diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookModels.kt b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookModels.kt
new file mode 100644
index 0000000..c0080cb
--- /dev/null
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookModels.kt
@@ -0,0 +1,65 @@
+package org.modg.bookshelf.ui.add
+
+import org.modg.bookshelf.data.metadata.IsbnUtils
+
+/**
+ * The add-by-hand form's fields, independent of any particular entry point.
+ * [org.modg.bookshelf.ui.nav.Routes.addBook] pre-fills [title]/[isbn] today —
+ * from the scan screen's manual-ISBN dialog, or the library FAB with neither.
+ * A follow-up wave (online search) is expected to pre-fill more fields from a
+ * search hit; [fromRouteArgs] is the one place the route-args-to-draft mapping
+ * lives, so extending it later is a small, localized change.
+ */
+data class BookDraft(
+    val title: String = "",
+    val subtitle: String = "",
+    val authors: String = "",
+    val publisher: String = "",
+    val publishedDate: String = "",
+    val pages: String = "",
+    val isbn: String = "",
+    val description: String = "",
+) {
+    companion object {
+        fun fromRouteArgs(title: String?, isbn: String?): BookDraft =
+            BookDraft(title = title.orEmpty(), isbn = isbn.orEmpty())
+    }
+}
+
+/**
+ * [BookDraft.isbn] parsed per SPEC's "ISBN-10 or ISBN-13, with or without
+ * hyphens" (same rule [IsbnUtils.toIsbn13] already enforces for scanning).
+ * Blank is valid — no ISBN is a legal book. A non-blank value that fails to
+ * parse is [Invalid], never silently dropped: wave 5 fixed exactly that
+ * silent-discard bug in the scan screen's manual-ISBN dialog, and this form
+ * must not reintroduce it.
+ */
+sealed interface IsbnFieldState {
+    data object Blank : IsbnFieldState
+    data class Valid(val isbn13: String, val isbn10: String?) : IsbnFieldState
+    data object Invalid : IsbnFieldState
+}
+
+fun validateIsbn(raw: String): IsbnFieldState {
+    if (raw.isBlank()) return IsbnFieldState.Blank
+    val isbn13 = IsbnUtils.toIsbn13(raw) ?: return IsbnFieldState.Invalid
+    val normalized = IsbnUtils.normalize(raw)
+    // Keep the ISBN-10 alongside the normalized ISBN-13 only when the user actually
+    // typed a valid ISBN-10 — a 13-digit entry has no ISBN-10 form to record.
+    val isbn10 = normalized.takeIf { it.length == 10 && IsbnUtils.isValidIsbn10(it) }
+    return IsbnFieldState.Valid(isbn13, isbn10)
+}
+
+/** [BookDraft.pages] — SPEC "digits only". Blank means unknown, not zero. */
+sealed interface PagesFieldState {
+    data object Blank : PagesFieldState
+    data class Valid(val pages: Int) : PagesFieldState
+    data object Invalid : PagesFieldState
+}
+
+fun validatePages(raw: String): PagesFieldState {
+    if (raw.isBlank()) return PagesFieldState.Blank
+    if (!raw.all(Char::isDigit)) return PagesFieldState.Invalid
+    val pages = raw.toIntOrNull() ?: return PagesFieldState.Invalid
+    return PagesFieldState.Valid(pages)
+}
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookScreen.kt b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookScreen.kt
new file mode 100644
index 0000000..3a95d79
--- /dev/null
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookScreen.kt
@@ -0,0 +1,319 @@
+package org.modg.bookshelf.ui.add
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.imePadding
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.outlined.ArrowBack
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.focus.FocusDirection
+import androidx.compose.ui.focus.FocusRequester
+import androidx.compose.ui.focus.focusRequester
+import androidx.compose.ui.platform.LocalFocusManager
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.text.input.KeyboardCapitalization
+import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import org.modg.bookshelf.AppContainer
+import org.modg.bookshelf.ui.components.BookshelfScaffold
+import org.modg.bookshelf.ui.components.PaperSurface
+import org.modg.bookshelf.ui.components.PrimaryButton
+import org.modg.bookshelf.ui.components.SecondaryButton
+import org.modg.bookshelf.ui.scan.DuplicateStatus
+import org.modg.bookshelf.ui.scan.ShelfPicker
+
+/**
+ * SPEC gap: there was no way to add a book with no barcode — every save path
+ * started from a scanned/typed ISBN. A full screen, not a sheet: the library
+ * has no camera context to anchor a bottom sheet to (unlike [org.modg.bookshelf.ui.scan.ManualEntrySheet]),
+ * and this form is longer than that sheet's two fields.
+ */
+@Composable
+fun AddBookScreen(
+    initialTitle: String?,
+    initialIsbn: String?,
+    onBack: () -> Unit,
+    onSaved: (bookId: String) -> Unit,
+    container: AppContainer,
+) {
+    val viewModel: AddBookViewModel = viewModel(
+        factory = viewModelFactory {
+            initializer {
+                AddBookViewModel(
+                    bookRepository = container.bookRepository,
+                    locationRepository = container.locationRepository,
+                    settingsStore = container.settingsStore,
+                    initialDraft = BookDraft.fromRouteArgs(initialTitle, initialIsbn),
+                )
+            }
+        },
+    )
+    val state by viewModel.uiState.collectAsState()
+
+    AddBookContent(
+        state = state,
+        callbacks = AddBookCallbacks(
+            onTitleChanged = viewModel::onTitleChanged,
+            onSubtitleChanged = viewModel::onSubtitleChanged,
+            onAuthorsChanged = viewModel::onAuthorsChanged,
+            onPublisherChanged = viewModel::onPublisherChanged,
+            onPublishedDateChanged = viewModel::onPublishedDateChanged,
+            onPagesChanged = viewModel::onPagesChanged,
+            onIsbnChanged = viewModel::onIsbnChanged,
+            onDescriptionChanged = viewModel::onDescriptionChanged,
+            onShelfSelected = viewModel::onShelfSelected,
+            onSave = { viewModel.save(onSaved) },
+            onSaveAndAddAnother = viewModel::saveAndAddAnother,
+            onBack = onBack,
+        ),
+    )
+}
+
+/**
+ * Every callback [AddBookContent] needs, grouped into one object per the task's
+ * `AddBookContent(state, callbacks)` shape — so the Paparazzi test can render
+ * this REAL composable fed with static data, instead of a hand-rolled lookalike
+ * (wave 6 shipped exactly that for Locations; HANDOFF.md records it as a known
+ * soft spot this wave was told not to repeat).
+ */
+data class AddBookCallbacks(
+    val onTitleChanged: (String) -> Unit,
+    val onSubtitleChanged: (String) -> Unit,
+    val onAuthorsChanged: (String) -> Unit,
+    val onPublisherChanged: (String) -> Unit,
+    val onPublishedDateChanged: (String) -> Unit,
+    val onPagesChanged: (String) -> Unit,
+    val onIsbnChanged: (String) -> Unit,
+    val onDescriptionChanged: (String) -> Unit,
+    val onShelfSelected: (String?) -> Unit,
+    val onSave: () -> Unit,
+    val onSaveAndAddAnother: () -> Unit,
+    val onBack: () -> Unit,
+)
+
+@Composable
+fun AddBookContent(state: AddBookUiState, callbacks: AddBookCallbacks, modifier: Modifier = Modifier) {
+    val focusManager = LocalFocusManager.current
+    val titleFocusRequester = remember { FocusRequester() }
+
+    // "Save & add another" clears the form and SPEC wants focus back in Title.
+    // savedCount only increments on a successful save (not on every keystroke), and
+    // the empty-title check keeps this from re-stealing focus if the user has
+    // already started typing the next book by the time recomposition catches up.
+    LaunchedEffect(state.savedCount) {
+        if (state.savedCount > 0 && state.draft.title.isEmpty()) {
+            runCatching { titleFocusRequester.requestFocus() }
+        }
+    }
+
+    BookshelfScaffold(
+        title = "Add a book",
+        navigationIcon = {
+            IconButton(onClick = callbacks.onBack) {
+                Icon(Icons.AutoMirrored.Outlined.ArrowBack, contentDescription = "Back")
+            }
+        },
+        modifier = modifier,
+    ) { innerPadding ->
+        PaperSurface(modifier = Modifier.fillMaxSize()) {
+            // Same fix as the setup screen (see its KDoc): imePadding OUTSIDE
+            // verticalScroll shrinks the scrollable viewport instead of letting the
+            // keyboard cover it, so a field low in this (longer) form isn't
+            // stranded behind the IME. BookshelfScaffold's own innerPadding only
+            // accounts for the top/bottom bars, not the IME, so this screen still
+            // needs to handle it itself.
