feat(projects): add to an existing project, and names instead of hashes

Phase 7c of docs/project-feature.md, and the last of the phases this plan
builds. 8 and 9 -- removal, and projects that span rooms -- stay deferred.

The resolver comes first because the screen depends on it. A membership event
carries two 64-character ids and nothing else, so proposing one on its own
means every other member is shown "sign a4f1be55d0c3" and asked to agree. That
is not a question anybody can answer, and the plan said not to ship this screen
without the fix.

So `FrostSigningViewModel` resolves what the proposed events refer to -- the
profile behind a creator or an owner, the artifact and label behind a version,
the name behind a project -- and hands `summarize` a lookup. Synchronous, because
two of the four call sites are composables and cannot await a database;
pre-resolved in the view model for the same reason. Only what this device
already holds: a key with no profile and an id with no row are left out and fall
back to a short hash, which is truthful rather than a gap.

A project's own id still resolves to nothing while it is being proposed, since
nothing has applied it yet. That is why a membership's summary says the version
first.

`AddToProjectScreen` is the simpler half of founding a project: the project
exists, so its id is known and there is no lead and no batch -- one event, one
session. Candidates are filtered to what the project does not already hold
rather than shown and refused, because a duplicate membership is a second event
with its own id and nothing downstream would stop it; it would just cost a
quorum to say what the group has already said.

One at a time, by radio button rather than checkboxes. A quorum per thing added
is the grain this app signs at, and a multi-select here would quietly be a batch
whose items a member has to weigh separately anyway.

M3 budgets met. 1403 tests, no failures.

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

composeApp/src/commonMain/composeResources/values/strings.xml

@@ -22,6 +22,8 @@
     -->
     <string name="add_an_owner">Add an owner</string>
     <string name="add_project">Add project</string>
+    <string name="add_source_version_to_project">Add source version</string>
+    <string name="add_translation_to_project">Add translation</string>
     <string name="an_owner_is_a_64_character_public_key">An owner is a 64-character public key.</string>
     <string name="app_name">Mantra</string>
     <string name="add_a_dialect_the_group_can_translate_into">Add a dialect the group can translate into</string>
@@ -64,6 +66,8 @@
     <string name="created_by">Created by</string>
     <string name="describe_the_project">What this project is</string>
     <string name="eg_the_four_gospels_into_sesotho">e.g. The four gospels into Sesotho</string>
+    <string name="every_translation_is_already_in_this_project">Every translation in this group is already in this project.</string>
+    <string name="everything_in_the_library_is_already_in_this_project">Everything in this group's library is already in this project.</string>
     <string name="name_of_project">Name of project</string>
     <string name="no_source_versions_in_this_project">No source versions in this project yet.</string>
     <string name="no_translations_in_this_project">No translations in this project yet.</string>
@@ -71,6 +75,7 @@
     <string name="owner_public_key">Owner public key</string>
     <string name="owners">Owners</string>
     <string name="project_detail">Project detail</string>
+    <string name="propose_adding_to_the_project">Propose adding</string>
     <string name="propose_project">Propose project</string>
     <string name="remove_owner">Remove owner</string>
     <string name="source_versions">Source versions</string>

