* NativeServices.swift */; };
+		63229CACE4281880037D33E6 /* ShareViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 27BDF61F5197F9B8F648E8AE /* ShareViewController.swift */; };
 		66D3CBDE6B3CD3DC578CECBE /* WebDAV.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F798220CB598B611CA03EFC /* WebDAV.swift */; };
 		74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
 		7884E8682EC3CC0700C636F2 /* SceneDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7884E8672EC3CC0400C636F2 /* SceneDelegate.swift */; };
 		78A318202AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage in Frameworks */ = {isa = PBXBuildFile; productRef = 78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */; };
+		91C1658DC7467CACB2AAC7FF /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 0AE6F681A3100A461B4A5318 /* Foundation.framework */; };
 		97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
 		97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FD1CF9000F007C117D /* Assets.xcassets */; };
 		97C147011CF9000F007C117D /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FF1CF9000F007C117D /* LaunchScreen.storyboard */; };
+		F8D51B4045340275FBD12D16 /* SharedInbox.swift in Sources */ = {isa = PBXBuildFile; fileRef = 836D37F2376AFCE0EFDD30A7 /* SharedInbox.swift */; };
 		FDFA55C4921747A9CBCBBEEC /* TransferManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8064CC1652B8F0A44E371638 /* TransferManager.swift */; };
 /* End PBXBuildFile section */
 