+            Column(
+                modifier = Modifier
+                    .padding(innerPadding)
+                    .fillMaxSize()
+                    .imePadding()
+                    .verticalScroll(rememberScrollState())
+                    .padding(16.dp),
+            ) {
+                if (state.lastSavedTitle != null) {
+                    Text(
+                        text = "Saved “${state.lastSavedTitle}”. ${state.savedCount} added this session.",
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.primary,
+                        modifier = Modifier.padding(bottom = 12.dp),
+                    )
+                }
+
+                OutlinedTextField(
+                    value = state.draft.title,
+                    onValueChange = callbacks.onTitleChanged,
+                    label = { Text("Title") },
+                    singleLine = true,
+                    keyboardOptions = KeyboardOptions(
+                        capitalization = KeyboardCapitalization.Words,
+                        imeAction = ImeAction.Next,
+                    ),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().focusRequester(titleFocusRequester),
+                )
+                OutlinedTextField(
+                    value = state.draft.subtitle,
+                    onValueChange = callbacks.onSubtitleChanged,
+                    label = { Text("Subtitle") },
+                    singleLine = true,
+                    keyboardOptions = KeyboardOptions(
+                        capitalization = KeyboardCapitalization.Words,
+                        imeAction = ImeAction.Next,
+                    ),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                OutlinedTextField(
+                    value = state.draft.authors,
+                    onValueChange = callbacks.onAuthorsChanged,
+                    label = { Text("Authors (comma-separated)") },
+                    singleLine = true,
+                    keyboardOptions = KeyboardOptions(
+                        capitalization = KeyboardCapitalization.Words,
+                        imeAction = ImeAction.Next,
+                    ),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                OutlinedTextField(
+                    value = state.draft.publisher,
+                    onValueChange = callbacks.onPublisherChanged,
+                    label = { Text("Publisher") },
+                    singleLine = true,
+                    keyboardOptions = KeyboardOptions(
+                        capitalization = KeyboardCapitalization.Words,
+                        imeAction = ImeAction.Next,
+                    ),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                OutlinedTextField(
+                    value = state.draft.publishedDate,
+                    onValueChange = callbacks.onPublishedDateChanged,
+                    label = { Text("Published") },
+                    placeholder = { Text("1960, or 1999-04") },
+                    singleLine = true,
+                    keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                OutlinedTextField(
+                    value = state.draft.pages,
+                    onValueChange = callbacks.onPagesChanged,
+                    label = { Text("Pages") },
+                    singleLine = true,
+                    isError = state.pagesError != null,
+                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number, imeAction = ImeAction.Next),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                if (state.pagesError != null) {
+                    Text(
+                        text = state.pagesError!!,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(top = 4.dp),
+                    )
+                }
+                OutlinedTextField(
+                    value = state.draft.isbn,
+                    onValueChange = callbacks.onIsbnChanged,
+                    label = { Text("ISBN") },
+                    placeholder = { Text("Optional — ISBN-10 or ISBN-13") },
+                    singleLine = true,
+                    isError = state.isbnError != null,
+                    keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
+                    keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+                if (state.isbnError != null) {
+                    Text(
+                        text = state.isbnError!!,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(top = 4.dp),
+                    )
+                }
+                val duplicate = state.duplicate
+                if (duplicate is DuplicateStatus.AlreadyOwned) {
+                    // A warning, not a block — SPEC: two copies of a book is legal. Same
+                    // copy the scan sheet uses, for consistency (see FoundBookSheet).
+                    Text(
+                        text = "You already own this book (\"${duplicate.title}\").",
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(top = 4.dp),
+                    )
+                }
+                OutlinedTextField(
+                    value = state.draft.description,
+                    onValueChange = callbacks.onDescriptionChanged,
+                    label = { Text("Description") },
+                    minLines = 3,
+                    keyboardOptions = KeyboardOptions(
+                        capitalization = KeyboardCapitalization.Sentences,
+                        imeAction = ImeAction.Done,
+                    ),
+                    keyboardActions = KeyboardActions(onDone = { focusManager.clearFocus() }),
+                    modifier = Modifier.fillMaxWidth().padding(top = 8.dp),
+                )
+
+                ShelfPicker(
+                    bookcases = state.bookcases,
+                    shelves = state.shelves,
+                    selectedShelfId = state.selectedShelfId,
+                    recentShelfId = state.recentShelfId,
+                    onShelfSelected = callbacks.onShelfSelected,
+                )
+
+                if (state.saveError != null) {
+                    Text(
+                        text = "Couldn't save: ${state.saveError}",
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(top = 12.dp),
+                    )
+                }
+
+                Row(
+                    modifier = Modifier.fillMaxWidth().padding(top = 16.dp),
+                    horizontalArrangement = Arrangement.spacedBy(12.dp),
+                ) {
+                    SecondaryButton(
+                        text = "Save & add another",
+                        enabled = state.canSave,
+                        onClick = callbacks.onSaveAndAddAnother,
+                        modifier = Modifier.weight(1f),
+                    )
+                    PrimaryButton(
+                        text = if (state.isSaving) "Saving…" else "Save",
+                        enabled = state.canSave,
+                        onClick = callbacks.onSave,
+                        modifier = Modifier.weight(1f),
+                    )
+                }
+            }
+        }
+    }
+}
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookViewModel.kt b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookViewModel.kt
new file mode 100644
index 0000000..cf39f57
--- /dev/null
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookViewModel.kt
@@ -0,0 +1,226 @@
+package org.modg.bookshelf.ui.add
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+import org.modg.bookshelf.data.local.BookcaseEntity
+import org.modg.bookshelf.data.local.ShelfEntity
+import org.modg.bookshelf.data.prefs.SettingsStore
+import org.modg.bookshelf.data.repo.BookRepository
+import org.modg.bookshelf.data.repo.LocationRepository
+import org.modg.bookshelf.ui.scan.DuplicateCheck
+import org.modg.bookshelf.ui.scan.DuplicateStatus
+
+/** Everything [AddBookContent] needs to render the form. */
+data class AddBookUiState(
+    val draft: BookDraft = BookDraft(),
+    val bookcases: List<BookcaseEntity> = emptyList(),
+    val shelves: List<ShelfEntity> = emptyList(),
+    val selectedShelfId: String? = null,
+    val recentShelfId: String? = null,
+    val duplicate: DuplicateStatus = DuplicateStatus.New,
+    val isSaving: Boolean = false,
+    val saveError: String? = null,
+    val savedCount: Int = 0,
+    val lastSavedTitle: String? = null,
+) {
+    val isbnError: String?
+        get() = if (validateIsbn(draft.isbn) is IsbnFieldState.Invalid) {
+            "That isn't a valid ISBN — check the digits."
+        } else {
+            null
+        }
+
+    val pagesError: String?
+        get() = if (validatePages(draft.pages) is PagesFieldState.Invalid) "Pages must be a number." else null
+
+    /** Title is the only required field; a field in error or a save already in flight blocks both Save actions. */
+    val canSave: Boolean
+        get() = draft.title.isNotBlank() && isbnError == null && pagesError == null && !isSaving
+}
+
+/**
+ * Owns the add-by-hand form (SPEC gap: no way to add a book with no barcode).
+ * Offline-first like every other screen: [bookRepository]/[locationRepository]
+ * are Room only, nothing here touches the network.
+ */
+class AddBookViewModel(
+    private val bookRepository: BookRepository,
+    locationRepository: LocationRepository,
+    private val settingsStore: SettingsStore,
+    initialDraft: BookDraft = BookDraft(),
+) : ViewModel() {
+
+    private data class FormState(
+        val draft: BookDraft,
+        val selectedShelfId: String? = null,
+        val duplicate: DuplicateStatus = DuplicateStatus.New,
+        val isSaving: Boolean = false,
+        val saveError: String? = null,
+        val savedCount: Int = 0,
+        val lastSavedTitle: String? = null,
+    )
+
+    private val _formState = MutableStateFlow(FormState(draft = initialDraft))
+    private var duplicateCheckJob: Job? = null
+
+    val bookcases: StateFlow<List<BookcaseEntity>> = locationRepository.observeBookcases()
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())
+    val shelves: StateFlow<List<ShelfEntity>> = locationRepository.observeShelves()
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())
+
+    /** Surfaced as the shelf picker's "Recent" shortcut, same as the scan screen's. */
+    val recentShelfId: StateFlow<String?> = settingsStore.lastShelfId
+        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
+
+    // WhileSubscribed, matching Library/LocationsViewModel's uiState — but note this
+    // means .value only reflects post-action state to a caller that is actively
+    // collecting (e.g. Compose's collectAsState, or a test using .first()); a bare
+    // .value read with no live collector sees only the seed passed to stateIn.