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/AddToProjectScreen.kt

@@ -0,0 +1,302 @@
+package press.mantra.compose.ui.composable
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.Article
+import androidx.compose.material.icons.filled.Translate
+import androidx.compose.material3.BottomAppBar
+import androidx.compose.material3.Card
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.Icon
+import androidx.compose.material3.ListItem
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.RadioButton
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextAlign
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import mantra.composeapp.generated.resources.Res
+import mantra.composeapp.generated.resources.add_source_version_to_project
+import mantra.composeapp.generated.resources.add_translation_to_project
+import mantra.composeapp.generated.resources.every_translation_is_already_in_this_project
+import mantra.composeapp.generated.resources.everything_in_the_library_is_already_in_this_project
+import mantra.composeapp.generated.resources.project_detail
+import mantra.composeapp.generated.resources.propose_adding_to_the_project
+import org.jetbrains.compose.resources.stringResource
+import press.mantra.compose.repository.ChatRepository
+import press.mantra.compose.repository.FrostSigningRepository
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.ui.composable.navigation.routes.FrostSigningRoute
+import press.mantra.compose.ui.composable.navigation.routes.ImplementationPendingRoute
+import press.mantra.compose.ui.composable.navigation.routes.Route
+import press.mantra.compose.ui.composable.widgets.Decorative
+import press.mantra.compose.ui.composable.widgets.LoadingDataIndicator
+import press.mantra.compose.ui.composable.widgets.LocalSnackbarHostState
+import press.mantra.compose.ui.composable.widgets.NavigateBackButton
+import press.mantra.compose.ui.composable.widgets.ScreenStateTransition
+import press.mantra.compose.ui.composable.widgets.buttons.ExtendedFab
+import press.mantra.compose.ui.theme.ConformancePreviews
+import press.mantra.compose.ui.theme.MantraTheme
+import press.mantra.compose.ui.theme.readableContent
+import press.mantra.compose.ui.theme.spacing
+import press.mantra.compose.ui.view.model.AddToProjectViewModel
+import press.mantra.compose.ui.view.state.AddToProjectUIState
+
+/**
+ * One more piece of work into a project that already exists.
+ *
+ * Unlike founding a project, this proposes a single membership -- so the whole
+ * of what the group is asked to agree to is two ids. That is why
+ * `FrostSigningViewModel` resolves names for them: without it the other members
+ * are shown a truncated hash and asked to sign it, which is not a question
+ * anybody can answer.
+ */
+@OptIn(ExperimentalMaterial3ExpressiveApi::class, ExperimentalMaterial3Api::class)
+@Composable
+fun AddToProjectScreen(
+    activeUserPublicKey: HexKey,
+    projectId: String,
+    chatRoomId: String,
+    translations: Boolean,
+    relayHint: String?,
+    initialAddToProjectUIState: AddToProjectUIState = AddToProjectUIState.Loading,
+    chatRepository: ChatRepository,
+    mantraRepository: MantraRepository,
+    frostSigningRepository: FrostSigningRepository,
+    onNavigateToRouteAndPopUpInclusive: (Route) -> Unit,
+    onNavigateToRoute: (Route) -> Unit,
+    onNavigateBack: () -> Unit,
+) {
+    val addToProjectViewModel: AddToProjectViewModel = viewModel(
+        factory = AddToProjectViewModel.factory(
+            activeUserPublicKey = activeUserPublicKey,
+            projectId = projectId,
+            chatRoomId = chatRoomId,
+            translations = translations,
+            relayHint = relayHint,
+            initialAddToProjectUIState = initialAddToProjectUIState,
+            chatRepository = chatRepository,
+            mantraRepository = mantraRepository,
+            frostSigningRepository = frostSigningRepository,
+        )
+    )
+
+    ScreenStateTransition(addToProjectViewModel.addToProjectUIState) { uiState ->
+        when (val addToProjectUIState = uiState) {
+            is AddToProjectUIState.Error -> {
+                Column(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalAlignment = Alignment.CenterHorizontally
+                ) {
+                    Spacer(modifier = Modifier.height(MaterialTheme.spacing.space600))
+                    Text(text = addToProjectUIState.message)
+                }
+            }
+
+            is AddToProjectUIState.Loaded -> {
+                var selectedId: HexKey? by remember { mutableStateOf(null) }
+
+                Scaffold(
+                    snackbarHost = { SnackbarHost(LocalSnackbarHostState.current) },
+                    topBar = {
+                        TopAppBar(
+                            title = {
+                                Text(
+                                    if (translations) {
+                                        stringResource(Res.string.add_translation_to_project)
+                                    } else {
+                                        stringResource(Res.string.add_source_version_to_project)
+                                    }
+                                )
+                            },
+                            navigationIcon = { NavigateBackButton(onNavigateBack) },
+                        )
+                    },
+                    bottomBar = {
+                        BottomAppBar(
+                            actions = {},
+                            floatingActionButton = {
+                                ExtendedFab(
+                                    label = stringResource(
+                                        Res.string.propose_adding_to_the_project
+                                    ),
+                                    icon = {
+                                        Icon(Icons.Default.Add, contentDescription = Decorative)
+                                    },
+                                    enabled = selectedId != null && addToProjectUIState.canSign,
+                                    onClick = {
+                                        val chosen = selectedId ?: return@ExtendedFab
+
+                                        addToProjectViewModel.addToProject(
+                                            localChatRoom = addToProjectUIState.localChatRoom,
+                                            selectedId = chosen,
+                                            onSuccess = { sessionId ->
+                                                onNavigateToRouteAndPopUpInclusive.invoke(
+                                                    FrostSigningRoute(
+                                                        activeUserPublicKey = activeUserPublicKey,
+                                                        chatRoomId = chatRoomId,
+                                                        sessionId = sessionId
+                                                    )
+                                                )
+                                            },
+                                            onFailure = {
+                                                onNavigateToRoute.invoke(
+                                                    ImplementationPendingRoute(
+                                                        "Failed project membership"
+                                                    )
+                                                )
+                                            }
+                                        )
+                                    }
+                                )
+                            }
+                        )
+                    }
+                ) { innerPadding ->
+                    LazyColumn(
+                        modifier = Modifier
+                            .padding(innerPadding)
+                            .readableContent()
+                            .fillMaxSize()
+                            .padding(MaterialTheme.spacing.space250),
+                        verticalArrangement = Arrangement.spacedBy(MaterialTheme.spacing.space125)
+                    ) {
+                        item { Text(addToProjectUIState.project.name) }
+
+                        if (!addToProjectUIState.canSign) {
+                            item {
+                                Text(
+                                    text = "This group has no shared key, so it cannot sign " +
+                                        "anything into this project. Run a shared key " +
+                                        "ceremony first.",
+                                    style = MaterialTheme.typography.bodySmall,
+                                    color = MaterialTheme.colorScheme.error
+                                )
+                            }
+                        }
+
+                        if (addToProjectUIState.candidates.isEmpty()) {
+                            item {
+                                Text(
+                                    if (translations) {
+                                        stringResource(
+                                            Res.string
+                                                .every_translation_is_already_in_this_project
+                                        )
+                                    } else {
+                                        stringResource(
+                                            Res.string
+                                                .everything_in_the_library_is_already_in_this_project
+                                        )
+                                    }
+                                )
+                            }
+                        } else {
+                            items(
+                                items = addToProjectUIState.candidates,
+                                key = { candidate -> candidate.id }
+                            ) { candidate ->
+                                Card(onClick = { selectedId = candidate.id }) {
+                                    ListItem(
+                                        leadingContent = {
+                                            Icon(
+                                                if (translations) {
+                                                    Icons.Default.Translate
+                                                } else {
+                                                    Icons.Default.Article
+                                                },
+                                                contentDescription = Decorative
+                                            )
+                                        },
+                                        trailingContent = {
+                                            // One at a time: the proposal is one
+                                            // event, and a quorum per thing added
+                                            // is the grain the group signs at.
+                                            RadioButton(
+                                                selected = selectedId == candidate.id,
+                                                onClick = { selectedId = candidate.id }
+                                            )
+                                        },
+                                        headlineContent = { Text(candidate.label) },
+                                        supportingContent = candidate.detail?.let { detail ->
+                                            { Text(detail) }
+                                        }
+                                    )
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+
+            AddToProjectUIState.Loading -> {
+                Column(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(MaterialTheme.spacing.space250),
+                    horizontalAlignment = Alignment.CenterHorizontally,
+                    verticalArrangement = Arrangement.spacedBy(MaterialTheme.spacing.space250)
+                ) {
+                    Spacer(modifier = Modifier.weight(1f))
+                    Text(
+                        text = stringResource(Res.string.project_detail),
+                        style = MaterialTheme.typography.bodyLarge,
+                        textAlign = TextAlign.Center
+                    )
+                    LoadingDataIndicator(fillScreen = false)
+                    Spacer(modifier = Modifier.weight(2f))
+                }
+            }
+        }
+    }
+
+    LaunchedEffect(true) {
+        if (initialAddToProjectUIState == AddToProjectUIState.Loading) {
+            addToProjectViewModel.initiateAddToProject()
+        }
+    }
+}
+
+@ConformancePreviews
+@Composable
+private fun AddToProjectScreenPreview() {
+    MantraTheme {
+        Surface(modifier = Modifier.fillMaxSize()) {
+            AddToProjectScreen(
+                activeUserPublicKey = "a".repeat(64),
+                projectId = "p".repeat(64),
+                chatRoomId = "b".repeat(64),
+                translations = false,
+                relayHint = null,
+                chatRepository = ChatRepository.NO_OP_CHAT_REPOSITORY,
+                mantraRepository = MantraRepository.NO_OP_MANTRA_REPOSITORY,
+                frostSigningRepository = FrostSigningRepository.NO_OP_FROST_SIGNING_REPOSITORY,
+                onNavigateToRouteAndPopUpInclusive = {},
+                onNavigateToRoute = {},
+                onNavigateBack = {},
+            )
+        }
+    }
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/FrostSigningScreen.kt

