feat(core,fuse,gui): find and trash duplicate photos

A "Find duplicates" button in the Photos header opens a review of every
set of files that share a content hash. Each set shows its copies side by
side with a Keep toggle; the copy in the most albums, then in the larger
RAW+JPEG group, then the oldest, is kept by default, and a set can't lose
its last kept copy. The copies not kept move to Trash one file at a time.

- core: Db::photo_duplicates, Request::PhotoDuplicates, and a files_only
  flag on TrashNodes (defaults to false, so old clients still trash whole
  groups).
- core: deleting a group's representative now clears the group key of its
  remaining files instead of leaving them pointing at a missing uid.
- fuse: handlers for both requests.

crates/pdfs-core/src/control.rs

@@ -88,6 +88,9 @@ pub enum Request {
     /// `limit` of them — the "On this day" strip above the timeline. Replies
     /// with [`Response::Photos`]; a front-end groups them by year itself.
     PhotosOnThisDay { limit: usize },
+    /// Sets of photos that are byte-identical copies of each other, going by
+    /// the server's content hash. Replies with [`Response::PhotoDuplicates`].
+    PhotoDuplicates,
     /// List the account's photo albums, newest activity first, including the
     /// albums other people share with us. Metadata only — an album's cover
     /// thumbnail is fetched with [`Request::PhotoThumbs`] like any other photo.
@@ -134,8 +137,14 @@ pub enum Request {
     ///
     /// A photo that belongs to a group takes the whole group with it: trashing
     /// the JPEG of a shot and leaving its RAW behind is not what anyone means by
-    /// deleting that photo.
-    TrashNodes { uids: Vec<String> },
+    /// deleting that photo. With `files_only` set, exactly the listed files
+    /// go and their groups stay: the duplicate finder removes one copy of a
+    /// shot, not the shot. Older front-ends omit it and trash whole groups.
+    TrashNodes {
+        uids: Vec<String>,
+        #[serde(default)]
+        files_only: bool,
+    },
     /// Fetch thumbnails for ordinary Drive image files shown outside the Photos
     /// timeline. The modification time is the cache validity tag, so replacing
     /// an image can never reuse its previous revision's thumbnail.
@@ -1784,6 +1793,9 @@ pub enum Response {
     /// The months the timeline spans (reply to [`Request::PhotoMonths`]),
     /// newest first.
     PhotoMonths { months: Vec<PhotoMonth> },
+    /// The duplicate sets (reply to [`Request::PhotoDuplicates`]), newest
+    /// first. Each set lists the copy worth keeping first.
+    PhotoDuplicates { sets: Vec<Vec<PhotoItem>> },
     /// Thumbnails for a [`Request::PhotoThumbs`] batch.
     Thumbs { items: Vec<PhotoThumb> },
     /// Per-node outcome of a [`Request::TrashNodes`] batch. Reported per uid
@@ -2180,7 +2192,17 @@ mod tests {
     fn trash_requests_and_outcomes_roundtrip() {
         let request = Request::TrashNodes {
             uids: vec!["volume~first".into(), "volume~second".into()],
+            files_only: false,
         };
+        // An older front-end's request trashes whole groups.
+        let old: Request = serde_json::from_str(r#"{"TrashNodes":{"uids":["v~a"]}}"#).unwrap();
+        assert!(matches!(
+            old,
+            Request::TrashNodes {
+                files_only: false,
+                ..
+            }
+        ));
         let line = serde_json::to_string(&request).unwrap();
         assert!(!line.contains('\n'), "wire form must be a single line");
         let decoded: Request = serde_json::from_str(&line).unwrap();

crates/pdfs-core/src/db/photos.rs

@@ -3,7 +3,7 @@
 
 use rusqlite::params;
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
 use super::Db;
 use crate::Result;
@@ -447,6 +447,14 @@ impl Db {
                 albums.execute([uid])?;
             }
         }
+        // A group whose representative went is left pointing at nothing, which
+        // drops its other files off every page. Make them stand alone until the
+        // next refresh groups them again.
+        tx.execute(
+            "UPDATE photos SET group_key = NULL WHERE group_key IS NOT NULL \
+             AND group_key NOT IN (SELECT uid FROM photos)",
+            [],
+        )?;
         tx.commit()?;
         Ok(removed)
     }
@@ -609,6 +617,57 @@ impl Db {
         Ok(rows)
     }
 