+    val uiState: StateFlow<AddBookUiState> = combine(
+        _formState, bookcases, shelves, recentShelfId,
+    ) { form, cases, shelfList, recent ->
+        AddBookUiState(
+            draft = form.draft,
+            bookcases = cases,
+            shelves = shelfList,
+            selectedShelfId = form.selectedShelfId,
+            recentShelfId = recent,
+            duplicate = form.duplicate,
+            isSaving = form.isSaving,
+            saveError = form.saveError,
+            savedCount = form.savedCount,
+            lastSavedTitle = form.lastSavedTitle,
+        )
+    }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), AddBookUiState(draft = initialDraft))
+
+    init {
+        // SPEC: pre-select the remembered last shelf. The scan sheet only offers this
+        // as a "Recent" shortcut because it also has a per-scan shelf that sticks
+        // across a continuous session; a hand-entry form has no such session anchor,
+        // so here the remembered shelf IS the default.
+        viewModelScope.launch {
+            val remembered = settingsStore.lastShelfId.first()
+            if (remembered != null) _formState.update { it.copy(selectedShelfId = remembered) }
+        }
+        if (initialDraft.isbn.isNotBlank()) scheduleDuplicateCheck(initialDraft.isbn)
+    }
+
+    fun onTitleChanged(value: String) = updateDraft { it.copy(title = value) }
+    fun onSubtitleChanged(value: String) = updateDraft { it.copy(subtitle = value) }
+    fun onAuthorsChanged(value: String) = updateDraft { it.copy(authors = value) }
+    fun onPublisherChanged(value: String) = updateDraft { it.copy(publisher = value) }
+    fun onPublishedDateChanged(value: String) = updateDraft { it.copy(publishedDate = value) }
+    fun onPagesChanged(value: String) = updateDraft { it.copy(pages = value) }
+    fun onDescriptionChanged(value: String) = updateDraft { it.copy(description = value) }
+
+    fun onIsbnChanged(value: String) {
+        updateDraft { it.copy(isbn = value) }
+        scheduleDuplicateCheck(value)
+    }
+
+    fun onShelfSelected(shelfId: String?) {
+        _formState.update { it.copy(selectedShelfId = shelfId) }
+    }
+
+    private inline fun updateDraft(transform: (BookDraft) -> BookDraft) {
+        _formState.update { it.copy(draft = transform(it.draft)) }
+    }
+
+    /** SPEC scan-sheet parity: a warning, not a block — two copies of a book is legal. */
+    private fun scheduleDuplicateCheck(rawIsbn: String) {
+        duplicateCheckJob?.cancel()
+        val isbn13 = (validateIsbn(rawIsbn) as? IsbnFieldState.Valid)?.isbn13
+        if (isbn13 == null) {
+            _formState.update { it.copy(duplicate = DuplicateStatus.New) }
+            return
+        }
+        duplicateCheckJob = viewModelScope.launch {
+            val existing = bookRepository.findByIsbn13(isbn13)
+            _formState.update { it.copy(duplicate = DuplicateCheck.check(existing)) }
+        }
+    }
+
+    /** "Save" — navigates to the new book's detail screen on success (see [AddBookScreen]). */
+    fun save(onSaved: (bookId: String) -> Unit) {
+        viewModelScope.launch {
+            val id = performSave(clearAfterSave = false)
+            if (id != null) onSaved(id)
+        }
+    }
+
+    /** "Save & add another" — SPEC's real use case, shelving a box of books at once. */
+    fun saveAndAddAnother() {
+        viewModelScope.launch { performSave(clearAfterSave = true) }
+    }
+
+    /**
+     * The actual save, split out so tests can await it directly — same reasoning
+     * as [org.modg.bookshelf.ui.scan.ScanViewModel.performSave]. HANDOFF.md flagged
+     * that ViewModel's save paths as still making unguarded Room calls after wave 8
+     * guarded only the lookup path; this one is guarded from the start. Catches
+     * [Throwable] — [CancellationException] is rethrown FIRST, ahead of that catch,
+     * because a cancelled save (screen left mid-save) is normal control flow, not a
+     * failure, and must propagate rather than being reported as one. Re-entrancy is
+     * guarded here rather than trusted to the caller's disabled-button state, so a
+     * genuine double-tap (two taps landing before recomposition disables the
+     * button) still can't create two books.
+     */
+    internal suspend fun performSave(clearAfterSave: Boolean): String? {
+        if (_formState.value.isSaving) return null
+        _formState.update { it.copy(isSaving = true, saveError = null) }
+        val form = _formState.value
+        val draft = form.draft
+        return try {
+            val isbnValidation = validateIsbn(draft.isbn)
+            val isbn13 = (isbnValidation as? IsbnFieldState.Valid)?.isbn13
+            val isbn10 = (isbnValidation as? IsbnFieldState.Valid)?.isbn10
+            val pageCount = (validatePages(draft.pages) as? PagesFieldState.Valid)?.pages
+            val authors = draft.authors.split(",").map(String::trim).filter(String::isNotEmpty)
+            val savedTitle = draft.title.trim()
+            val bookId = bookRepository.createBook(
+                title = savedTitle,
+                subtitle = draft.subtitle.trim().ifEmpty { null },
+                authors = authors,
+                isbn13 = isbn13,
+                isbn10 = isbn10,
+                publisher = draft.publisher.trim().ifEmpty { null },
+                publishedDate = draft.publishedDate.trim().ifEmpty { null },
+                pageCount = pageCount,
+                description = draft.description.trim().ifEmpty { null },
+                shelfId = form.selectedShelfId,
+            )
+            rememberShelf(form.selectedShelfId)
+            _formState.update {
+                it.copy(
+                    draft = if (clearAfterSave) BookDraft() else it.draft,
+                    isSaving = false,
+                    saveError = null,
+                    savedCount = it.savedCount + 1,
+                    lastSavedTitle = savedTitle,
+                )
+            }
+            if (clearAfterSave) scheduleDuplicateCheck("") // the ISBN field just cleared; the warning must too
+            bookId
+        } catch (e: CancellationException) {
+            throw e
+        } catch (e: Throwable) {
+            _formState.update { it.copy(isSaving = false, saveError = e.javaClass.simpleName) }
+            null
+        }
+    }
+
+    /** "Not shelved" (null) must never overwrite the memory — it isn't a shelf. */
+    private suspend fun rememberShelf(shelfId: String?) {
+        if (shelfId != null) settingsStore.setLastShelfId(shelfId)
+    }
+}
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/library/LibraryScreen.kt b/app/app/src/main/java/org/modg/bookshelf/ui/library/LibraryScreen.kt
index cb6c2b9..cf1d5b5 100644
--- a/app/app/src/main/java/org/modg/bookshelf/ui/library/LibraryScreen.kt
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/library/LibraryScreen.kt
@@ -11,8 +11,11 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.items
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.height
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.outlined.Clear
+import androidx.compose.material.icons.outlined.EditNote
 import androidx.compose.material.icons.outlined.FilterList
 import androidx.compose.material.icons.outlined.QrCodeScanner
 import androidx.compose.material.icons.outlined.Search
@@ -26,6 +29,7 @@ import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.SmallFloatingActionButton
 import androidx.compose.material3.Text
 import androidx.compose.material3.pulltorefresh.PullToRefreshBox
 import androidx.compose.runtime.Composable
@@ -54,6 +58,7 @@ import org.modg.bookshelf.ui.components.EmptyState
 import org.modg.bookshelf.ui.components.BookshelfScaffold
 import org.modg.bookshelf.ui.components.PaperSurface
 import org.modg.bookshelf.ui.components.PrimaryButton
+import org.modg.bookshelf.ui.components.SecondaryButton
 import org.modg.bookshelf.ui.components.SyncStatus
 import org.modg.bookshelf.ui.components.SyncStatusBar
 
@@ -68,6 +73,7 @@ fun LibraryScreen(
     shelfIdFilter: String?,
     onBookClick: (String) -> Unit,
     onScanClick: () -> Unit,
+    onAddByHandClick: () -> Unit,
     onLocationsClick: () -> Unit,
     onSettingsClick: () -> Unit,
     container: AppContainer,
@@ -105,8 +111,18 @@ fun LibraryScreen(
             }
         },
         floatingActionButton = {
-            FloatingActionButton(onClick = onScanClick) {
-                Icon(Icons.Outlined.QrCodeScanner, contentDescription = "Scan a book")
+            // Scan stays the one primary action (it's the SPEC use case — a box of
+            // books, one after another); "Add by hand" is a small satellite FAB
+            // stacked above it rather than a second full-size FAB competing for
+            // attention, or a toolbar icon that would bury it below Locations/Settings.