@@ -48,6 +48,8 @@ import press.mantra.compose.database.model.types.FrostSigningStage
 import press.mantra.compose.managers.FrostSigningManager
 import press.mantra.compose.repository.ChatRepository
 import press.mantra.compose.repository.FrostSigningRepository
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.repository.NostrRepository
 import press.mantra.compose.text.ProposedEvent
 import press.mantra.compose.ui.composable.widgets.profile.ProfileAvatar
 import press.mantra.compose.ui.theme.MantraTheme
@@ -93,6 +95,8 @@ fun FrostSigningScreen(
     initialFrostSigningUIState: FrostSigningUIState = FrostSigningUIState.Loading,
     chatRepository: ChatRepository,
     frostSigningRepository: FrostSigningRepository,
+    mantraRepository: MantraRepository,
+    nostrRepository: NostrRepository,
     onNavigateBack: () -> Unit,
 ) {
     val frostSigningViewModel: FrostSigningViewModel = viewModel(
@@ -102,7 +106,9 @@ fun FrostSigningScreen(
             activeUserPublicKey = activeUserPublicKey,
             initialFrostSigningUIState = initialFrostSigningUIState,
             chatRepository = chatRepository,
-            frostSigningRepository = frostSigningRepository
+            frostSigningRepository = frostSigningRepository,
+            mantraRepository = mantraRepository,
+            nostrRepository = nostrRepository
         )
     )
 
