fix: address audit findings on the media share targets

- Correct the KDoc on the Shorts and Longs composers. They claimed
  everything posted from them lands in that feed; VideoPostKind only
  governs videos, and the gallery picker takes images with no mime
  filter, so a picked JPEG still posts as a kind-20 picture that
  neither feed reads. Say so instead of asserting a false invariant.

- Forward the shared text as the composer's caption. The media targets
  dropped EXTRA_TEXT entirely, so sharing a photo with a caption lost
  it — while the DM target kept it. The routes now carry the message
  and NewMediaModel.load() seeds the caption field from it.

- Accept SEND_MULTIPLE on the three media targets. Sharing several
  files at once previously did not offer Amethyst at all, even though
  the picture composer publishes N images as one kind-20 event. Routes
  carry a URI list; other targets take the first.

- Replace, rather than stack, a feed entry when a second share arrives
  while the first is still open. Only entries that carry attachments
  are replaced, so a feed reached from the bottom bar keeps its
  tab-root marker underneath.

- Rename NewImageButton to NewVideoFeedButton: it is the Video feed's
  composer and handles pictures and video alike.

Adds ShareTargetManifestTest, which pins the activity-alias names in
AndroidManifest.xml to the constants ShareIntentRouting matches them
by — in both directions, plus the SEND_MULTIPLE filters. That link is
invisible to the compiler and fails silently at runtime by routing a
share to the wrong composer. Verified the guard bites by renaming an
alias in the manifest alone: three of its four tests go red.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01R4WsYWaNMPD34SBc6Ej6hx

amethyst/src/main/AndroidManifest.xml

@@ -310,6 +310,12 @@
                 <category android:name="android.intent.category.DEFAULT" />
                 <data android:mimeType="image/*" />
             </intent-filter>
+
+            <intent-filter android:label="@string/share_target_as_picture">
+                <action android:name="android.intent.action.SEND_MULTIPLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="image/*" />
+            </intent-filter>
         </activity-alias>
 
         <!-- "New Short" share target: a video shared here always becomes a NIP-71 kind-22 short so
@@ -327,6 +333,12 @@
                 <category android:name="android.intent.category.DEFAULT" />
                 <data android:mimeType="video/*" />
             </intent-filter>
+
+            <intent-filter android:label="@string/share_target_as_short_video">
+                <action android:name="android.intent.action.SEND_MULTIPLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="video/*" />
+            </intent-filter>
         </activity-alias>
 
         <!-- "New Video" share target: opens the Video feed's media composer, which publishes a
@@ -344,6 +356,12 @@
                 <category android:name="android.intent.category.DEFAULT" />
                 <data android:mimeType="video/*" />
             </intent-filter>
+
+            <intent-filter android:label="@string/share_target_as_video">
+                <action android:name="android.intent.action.SEND_MULTIPLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="video/*" />
+            </intent-filter>
         </activity-alias>
 
         <!-- "New Highlight" share target: a browser (or reader) shares a selected passage of

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/actions/NewMediaModel.kt

@@ -81,8 +81,9 @@ open class NewMediaModel : ViewModel() {
         account: Account,
         uris: ImmutableList<SelectedMedia>,
         videoKind: VideoPostKind = VideoPostKind.AUTO,
+        caption: String = "",
     ) {
-        this.caption = ""
+        this.caption = caption
         this.account = account
         this.multiOrchestrator = MultiOrchestrator(uris)
         this.selectedServer = defaultServer()

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/actions/NewMediaView.kt

@@ -81,14 +81,15 @@ fun NewMediaView(
     accountViewModel: AccountViewModel,
     nav: INav,
     videoKind: VideoPostKind = VideoPostKind.AUTO,
+    initialCaption: String = "",
 ) {
     val account = accountViewModel.account
     val context = LocalContext.current
 
     val scrollState = rememberScrollState()
 
-    LaunchedEffect(uris, videoKind) {
-        postViewModel.load(account, uris, videoKind)
+    LaunchedEffect(uris, videoKind, initialCaption) {
+        postViewModel.load(account, uris, videoKind, initialCaption)
     }
 
     StrippingFailureDialog(postViewModel.strippingFailureConfirmation)

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/actions/uploads/SharedMediaResolver.kt