+    /// Sets of photos with the same content hash, each set ordered with the
+    /// copy worth keeping first, and the sets newest first.
+    ///
+    /// The copy to keep is the one in the most albums, then the one that is part
+    /// of a larger group (the JPEG's RAW is filed with it, a stray re-upload is
+    /// not), then the earliest in server order. At most one file per group is
+    /// listed: the files of one RAW+JPEG shot are not copies of each other, and a
+    /// set left with one member is no set.
+    pub fn photo_duplicates(&self) -> Result<Vec<Vec<StoredPhoto>>> {
+        let rows: Vec<(String, String, String)> = {
+            let conn = self.read();
+            let mut stmt = conn.prepare(
+                "SELECT p.uid, p.content_hash, COALESCE(p.group_key, p.uid) AS k FROM photos p \
+                 WHERE p.content_hash IN (SELECT content_hash FROM photos \
+                     WHERE content_hash IS NOT NULL GROUP BY content_hash HAVING COUNT(*) > 1) \
+                 ORDER BY p.content_hash, \
+                     (SELECT COUNT(*) FROM album_photos a WHERE a.uid = p.uid) DESC, \
+                     (SELECT COUNT(*) FROM photos m WHERE COALESCE(m.group_key, m.uid) = COALESCE(p.group_key, p.uid)) DESC, \
+                     p.seq",
+            )?;
+            stmt.query_map([], |r| Ok((r.get(0)?, r.get(1)?, r.get(2)?)))?
+                .collect::<rusqlite::Result<_>>()?
+        };
+        let uids: Vec<String> = rows.iter().map(|(uid, _, _)| uid.clone()).collect();
+        let mut stored: HashMap<String, StoredPhoto> = self
+            .photos_by_uid(&uids)?
+            .into_iter()
+            .map(|photo| (photo.uid.clone(), photo))
+            .collect();
+
+        let mut sets: Vec<Vec<StoredPhoto>> = Vec::new();
+        let mut hash_of_set: Option<&str> = None;
+        let mut groups_in_set: HashSet<&str> = HashSet::new();
+        for (uid, hash, group) in &rows {
+            if hash_of_set != Some(hash.as_str()) {
+                hash_of_set = Some(hash);
+                groups_in_set.clear();
+                sets.push(Vec::new());
+            }
+            if !groups_in_set.insert(group) {
+                continue;
+            }
+            if let (Some(set), Some(photo)) = (sets.last_mut(), stored.remove(uid)) {
+                set.push(photo);
+            }
+        }
+        sets.retain(|set| set.len() > 1);
+        sets.sort_by_key(|set| std::cmp::Reverse(set.iter().map(|p| p.capture_time).max()));
+        Ok(sets)
+    }
+
     /// Per-tab counts for the Photos page subtitle: `(photos, videos, raw)`.
     pub fn photos_counts(&self) -> Result<(usize, usize, usize)> {
         use crate::control::PhotoKind;

crates/pdfs-core/src/db/tests.rs

@@ -285,6 +285,64 @@ fn on_this_day_finds_the_same_date_in_earlier_years() {
     );
 }
 