+            Column(horizontalAlignment = Alignment.End) {
+                SmallFloatingActionButton(onClick = onAddByHandClick) {
+                    Icon(Icons.Outlined.EditNote, contentDescription = "Add a book by hand")
+                }
+                Spacer(modifier = Modifier.height(12.dp))
+                FloatingActionButton(onClick = onScanClick) {
+                    Icon(Icons.Outlined.QrCodeScanner, contentDescription = "Scan a book")
+                }
             }
         },
         syncStatusBar = {
@@ -137,7 +153,12 @@ fun LibraryScreen(
                         !uiState.hasAnyBooks -> EmptyState(
                             title = "Your shelves are empty",
                             message = "Scan a barcode to add your first book.",
-                            action = { PrimaryButton(text = "Scan a book", onClick = onScanClick) },
+                            action = {
+                                Row(horizontalArrangement = Arrangement.spacedBy(12.dp)) {
+                                    PrimaryButton(text = "Scan a book", onClick = onScanClick)
+                                    SecondaryButton(text = "Add by hand", onClick = onAddByHandClick)
+                                }
+                            },
                         )
                         uiState.books.isEmpty() -> EmptyState(
                             title = "No books match",
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/nav/BookshelfNavHost.kt b/app/app/src/main/java/org/modg/bookshelf/ui/nav/BookshelfNavHost.kt
index 4bd5985..fd7f6a5 100644
--- a/app/app/src/main/java/org/modg/bookshelf/ui/nav/BookshelfNavHost.kt
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/nav/BookshelfNavHost.kt
@@ -8,6 +8,7 @@ import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
 import org.modg.bookshelf.AppContainer
+import org.modg.bookshelf.ui.add.AddBookScreen
 import org.modg.bookshelf.ui.detail.DetailScreen
 import org.modg.bookshelf.ui.library.LibraryScreen
 import org.modg.bookshelf.ui.locations.LocationsScreen
@@ -52,6 +53,7 @@ fun BookshelfNavHost(
                 shelfIdFilter = backStackEntry.arguments?.getString(Routes.LIBRARY_SHELF_ARG),
                 onBookClick = { bookId -> navController.navigate(Routes.detail(bookId)) },
                 onScanClick = { navController.navigate(Routes.SCAN) },
+                onAddByHandClick = { navController.navigate(Routes.addBook()) },
                 onLocationsClick = { navController.navigate(Routes.LOCATIONS) },
                 onSettingsClick = { navController.navigate(Routes.SETTINGS) },
                 container = container,
@@ -70,6 +72,37 @@ fun BookshelfNavHost(
         composable(Routes.SCAN) {
             ScanScreen(
                 onBack = { navController.popBackStack() },
+                onEnterByHand = { navController.navigate(Routes.addBook()) },
+                container = container,
+            )
+        }
+        composable(
+            route = Routes.ADD_BOOK,
+            arguments = listOf(
+                navArgument(Routes.ADD_BOOK_TITLE_ARG) {
+                    type = NavType.StringType
+                    nullable = true
+                    defaultValue = null
+                },
+                navArgument(Routes.ADD_BOOK_ISBN_ARG) {
+                    type = NavType.StringType
+                    nullable = true
+                    defaultValue = null
+                },
+            ),
+        ) { backStackEntry ->
+            AddBookScreen(
+                initialTitle = backStackEntry.arguments?.getString(Routes.ADD_BOOK_TITLE_ARG),
+                initialIsbn = backStackEntry.arguments?.getString(Routes.ADD_BOOK_ISBN_ARG),
+                onBack = { navController.popBackStack() },
+                onSaved = { bookId ->
+                    // Removes the add screen from the back stack, per the task's "Save"
+                    // contract, so Back from detail returns to the library rather than
+                    // to a form that was just successfully submitted.
+                    navController.navigate(Routes.detail(bookId)) {
+                        popUpTo(Routes.ADD_BOOK) { inclusive = true }
+                    }
+                },
                 container = container,
             )
         }
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/nav/Routes.kt b/app/app/src/main/java/org/modg/bookshelf/ui/nav/Routes.kt
index 5bb9f8f..12b6f41 100644
--- a/app/app/src/main/java/org/modg/bookshelf/ui/nav/Routes.kt
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/nav/Routes.kt
@@ -1,5 +1,7 @@
 package org.modg.bookshelf.ui.nav
 
+import android.net.Uri
+
 /**
  * Route string constants for [BookshelfNavHost]. Fixed by the wave-3 screen
  * contract shared with Worker E2 — do not rename or restructure these; E2's
@@ -16,6 +18,37 @@ object Routes {
     const val LOCATIONS = "locations"
     const val SETTINGS = "settings"
 
+    const val ADD_BOOK_TITLE_ARG = "title"
+    const val ADD_BOOK_ISBN_ARG = "isbn"
+    private const val ADD_BOOK_BASE = "add"
+
+    /**
+     * Both args are optional (wave 9: "add a book by hand" with nothing pre-filled)
+     * — nullable/defaultValue-null args, same pattern [LIBRARY_WITH_SHELF] uses so
+     * this one route also matches the bare "add" entry with neither supplied.
+     */
+    const val ADD_BOOK = "$ADD_BOOK_BASE?$ADD_BOOK_TITLE_ARG={$ADD_BOOK_TITLE_ARG}&$ADD_BOOK_ISBN_ARG={$ADD_BOOK_ISBN_ARG}"
+
     fun libraryFilteredByShelf(shelfId: String) = "library?shelfId=$shelfId"
     fun detail(bookId: String) = "detail/$bookId"
+
+    /**
+     * Builds the add-by-hand route, percent-encoding [title]/[isbn] so values
+     * containing `&`, `?`, `/`, `#` etc. (titles routinely do) survive as a single
+     * query value instead of corrupting the route string. [Uri.encode] rather than
+     * [java.net.URLEncoder] because the latter encodes space as `+`, which
+     * Navigation Compose's Uri-pattern argument matching does NOT decode back to
+     * space (it does standard percent-decoding, not form-decoding) — see
+     * RoutesTest for the round-trip this must survive. A null arg is omitted
+     * entirely rather than encoded as the literal string "null", so a caller with
+     * nothing to pre-fill (e.g. the plain library FAB) gets exactly the bare
+     * "add" route wave 9's [org.modg.bookshelf.ui.add.AddBookScreen] expects.
+     */
+    fun addBook(title: String? = null, isbn: String? = null): String {
+        val query = buildList {
+            title?.let { add("$ADD_BOOK_TITLE_ARG=${Uri.encode(it)}") }
+            isbn?.let { add("$ADD_BOOK_ISBN_ARG=${Uri.encode(it)}") }
+        }
+        return if (query.isEmpty()) ADD_BOOK_BASE else "$ADD_BOOK_BASE?" + query.joinToString("&")
+    }
 }
diff --git a/app/app/src/main/java/org/modg/bookshelf/ui/scan/ScanScreen.kt b/app/app/src/main/java/org/modg/bookshelf/ui/scan/ScanScreen.kt
index bd299f0..10cf6da 100644
--- a/app/app/src/main/java/org/modg/bookshelf/ui/scan/ScanScreen.kt
+++ b/app/app/src/main/java/org/modg/bookshelf/ui/scan/ScanScreen.kt
@@ -33,6 +33,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.ModalBottomSheet
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
@@ -80,6 +81,7 @@ import org.modg.bookshelf.ui.components.ShelfPickerSheet
 @Composable
 fun ScanScreen(
     onBack: () -> Unit,
+    onEnterByHand: () -> Unit,
     container: AppContainer,
 ) {
     val viewModel: ScanViewModel = viewModel(
@@ -205,6 +207,7 @@ fun ScanScreen(
         ManualIsbnDialog(
             onDismiss = { showManualEntry = false },
             onSubmit = { isbn -> showManualEntry = false; viewModel.manualIsbnEntered(isbn) },
+            onEnterByHand = { showManualEntry = false; onEnterByHand() },
         )
     }
 }
@@ -523,7 +526,7 @@ internal fun ShelfPicker(
 }
 
 @Composable
-private fun ManualIsbnDialog(onDismiss: () -> Unit, onSubmit: (String) -> Unit) {
+private fun ManualIsbnDialog(onDismiss: () -> Unit, onSubmit: (String) -> Unit, onEnterByHand: () -> Unit) {
     var text by remember { mutableStateOf("") }
     // Validate here rather than letting ScanViewModel.manualIsbnEntered drop an
     // unparseable ISBN on the floor. A typed-in check digit is easy to get wrong,
@@ -561,6 +564,12 @@ private fun ManualIsbnDialog(onDismiss: () -> Unit, onSubmit: (String) -> Unit)
                         modifier = Modifier.padding(top = 4.dp),
                     )
                 }
+                // Escape hatch for the books this dialog can't help with at all — SPEC
+                // gap: older/self-published/foreign books often have no ISBN, and this
+                // dialog only ever accepts one.