@@ -22,6 +22,9 @@ package com.vitorpamplona.amethyst.ui.actions.uploads
 
 import android.content.Context
 import androidx.core.net.toUri
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.persistentListOf
+import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 
@@ -40,3 +43,20 @@ suspend fun resolveSharedMedia(
             SelectedMedia(uri, context.contentResolver.getType(uri))
         }
     }
+
+/**
+ * Batch form for SEND_MULTIPLE shares: resolves every URI in one trip to the IO dispatcher
+ * instead of one context switch per file. Blank entries are dropped, so an empty list in means
+ * an empty list out and the composer stays closed.
+ */
+suspend fun resolveSharedMedia(
+    context: Context,
+    uriStrings: List<String>,
+): ImmutableList<SelectedMedia> {
+    val uris = uriStrings.mapNotNull { it.ifBlank { null }?.toUri() }
+    if (uris.isEmpty()) return persistentListOf()
+
+    return withContext(Dispatchers.IO) {
+        uris.map { SelectedMedia(it, context.contentResolver.getType(it)) }.toImmutableList()
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/AppNavigation.kt

@@ -72,6 +72,7 @@ import com.vitorpamplona.amethyst.ui.navigation.bottombars.TabReselectCoordinato
 import com.vitorpamplona.amethyst.ui.navigation.bottombars.favoriteIds
 import com.vitorpamplona.amethyst.ui.navigation.navs.Nav
 import com.vitorpamplona.amethyst.ui.navigation.navs.rememberNav
+import com.vitorpamplona.amethyst.ui.navigation.routes.MediaFeedRoute
 import com.vitorpamplona.amethyst.ui.navigation.routes.Route
 import com.vitorpamplona.amethyst.ui.navigation.routes.getRouteWithArguments
 import com.vitorpamplona.amethyst.ui.navigation.routes.isBaseRoute
@@ -428,7 +429,7 @@ fun BuildNavigation(
     ) {
         composableCapped<Route.Home> { HomeScreen(accountViewModel, nav) }
         composable<Route.Message> { MessagesScreen(accountViewModel, nav) }
-        composableArgs<Route.Video> { VideoScreen(accountViewModel, nav, it.attachment) }
+        composableArgs<Route.Video> { VideoScreen(accountViewModel, nav, it.attachments, it.message) }
         composableArgs<Route.Discover> { DiscoverScreen(it.initialTab, accountViewModel, nav) }
         composableArgs<Route.Notification> { NotificationScreen(it.scrollToEventId, accountViewModel, nav) }
         composableFromEnd<Route.Polls> { PollsScreen(accountViewModel, nav) }
@@ -439,7 +440,7 @@ fun BuildNavigation(
         composableFromEnd<Route.ProfileBadges> { ProfileBadgesScreen(accountViewModel, nav) }
         composableFromEnd<Route.ProfileAppRecommendations> { ProfileAppRecommendationsScreen(accountViewModel, nav) }
         composableFromBottomArgs<Route.AwardBadge> { AwardBadgeScreen(it.kind, it.pubKeyHex, it.dTag, accountViewModel, nav) }
-        composableFromEndArgs<Route.Pictures> { PicturesScreen(accountViewModel, nav, it.attachment) }
+        composableFromEndArgs<Route.Pictures> { PicturesScreen(accountViewModel, nav, it.attachments, it.message) }
         composableFromEnd<Route.Workouts> { WorkoutsScreen(accountViewModel, nav) }
         composableFromEnd<Route.GitRepositories> { GitRepositoriesScreen(accountViewModel, nav) }
 
@@ -469,7 +470,7 @@ fun BuildNavigation(
         }
         composableFromBottomArgs<Route.NewCalendarCollection> { NewCalendarCollectionScreen(nav, accountViewModel, it.dTag) }
         composableFromEnd<Route.Products> { ProductsScreen(accountViewModel, nav) }
-        composableFromEndArgs<Route.Shorts> { ShortsScreen(accountViewModel, nav, it.attachment) }
+        composableFromEndArgs<Route.Shorts> { ShortsScreen(accountViewModel, nav, it.attachments, it.message) }
         composableFromEnd<Route.PublicChats> { PublicChatsScreen(accountViewModel, nav) }
         composableFromEnd<Route.RelayGroups> { RelayGroupDiscoveryScreen(accountViewModel, nav) }
         composableFromEndArgs<Route.BuzzDmList> { BuzzDmListScreen(it.relayUrl, accountViewModel, nav) }
@@ -971,6 +972,42 @@ fun BuildNavigation(
     }
 }
 