+fn hashed(uid: &str, capture_time: i64, name: &str, hash: &str) -> TimelineRow {
+    TimelineRow {
+        name: Some(name.into()),
+        content_hash: Some(hash.into()),
+        ..TimelineRow::new(uid, capture_time)
+    }
+}
+
+/// A copy an album holds is the one kept; the files of one RAW+JPEG shot are
+/// never copies of each other; a hash only one file carries is no set.
+#[test]
+fn duplicates_list_the_copy_to_keep_first() {
+    let db = Db::open_in_memory().unwrap();
+    db.photos_replace(&[
+        hashed("copy", 500, "IMG_2.JPG", "h2"),
+        hashed("filed", 400, "IMG_2(1).JPG", "h2"),
+        hashed("jpeg", 300, "IMG_1.JPG", "h1"),
+        hashed("raw", 300, "IMG_1.CR2", "h1"),
+        hashed("stray", 200, "IMG_1(1).CR2", "h1"),
+        hashed("alone", 100, "IMG_3.JPG", "h3"),
+    ])
+    .unwrap();
+    db.album_photos_replace("a1", &[("filed".into(), 400, None, None)])
+        .unwrap();
+
+    let sets = db.photo_duplicates().unwrap();
+    let uids: Vec<Vec<&str>> = sets
+        .iter()
+        .map(|set| set.iter().map(|p| p.uid.as_str()).collect())
+        .collect();
+    assert_eq!(uids, [vec!["filed", "copy"], vec!["jpeg", "stray"]]);
+}
+
+/// Trashing the file a group is shown as leaves the rest of the group on the
+/// timeline instead of pointing at a photo that is gone.
+#[test]
+fn deleting_a_group_representative_keeps_its_other_files() {
+    let db = Db::open_in_memory().unwrap();
+    db.photos_replace(&[
+        hashed("jpeg", 300, "IMG_1.JPG", "h1"),
+        hashed("raw", 300, "IMG_1.CR2", "h2"),
+    ])
+    .unwrap();
+    assert_eq!(
+        db.photos_page(0, 10, None, None, false, false)
+            .unwrap()
+            .len(),
+        1
+    );
+
+    db.photos_delete(&["jpeg".into()]).unwrap();
+    let page = db.photos_page(0, 10, None, None, false, false).unwrap();
+    assert_eq!(
+        page.iter().map(|p| p.uid.as_str()).collect::<Vec<_>>(),
+        ["raw"]
+    );
+}
+
 #[test]
 fn not_in_album_hides_photos_any_album_holds() {
     let db = Db::open_in_memory().unwrap();

crates/pdfs-fuse/src/control.rs

@@ -461,6 +461,10 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
             },
             Err(e) => CtlResponse::error(e),
         },
+        Ok(CtlRequest::PhotoDuplicates) => match core.photo_duplicates() {
+            Ok(sets) => CtlResponse::PhotoDuplicates { sets },
+            Err(e) => CtlResponse::error(e),
+        },
         Ok(CtlRequest::PhotosOnThisDay { limit }) => {
             match core.photos_on_this_day(clamp_limit(limit)) {
                 Ok(items) => CtlResponse::Photos {
@@ -564,8 +568,8 @@ fn handle_control_conn(core: &Core, username: &str, mountpoint: &Path, stream: U
                 items: core.photo_thumbs(&parsed),
             }
         }
-        Ok(CtlRequest::TrashNodes { uids }) => match Core::parse_uids(&uids) {
-            Ok(parsed) => match core.trash_photos(&parsed) {
+        Ok(CtlRequest::TrashNodes { uids, files_only }) => match Core::parse_uids(&uids) {
+            Ok(parsed) => match core.trash_photos(&parsed, files_only) {
                 Ok((trashed, failed)) => CtlResponse::Trashed {
                     trashed,
                     failed: failed

crates/pdfs-fuse/src/photos.rs

@@ -729,6 +729,16 @@ impl Core {
         Ok(())
     }
 
+    /// The timeline's duplicate sets, as wire items (see
+    /// [`db::Db::photo_duplicates`]).
+    pub(crate) fn photo_duplicates(&self) -> CoreResult<Vec<Vec<PhotoItem>>> {
+        let sets = self.db.photo_duplicates().map_err(CoreError::from)?;
+        Ok(sets
+            .into_iter()
+            .map(|set| set.into_iter().map(|p| self.photo_item(p)).collect())
+            .collect())
+    }
+
     /// Photos taken on today's date in earlier years, as wire items. Served
     /// from the stored timeline only: the strip is a nicety, not worth a wait
     /// on the network, and the timeline's own load keeps that store fresh.
@@ -822,12 +832,23 @@ impl Core {
     /// A photo that is one file of a group takes its whole group with it. The
     /// gallery shows a RAW+JPEG shot as one tile, so deleting that tile has to
     /// delete the shot — leaving the RAW behind would put the photo back on the
-    /// Raw tab and nowhere else.
-    pub(crate) fn trash_photos(&self, uids: &[NodeUid]) -> CoreResult<TrashOutcome> {
+    /// Raw tab and nowhere else. `files_only` turns that off, for removing
+    /// one copy of a shot that is stored twice.
+    pub(crate) fn trash_photos(
+        &self,
+        uids: &[NodeUid],
+        files_only: bool,
+    ) -> CoreResult<TrashOutcome> {
         if uids.is_empty() {
             return Ok((Vec::new(), Vec::new()));
         }
-        let uids = &self.expand_photo_groups(uids);
+        let expanded;
+        let uids = if files_only {
+            uids
+        } else {
+            expanded = self.expand_photo_groups(uids);
+            &expanded
+        };
         for uid in uids {
             self.require_photo_writable(uid)
                 .map_err(|errno| self.errno_error(errno, "trash access"))?;