@@ -169,6 +175,7 @@ fun FrostSigningScreen(
                         events = proposed,
                         expected = state.items.size,
                         chatRoomId = state.localChatRoom.chatRoom.id,
+                        names = state.names,
                     )
 
                     HorizontalDivider()
@@ -339,7 +346,12 @@ private fun Loading(padding: androidx.compose.foundation.layout.PaddingValues) {
  * sign something they cannot check.
  */
 @Composable
-private fun WhatIsBeingSigned(events: List<Event>, expected: Int, chatRoomId: String) {
+private fun WhatIsBeingSigned(
+    events: List<Event>,
+    expected: Int,
+    chatRoomId: String,
+    names: Map<HexKey, String>,
+) {
     if (expected == 0 || events.size != expected) {
         Text(
             text = if (expected <= 1) {
@@ -365,7 +377,7 @@ private fun WhatIsBeingSigned(events: List<Event>, expected: Int, chatRoomId: St
         events.forEachIndexed { index, event ->
             if (index > 0) HorizontalDivider()
 
-            OneThingBeingSigned(event, chatRoomId)
+            OneThingBeingSigned(event, chatRoomId, names)
         }
 
         Text(
@@ -380,9 +392,18 @@ private fun WhatIsBeingSigned(events: List<Event>, expected: Int, chatRoomId: St
 
 /** One event of the batch, described as the thing it is. */
 @Composable
-private fun OneThingBeingSigned(event: Event, chatRoomId: String) {
-    // The room, so a project owned by this group does not say so on every line.
-    val summary = ProposedEvent.summarize(event, chatRoomId = chatRoomId)
+private fun OneThingBeingSigned(
+    event: Event,
+    chatRoomId: String,
+    names: Map<HexKey, String>,
+) {
+    // The room, so a project owned by this group does not say so on every line;
+    // and the names, so what is being signed is a thing rather than a hash.
+    val summary = ProposedEvent.summarize(
+        event = event,
+        chatRoomId = chatRoomId,
+        resolve = names::get,
+    )
 
     Column(verticalArrangement = Arrangement.spacedBy(MaterialTheme.spacing.space50)) {
         Text(text = summary.label, style = MaterialTheme.typography.labelMedium)
@@ -430,6 +451,8 @@ private fun FrostSigningScreenPreview() {
                 ),
                 chatRepository = ChatRepository.NO_OP_CHAT_REPOSITORY,
                 frostSigningRepository = FrostSigningRepository.NO_OP_FROST_SIGNING_REPOSITORY,
+                mantraRepository = MantraRepository.NO_OP_MANTRA_REPOSITORY,
+                nostrRepository = NostrRepository.NO_OP_NOSTR_REPOSITORY,
                 onNavigateBack = {}
             )
         }

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/ProjectDetailScreen.kt

@@ -5,12 +5,14 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Article
+import androidx.compose.material.icons.filled.PostAdd
 import androidx.compose.material.icons.filled.Translate
 import androidx.compose.material3.Card
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -22,6 +24,7 @@ import androidx.compose.material3.Scaffold
 import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBar
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -31,6 +34,8 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import mantra.composeapp.generated.resources.Res
+import mantra.composeapp.generated.resources.add_source_version_to_project
+import mantra.composeapp.generated.resources.add_translation_to_project
 import mantra.composeapp.generated.resources.created_by
 import mantra.composeapp.generated.resources.details
 import mantra.composeapp.generated.resources.no_source_versions_in_this_project
@@ -47,6 +52,7 @@ import press.mantra.compose.extensions.shortened
 import press.mantra.compose.repository.FrostSigningRepository
 import press.mantra.compose.repository.MantraRepository
 import press.mantra.compose.repository.NostrRepository
+import press.mantra.compose.ui.composable.navigation.routes.AddToProjectRoute
 import press.mantra.compose.ui.composable.navigation.routes.Route
 import press.mantra.compose.ui.composable.navigation.routes.TranslationArtifactVersionDetailRoute
 import press.mantra.compose.ui.composable.widgets.Decorative
@@ -166,6 +172,27 @@ fun ProjectDetailScreen(
                                 }
                             }
                         }
+                        item {
+                            TextButton(
+                                enabled = projectDetailUIState.canSign,
+                                onClick = {
+                                    onNavigateToRoute.invoke(
+                                        AddToProjectRoute(
+                                            activeUserPublicKey = activeUserPublicKey,
+                                            projectId = project.id,
+                                            chatRoomId = chatRoomId,
+                                            translations = false,
+                                            relayHint = relayHint,
+                                        )
+                                    )
+                                }
+                            ) {
+                                Icon(Icons.Default.PostAdd, contentDescription = Decorative)
+                                Spacer(modifier = Modifier.width(MaterialTheme.spacing.space125))
+                                Text(stringResource(Res.string.add_source_version_to_project))
+                            }
+                        }
+
                         item { HorizontalDivider() }
 