+                TextButton(onClick = onEnterByHand, modifier = Modifier.padding(top = 8.dp)) {
+                    Text("No ISBN? Enter the details by hand")
+                }
             }
         },
         confirmButton = {
diff --git a/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookModelsTest.kt b/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookModelsTest.kt
new file mode 100644
index 0000000..ef5dbca
--- /dev/null
+++ b/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookModelsTest.kt
@@ -0,0 +1,126 @@
+package org.modg.bookshelf.ui.add
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Pure validation logic for the add-by-hand form — no ViewModel/Room needed.
+ * See [AddBookViewModelTest] for how [AddBookUiState.canSave] and the save
+ * paths build on these.
+ */
+class AddBookModelsTest {
+
+    // --- BookDraft.fromRouteArgs ---
+
+    @Test
+    fun `fromRouteArgs fills title and isbn when both present`() {
+        val draft = BookDraft.fromRouteArgs(title = "Dune", isbn = "9780441013593")
+
+        assertEquals("Dune", draft.title)
+        assertEquals("9780441013593", draft.isbn)
+    }
+
+    @Test
+    fun `fromRouteArgs defaults absent args to blank, not the literal string null`() {
+        val draft = BookDraft.fromRouteArgs(title = null, isbn = null)
+
+        assertEquals("", draft.title)
+        assertEquals("", draft.isbn)
+    }
+
+    // --- validateIsbn ---
+
+    @Test
+    fun `blank isbn is valid — no ISBN is a legal book`() {
+        assertEquals(IsbnFieldState.Blank, validateIsbn(""))
+        assertEquals(IsbnFieldState.Blank, validateIsbn("   "))
+    }
+
+    @Test
+    fun `valid isbn13 is accepted and carries no isbn10`() {
+        val result = validateIsbn("9780441013593")
+
+        val valid = result as? IsbnFieldState.Valid
+        checkNotNull(valid) { "expected Valid, got $result" }
+        assertEquals("9780441013593", valid.isbn13)
+        assertNull(valid.isbn10)
+    }
+
+    @Test
+    fun `valid isbn10 is normalized to isbn13 and the isbn10 is kept`() {
+        val result = validateIsbn("0-441-01359-7") // Dune's ISBN-10, hyphenated
+
+        val valid = result as? IsbnFieldState.Valid
+        checkNotNull(valid) { "expected Valid, got $result" }
+        assertEquals("9780441013593", valid.isbn13)
+        assertEquals("0441013597", valid.isbn10)
+    }
+
+    @Test
+    fun `a bad checksum is Invalid, not silently dropped`() {
+        // wave 5 fixed exactly this silent-discard bug in the scan screen's
+        // manual-ISBN dialog; this form must not reintroduce it.
+        assertEquals(IsbnFieldState.Invalid, validateIsbn("9780441013594")) // last digit wrong
+        assertEquals(IsbnFieldState.Invalid, validateIsbn("not-an-isbn"))
+    }
+
+    // --- validatePages ---
+
+    @Test
+    fun `blank pages is valid and means unknown, not zero`() {
+        assertEquals(PagesFieldState.Blank, validatePages(""))
+    }
+
+    @Test
+    fun `digit-only pages is valid`() {
+        assertEquals(PagesFieldState.Valid(412), validatePages("412"))
+    }
+
+    @Test
+    fun `non-digit pages is rejected`() {
+        assertEquals(PagesFieldState.Invalid, validatePages("412pp"))
+        assertEquals(PagesFieldState.Invalid, validatePages("-5"))
+        assertEquals(PagesFieldState.Invalid, validatePages("4.5"))
+    }
+
+    // --- AddBookUiState.canSave ---
+
+    @Test
+    fun `canSave is false with a blank title`() {
+        val state = AddBookUiState(draft = BookDraft(title = ""))
+
+        assertTrue(!state.canSave)
+    }
+
+    @Test
+    fun `canSave is true with only a title — every other field is optional`() {
+        val state = AddBookUiState(draft = BookDraft(title = "Dune"))
+
+        assertTrue(state.canSave)
+    }
+
+    @Test
+    fun `canSave is false while an isbn error is showing`() {
+        val state = AddBookUiState(draft = BookDraft(title = "Dune", isbn = "not-an-isbn"))
+
+        assertTrue(!state.canSave)
+        assertEquals("That isn't a valid ISBN — check the digits.", state.isbnError)
+    }
+
+    @Test
+    fun `canSave is false while a pages error is showing`() {
+        val state = AddBookUiState(draft = BookDraft(title = "Dune", pages = "412pp"))
+
+        assertTrue(!state.canSave)
+        assertEquals("Pages must be a number.", state.pagesError)
+    }
+
+    @Test
+    fun `canSave is false while a save is already in flight`() {
+        val state = AddBookUiState(draft = BookDraft(title = "Dune"), isSaving = true)
+
+        assertTrue(!state.canSave)
+    }
+}
diff --git a/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookViewModelTest.kt b/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookViewModelTest.kt
new file mode 100644
index 0000000..32a5a4f
--- /dev/null
+++ b/app/app/src/test/java/org/modg/bookshelf/ui/add/AddBookViewModelTest.kt
@@ -0,0 +1,292 @@
+package org.modg.bookshelf.ui.add
+
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Assert.fail
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.modg.bookshelf.data.local.BookDao
+import org.modg.bookshelf.data.local.BookEntity
+import org.modg.bookshelf.data.local.BookshelfDatabase
+import org.modg.bookshelf.data.prefs.SettingsStore
+import org.modg.bookshelf.data.repo.BookRepository
+import org.modg.bookshelf.data.repo.LocationRepository
+import org.modg.bookshelf.data.repo.decodeAuthors
+import org.modg.bookshelf.ui.scan.DuplicateStatus
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [34])
+class AddBookViewModelTest {
+
+    private lateinit var db: BookshelfDatabase
+    private lateinit var settingsStore: SettingsStore
+    private lateinit var locationRepository: LocationRepository
+    private lateinit var bookRepository: BookRepository
+    private lateinit var viewModel: AddBookViewModel
+    private lateinit var shelfId: String
+    private lateinit var context: android.content.Context
+
+    @Before
+    fun setUp() = runTest {
+        // AddBookViewModel.uiState is a combine(...).stateIn(viewModelScope, ...) —
+        // viewModelScope runs on Dispatchers.Main, which nothing else in this test
+        // class supplies. Without this, the combine's collector coroutine either
+        // never runs or runs on Robolectric's paused main looper, so uiState.value
+        // stays stuck at its initial seed forever (and any `.first { predicate }`
+        // await hangs). Unconfined so it drains synchronously with no explicit
+        // advanceUntilIdle() needed at each assertion site.
+        Dispatchers.setMain(UnconfinedTestDispatcher())
+        context = ApplicationProvider.getApplicationContext()
+        db = Room.inMemoryDatabaseBuilder(context, BookshelfDatabase::class.java)
+            .allowMainThreadQueries()
+            .build()
+        settingsStore = SettingsStore(context)
+        locationRepository = LocationRepository(db.bookcaseDao(), db.shelfDao(), db.bookDao())
+        bookRepository = BookRepository(db.bookDao(), context)
+        val bookcaseId = locationRepository.createBookcase(name = "Living Room")
+        shelfId = locationRepository.createShelf(bookcaseId, label = "Top shelf")
+
+        viewModel = AddBookViewModel(
+            bookRepository = bookRepository,
+            locationRepository = locationRepository,
+            settingsStore = settingsStore,
+        )
+    }
+
+    @After
+    fun tearDown() {
+        db.close()
+        Dispatchers.resetMain()
+    }
+
+    // --- field mapping ---
+
+    @Test
+    fun `save maps every field, splitting and trimming authors and dropping empty entries`() = runTest {
+        viewModel.onTitleChanged("  Dune  ")
+        viewModel.onSubtitleChanged("A novel")
+        viewModel.onAuthorsChanged(" Frank Herbert ,, Brian Herbert , ")
+        viewModel.onPublisherChanged("Ace")
+        viewModel.onPublishedDateChanged("1965")
+        viewModel.onPagesChanged("412")
+        viewModel.onIsbnChanged("9780441013593")
+        viewModel.onDescriptionChanged("A desert planet.")