crates/pdfs-gui/src/app/main.rs

@@ -9,6 +9,7 @@ use pages::activity::*;
 use pages::albums::*;
 use pages::browser::*;
 use pages::devices::*;
+use pages::duplicates::*;
 use pages::locations::*;
 use pages::login::*;
 use pages::photo_viewer::*;
@@ -726,6 +727,10 @@ fn build_window(app: &adw::Application) {
         &gallery_widgets.empty_upload,
         &gallery_widgets.empty_import,
     );
+    let ui_duplicates = ui.clone();
+    gallery_widgets
+        .duplicates
+        .connect_clicked(move |_| show_duplicates(&ui_duplicates));
     wire_albums(&ui);
     wire_trash(&ui, &trash_widgets);
     wire_shared(&ui, &shared_widgets.retry, &shared_widgets.add_bookmark);

crates/pdfs-gui/src/app/pages/duplicates.rs

@@ -0,0 +1,246 @@
+use crate::*;
+
+/// Side of a copy's thumbnail in the duplicates dialog, in px.
+const COPY_SIZE: i32 = 150;
+
+/// Each set's copies with their Keep toggles.
+type SetToggles = Vec<Vec<(PhotoItem, gtk4::ToggleButton)>>;
+
+/// Open the duplicate finder: every set of photos stored more than once, side
+/// by side, with the copy worth keeping ticked. The copies left unticked go to
+/// Trash — one file each, never the rest of their shot.
+pub(crate) fn show_duplicates(ui: &Rc<Ui>) {
+    let status = adw::StatusPage::builder()
+        .icon_name("edit-copy-symbolic")
+        .title(gettext("Looking for duplicates…"))
+        .vexpand(true)
+        .build();
+    status.add_css_class("compact");
+
+    let stack = gtk4::Stack::new();
+    stack.add_named(&status, Some("status"));
+
+    let trash = gtk4::Button::builder()
+        .label(gettext("Move to Trash"))
+        .halign(gtk4::Align::End)
+        .sensitive(false)
+        .build();
+    trash.add_css_class("destructive-action");
+    trash.add_css_class("pill");
+    let bottom = gtk4::Box::new(gtk4::Orientation::Horizontal, 0);
+    bottom.add_css_class("toolbar");
+    bottom.set_halign(gtk4::Align::End);
+    bottom.append(&trash);
+
+    let toolbar = adw::ToolbarView::new();
+    toolbar.add_top_bar(&adw::HeaderBar::new());
+    toolbar.set_content(Some(&stack));
+    toolbar.add_bottom_bar(&bottom);
+    toolbar.set_reveal_bottom_bars(false);
+
+    let dialog = adw::Dialog::builder()
+        .title(gettext("Duplicates"))
+        .content_width(760)
+        .content_height(640)
+        .child(&toolbar)
+        .build();
+    dialog.present(ui_window(ui).as_ref());
+
+    let rx = spawn_request(ui.dirs.control_socket(), Request::PhotoDuplicates);
+    let ui = ui.clone();
+    glib::spawn_future_local(async move {
+        let sets = match rx.recv().await {
+            Ok(Ok(Response::PhotoDuplicates { sets })) => sets,
+            Ok(Ok(Response::Error { message, .. })) => {
+                status.set_icon_name(Some("dialog-warning-symbolic"));
+                status.set_title(&gettext("Couldn't look for duplicates"));
+                status.set_description(Some(&message));
+                return;
+            }
+            _ => {
+                status.set_icon_name(Some("dialog-warning-symbolic"));
+                status.set_title(&gettext("Couldn't look for duplicates"));
+                status.set_description(Some(&gettext("The mount service didn't respond.")));
+                return;
+            }
+        };
+        if sets.is_empty() {
+            status.set_icon_name(Some("emblem-ok-symbolic"));
+            status.set_title(&gettext("No duplicates"));
+            status.set_description(Some(&gettext(
+                "Every photo in your library is stored once.",
+            )));
+            return;
+        }
+        let review = duplicate_review(&ui, sets, &trash);
+        stack.add_named(&review, Some("review"));