                         // Translations
@@ -208,6 +235,27 @@ fun ProjectDetailScreen(
                                 }
                             }
                         }
+                        item {
+                            TextButton(
+                                enabled = projectDetailUIState.canSign,
+                                onClick = {
+                                    onNavigateToRoute.invoke(
+                                        AddToProjectRoute(
+                                            activeUserPublicKey = activeUserPublicKey,
+                                            projectId = project.id,
+                                            chatRoomId = chatRoomId,
+                                            translations = true,
+                                            relayHint = relayHint,
+                                        )
+                                    )
+                                }
+                            ) {
+                                Icon(Icons.Default.Translate, contentDescription = Decorative)
+                                Spacer(modifier = Modifier.width(MaterialTheme.spacing.space125))
+                                Text(stringResource(Res.string.add_translation_to_project))
+                            }
+                        }
+
                         item { HorizontalDivider() }
 
                         // Who it belongs to

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/navigation/MantraNavHost.kt

@@ -136,6 +136,7 @@ import press.mantra.compose.database.repository.DatabaseMantraRepository
 import press.mantra.compose.ui.composable.AddArtifactScreen
 import press.mantra.compose.ui.composable.navigation.routes.AddArtifactRoute
 import press.mantra.compose.ui.composable.navigation.routes.AddProjectRoute
+import press.mantra.compose.ui.composable.navigation.routes.AddToProjectRoute
 import press.mantra.compose.ui.composable.navigation.routes.AddDialectRoute
 import press.mantra.compose.ui.composable.navigation.routes.BroadcastGroupSignedEventRoute
 import press.mantra.compose.ui.composable.navigation.routes.FrostSigningRoute
@@ -149,6 +150,7 @@ import press.mantra.compose.ui.composable.navigation.routes.TranslateChunkRoute
 import press.mantra.compose.ui.composable.navigation.routes.TranslationChapterRoute
 import press.mantra.compose.ui.composable.navigation.routes.TranslationArtifactVersionDetailRoute
 import press.mantra.compose.ui.composable.AddProjectScreen
+import press.mantra.compose.ui.composable.AddToProjectScreen
 import press.mantra.compose.ui.composable.ArtifactDetailScreen
 import press.mantra.compose.ui.composable.ProjectDetailScreen
 import press.mantra.compose.ui.composable.AddChapterScreen
@@ -1094,6 +1096,39 @@ fun MantraNavHost(
                     },
                 )
             }
+            composable<AddToProjectRoute> { backStackEntry ->
+                val route = backStackEntry.toRoute<AddToProjectRoute>()
+
+                AddToProjectScreen(
+                    activeUserPublicKey = route.activeUserPublicKey,
+                    projectId = route.projectId,
+                    chatRoomId = route.chatRoomId,
+                    translations = route.translations,
+                    relayHint = route.relayHint,
+                    chatRepository = databaseChatRepository,
+                    mantraRepository = databaseMantraRepository,
+                    frostSigningRepository = databaseFrostSigningRepository,
+                    onNavigateToRouteAndPopUpInclusive = { signingRoute ->
+                        // Replace this picker so back returns to the project
+                        // rather than to a form whose proposal has gone out.
+                        navController.navigate(
+                            route = signingRoute
+                        ) {
+                            popUpTo(route) {
+                                inclusive = true
+                            }
+                        }
+                    },
+                    onNavigateToRoute = { actionRoute ->
+                        navController.navigate(
+                            route = actionRoute
+                        )
+                    },
+                    onNavigateBack = {
+                        navController.popBackStack()
+                    }
+                )
+            }
             composable<AddProjectRoute> { backStackEntry ->
                 val route = backStackEntry.toRoute<AddProjectRoute>()
 
@@ -1215,6 +1250,8 @@ fun MantraNavHost(
                     sessionId = route.sessionId,
                     chatRepository = databaseChatRepository,
                     frostSigningRepository = databaseFrostSigningRepository,
+                    mantraRepository = databaseMantraRepository,
+                    nostrRepository = databaseNostrRepository,
                     onNavigateBack = {
                         navController.popBackStack()
                     }

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/navigation/routes/AddToProjectRoute.kt