+        viewModel.onShelfSelected(shelfId)
+
+        val bookId = viewModel.performSave(clearAfterSave = false)
+        checkNotNull(bookId)
+
+        val saved = bookRepository.getById(bookId)
+        checkNotNull(saved)
+        assertEquals("Dune", saved.title)
+        assertEquals("A novel", saved.subtitle)
+        assertEquals(listOf("Frank Herbert", "Brian Herbert"), decodeAuthors(saved.authorsJson))
+        assertEquals("Ace", saved.publisher)
+        assertEquals("1965", saved.publishedDate)
+        assertEquals(412, saved.pageCount)
+        assertEquals("9780441013593", saved.isbn13)
+        assertEquals("A desert planet.", saved.description)
+        assertEquals(shelfId, saved.shelfId)
+    }
+
+    @Test
+    fun `blank isbn saves as null, not a silent parse failure`() = runTest {
+        viewModel.onTitleChanged("Untitled Pamphlet")
+
+        val bookId = viewModel.performSave(clearAfterSave = false)
+        checkNotNull(bookId)
+
+        val saved = bookRepository.getById(bookId)
+        checkNotNull(saved)
+        assertNull(saved.isbn13)
+        assertNull(saved.isbn10)
+    }
+
+    @Test
+    fun `a valid isbn10 is saved as both the normalized isbn13 and the original isbn10`() = runTest {
+        viewModel.onTitleChanged("Dune")
+        viewModel.onIsbnChanged("0-441-01359-7")
+
+        val bookId = viewModel.performSave(clearAfterSave = false)
+        checkNotNull(bookId)
+
+        val saved = bookRepository.getById(bookId)
+        checkNotNull(saved)
+        assertEquals("9780441013593", saved.isbn13)
+        assertEquals("0441013597", saved.isbn10)
+    }
+
+    // --- duplicate warning ---
+
+    @Test
+    fun `entering the isbn of an already-owned book surfaces the AlreadyOwned warning`() = runTest {
+        bookRepository.createBook(title = "Dune", isbn13 = "9780441013593")
+
+        viewModel.onIsbnChanged("9780441013593")
+
+        val duplicate = viewModel.uiState.first { it.duplicate !is DuplicateStatus.New }.duplicate
+        val alreadyOwned = duplicate as? DuplicateStatus.AlreadyOwned
+        checkNotNull(alreadyOwned) { "expected AlreadyOwned, got $duplicate" }
+        assertEquals("Dune", alreadyOwned.title)
+    }
+
+    @Test
+    fun `an isbn nobody owns yet stays New`() = runTest {
+        viewModel.onIsbnChanged("9780441013593")
+        // Let the duplicate check actually run before asserting on it.
+        bookRepository.findByIsbn13("9780441013593")
+
+        // .first(), not .value — see the KDoc on AddBookViewModel.uiState.
+        assertEquals(DuplicateStatus.New, viewModel.uiState.first().duplicate)
+    }
+
+    // --- save & add another ---
+
+    @Test
+    fun `save and add another clears the form but keeps the shelf and increments the count`() = runTest {
+        viewModel.onShelfSelected(shelfId)
+        viewModel.onTitleChanged("Dune")
+        viewModel.onAuthorsChanged("Frank Herbert")
+
+        viewModel.performSave(clearAfterSave = true)
+
+        // .first(), not .value — see the KDoc on AddBookViewModel.uiState.
+        val state = viewModel.uiState.first()
+        assertEquals("", state.draft.title)
+        assertEquals("", state.draft.authors)
+        assertEquals(shelfId, state.selectedShelfId)
+        assertEquals(1, state.savedCount)
+        assertEquals("Dune", state.lastSavedTitle)
+    }
+
+    @Test
+    fun `plain save does not clear the form`() = runTest {
+        viewModel.onTitleChanged("Dune")
+
+        viewModel.performSave(clearAfterSave = false)
+
+        // .first(), not .value — see the KDoc on AddBookViewModel.uiState.
+        val state = viewModel.uiState.first()
+        assertEquals("Dune", state.draft.title)
+        assertEquals(1, state.savedCount)
+    }
+
+    // --- failure handling: §4 of the task, mirroring ScanViewModel's runLookup guard ---
+
+    @Test
+    fun `a repository failure leaves the form intact, reports the exception class, and does not throw`() = runTest {
+        val vm = viewModelWithThrowingCreateBook(IllegalStateException("disk full"))
+        vm.onTitleChanged("Dune")
+        vm.onAuthorsChanged("Frank Herbert")
+
+        val result = vm.performSave(clearAfterSave = false) // must not throw
+
+        assertNull(result)
+        // .first(), not .value — see the KDoc on AddBookViewModel.uiState.
+        val state = vm.uiState.first()
+        assertEquals("Dune", state.draft.title) // form intact
+        assertEquals("Frank Herbert", state.draft.authors)
+        assertEquals("IllegalStateException", state.saveError)
+        assertTrue(!state.isSaving)
+        assertEquals(0, state.savedCount)
+    }
+
+    @Test
+    fun `a CancellationException during save is rethrown, not swallowed as a failure`() = runTest {
+        val vm = viewModelWithThrowingCreateBook(CancellationException("scope cancelled"))
+        vm.onTitleChanged("Dune")
+
+        try {
+            vm.performSave(clearAfterSave = false)
+            fail("expected CancellationException to propagate")
+        } catch (e: CancellationException) {
+            // expected — a cancelled save is not a failed one.
+        }
+    }
+
+    // --- double-tap guard ---
+
+    @Test
+    fun `a second save while one is in flight does not create a second book`() = runTest {
+        viewModel.onTitleChanged("Dune")
+
+        val first = launch { viewModel.performSave(clearAfterSave = false) }
+        val second = launch { viewModel.performSave(clearAfterSave = false) }
+        first.join()
+        second.join()
+
+        val allBooks = mutableListOf<BookEntity>()
+        bookRepository.observeAll().let { flow -> allBooks.addAll(flow.first()) }
+        assertEquals(1, allBooks.size)
+        // .first(), not .value — see the KDoc on AddBookViewModel.uiState.
+        assertEquals(1, viewModel.uiState.first().savedCount)
+    }
+
+    // --- remembered shelf ---
+
+    @Test
+    fun `saving to a shelf remembers it for next time`() = runTest {
+        viewModel.onTitleChanged("Dune")
+        viewModel.onShelfSelected(shelfId)
+
+        viewModel.performSave(clearAfterSave = false)
+
+        assertEquals(shelfId, settingsStore.lastShelfId.first())
+    }
+
+    @Test
+    fun `saving as Not shelved does not overwrite the remembered shelf`() = runTest {
+        settingsStore.setLastShelfId(shelfId)
+        viewModel.onTitleChanged("Dune")
+        viewModel.onShelfSelected(null)
+
+        viewModel.performSave(clearAfterSave = false)
+
+        assertEquals(shelfId, settingsStore.lastShelfId.first())
+    }
+
+    @Test
+    fun `the remembered shelf pre-selects the picker on a fresh form`() = runTest {
+        settingsStore.setLastShelfId(shelfId)
+
+        val vm = AddBookViewModel(
+            bookRepository = bookRepository,
+            locationRepository = locationRepository,
+            settingsStore = settingsStore,
+        )
+
+        val preSelected = vm.uiState.first { it.selectedShelfId != null }
+        assertEquals(shelfId, preSelected.selectedShelfId)
+    }
+
+    private fun viewModelWithThrowingCreateBook(toThrow: Throwable): AddBookViewModel = AddBookViewModel(
+        bookRepository = BookRepository(ThrowingUpsertBookDao(db.bookDao(), toThrow), context),
+        locationRepository = locationRepository,
+        settingsStore = settingsStore,
+    )
+
+    /** Delegates every query to the real DAO except [upsert], which [AddBookViewModel.performSave]'s createBook hits. */
+    private class ThrowingUpsertBookDao(
+        private val delegate: BookDao,
+        private val toThrow: Throwable,
+    ) : BookDao by delegate {
+        override suspend fun upsert(book: BookEntity) = throw toThrow
+    }
+}
diff --git a/app/app/src/test/java/org/modg/bookshelf/ui/nav/RoutesTest.kt b/app/app/src/test/java/org/modg/bookshelf/ui/nav/RoutesTest.kt
new file mode 100644
index 0000000..faf6a64
--- /dev/null
+++ b/app/app/src/test/java/org/modg/bookshelf/ui/nav/RoutesTest.kt
@@ -0,0 +1,77 @@
+package org.modg.bookshelf.ui.nav
+
+import android.net.Uri
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+/**
+ * [Routes.addBook] must percent-encode its args well enough to survive the
+ * query-string round trip Navigation Compose actually performs on a real
+ * device: it parses the built route as a [Uri] and extracts each `{arg}`
+ * placeholder via [Uri.getQueryParameter], which does standard percent-
+ * decoding (not `+`-as-space form-decoding) — so this test decodes the same
+ * way, via a real [Uri] under Robolectric, rather than re-implementing
+ * decoding by hand and only proving the two sides of one hand-rolled pair
+ * agree with each other.