@@ -29,9 +34,27 @@
 			remoteGlobalIDString = 97C146ED1CF9000F007C117D;
 			remoteInfo = Runner;
 		};
+		850C66E713F7C56BDA822FB7 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 97C146E61CF9000F007C117D /* Project object */;
+			proxyType = 1;
+			remoteGlobalIDString = F9BE9B2F18B10324D7B84776;
+			remoteInfo = ShareExtension;
+		};
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXCopyFilesBuildPhase section */
+		201269C4EFA9E5FDBC74F86F /* Embed Foundation Extensions */ = {
+			isa = PBXCopyFilesBuildPhase;
+			buildActionMask = 2147483647;
+			dstPath = "";
+			dstSubfolderSpec = 13;
+			files = (
+				223784E5DAE5A653F0F61771 /* ShareExtension.appex in Embed Foundation Extensions */,
+			);
+			name = "Embed Foundation Extensions";
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 		9705A1C41CF9048500538489 /* Embed Frameworks */ = {
 			isa = PBXCopyFilesBuildPhase;
 			buildActionMask = 2147483647;
@@ -45,11 +68,16 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		0AE6F681A3100A461B4A5318 /* Foundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Foundation.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS18.0.sdk/System/Library/Frameworks/Foundation.framework; sourceTree = DEVELOPER_DIR; };
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
+		27BDF61F5197F9B8F648E8AE /* ShareViewController.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = ShareViewController.swift; sourceTree = "<group>"; };
 		331C807B294A618700263BE5 /* RunnerTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RunnerTests.swift; sourceTree = "<group>"; };
 		331C8081294A63A400263BE5 /* RunnerTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = RunnerTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
+		405A5408F4071B4D12F08B21 /* ShareExtension.appex */ = {isa = PBXFileReference; explicitFileType = "wrapper.app-extension"; includeInIndex = 0; path = ShareExtension.appex; sourceTree = BUILT_PRODUCTS_DIR; };
+		49213989F0FA1B83B0B8A523 /* Info.plist */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		65F57A1EB0C62774E561860D /* ShareExtension.entitlements */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.plist.entitlements; path = ShareExtension.entitlements; sourceTree = "<group>"; };
 		6F798220CB598B611CA03EFC /* WebDAV.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = WebDAV.swift; sourceTree = "<group>"; };
 		74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Runner-Bridging-Header.h"; sourceTree = "<group>"; };
 		74858FAE1ED2DC5600515810 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -57,6 +85,8 @@
 		78E0A7A72DC9AD7400C4905E /* FlutterGeneratedPluginSwiftPackage */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = FlutterGeneratedPluginSwiftPackage; path = Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage; sourceTree = "<group>"; };
 		7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
 		8064CC1652B8F0A44E371638 /* TransferManager.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = TransferManager.swift; sourceTree = "<group>"; };
+		836D37F2376AFCE0EFDD30A7 /* SharedInbox.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = SharedInbox.swift; sourceTree = "<group>"; };
+		857A0E7637776A71AFBB0614 /* Runner.entitlements */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.plist.entitlements; path = Runner.entitlements; sourceTree = "<group>"; };
 		901C0CDB4FB819302E2A7563 /* NativeServices.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = NativeServices.swift; sourceTree = "<group>"; };
 		9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
 		9740EEB31CF90195004384FC /* Generated.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Generated.xcconfig; path = Flutter/Generated.xcconfig; sourceTree = "<group>"; };
@@ -68,6 +98,14 @@
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
+		807C81744907462A25A6C1F8 /* Frameworks */ = {
+			isa = PBXFrameworksBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				91C1658DC7467CACB2AAC7FF /* Foundation.framework in Frameworks */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 		97C146EB1CF9000F007C117D /* Frameworks */ = {
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
@@ -79,6 +117,14 @@
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
+		2B7F16B0F0EA2C5A842ED860 /* iOS */ = {
+			isa = PBXGroup;
+			children = (
+				0AE6F681A3100A461B4A5318 /* Foundation.framework */,
+			);
+			name = iOS;
+			sourceTree = "<group>";
+		};
 		331C8082294A63A400263BE5 /* RunnerTests */ = {
 			isa = PBXGroup;
 			children = (
@@ -87,6 +133,17 @@
 			path = RunnerTests;
 			sourceTree = "<group>";
 		};
+		3664F08C433ECEB00D1C4BDB /* ShareExtension */ = {
+			isa = PBXGroup;
+			children = (
+				27BDF61F5197F9B8F648E8AE /* ShareViewController.swift */,
+				49213989F0FA1B83B0B8A523 /* Info.plist */,
+				65F57A1EB0C62774E561860D /* ShareExtension.entitlements */,
+			);
+			name = ShareExtension;
+			path = ShareExtension;
+			sourceTree = "<group>";
+		};
 		5055E53DC55C0BCABD5F04F4 /* Native */ = {
 			isa = PBXGroup;
 			children = (
@@ -98,6 +155,15 @@
 			path = Native;
 			sourceTree = "<group>";
 		};
+		5DF0A9032A8500B67D6C89AE /* Shared */ = {
+			isa = PBXGroup;
+			children = (
+				836D37F2376AFCE0EFDD30A7 /* SharedInbox.swift */,
+			);
+			name = Shared;
+			path = Shared;
+			sourceTree = "<group>";
+		};
 		9740EEB11CF90186004384FC /* Flutter */ = {
 			isa = PBXGroup;
 			children = (
@@ -117,6 +183,9 @@
 				97C146F01CF9000F007C117D /* Runner */,
 				97C146EF1CF9000F007C117D /* Products */,
 				331C8082294A63A400263BE5 /* RunnerTests */,
+				5DF0A9032A8500B67D6C89AE /* Shared */,
+				3664F08C433ECEB00D1C4BDB /* ShareExtension */,
+				A5B80AB7F4AB17F90B745D0D /* Frameworks */,
 			);
 			sourceTree = "<group>";
 		};
@@ -125,6 +194,7 @@
 			children = (
 				97C146EE1CF9000F007C117D /* Runner.app */,
 				331C8081294A63A400263BE5 /* RunnerTests.xctest */,
+				405A5408F4071B4D12F08B21 /* ShareExtension.appex */,
 			);
 			name = Products;
 			sourceTree = "<group>";
@@ -142,10 +212,19 @@
 				7884E8672EC3CC0400C636F2 /* SceneDelegate.swift */,
 				74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */,
 				5055E53DC55C0BCABD5F04F4 /* Native */,
+				857A0E7637776A71AFBB0614 /* Runner.entitlements */,
 			);
 			path = Runner;
 			sourceTree = "<group>";
 		};
+		A5B80AB7F4AB17F90B745D0D /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				2B7F16B0F0EA2C5A842ED860 /* iOS */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -170,6 +249,7 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 97C147051CF9000F007C117D /* Build configuration list for PBXNativeTarget "Runner" */;
 			buildPhases = (
+				201269C4EFA9E5FDBC74F86F /* Embed Foundation Extensions */,
 				9740EEB61CF901F6004384FC /* Run Script */,
 				97C146EA1CF9000F007C117D /* Sources */,
 				97C146EB1CF9000F007C117D /* Frameworks */,
@@ -180,6 +260,7 @@
 			buildRules = (
 			);
 			dependencies = (
+				6E0BAC83BFDF8623DBFB9D75 /* PBXTargetDependency */,
 			);
 			name = Runner;
 			packageProductDependencies = (
@@ -189,6 +270,23 @@
 			productReference = 97C146EE1CF9000F007C117D /* Runner.app */;
 			productType = "com.apple.product-type.application";
 		};
+		F9BE9B2F18B10324D7B84776 /* ShareExtension */ = {
+			isa = PBXNativeTarget;
+			buildConfigurationList = E1076120E395D274D37607ED /* Build configuration list for PBXNativeTarget "ShareExtension" */;
+			buildPhases = (
+				3CD40C8747E650E6F817CDDB /* Sources */,
+				807C81744907462A25A6C1F8 /* Frameworks */,
+				4EDBC7D61EA0C0974DA27BD6 /* Resources */,
+			);
+			buildRules = (
+			);
+			dependencies = (
+			);
+			name = ShareExtension;
+			productName = ShareExtension;
+			productReference = 405A5408F4071B4D12F08B21 /* ShareExtension.appex */;
+			productType = "com.apple.product-type.app-extension";
+		};
 /* End PBXNativeTarget section */
 