@@ -0,0 +1,20 @@
+package press.mantra.compose.ui.composable.navigation.routes
+
+import kotlinx.serialization.Serializable
+
+/**
+ * [translations] picks which half of a project this adds to: its translations
+ * when true, its source versions when false.
+ *
+ * One route rather than two because the screen is the same screen -- a list to
+ * pick from and one proposal -- and the two differ only in which list and which
+ * kind. Two routes would be two view models with one body between them.
+ */
+@Serializable
+data class AddToProjectRoute(
+    val activeUserPublicKey: String,
+    val projectId: String,
+    val chatRoomId: String,
+    val translations: Boolean,
+    val relayHint: String?
+): Route()

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/model/AddToProjectViewModel.kt

@@ -0,0 +1,190 @@
+package press.mantra.compose.ui.view.model
+
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import co.touchlab.kermit.Logger
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.IO
+import kotlinx.coroutines.launch
+import press.mantra.compose.database.model.intermdiate.LocalChatRoom
+import press.mantra.compose.nostr.nip30303.ProjectArtifactVersionEvent
+import press.mantra.compose.nostr.nip30303.ProjectTranslationArtifactVersionEvent
+import press.mantra.compose.repository.ChatRepository
+import press.mantra.compose.repository.FrostSigningRepository
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.ui.view.state.AddToProjectUIState
+
+/**
+ * Adding one more piece of work to a project that already exists.
+ *
+ * The other half of `AddProjectViewModel`, and the simpler one: the project's
+ * id is known, so there is no batch and no lead -- one event, one session.
+ */
+class AddToProjectViewModel(
+    val projectId: String,
+    val chatRoomId: String,
+    val activeUserPublicKey: HexKey,
+    val translations: Boolean,
+    val relayHint: String?,
+    initialAddToProjectUIState: AddToProjectUIState,
+    val chatRepository: ChatRepository,
+    val mantraRepository: MantraRepository,
+    val frostSigningRepository: FrostSigningRepository,
+): ViewModel() {
+
+    var addToProjectUIState: AddToProjectUIState by mutableStateOf(initialAddToProjectUIState)
+        private set
+
+    private val logger = Logger.withTag(TAG)
+
+    val isActionPending: MutableState<Boolean> = mutableStateOf(false)
+
+    fun initiateAddToProject() {
+        logger.d("initiateAddToProject: $projectId translations=$translations")
+        viewModelScope.launch(Dispatchers.IO) {
+            val localChatRoom = chatRepository.getChatRoomByIdentifier(chatRoomId)
+            val project = mantraRepository.getProject(projectId)
+
+            addToProjectUIState = when {
+                localChatRoom == null -> AddToProjectUIState.Error("Couldn't find the chat room")
+                project == null -> AddToProjectUIState.Error("Couldn't find the project")
+                else -> AddToProjectUIState.Loaded(
+                    localChatRoom = localChatRoom,
+                    project = project,
+                    candidates = candidatesFor(localChatRoom.chatRoom.id),
+                    canSign = frostSigningRepository.canSign(chatRoomId),
+                )
+            }
+        }
+    }
+
+    /**
+     * What the room has that the project does not already hold.
+     *
+     * Filtered rather than shown and refused: a duplicate membership is a
+     * second event with its own id, so nothing downstream would stop it -- it
+     * would just cost a quorum to say what the group has already said.
+     */
+    private suspend fun candidatesFor(chatRoomId: String): List<AddToProjectUIState.Candidate> {
+        val versions = mantraRepository.getArtifacts(chatRoomId)
+            .flatMap { mantraRepository.getArtifactVersions(it.id) }
+
+        return if (translations) {
+            val already = mantraRepository.getProjectTranslationArtifactVersions(projectId)
+                .map { it.id }
+                .toSet()
+
+            versions
+                .flatMap { mantraRepository.getTranslationsForArtifactVersion(it.id) }
+                .filterNot { it.id in already }
+                .map {
+                    AddToProjectUIState.Candidate(
+                        id = it.id,
+                        label = it.name,
+                        detail = null,
+                    )
+                }
+        } else {
+            val already = mantraRepository.getProjectArtifactVersions(projectId)
+                .map { it.id }
+                .toSet()
+
+            versions
+                .filterNot { it.id in already }
+                .map { version ->
+                    AddToProjectUIState.Candidate(
+                        id = version.id,
+                        label = version.versionLabel,
+                        // The artifact, because a version label on its own is
+                        // "1.0" and a room has several of those.
+                        detail = mantraRepository.getArtifact(version.artifactId)?.name,
+                    )
+                }
+        }
+    }
+
+    /**
+     * Asks the group to sign one thing into the project.
+     *
+     * One event, so [FrostSigningRepository.proposeSigning]'s flat batch rather
+     * than the lead-and-dependents form: this screen knows the project's id
+     * because the project exists.
+     */
+    fun addToProject(
+        localChatRoom: LocalChatRoom,
+        selectedId: HexKey,
+        onSuccess: (sessionId: String) -> Unit,
+        onFailure: () -> Unit
+    ) {
+        if (isActionPending.value) return
+        isActionPending.value = true
+
+        viewModelScope.launch(Dispatchers.IO) {
+            val template = if (translations) {
+                ProjectTranslationArtifactVersionEvent.build(
+                    projectId = projectId,
+                    translationArtifactVersionId = selectedId,
+                )
+            } else {
+                ProjectArtifactVersionEvent.build(
+                    projectId = projectId,
+                    artifactVersionId = selectedId,
+                )
+            }
+
+            val session = runCatching {
+                frostSigningRepository.proposeSigningBatch(
+                    localChatRoom = localChatRoom,
+                    userPublicKey = activeUserPublicKey,
+                    events = listOf(template),
+                )
+            }.onFailure { error ->
+                logger.e("Failed to propose adding to project $projectId", error)
+            }.getOrNull()
+
+            viewModelScope.launch(Dispatchers.Main) {
+                if (session != null) onSuccess.invoke(session.id) else onFailure.invoke()
+            }
+
+            isActionPending.value = false
+        }
+    }
+
+    companion object {
+        private const val TAG = "AddToProjectViewModel"
+
+        fun factory(
+            activeUserPublicKey: HexKey,
+            projectId: String,
+            chatRoomId: String,
+            translations: Boolean,
+            relayHint: String?,
+            initialAddToProjectUIState: AddToProjectUIState = AddToProjectUIState.Loading,
+            chatRepository: ChatRepository,
+            mantraRepository: MantraRepository,
+            frostSigningRepository: FrostSigningRepository,
+        ): ViewModelProvider.Factory = viewModelFactory {
+            initializer {
+                AddToProjectViewModel(
+                    activeUserPublicKey = activeUserPublicKey,
+                    projectId = projectId,
+                    chatRoomId = chatRoomId,
+                    translations = translations,
+                    relayHint = relayHint,
+                    initialAddToProjectUIState = initialAddToProjectUIState,
+                    chatRepository = chatRepository,
+                    mantraRepository = mantraRepository,
+                    frostSigningRepository = frostSigningRepository,
+                )
+            }
+        }
+    }
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/model/FrostSigningViewModel.kt