+/** True for both share flavors: a single file/text (SEND) and a multi-file selection (SEND_MULTIPLE). */
+private fun Intent.isShareAction(): Boolean = action == Intent.ACTION_SEND || action == Intent.ACTION_SEND_MULTIPLE
+
+/** The text Android sent with the share — a caption, a URL, or the whole payload of a text-only share. */
+private fun Intent.sharedText(): String? = getStringExtra(Intent.EXTRA_TEXT)?.ifBlank { null }
+
+/**
+ * Every content URI the share carries, in the order the sending app listed them. SEND_MULTIPLE
+ * puts them in a parcelable ArrayList; plain SEND has at most one. Only the media targets declare
+ * SEND_MULTIPLE, so every other caller can just take the first.
+ */
+private fun Intent.sharedStreamUris(): List<String> =
+    if (action == Intent.ACTION_SEND_MULTIPLE) {
+        IntentCompat
+            .getParcelableArrayListExtra(this, Intent.EXTRA_STREAM, Uri::class.java)
+            ?.map { it.toString() }
+            .orEmpty()
+    } else {
+        listOfNotNull(IntentCompat.getParcelableExtra(this, Intent.EXTRA_STREAM, Uri::class.java)?.toString())
+    }
+
+/**
+ * Opens a media feed on a share. Sharing again while an earlier share is still on screen replaces
+ * it instead of stacking a second copy of the feed — but only when the entry on top is itself a
+ * share (it carries attachments). A feed the user opened from the bottom bar carries none, so it
+ * stays put underneath and keeps its tab-root marker.
+ */
+private inline fun <reified T> Nav.navToSharedFeed(route: T) where T : Route, T : MediaFeedRoute {
+    val current = getRouteWithArguments(T::class, controller)
+    if (current is MediaFeedRoute && current.attachments.isNotEmpty()) {
+        popUpTo(route, T::class)
+    } else {
+        newStack(route)
+    }
+}
+
 @Composable
 private fun NavigateIfIntentRequested(
     nav: Nav,
@@ -987,7 +1024,7 @@ private fun NavigateIfIntentRequested(
 
     val activity = LocalContext.current.getActivity()
 
-    if (activity.intent.action == Intent.ACTION_SEND) {
+    if (activity.intent.isShareAction()) {
         val target = ShareIntentRouting.targetOf(activity.intent.component?.className)
 
         // avoids restarting the destination screen when the intent is for the screen.
@@ -1002,19 +1039,8 @@ private fun NavigateIfIntentRequested(
         }
 
         // saves the intent to avoid processing again
-        val message by remember {
-            mutableStateOf(
-                activity.intent.getStringExtra(Intent.EXTRA_TEXT)?.let {
-                    it.ifBlank { null }
-                },
-            )
-        }
-
-        val media by remember {
-            mutableStateOf(
-                IntentCompat.getParcelableExtra(activity.intent, Intent.EXTRA_STREAM, Uri::class.java),
-            )
-        }
+        val message = remember { activity.intent.sharedText() }
+        val attachments = remember { activity.intent.sharedStreamUris() }
 
         when (target) {
             ShareTarget.HIGHLIGHT -> {
@@ -1028,11 +1054,13 @@ private fun NavigateIfIntentRequested(
                     ),
                 )
             }
-            ShareTarget.DIRECT_MESSAGE -> nav.newStack(Route.ShareToDM(message = message, attachment = media?.toString()))
-            ShareTarget.PICTURE -> nav.newStack(Route.Pictures(attachment = media?.toString()))
-            ShareTarget.SHORT_VIDEO -> nav.newStack(Route.Shorts(attachment = media?.toString()))
-            ShareTarget.VIDEO -> nav.newStack(Route.Video(attachment = media?.toString()))
-            ShareTarget.NEW_POST -> nav.newStack(Route.NewShortNote(message = message, attachment = media?.toString()))
+            // The single-file composers take the first URI: only the media targets declare
+            // SEND_MULTIPLE, so anything else can only be carrying one.
+            ShareTarget.DIRECT_MESSAGE -> nav.newStack(Route.ShareToDM(message = message, attachment = attachments.firstOrNull()))
+            ShareTarget.PICTURE -> nav.navToSharedFeed(Route.Pictures(attachments = attachments, message = message))
+            ShareTarget.SHORT_VIDEO -> nav.navToSharedFeed(Route.Shorts(attachments = attachments, message = message))
+            ShareTarget.VIDEO -> nav.navToSharedFeed(Route.Video(attachments = attachments, message = message))
+            ShareTarget.NEW_POST -> nav.newStack(Route.NewShortNote(message = message, attachment = attachments.firstOrNull()))
         }
 