 /* Begin PBXProject section */
@@ -227,6 +325,7 @@
 			targets = (
 				97C146ED1CF9000F007C117D /* Runner */,
 				331C8080294A63A400263BE5 /* RunnerTests */,
+				F9BE9B2F18B10324D7B84776 /* ShareExtension */,
 			);
 		};
 /* End PBXProject section */
@@ -239,6 +338,13 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
+		4EDBC7D61EA0C0974DA27BD6 /* Resources */ = {
+			isa = PBXResourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 		97C146EC1CF9000F007C117D /* Resources */ = {
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
@@ -295,6 +401,15 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
+		3CD40C8747E650E6F817CDDB /* Sources */ = {
+			isa = PBXSourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				63229CACE4281880037D33E6 /* ShareViewController.swift in Sources */,
+				33B3C3BED4C1F26439DD6825 /* SharedInbox.swift in Sources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 		97C146EA1CF9000F007C117D /* Sources */ = {
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
@@ -305,6 +420,7 @@
 				66D3CBDE6B3CD3DC578CECBE /* WebDAV.swift in Sources */,
 				FDFA55C4921747A9CBCBBEEC /* TransferManager.swift in Sources */,
 				5694337ECF8D3ADD3695CBCD /* NativeServices.swift in Sources */,
+				F8D51B4045340275FBD12D16 /* SharedInbox.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -316,6 +432,12 @@
 			target = 97C146ED1CF9000F007C117D /* Runner */;
 			targetProxy = 331C8085294A63A400263BE5 /* PBXContainerItemProxy */;
 		};
+		6E0BAC83BFDF8623DBFB9D75 /* PBXTargetDependency */ = {
+			isa = PBXTargetDependency;
+			name = ShareExtension;
+			target = F9BE9B2F18B10324D7B84776 /* ShareExtension */;
+			targetProxy = 850C66E713F7C56BDA822FB7 /* PBXContainerItemProxy */;
+		};
 /* End PBXTargetDependency section */
 