+ */
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [34])
+class RoutesTest {
+
+    private fun decode(route: String, arg: String): String? =
+        Uri.parse("scheme://host/$route").getQueryParameter(arg)
+
+    @Test
+    fun `round-trips a title containing query-breaking characters`() {
+        val title = "Hänsel & Gretel / Part 1?"
+        val route = Routes.addBook(title = title)
+
+        assertEquals(title, decode(route, Routes.ADD_BOOK_TITLE_ARG))
+    }
+
+    @Test
+    fun `round-trips a title containing a hash`() {
+        val title = "Chapter #3: The Return"
+        val route = Routes.addBook(title = title)
+
+        assertEquals(title, decode(route, Routes.ADD_BOOK_TITLE_ARG))
+    }
+
+    @Test
+    fun `round-trips spaces and non-ASCII`() {
+        val title = "Le Petit Prince — a été traduit"
+        val route = Routes.addBook(title = title)
+
+        assertEquals(title, decode(route, Routes.ADD_BOOK_TITLE_ARG))
+    }
+
+    @Test
+    fun `round-trips both title and isbn together`() {
+        val title = "Q&A: Life, the Universe / Everything?"
+        val isbn = "978-0-13-468599-1"
+        val route = Routes.addBook(title = title, isbn = isbn)
+
+        assertEquals(title, decode(route, Routes.ADD_BOOK_TITLE_ARG))
+        assertEquals(isbn, decode(route, Routes.ADD_BOOK_ISBN_ARG))
+    }
+
+    @Test
+    fun `omits absent args entirely rather than encoding a literal null`() {
+        assertEquals("add", Routes.addBook())
+        assertEquals("add?title=${Uri.encode("Dune")}", Routes.addBook(title = "Dune"))
+
+        val isbnOnlyRoute = Routes.addBook(isbn = "9780441013593")
+        assertNull(decode(isbnOnlyRoute, Routes.ADD_BOOK_TITLE_ARG))
+        assertEquals("9780441013593", decode(isbnOnlyRoute, Routes.ADD_BOOK_ISBN_ARG))
+    }
+
+    @Test
+    fun `bare add route matches the ADD_BOOK pattern's base path`() {
+        assertEquals("add", Routes.addBook().substringBefore("?"))
+        assertEquals("add", Routes.ADD_BOOK.substringBefore("?"))
+    }
+}
diff --git a/app/app/src/test/java/org/modg/bookshelf/ui/screens/AddBookScreenPaparazziTest.kt b/app/app/src/test/java/org/modg/bookshelf/ui/screens/AddBookScreenPaparazziTest.kt
new file mode 100644
index 0000000..69c0d20
--- /dev/null
+++ b/app/app/src/test/java/org/modg/bookshelf/ui/screens/AddBookScreenPaparazziTest.kt
@@ -0,0 +1,86 @@
+package org.modg.bookshelf.ui.screens
+
+import androidx.compose.runtime.Composable
+import app.cash.paparazzi.DeviceConfig
+import app.cash.paparazzi.Paparazzi
+import org.junit.Rule
+import org.junit.Test
+import org.modg.bookshelf.ui.add.AddBookCallbacks
+import org.modg.bookshelf.ui.add.AddBookContent
+import org.modg.bookshelf.ui.add.AddBookUiState
+import org.modg.bookshelf.ui.add.BookDraft
+import org.modg.bookshelf.ui.scan.DuplicateStatus
+import org.modg.bookshelf.ui.theme.BookshelfTheme
+
+/**
+ * SPEC gap: add-by-hand form for books with no barcode. Renders the REAL
+ * [AddBookContent] fed with static [AddBookUiState] — no hand-rolled lookalike
+ * (see [ScreenFixtures]'s KDoc for why a real [org.modg.bookshelf.AppContainer]
+ * can't drive this inside Paparazzi, and HANDOFF.md for why wave 6's Locations
+ * shortcut isn't repeated here).
+ */
+class AddBookScreenPaparazziTest {
+
+    @get:Rule
+    val paparazzi = Paparazzi(deviceConfig = DeviceConfig.PIXEL_6)
+
+    @Test
+    fun addBookEmptyLight() = snapshotBoth("add-book-empty") {
+        AddBookContent(state = AddBookUiState(), callbacks = noopCallbacks())
+    }
+
+    @Test
+    fun addBookFilledWithDuplicateLight() = snapshotBoth("add-book-filled-duplicate") {
+        AddBookContent(
+            state = AddBookUiState(
+                draft = BookDraft(
+                    title = "Dune",
+                    subtitle = "",
+                    authors = "Frank Herbert",
+                    publisher = "Ace",
+                    publishedDate = "1965",
+                    pages = "412",
+                    isbn = "9780441013593",
+                    description = "A desert planet, a young man's destiny, and the spice that binds it all.",
+                ),
+                bookcases = ScreenFixtures.bookcases,
+                shelves = ScreenFixtures.shelves,
+                selectedShelfId = ScreenFixtures.topShelf.id,
+                duplicate = DuplicateStatus.AlreadyOwned(bookId = "b1", title = "Dune"),
+            ),
+            callbacks = noopCallbacks(),
+        )
+    }
+
+    @Test
+    fun addBookIsbnErrorLight() = snapshotBoth("add-book-isbn-error") {
+        AddBookContent(
+            state = AddBookUiState(
+                draft = BookDraft(title = "Old Pamphlet", isbn = "not-an-isbn"),
+                bookcases = ScreenFixtures.bookcases,
+                shelves = ScreenFixtures.shelves,
+            ),
+            callbacks = noopCallbacks(),
+        )
+    }
+
+    private fun noopCallbacks() = AddBookCallbacks(
+        onTitleChanged = {},
+        onSubtitleChanged = {},
+        onAuthorsChanged = {},
+        onPublisherChanged = {},
+        onPublishedDateChanged = {},
+        onPagesChanged = {},
+        onIsbnChanged = {},
+        onDescriptionChanged = {},
+        onShelfSelected = {},
+        onSave = {},
+        onSaveAndAddAnother = {},
+        onBack = {},
+    )
+
+    private fun snapshotBoth(name: String, content: @Composable () -> Unit) {
+        paparazzi.snapshot(name = "$name-light") { BookshelfTheme(darkTheme = false) { content() } }
+        paparazzi.snapshot(name = "$name-dark") { BookshelfTheme(darkTheme = true) { content() } }
+    }
+}
diff --git a/app/app/src/test/java/org/modg/bookshelf/ui/screens/LibraryScreenPaparazziTest.kt b/app/app/src/test/java/org/modg/bookshelf/ui/screens/LibraryScreenPaparazziTest.kt
index 0b964e8..c907751 100644
--- a/app/app/src/test/java/org/modg/bookshelf/ui/screens/LibraryScreenPaparazziTest.kt
+++ b/app/app/src/test/java/org/modg/bookshelf/ui/screens/LibraryScreenPaparazziTest.kt
@@ -3,12 +3,16 @@ package org.modg.bookshelf.ui.screens
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.items
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.outlined.EditNote
 import androidx.compose.material.icons.outlined.QrCodeScanner
 import androidx.compose.material.icons.outlined.Settings
 import androidx.compose.material.icons.outlined.Warehouse
@@ -16,7 +20,9 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.FloatingActionButton
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
+import androidx.compose.material3.SmallFloatingActionButton
 import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import app.cash.paparazzi.DeviceConfig
@@ -28,6 +34,7 @@ import org.modg.bookshelf.ui.components.BookshelfScaffold
 import org.modg.bookshelf.ui.components.EmptyState
 import org.modg.bookshelf.ui.components.PaperSurface
 import org.modg.bookshelf.ui.components.PrimaryButton
+import org.modg.bookshelf.ui.components.SecondaryButton
 import org.modg.bookshelf.ui.components.SyncStatus
 import org.modg.bookshelf.ui.components.SyncStatusBar
 import org.modg.bookshelf.ui.library.LibraryBookCard
@@ -71,7 +78,11 @@ class LibraryScreenPaparazziTest {
                 IconButton(onClick = {}) { Icon(Icons.Outlined.Settings, contentDescription = "Settings") }
             },
             floatingActionButton = {
-                FloatingActionButton(onClick = {}) { Icon(Icons.Outlined.QrCodeScanner, contentDescription = "Scan a book") }
+                Column(horizontalAlignment = Alignment.End) {
+                    SmallFloatingActionButton(onClick = {}) { Icon(Icons.Outlined.EditNote, contentDescription = "Add a book by hand") }
+                    Spacer(modifier = Modifier.height(12.dp))
+                    FloatingActionButton(onClick = {}) { Icon(Icons.Outlined.QrCodeScanner, contentDescription = "Scan a book") }