         // Consume the launch intent so a later recomposition can't re-fire
@@ -1099,11 +1127,11 @@ private fun NavigateIfIntentRequested(
         DisposableEffect(nav, activity) {
             val consumer =
                 Consumer<Intent> { intent ->
-                    if (intent.action == Intent.ACTION_SEND) {
+                    if (intent.isShareAction()) {
                         val target = ShareIntentRouting.targetOf(intent.component?.className)
-                        val message = intent.getStringExtra(Intent.EXTRA_TEXT)?.ifBlank { null }
-                        val attachment =
-                            IntentCompat.getParcelableExtra(intent, Intent.EXTRA_STREAM, Uri::class.java)?.toString()
+                        val message = intent.sharedText()
+                        val attachments = intent.sharedStreamUris()
+                        val attachment = attachments.firstOrNull()
 
                         // avoids restarting the destination screen when the intent is for the screen.
                         // Microsoft's swift key sends Gifs as new actions.
@@ -1129,9 +1157,9 @@ private fun NavigateIfIntentRequested(
                                     nav.newStack(Route.ShareToDM(message = message, attachment = attachment))
                                 }
 
-                            ShareTarget.PICTURE -> nav.newStack(Route.Pictures(attachment = attachment))
-                            ShareTarget.SHORT_VIDEO -> nav.newStack(Route.Shorts(attachment = attachment))
-                            ShareTarget.VIDEO -> nav.newStack(Route.Video(attachment = attachment))
+                            ShareTarget.PICTURE -> nav.navToSharedFeed(Route.Pictures(attachments = attachments, message = message))
+                            ShareTarget.SHORT_VIDEO -> nav.navToSharedFeed(Route.Shorts(attachments = attachments, message = message))
+                            ShareTarget.VIDEO -> nav.navToSharedFeed(Route.Video(attachments = attachments, message = message))
 
                             ShareTarget.NEW_POST ->
                                 if (!isBaseRoute<Route.NewShortNote>(nav.controller) && (message != null || attachment != null)) {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/routes/Routes.kt

@@ -30,18 +30,32 @@ import com.vitorpamplona.quartz.nip17Dm.base.ChatroomKey
 import kotlinx.serialization.Serializable
 import kotlin.reflect.KClass
 
+/**
+ * A feed whose composer can be pre-loaded from an Android share. [attachments] holds the shared
+ * content URIs and [message] the text sent alongside them; both are empty/null for every other way
+ * of reaching the feed, which is how the share flow tells its own entries apart from an ordinary
+ * bottom-bar visit.
+ */
+sealed interface MediaFeedRoute {
+    val attachments: List<String>
+    val message: String?
+}
+
 sealed class Route {
     @Serializable object Home : Route()
 
     @Serializable object Message : Route()
 
     /**
-     * The mixed media feed. [attachment] is set by the "New Video" share target and pre-loads the
-     * media composer with the shared content URI.
+     * The mixed media feed. [attachments] and [message] are set by the "New Video" share target: the content
+     * URIs of the shared files and the text Android sent alongside them, which pre-load the media
+     * composer and its caption. Empty for every other way of reaching the feed.
      */
     @Serializable data class Video(
-        val attachment: String? = null,
-    ) : Route()
+        override val attachments: List<String> = emptyList(),
+        override val message: String? = null,
+    ) : Route(),
+        MediaFeedRoute
 
     @Serializable data class Discover(
         val initialTab: DiscoverTab? = null,
@@ -88,12 +102,15 @@ sealed class Route {
     }
 