 /* Begin PBXVariantGroup section */
@@ -396,6 +518,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_ENABLE_MODULES = YES;
+				CODE_SIGN_ENTITLEMENTS = Runner/Runner.entitlements;
 				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
 				ENABLE_BITCODE = NO;
 				INFOPLIST_FILE = Runner/Info.plist;
@@ -458,6 +581,89 @@
 			};
 			name = Profile;
 		};
+		3B057BF66761E30DEABF8B30 /* Profile */ = {
+			isa = XCBuildConfiguration;
+			baseConfigurationReference = 7AFA3C8E1D35360C0083082E /* Release.xcconfig */;
+			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
+				CLANG_ENABLE_OBJC_WEAK = NO;
+				CODE_SIGN_ENTITLEMENTS = ShareExtension/ShareExtension.entitlements;
+				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
+				GENERATE_INFOPLIST_FILE = NO;
+				INFOPLIST_FILE = ShareExtension/Info.plist;
+				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+					"@executable_path/../../Frameworks",
+				);
+				MARKETING_VERSION = "$(FLUTTER_BUILD_NAME)";
+				PRODUCT_BUNDLE_IDENTIFIER = dev.ayushya.noo.ShareExtension;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SDKROOT = iphoneos;
+				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 5.0;
+				TARGETED_DEVICE_FAMILY = "1,2";
+				VALIDATE_PRODUCT = YES;
+			};
+			name = Profile;
+		};
+		6BF252CEA7A55024A2F58A36 /* Release */ = {
+			isa = XCBuildConfiguration;
+			baseConfigurationReference = 7AFA3C8E1D35360C0083082E /* Release.xcconfig */;
+			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
+				CLANG_ENABLE_OBJC_WEAK = NO;
+				CODE_SIGN_ENTITLEMENTS = ShareExtension/ShareExtension.entitlements;
+				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
+				GENERATE_INFOPLIST_FILE = NO;
+				INFOPLIST_FILE = ShareExtension/Info.plist;
+				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+					"@executable_path/../../Frameworks",
+				);
+				MARKETING_VERSION = "$(FLUTTER_BUILD_NAME)";
+				PRODUCT_BUNDLE_IDENTIFIER = dev.ayushya.noo.ShareExtension;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SDKROOT = iphoneos;
+				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 5.0;
+				TARGETED_DEVICE_FAMILY = "1,2";
+				VALIDATE_PRODUCT = YES;
+			};
+			name = Release;
+		};
+		6FB3F72FB5A94DE254FF4FBF /* Debug */ = {
+			isa = XCBuildConfiguration;
+			baseConfigurationReference = 9740EEB21CF90195004384FC /* Debug.xcconfig */;
+			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
+				CLANG_ENABLE_OBJC_WEAK = NO;
+				CODE_SIGN_ENTITLEMENTS = ShareExtension/ShareExtension.entitlements;
+				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
+				GENERATE_INFOPLIST_FILE = NO;
+				INFOPLIST_FILE = ShareExtension/Info.plist;
+				IPHONEOS_DEPLOYMENT_TARGET = 15.0;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+					"@executable_path/../../Frameworks",
+				);
+				MARKETING_VERSION = "$(FLUTTER_BUILD_NAME)";
+				PRODUCT_BUNDLE_IDENTIFIER = dev.ayushya.noo.ShareExtension;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SDKROOT = iphoneos;
+				SKIP_INSTALL = YES;
+				SWIFT_VERSION = 5.0;
+				TARGETED_DEVICE_FAMILY = "1,2";
+			};
+			name = Debug;
+		};
 		97C147031CF9000F007C117D /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
@@ -575,6 +781,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_ENABLE_MODULES = YES;
+				CODE_SIGN_ENTITLEMENTS = Runner/Runner.entitlements;
 				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
 				ENABLE_BITCODE = NO;
 				INFOPLIST_FILE = Runner/Info.plist;
@@ -597,6 +804,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_ENABLE_MODULES = YES;
+				CODE_SIGN_ENTITLEMENTS = Runner/Runner.entitlements;
 				CURRENT_PROJECT_VERSION = "$(FLUTTER_BUILD_NUMBER)";
 				ENABLE_BITCODE = NO;
 				INFOPLIST_FILE = Runner/Info.plist;
@@ -645,6 +853,16 @@
 			defaultConfigurationIsVisible = 0;
 			defaultConfigurationName = Release;
 		};
+		E1076120E395D274D37607ED /* Build configuration list for PBXNativeTarget "ShareExtension" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				6BF252CEA7A55024A2F58A36 /* Release */,
+				6FB3F72FB5A94DE254FF4FBF /* Debug */,
+				3B057BF66761E30DEABF8B30 /* Profile */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
 /* End XCConfigurationList section */
 