+                }
             },
             syncStatusBar = { SyncStatusBar(status = syncStatus, label = syncLabel) },
         ) { innerPadding ->
@@ -91,7 +102,12 @@ class LibraryScreenPaparazziTest {
                         EmptyState(
                             title = "Your shelves are empty",
                             message = "Scan a barcode to add your first book.",
-                            action = { PrimaryButton(text = "Scan a book", onClick = {}) },
+                            action = {
+                                Row(horizontalArrangement = Arrangement.spacedBy(12.dp)) {
+                                    PrimaryButton(text = "Scan a book", onClick = {})
+                                    SecondaryButton(text = "Add by hand", onClick = {})
+                                }
+                            },
                         )
                     } else {
                         LazyVerticalGrid(
diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookEmptyLight_add-book-empty-dark.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookEmptyLight_add-book-empty-dark.png
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new file mode 100644
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diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookFilledWithDuplicateLight_add-book-filled-duplicate-dark.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookFilledWithDuplicateLight_add-book-filled-duplicate-dark.png
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diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookFilledWithDuplicateLight_add-book-filled-duplicate-light.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookFilledWithDuplicateLight_add-book-filled-duplicate-light.png
new file mode 100644
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diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookIsbnErrorLight_add-book-isbn-error-dark.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookIsbnErrorLight_add-book-isbn-error-dark.png
new file mode 100644
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diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookIsbnErrorLight_add-book-isbn-error-light.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_AddBookScreenPaparazziTest_addBookIsbnErrorLight_add-book-isbn-error-light.png
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diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-dark.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-dark.png
index ecd0f24..caf2737 100644
Binary files a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-dark.png and b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-dark.png differ
diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-light.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-light.png
index 0a298ed..3b2e6d0 100644
Binary files a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-light.png and b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryEmptyLight_library-empty-light.png differ
diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-dark.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-dark.png
index 6b4131b..c0953a6 100644
Binary files a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-dark.png and b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-dark.png differ
diff --git a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-light.png b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-light.png
index b578d34..bcc75c3 100644
Binary files a/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-light.png and b/app/app/src/test/snapshots/images/org.modg.bookshelf.ui.screens_LibraryScreenPaparazziTest_libraryPopulatedLight_library-populated-light.png differ
diff --git a/logs/K-manual-fix.sid b/logs/K-manual-fix.sid
new file mode 100644
index 0000000..e075c3a
--- /dev/null
+++ b/logs/K-manual-fix.sid
@@ -0,0 +1 @@
+3eb4f3f4-1013-4838-91eb-d217251be382
diff --git a/logs/K-manual-fix.summary b/logs/K-manual-fix.summary
new file mode 100644
index 0000000..c138d47
--- /dev/null
+++ b/logs/K-manual-fix.summary
@@ -0,0 +1,34 @@
+=== K-manual-fix  attempts=1 quota_waits=0 hard_fails=0 ===
+cost=$7.268144399999997 turns=7 err=?
+--- result (tail) ---
+59-6` → `...01359-7`, and the corresponding expected `isbn10` value); added `Dispatchers.setMain(UnconfinedTestDispatcher())`/`resetMain()` in `@Before`/`@After`; added `@OptIn(ExperimentalCoroutinesApi::class)` (matches `ScannerControllerTest`'s existing convention, silences the opt-in warning); switched 5 direct `.value` reads to `.first()`.
+- `app/app/src/main/java/org/modg/bookshelf/ui/add/AddBookViewModel.kt`: added a KDoc comment on `uiState` explaining the `WhileSubscribed` caveat for future readers — no behavioral change.
+- Recorded and eyeballed the new Paparazzi goldens (`AddBookScreenPaparazziTest` ×3 states ×2 themes, `LibraryScreenPaparazziTest` re-recorded ×2 states ×2 themes) — all render correctly: form fields, ISBN error state, duplicate warning, the new satellite "Add by hand" FAB, and the empty-state secondary button, in both themes.
+
+Nothing else touched — the feature itself (screens, nav, routes, entry points) is exactly as the previous worker left it.
+
+### Gate output (verbatim tails)
+
+```
+./tasks/gw assembleDebug
+BUILD SUCCESSFUL in 1m 43s
+39 actionable tasks: 3 executed, 36 up-to-date
+
+./tasks/gw testDebugUnitTest
+BUILD SUCCESSFUL in 1m 24s
+34 actionable tasks: 1 executed, 33 up-to-date
+```
+Summed from `TEST-*.xml`: **tests=241 skipped=2 failures=0 errors=0** (baseline was 205; up 36, zero failures/skips beyond the 2 pre-existing opt-in live tests).
+
+```
+./tasks/gw recordPaparazziDebug   -> BUILD SUCCESSFUL in 3m 42s
+./tasks/gw verifyPaparazziDebug
+BUILD SUCCESSFUL in 48s
+34 actionable tasks: 1 executed, 33 up-to-date
+```
+
+No Kotlin warnings on any touched file in the full build log (`grep "^w:"` empty).
+
+### Not committed
+
+Working tree only, as required — `git status` shows the modifications/new files, nothing staged or committed.
diff --git a/logs/K-manual.sid b/logs/K-manual.sid
new file mode 100644
index 0000000..217f282
--- /dev/null
+++ b/logs/K-manual.sid
@@ -0,0 +1 @@
+1f9304e1-ad80-456e-ab8c-3720b352905e
diff --git a/logs/K-manual.summary b/logs/K-manual.summary
new file mode 100644
index 0000000..e7bcf84
--- /dev/null
+++ b/logs/K-manual.summary
@@ -0,0 +1,4 @@
+=== K-manual  attempts=1 quota_waits=0 hard_fails=0 ===
+cost=$5.051114400000003 turns=108 err=?
+--- result (tail) ---
+I'll stop polling now and wait for the background monitor to notify me when `testDebugUnitTest` completes.
diff --git a/tasks/K-manual-fix.txt b/tasks/K-manual-fix.txt
new file mode 100644
index 0000000..bf5fea1
--- /dev/null
+++ b/tasks/K-manual-fix.txt
@@ -0,0 +1,14 @@
+A previous worker implemented the task in ~/bookshelf/tasks/K-manual.txt and left the
+working tree FAILING its acceptance gate. Read, in order: ~/bookshelf/docs/SPEC.md,
+~/bookshelf/tasks/K-manual.txt (the original instructions — every constraint in it binds
+you too), ~/bookshelf/logs/K-manual.summary (that worker's report), then the gate output at
+~/bookshelf/logs/gate-K-manual.log. Lines starting "GATE:" and non-zero exits are the failures.
+
+Fix ONLY what makes the gate red. Do not redesign or re-implement the feature. The
+test count must end ABOVE 205 with zero failures; do not delete or @Ignore tests to
+get there. If a Paparazzi verify failed because snapshots were never recorded, record
+them and LOOK at the PNGs before accepting them.
+
+Run in the FOREGROUND (never background a build): ./tasks/gw assembleDebug,
+./tasks/gw testDebugUnitTest, ./tasks/gw verifyPaparazziDebug. Do not git commit/add/push.
+Report what was wrong, what you changed, and the verbatim output tails.