     /**
-     * The picture feed. [attachment] is set by the "New Picture" share target and pre-loads the
-     * media composer with the shared content URI.
+     * The picture feed. [attachments] and [message] are set by the "New Picture" share target: the content
+     * URIs of the shared files and the text Android sent alongside them, which pre-load the media
+     * composer and its caption. Empty for every other way of reaching the feed.
      */
     @Serializable data class Pictures(
-        val attachment: String? = null,
-    ) : Route()
+        override val attachments: List<String> = emptyList(),
+        override val message: String? = null,
+    ) : Route(),
+        MediaFeedRoute
 
     @Serializable object Workouts : Route()
 
@@ -188,12 +205,15 @@ sealed class Route {
     @Serializable object Products : Route()
 
     /**
-     * The short-video feed. [attachment] is set by the "New Short" share target and pre-loads the
-     * media composer with the shared content URI.
+     * The short-video feed. [attachments] and [message] are set by the "New Short" share target: the content
+     * URIs of the shared files and the text Android sent alongside them, which pre-load the media
+     * composer and its caption. Empty for every other way of reaching the feed.
      */
     @Serializable data class Shorts(
-        val attachment: String? = null,
-    ) : Route()
+        override val attachments: List<String> = emptyList(),
+        override val message: String? = null,
+    ) : Route(),
+        MediaFeedRoute
 
     @Serializable object PublicChats : Route()
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/longs/NewLongVideoButton.kt

@@ -65,8 +65,10 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 /**
- * Everything posted from here is a NIP-71 kind 21 video, whether it was recorded, picked or shared,
- * so it always lands in the Longs feed the composer was opened from — portrait footage included.
+ * The Longs feed's composer. Every *video* posted from here is a NIP-71 kind-21 video — recorded or
+ * picked alike — so portrait footage lands in the Longs feed too instead of being routed to kind 22
+ * by its orientation. Images are unaffected: the gallery picker accepts them and they still post as
+ * NIP-68 kind-20 pictures, which the Longs feed does not read.
  */
 @Composable
 fun NewLongVideoButton(

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/pictures/NewPictureButton.kt

@@ -67,16 +67,22 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 /**
- * @param sharedAttachment content URI of a picture handed over by the "New Picture" share target.
- *   When present the composer opens on it right away, so the share lands as a NIP-68 picture post
- *   in this feed instead of a text note.
+ * The picture feed's composer. Images post as NIP-68 kind-20 pictures and land in this feed; a
+ * video picked from the gallery still posts as a NIP-71 video and shows up in the video feeds
+ * instead, since the file's mime type — not the host feed — decides picture vs. video.
+ *
+ * @param sharedAttachments content URIs handed over by the "New Picture" share target. When
+ *   non-empty the composer opens on them right away, so the share lands as a picture post instead
+ *   of a text note with a link.
+ * @param sharedCaption text Android sent alongside the files; pre-fills the caption field.
  */
 @Composable
 fun NewPictureButton(
     accountViewModel: AccountViewModel,
     nav: INav,
     navScrollToTop: () -> Unit,
-    sharedAttachment: String? = null,
+    sharedAttachments: List<String> = emptyList(),
+    sharedCaption: String? = null,
 ) {
     var isOpen by remember { mutableStateOf(false) }
     var wantsToPostFromCamera by remember { mutableStateOf(false) }
@@ -93,8 +99,8 @@ fun NewPictureButton(
     }
 
     val context = LocalContext.current
-    LaunchedEffect(sharedAttachment) {
-        resolveSharedMedia(context, sharedAttachment)?.let { pickedURIs = persistentListOf(it) }
+    LaunchedEffect(sharedAttachments) {
+        resolveSharedMedia(context, sharedAttachments).takeIf { it.isNotEmpty() }?.let { pickedURIs = it }
     }
 
     if (wantsToPostFromCamera) {
@@ -120,6 +126,7 @@ fun NewPictureButton(
             postViewModel = postViewModel,
             accountViewModel = accountViewModel,
             nav = nav,
+            initialCaption = sharedCaption.orEmpty(),
         )
     }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/pictures/PicturesScreen.kt