 /* Begin XCLocalSwiftPackageReference section */

ios/Runner/Native/NativeServices.swift

@@ -1,8 +1,10 @@
 import Flutter
 import Foundation
+import UIKit
 
-/// Pushes upload-batch completions to Dart's `UploadService.completions`.
+/// Holds the one native-side listener of an `EventChannel` so Swift code can
-final class UploadStatusStreamHandler: NSObject, FlutterStreamHandler {
+/// push events to Dart whenever they happen.
+final class SinkStreamHandler: NSObject, FlutterStreamHandler {
   var sink: FlutterEventSink?
 
   func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink)
@@ -19,12 +21,12 @@ final class UploadStatusStreamHandler: NSObject, FlutterStreamHandler {
 }
 
 /// The iOS side of the `dev.ayushya.noo/*` channels `lib/services/` talks to
-/// (Android's lives in `MainActivity.kt`). Only the upload and download
+/// (Android's lives in `MainActivity.kt`). Upload, download and share (the
-/// services are implemented so far; the rest still throw
+/// receiving half of the Share Extension) are implemented so far; the rest
-/// `MissingPluginException`, which the Dart side treats as "unavailable"
+/// still throw `MissingPluginException`, which the Dart side treats as
-/// (`lib/services/native_channel.dart`).
+/// "unavailable" (`lib/services/native_channel.dart`).
 enum NativeServices {
-  private static let uploadStatus = UploadStatusStreamHandler()
+  private static let uploadStatus = SinkStreamHandler()
 
   static func register(messenger: FlutterBinaryMessenger) {
     FlutterMethodChannel(name: "dev.ayushya.noo/upload_service", binaryMessenger: messenger)
@@ -72,6 +74,46 @@ enum NativeServices {
       uploadStatus.sink?(["remoteFolder": folder, "succeeded": succeeded, "failed": failed])
     }
     TransferManager.shared.reconnect()
+    registerShare(messenger: messenger)
+  }
+
+  // MARK: - Share Extension inbox
+
+  private static let shareEvents = SinkStreamHandler()
+
+  /// `share_intent`: files the Share Extension left in the App Group inbox.
+  /// Cold start asks once (`getInitialShare`); a share that arrives while the
+  /// app is running is pushed when it next becomes active (the extension
+  /// can't signal the app any other way).
+  private static func registerShare(messenger: FlutterBinaryMessenger) {
+    FlutterMethodChannel(name: "dev.ayushya.noo/share_intent", binaryMessenger: messenger)
+      .setMethodCallHandler { call, result in
+        guard call.method == "getInitialShare" else { return result(FlutterMethodNotImplemented) }
+        result(consumeShared().map(encode))
+      }
+    FlutterEventChannel(name: "dev.ayushya.noo/share_intent/new", binaryMessenger: messenger)
+      .setStreamHandler(shareEvents)
+    NotificationCenter.default.addObserver(
+      forName: UIApplication.didBecomeActiveNotification, object: nil, queue: .main
+    ) { _ in
+      guard let sink = shareEvents.sink else { return }
+      let items = consumeShared()
+      if !items.isEmpty { sink(items.map(encode)) }
+    }
+  }
+
+  private static func consumeShared() -> [SharedItem] {
+    guard let root = AppGroup.containerURL else { return [] }
+    return SharedInbox.consume(in: root)
+  }
+
+  private static func encode(_ item: SharedItem) -> [String: Any] {
+    [
+      "uri": URL(fileURLWithPath: item.path).absoluteString,
+      "name": item.name,
+      "mimeType": item.mimeType ?? NSNull(),
+      "size": item.size,
+    ]
   }
 
   // MARK: - Argument helpers

ios/Runner/Native/TransferManager.swift

@@ -100,6 +100,11 @@ final class TransferManager: NSObject {
       let staged = stageDir.appendingPathComponent("\(index)-\(file.name)")
       do {
         try FileManager.default.copyItem(at: source, to: staged)
+        // A file the Share Extension left in the App Group is ours to clean
+        // up once it's staged; a picker's temp file isn't.
+        if source.path.contains("/\(SharedInbox.folderName)/") {
+          try? FileManager.default.removeItem(at: source)
+        }
       } catch {
         throw TransferError(message: "Can't read \(file.name): \(error.localizedDescription)")
       }

ios/Runner/Runner.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.dev.ayushya.noo</string>
+	</array>
+</dict>
+</plist>