@@ -19,8 +19,13 @@ import kotlinx.coroutines.launch
 import press.mantra.compose.database.model.FrostSigningItem
 import press.mantra.compose.database.model.FrostSigningSession
 import press.mantra.compose.nostr.frost.FrostSigningEvents
+import press.mantra.compose.nostr.nip30303.ProjectArtifactVersionEvent
+import press.mantra.compose.nostr.nip30303.ProjectEvent
+import press.mantra.compose.nostr.nip30303.ProjectTranslationArtifactVersionEvent
 import press.mantra.compose.repository.ChatRepository
 import press.mantra.compose.repository.FrostSigningRepository
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.repository.NostrRepository
 import press.mantra.compose.ui.view.state.FrostSigningUIState
 
 class FrostSigningViewModel(
@@ -30,6 +35,8 @@ class FrostSigningViewModel(
     initialFrostSigningUIState: FrostSigningUIState,
     val chatRepository: ChatRepository,
     val frostSigningRepository: FrostSigningRepository,
+    val mantraRepository: MantraRepository,
+    val nostrRepository: NostrRepository,
 ): ViewModel() {
 
     var frostSigningUIState: FrostSigningUIState by mutableStateOf(initialFrostSigningUIState)
@@ -72,12 +79,83 @@ class FrostSigningViewModel(
                         signed = messages
                             .filter { it.kind == FrostSigningEvents.PARTIAL_SIGNATURE }
                             .map { it.signerPublicKey }
-                            .toSet()
+                            .toSet(),
+                        names = namesIn(proposedEvents(items))
                     )
                 }
         }
     }
 