@@ -42,13 +42,15 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.pictures.datasource.Picture
 fun PicturesScreen(
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     PicturesScreen(
         picturesFeedContentState = accountViewModel.feedStates.picturesFeed,
         accountViewModel = accountViewModel,
         nav = nav,
-        attachment = attachment,
+        attachments = attachments,
+        message = message,
     )
 }
 
@@ -57,7 +59,8 @@ fun PicturesScreen(
     picturesFeedContentState: FeedContentState,
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     WatchLifecycleAndUpdateModel(picturesFeedContentState)
     WatchAccountForPicturesScreen(picturesFeedContentState = picturesFeedContentState, accountViewModel = accountViewModel)
@@ -79,7 +82,7 @@ fun PicturesScreen(
         },
         floatingButton = {
             FabBottomBarPadded(nav) {
-                NewPictureButton(accountViewModel, nav, picturesFeedContentState::sendToTop, attachment)
+                NewPictureButton(accountViewModel, nav, picturesFeedContentState::sendToTop, attachments, message)
             }
         },
         accountViewModel = accountViewModel,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/shorts/NewShortVideoButton.kt

@@ -68,18 +68,22 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 /**
- * @param sharedAttachment content URI of a video handed over by the "New Short" share target. When
- *   present the composer opens on it right away.
+ * The Shorts feed's composer. Every *video* posted from here is a NIP-71 kind-22 short — recorded,
+ * picked or shared alike — so landscape footage lands in the Shorts feed too instead of being
+ * routed to kind 21 by its orientation. Images are unaffected: the gallery picker accepts them and
+ * they still post as NIP-68 kind-20 pictures, which the Shorts feed does not read.
  *
- * Everything posted from here is a NIP-71 kind 22 short, whether it was recorded, picked or shared,
- * so it always lands in the Shorts feed the composer was opened from — landscape footage included.
+ * @param sharedAttachments content URIs handed over by the "New Short" share target. When non-empty
+ *   the composer opens on them right away.
+ * @param sharedCaption text Android sent alongside the files; pre-fills the caption field.
  */
 @Composable
 fun NewShortVideoButton(
     accountViewModel: AccountViewModel,
     nav: INav,
     navScrollToTop: () -> Unit,
-    sharedAttachment: String? = null,
+    sharedAttachments: List<String> = emptyList(),
+    sharedCaption: String? = null,
 ) {
     var isOpen by remember { mutableStateOf(false) }
     var wantsToRecordVideo by remember { mutableStateOf(false) }
@@ -96,8 +100,8 @@ fun NewShortVideoButton(
     }
 
     val context = LocalContext.current
-    LaunchedEffect(sharedAttachment) {
-        resolveSharedMedia(context, sharedAttachment)?.let { pickedURIs = persistentListOf(it) }
+    LaunchedEffect(sharedAttachments) {
+        resolveSharedMedia(context, sharedAttachments).takeIf { it.isNotEmpty() }?.let { pickedURIs = it }
     }
 
     if (wantsToRecordVideo) {
@@ -124,6 +128,7 @@ fun NewShortVideoButton(
             accountViewModel = accountViewModel,
             nav = nav,
             videoKind = VideoPostKind.SHORT,
+            initialCaption = sharedCaption.orEmpty(),
         )
     }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/shorts/ShortsScreen.kt

@@ -42,13 +42,15 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.shorts.datasource.ShortsFil
 fun ShortsScreen(
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     ShortsScreen(
         shortsFeedContentState = accountViewModel.feedStates.shortsFeed,
         accountViewModel = accountViewModel,
         nav = nav,
-        attachment = attachment,
+        attachments = attachments,
+        message = message,
     )
 }
 
@@ -57,7 +59,8 @@ fun ShortsScreen(
     shortsFeedContentState: FeedContentState,
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     WatchLifecycleAndUpdateModel(shortsFeedContentState)
     WatchAccountForShortsScreen(videoFeedState = shortsFeedContentState, accountViewModel = accountViewModel)
@@ -79,7 +82,7 @@ fun ShortsScreen(
         },
         floatingButton = {
             FabBottomBarPadded(nav) {
-                NewShortVideoButton(accountViewModel, nav, shortsFeedContentState::sendToTop, attachment)
+                NewShortVideoButton(accountViewModel, nav, shortsFeedContentState::sendToTop, attachments, message)
             }
         },
         accountViewModel = accountViewModel,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/video/NewVideoFeedButton.kt