ios/RunnerTests/RunnerTests.swift

@@ -49,4 +49,52 @@ class RunnerTests: XCTestCase {
     FileManager.default.createFile(atPath: dir.appendingPathComponent("README").path, contents: nil)
     XCTAssertEqual(LocalFiles.uniqueURL(in: dir, name: "README").lastPathComponent, "README (1)")
   }
+
+  // MARK: - SharedInbox (Share Extension hand-off)
+
+  private func makeRoot() throws -> URL {
+    let root = FileManager.default.temporaryDirectory
+      .appendingPathComponent("noo-inbox-\(UUID().uuidString)", isDirectory: true)
+    try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
+    addTeardownBlock { try? FileManager.default.removeItem(at: root) }
+    return root
+  }
+
+  private func makeSharedFile(in root: URL, name: String, contents: String = "hi") throws -> SharedItem {
+    let batch = try SharedInbox.makeBatchDirectory(in: root)
+    let file = batch.appendingPathComponent(name)
+    try contents.write(to: file, atomically: true, encoding: .utf8)
+    return SharedItem(path: file.path, name: name, mimeType: "text/plain", size: Int64(contents.utf8.count))
+  }
+
+  func testInboxConsumeReturnsAppendedItemsOnceThenNothing() throws {
+    let root = try makeRoot()
+    let a = try makeSharedFile(in: root, name: "a.txt")
+    let b = try makeSharedFile(in: root, name: "b.txt")
+    try SharedInbox.append([a], in: root)
+    try SharedInbox.append([b], in: root)
+
+    XCTAssertEqual(SharedInbox.consume(in: root), [a, b])
+    XCTAssertEqual(SharedInbox.consume(in: root), [], "each share is delivered once")
+  }
+
+  func testInboxConsumeDropsFilesThatNoLongerExist() throws {
+    let root = try makeRoot()
+    let kept = try makeSharedFile(in: root, name: "kept.txt")
+    let gone = try makeSharedFile(in: root, name: "gone.txt")
+    try SharedInbox.append([kept, gone], in: root)
+    try FileManager.default.removeItem(atPath: gone.path)
+
+    XCTAssertEqual(SharedInbox.consume(in: root), [kept])
+  }
+
+  func testInboxConsumeWithNothingPendingIsEmpty() throws {
+    XCTAssertEqual(SharedInbox.consume(in: try makeRoot()), [])
+  }
+
+  func testInboxAppendOfNothingCreatesNoManifest() throws {
+    let root = try makeRoot()
+    try SharedInbox.append([], in: root)
+    XCTAssertEqual(SharedInbox.consume(in: root), [])
+  }
 }

ios/ShareExtension/Info.plist

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>$(DEVELOPMENT_LANGUAGE)</string>
+	<key>CFBundleDisplayName</key>
+	<string>Noo</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
+	<key>CFBundleShortVersionString</key>
+	<string>$(MARKETING_VERSION)</string>
+	<key>CFBundleVersion</key>
+	<string>$(CURRENT_PROJECT_VERSION)</string>
+	<key>NSExtension</key>
+	<dict>
+		<key>NSExtensionAttributes</key>
+		<dict>
+			<key>NSExtensionActivationRule</key>
+			<dict>
+				<key>NSExtensionActivationSupportsFileWithMaxCount</key>
+				<integer>50</integer>
+				<key>NSExtensionActivationSupportsImageWithMaxCount</key>
+				<integer>50</integer>
+				<key>NSExtensionActivationSupportsMovieWithMaxCount</key>
+				<integer>50</integer>
+			</dict>
+		</dict>
+		<key>NSExtensionPointIdentifier</key>
+		<string>com.apple.share-services</string>
+		<key>NSExtensionPrincipalClass</key>
+		<string>$(PRODUCT_MODULE_NAME).ShareViewController</string>
+	</dict>
+</dict>
+</plist>

ios/ShareExtension/ShareExtension.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.dev.ayushya.noo</string>
+	</array>
+</dict>
+</plist>