+    /**
+     * Whatever the proposed events refer to, as words.
+     *
+     * Only the kinds that need it, and only what this device already holds. A
+     * key with no profile and an id with no row are both left out, and
+     * `ProposedEvent.summarize` falls back to a short hash -- which is truthful
+     * rather than a gap: the device has not seen the thing.
+     *
+     * A project's own id resolves to nothing while it is being proposed,
+     * because nothing has applied it yet. That is why a membership says the
+     * version first.
+     */
+    private suspend fun namesIn(events: List<Event>): Map<HexKey, String> = buildMap {
+        suspend fun person(publicKey: HexKey) {
+            if (containsKey(publicKey)) return
+            nostrRepository.getProfileWithPublicKey(publicKey)?.let {
+                put(publicKey, it.humanReadableNameOrPubkey())
+            }
+        }
+
+        suspend fun project(projectId: HexKey?) {
+            if (projectId == null || containsKey(projectId)) return
+            mantraRepository.getProject(projectId)?.let { put(projectId, it.name) }
+        }
+
+        events.forEach { event ->
+            when (event.kind) {
+                ProjectEvent.KIND -> {
+                    val proposed = ProjectEvent(
+                        event.id, event.pubKey, event.createdAt,
+                        event.tags, event.content, event.sig
+                    )
+                    proposed.creator()?.let { person(it) }
+                    proposed.owners().forEach { person(it) }
+                }
+
+                ProjectArtifactVersionEvent.KIND -> {
+                    val membership = ProjectArtifactVersionEvent(
+                        event.id, event.pubKey, event.createdAt,
+                        event.tags, event.content, event.sig
+                    )
+                    membership.artifactVersionId()?.let { versionId ->
+                        mantraRepository.getArtifactVersion(versionId)?.let { version ->
+                            val artifact = mantraRepository.getArtifact(version.artifactId)
+                            put(
+                                versionId,
+                                listOfNotNull(artifact?.name, version.versionLabel)
+                                    .joinToString(" ")
+                            )
+                        }
+                    }
+                    project(membership.projectId())
+                }
+
+                ProjectTranslationArtifactVersionEvent.KIND -> {
+                    val membership = ProjectTranslationArtifactVersionEvent(
+                        event.id, event.pubKey, event.createdAt,
+                        event.tags, event.content, event.sig
+                    )
+                    membership.translationArtifactVersionId()?.let { translationId ->
+                        mantraRepository.getTranslation(translationId)?.let {
+                            put(translationId, it.name)
+                        }
+                    }
+                    project(membership.projectId())
+                }
+            }
+        }
+    }
+
     /** The events the group is being asked to sign, for showing them before they agree. */
     fun proposedEvents(items: List<FrostSigningItem>): List<Event> =
         items.mapNotNull { Event.fromJsonOrNull(it.unsignedEventJson) }
@@ -133,6 +211,8 @@ class FrostSigningViewModel(
             initialFrostSigningUIState: FrostSigningUIState = FrostSigningUIState.Loading,
             chatRepository: ChatRepository,
             frostSigningRepository: FrostSigningRepository,
+            mantraRepository: MantraRepository,
+            nostrRepository: NostrRepository,
         ): ViewModelProvider.Factory = viewModelFactory {
             initializer {
                 FrostSigningViewModel(
@@ -141,7 +221,9 @@ class FrostSigningViewModel(
                     activeUserPublicKey = activeUserPublicKey,
                     initialFrostSigningUIState = initialFrostSigningUIState,
                     chatRepository = chatRepository,
-                    frostSigningRepository = frostSigningRepository
+                    frostSigningRepository = frostSigningRepository,
+                    mantraRepository = mantraRepository,
+                    nostrRepository = nostrRepository
                 )
             }
         }

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/state/AddToProjectUIState.kt

@@ -0,0 +1,32 @@
+package press.mantra.compose.ui.view.state
+
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import press.mantra.compose.database.model.MantraProject
+import press.mantra.compose.database.model.intermdiate.LocalChatRoom
+
+sealed interface AddToProjectUIState {
+    /**
+     * [candidates] is whatever is not already in the project: the room's source
+     * versions or its translations, depending on which half this screen is for.
+     *
+     * Already-included work is filtered out rather than shown and refused. A
+     * membership that duplicates one the group has already signed is a second
+     * event with a different id, so nothing would stop it -- it would simply
+     * cost a quorum to say what the group has already said.
+     */
+    data class Loaded(
+        val localChatRoom: LocalChatRoom,
+        val project: MantraProject,
+        val candidates: List<Candidate> = emptyList(),
+        val canSign: Boolean = false,
+    ): AddToProjectUIState
+
+    /** One thing that could be added, named the way the picker shows it. */
+    data class Candidate(val id: HexKey, val label: String, val detail: String?)
+
+    data class Error(
+        val message: String
+    ): AddToProjectUIState
+
+    data object Loading: AddToProjectUIState
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/state/FrostSigningUIState.kt

@@ -23,6 +23,22 @@ sealed interface FrostSigningUIState {
 
         /** Who has signed their part. */
         val signed: Set<HexKey> = emptySet(),
+
+        /**
+         * Names for the keys and ids the proposed events refer to.
+         *
+         * `ProposedEvent.summarize` is a pure function with no database -- two
+         * call sites show these words and two copies of the mapping would drift
+         * -- so whatever can be named is resolved here and handed in as a
+         * lookup.
+         *
+         * It matters most for a membership, which carries two 64-character ids
+         * and nothing else: unresolved, a member is asked to agree to "sign
+         * a4f1be55d0c3". Empty is the honest default, and what a batch founding
+         * a project sees for the project's own id, since nothing has applied it
+         * yet.
+         */
+        val names: Map<HexKey, String> = emptyMap(),
     ): FrostSigningUIState
 
     data class Error(