@@ -68,19 +68,22 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 /**
- * The composer for the Video feed, which renders every media kind. Videos keep the automatic
- * kind choice (portrait -> NIP-71 kind 22, landscape -> kind 21); either way they show up here.
+ * The Video feed's composer. That feed renders every media kind, so videos keep the automatic kind
+ * choice (portrait -> NIP-71 kind 22, landscape -> kind 21) and pictures post as NIP-68 kind 20 —
+ * all three show up here either way, which is why this is the one media composer that pins nothing.
  *
- * @param sharedAttachment content URI of a video handed over by the "New Video" share target. When
- *   present the composer opens on it right away, so the share lands as a NIP-71 video event in this
- *   feed instead of a text note.
+ * @param sharedAttachments content URIs handed over by the "New Video" share target. When non-empty
+ *   the composer opens on them right away, so the share lands as a NIP-71 video event instead of a
+ *   text note with a link.
+ * @param sharedCaption text Android sent alongside the files; pre-fills the caption field.
  */
 @Composable
-fun NewImageButton(
+fun NewVideoFeedButton(
     accountViewModel: AccountViewModel,
     nav: INav,
     navScrollToTop: () -> Unit,
-    sharedAttachment: String? = null,
+    sharedAttachments: List<String> = emptyList(),
+    sharedCaption: String? = null,
 ) {
     var isOpen by remember { mutableStateOf(false) }
 
@@ -103,8 +106,8 @@ fun NewImageButton(
     }
 
     val context = LocalContext.current
-    LaunchedEffect(sharedAttachment) {
-        resolveSharedMedia(context, sharedAttachment)?.let { pickedURIs = persistentListOf(it) }
+    LaunchedEffect(sharedAttachments) {
+        resolveSharedMedia(context, sharedAttachments).takeIf { it.isNotEmpty() }?.let { pickedURIs = it }
     }
 
     if (wantsToPostFromCamera) {
@@ -137,6 +140,7 @@ fun NewImageButton(
             postViewModel = postViewModel,
             accountViewModel = accountViewModel,
             nav = nav,
+            initialCaption = sharedCaption.orEmpty(),
         )
     }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/video/VideoScreen.kt

@@ -59,13 +59,15 @@ import com.vitorpamplona.quartz.nip94FileMetadata.FileHeaderEvent
 fun VideoScreen(
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     VideoScreen(
         accountViewModel.feedStates.videoFeed,
         accountViewModel,
         nav,
-        attachment,
+        attachments,
+        message,
     )
 }
 
@@ -74,7 +76,8 @@ fun VideoScreen(
     videoFeedContentState: FeedContentState,
     accountViewModel: AccountViewModel,
     nav: INav,
-    attachment: String? = null,
+    attachments: List<String> = emptyList(),
+    message: String? = null,
 ) {
     WatchLifecycleAndUpdateModel(videoFeedContentState)
     WatchAccountForVideoScreen(videoFeedContentState = videoFeedContentState, accountViewModel = accountViewModel)
@@ -96,7 +99,7 @@ fun VideoScreen(
         },
         floatingButton = {
             FabBottomBarPadded(nav) {
-                NewImageButton(accountViewModel, nav, videoFeedContentState::sendToTop, attachment)
+                NewVideoFeedButton(accountViewModel, nav, videoFeedContentState::sendToTop, attachments, message)
             }
         },
         accountViewModel = accountViewModel,

amethyst/src/test/java/com/vitorpamplona/amethyst/navigation/ShareTargetManifestTest.kt