ios/ShareExtension/ShareViewController.swift

@@ -0,0 +1,122 @@
+import UIKit
+import UniformTypeIdentifiers
+import UserNotifications
+
+/// "Share to Noo": copies whatever was shared into the App Group container
+/// (`SharedInbox`) and finishes. The extension can't pick a destination or
+/// upload - it has no session and a tight memory/time budget - so the app
+/// does that when it next opens, through its existing destination picker. A
+/// notification tells the user to open it, because an extension can't launch
+/// its host app.
+final class ShareViewController: UIViewController {
+  private let label = UILabel()
+  private let spinner = UIActivityIndicatorView(style: .large)
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+    view.backgroundColor = .systemBackground
+    label.text = "Saving to Noo…"
+    label.font = .preferredFont(forTextStyle: .headline)
+    label.textAlignment = .center
+    label.numberOfLines = 0
+    spinner.startAnimating()
+
+    let stack = UIStackView(arrangedSubviews: [spinner, label])
+    stack.axis = .vertical
+    stack.spacing = 16
+    stack.alignment = .center
+    stack.translatesAutoresizingMaskIntoConstraints = false
+    view.addSubview(stack)
+    NSLayoutConstraint.activate([
+      stack.centerXAnchor.constraint(equalTo: view.centerXAnchor),
+      stack.centerYAnchor.constraint(equalTo: view.centerYAnchor),
+      stack.leadingAnchor.constraint(greaterThanOrEqualTo: view.leadingAnchor, constant: 24),
+      stack.trailingAnchor.constraint(lessThanOrEqualTo: view.trailingAnchor, constant: -24),
+    ])
+
+    Task { await importSharedItems() }
+  }
+
+  private func importSharedItems() async {
+    guard let root = AppGroup.containerURL else {
+      return finish(message: "Noo isn't set up to receive files yet.", saved: 0)
+    }
+    let providers = (extensionContext?.inputItems as? [NSExtensionItem])?
+      .flatMap { $0.attachments ?? [] } ?? []
+
+    var saved: [SharedItem] = []
+    do {
+      let batch = try SharedInbox.makeBatchDirectory(in: root)
+      for provider in providers where provider.hasItemConformingToTypeIdentifier(UTType.item.identifier) {
+        if let item = try? await copy(provider, into: batch) { saved.append(item) }
+      }
+      try SharedInbox.append(saved, in: root)
+    } catch {
+      return finish(message: "Couldn't save to Noo: \(error.localizedDescription)", saved: 0)
+    }
+
+    if saved.isEmpty {
+      finish(message: "Noo can only receive files and photos.", saved: 0)
+    } else {
+      notify(count: saved.count)
+      finish(message: saved.count == 1 ? "Saved 1 file to Noo" : "Saved \(saved.count) files to Noo", saved: saved.count)
+    }
+  }
+
+  /// `loadFileRepresentation`'s URL only lives for the duration of its
+  /// callback, so the copy happens inside it.
+  private func copy(_ provider: NSItemProvider, into directory: URL) async throws -> SharedItem {
+    try await withCheckedThrowingContinuation { continuation in
+      provider.loadFileRepresentation(forTypeIdentifier: UTType.item.identifier) { url, error in
+        guard let url else {
+          return continuation.resume(throwing: error ?? CocoaError(.fileReadUnknown))
+        }
+        do {
+          let destination = Self.uniqueURL(in: directory, name: url.lastPathComponent)
+          try FileManager.default.copyItem(at: url, to: destination)
+          let size = (try? FileManager.default.attributesOfItem(atPath: destination.path))?[.size] as? Int64 ?? 0
+          let mime = UTType(filenameExtension: destination.pathExtension)?.preferredMIMEType
+          continuation.resume(
+            returning: SharedItem(
+              path: destination.path, name: destination.lastPathComponent, mimeType: mime, size: size))
+        } catch {
+          continuation.resume(throwing: error)
+        }
+      }
+    }
+  }
+
+  private static func uniqueURL(in directory: URL, name: String) -> URL {
+    var candidate = directory.appendingPathComponent(name)
+    var index = 1
+    while FileManager.default.fileExists(atPath: candidate.path) {
+      let ext = (name as NSString).pathExtension
+      let stem = (name as NSString).deletingPathExtension
+      candidate = directory.appendingPathComponent(ext.isEmpty ? "\(stem) (\(index))" : "\(stem) (\(index)).\(ext)")
+      index += 1
+    }
+    return candidate
+  }
+
+  private func notify(count: Int) {
+    let content = UNMutableNotificationContent()
+    content.title = "Noo"
+    content.body =
+      count == 1
+      ? "Open Noo to choose where to upload 1 file."
+      : "Open Noo to choose where to upload \(count) files."
+    content.sound = .default
+    UNUserNotificationCenter.current().add(
+      UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: nil))
+  }
+
+  private func finish(message: String, saved: Int) {
+    DispatchQueue.main.async {
+      self.spinner.stopAnimating()
+      self.label.text = message
+      DispatchQueue.main.asyncAfter(deadline: .now() + (saved > 0 ? 1.2 : 2.5)) {
+        self.extensionContext?.completeRequest(returningItems: nil)
+      }
+    }
+  }
+}

ios/Shared/SharedInbox.swift

@@ -0,0 +1,92 @@
+import Foundation
+
+/// The App Group both the app and its Share Extension belong to - the one
+/// place they can exchange files.
+enum AppGroup {
+  static let identifier = "group.dev.ayushya.noo"
+
+  static var containerURL: URL? {
+    FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: identifier)
+  }
+}
+
+/// One file the Share Extension copied into the group container.
+struct SharedItem: Codable, Equatable {
+  let path: String
+  let name: String
+  let mimeType: String?
+  let size: Int64
+}
+
+/// Files the Share Extension received, waiting for the app to ask the user
+/// where to upload them. The extension appends; the app consumes (reads and
+/// clears) when it launches or becomes active. Compiled into both targets.
+///
+/// Layout under `<root>/SharedInbox/`: `pending.json` (the manifest) and one
+/// `<batch-id>/` folder per share holding the copied files.
+enum SharedInbox {
+  static let folderName = "SharedInbox"
+  private static let manifestName = "pending.json"
+
+  static func directory(in root: URL) -> URL {
+    root.appendingPathComponent(folderName, isDirectory: true)
+  }
+
+  /// A fresh folder for one share's files.
+  static func makeBatchDirectory(in root: URL) throws -> URL {
+    let dir = directory(in: root).appendingPathComponent(UUID().uuidString, isDirectory: true)
+    try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+    return dir
+  }
+
+  static func append(_ items: [SharedItem], in root: URL) throws {
+    guard !items.isEmpty else { return }
+    try withManifestLock(in: root) {
+      let existing = (try? readManifest(in: root)) ?? []
+      try writeManifest(existing + items, in: root)
+    }
+  }
+
+  /// Everything pending, dropping entries whose file has gone missing, and
+  /// clears the manifest so each share is delivered once.
+  static func consume(in root: URL) -> [SharedItem] {
+    var items: [SharedItem] = []
+    try? withManifestLock(in: root) {
+      items = ((try? readManifest(in: root)) ?? []).filter {
+        FileManager.default.fileExists(atPath: $0.path)
+      }
+      try? FileManager.default.removeItem(at: manifestURL(in: root))
+    }
+    return items
+  }
+
+  private static func manifestURL(in root: URL) -> URL {
+    directory(in: root).appendingPathComponent(manifestName)
+  }
+
+  private static func readManifest(in root: URL) throws -> [SharedItem] {
+    let data = try Data(contentsOf: manifestURL(in: root))
+    return try JSONDecoder().decode([SharedItem].self, from: data)
+  }
+
+  private static func writeManifest(_ items: [SharedItem], in root: URL) throws {
+    try FileManager.default.createDirectory(
+      at: directory(in: root), withIntermediateDirectories: true)
+    try JSONEncoder().encode(items).write(to: manifestURL(in: root), options: .atomic)
+  }
+
+  /// The extension and the app are separate processes that can both touch the
+  /// manifest, so read-modify-write goes through a file coordinator.
+  private static func withManifestLock(in root: URL, _ body: () throws -> Void) throws {
+    try FileManager.default.createDirectory(
+      at: directory(in: root), withIntermediateDirectories: true)
+    var coordinationError: NSError?
+    var thrown: Error?
+    NSFileCoordinator().coordinate(
+      writingItemAt: directory(in: root), options: [], error: &coordinationError
+    ) { _ in
+      do { try body() } catch { thrown = error }
+    }
+    if let error = coordinationError ?? thrown.map({ $0 as NSError }) { throw error }
+  }
+}