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.navigation
+
+import com.vitorpamplona.amethyst.ui.navigation.ShareIntentRouting
+import com.vitorpamplona.amethyst.ui.navigation.ShareTarget
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import java.io.File
+
+/**
+ * Guards the one link in the share-target chain the compiler cannot see: the `<activity-alias>`
+ * names in AndroidManifest.xml against the `SHARE_AS_*_ALIAS_SIMPLE_NAME` constants that
+ * [ShareIntentRouting] matches them by. Renaming an alias on one side only still builds and still
+ * runs — the share just silently opens the wrong composer (a picture share falls through to the
+ * default "New Post" target and becomes a text note).
+ *
+ * Checked in both directions, so neither a renamed constant nor a new alias without a constant
+ * slips through.
+ */
+class ShareTargetManifestTest {
+    private val aliasPattern = Regex("""<activity-alias[^>]*android:name="\.ui\.(\w+)"""", RegexOption.DOT_MATCHES_ALL)
+
+    private fun manifest(): String {
+        // Gradle runs unit tests with the module directory as the working directory; fall back to
+        // the repo root so the test also passes when run from an IDE configured that way.
+        val candidates =
+            listOf(
+                File("src/main/AndroidManifest.xml"),
+                File("amethyst/src/main/AndroidManifest.xml"),
+            )
+        val found = candidates.firstOrNull { it.isFile }
+        assertTrue(
+            "Could not locate AndroidManifest.xml from ${File(".").absolutePath}",
+            found != null,
+        )
+        return found!!.readText()
+    }
+
+    private fun declaredAliases(): Set<String> =
+        aliasPattern
+            .findAll(manifest())
+            .map { it.groupValues[1] }
+            .toSet()
+
+    @Test
+    fun everyRoutedAliasIsDeclaredInTheManifest() {
+        val declared = declaredAliases()
+
+        val expected =
+            listOf(
+                ShareIntentRouting.SHARE_AS_DM_ALIAS_SIMPLE_NAME,
+                ShareIntentRouting.SHARE_AS_HIGHLIGHT_ALIAS_SIMPLE_NAME,
+                ShareIntentRouting.SHARE_AS_PICTURE_ALIAS_SIMPLE_NAME,
+                ShareIntentRouting.SHARE_AS_SHORT_VIDEO_ALIAS_SIMPLE_NAME,
+                ShareIntentRouting.SHARE_AS_VIDEO_ALIAS_SIMPLE_NAME,
+            )
+
+        expected.forEach {
+            assertTrue(
+                "ShareIntentRouting routes \"$it\" but AndroidManifest.xml declares no such " +
+                    "<activity-alias android:name=\".ui.$it\">. Declared: $declared",
+                it in declared,
+            )
+        }
+    }
+
+    @Test
+    fun everyDeclaredAliasRoutesToItsOwnTarget() {
+        declaredAliases().forEach { alias ->
+            val target = ShareIntentRouting.targetOf("com.vitorpamplona.amethyst.ui.$alias")
+            assertTrue(
+                "AndroidManifest.xml declares <activity-alias android:name=\".ui.$alias\"> but " +
+                    "ShareIntentRouting has no constant for it, so shares to it fall through to " +
+                    "the default New Post composer.",
+                target != ShareTarget.NEW_POST,
+            )
+        }
+    }
+
+    @Test
+    fun aliasesResolveToDistinctTargets() {
+        val aliases = declaredAliases()
+        val targets = aliases.map { ShareIntentRouting.targetOf("com.vitorpamplona.amethyst.ui.$it") }
+
+        assertEquals(
+            "Two aliases resolve to the same ShareTarget — one of them is shadowed by a " +
+                "suffix match. Aliases: $aliases, targets: $targets",
+            targets.size,
+            targets.toSet().size,
+        )
+    }
+
+    /** The media targets are the only ones that accept a multi-file selection. */
+    @Test
+    fun mediaAliasesAcceptSendMultiple() {
+        val text = manifest()
+
+        listOf(
+            ShareIntentRouting.SHARE_AS_PICTURE_ALIAS_SIMPLE_NAME,
+            ShareIntentRouting.SHARE_AS_SHORT_VIDEO_ALIAS_SIMPLE_NAME,
+            ShareIntentRouting.SHARE_AS_VIDEO_ALIAS_SIMPLE_NAME,
+        ).forEach { alias ->
+            val block =
+                text
+                    .substringAfter("android:name=\".ui.$alias\"")
+                    .substringBefore("</activity-alias>")
+
+            assertTrue(
+                "The \".ui.$alias\" share target has no SEND_MULTIPLE intent-filter, so sharing " +
+                    "several files at once will not offer it.",
+                block.contains("android.intent.action.SEND_MULTIPLE"),
+            )
+        }
+    }
+}