+        stack.set_visible_child_name("review");
+        toolbar.set_reveal_bottom_bars(true);
+        schedule_thumbs(&ui);
+    });
+}
+
+/// The review list: one section per set, each copy a thumbnail with a Keep
+/// toggle. Wires `trash` to move every copy not kept to Trash.
+fn duplicate_review(ui: &Rc<Ui>, sets: Vec<Vec<PhotoItem>>, trash: &gtk4::Button) -> gtk4::Widget {
+    let intro = gtk4::Label::builder()
+        .label(gettext(
+            "These photos are stored more than once. The copies you don't keep move to Trash, where you can restore them.",
+        ))
+        .wrap(true)
+        .xalign(0.0)
+        .build();
+    intro.add_css_class("dim-label");
+
+    let content = gtk4::Box::new(gtk4::Orientation::Vertical, 18);
+    content.set_margin_top(12);
+    content.set_margin_bottom(12);
+    content.set_margin_start(18);
+    content.set_margin_end(18);
+    content.append(&intro);
+
+    // Every copy's toggle, by set, so the button can count what goes.
+    let toggles: Rc<RefCell<SetToggles>> = Rc::new(RefCell::new(Vec::new()));
+    for set in sets {
+        let Some(first) = set.first() else {
+            continue;
+        };
+        let date = section_heading(first.capture_time, Grouping::Day);
+        // Translators: heading of one set in the duplicates dialog; {date} is the day the photo was taken.
+        let title = ngettext_f(
+            "{date}, {n} copy",
+            "{date}, {n} copies",
+            set.len() as u64,
+            &[("date", &date)],
+        );
+        let heading = gtk4::Label::builder().label(title).xalign(0.0).build();
+        heading.add_css_class("heading");
+        let row = gtk4::Box::new(gtk4::Orientation::Horizontal, 12);
+        let mut set_toggles = Vec::new();
+        for (index, photo) in set.into_iter().enumerate() {
+            let (card, keep) = copy_card(ui, &photo, index == 0);
+            row.append(&card);
+            set_toggles.push((photo, keep));
+        }
+        let row_scroll = gtk4::ScrolledWindow::builder()
+            .vscrollbar_policy(gtk4::PolicyType::Never)
+            .propagate_natural_height(true)
+            .child(&row)
+            .build();
+        let section = gtk4::Box::new(gtk4::Orientation::Vertical, 6);
+        section.append(&heading);
+        section.append(&row_scroll);
+        content.append(&section);
+        toggles.borrow_mut().push(set_toggles);
+    }
+
+    let sync = {
+        let toggles = toggles.clone();
+        let trash = trash.clone();
+        move || {
+            let n = doomed(&toggles.borrow()).len();
+            trash.set_label(&ngettext_f(
+                "Move {n} copy to Trash",
+                "Move {n} copies to Trash",
+                n as u64,
+                &[],
+            ));
+            trash.set_sensitive(n > 0);
+        }
+    };
+    sync();
+    for set in toggles.borrow().iter() {
+        for (_, keep) in set {
+            let toggles = toggles.clone();
+            let sync = sync.clone();
+            keep.connect_toggled(move |keep| {
+                // A set always keeps a copy: unticking the last one would trash
+                // the photo itself, which is not what removing duplicates means.
+                if !keep.is_active()
+                    && toggles.borrow().iter().any(|set| {
+                        set.iter().any(|(_, t)| t == keep)
+                            && set.iter().all(|(_, t)| !t.is_active())
+                    })
+                {
+                    keep.set_active(true);
+                    return;
+                }
+                sync();
+            });
+        }
+    }
+
+    let ui_trash = ui.clone();
+    trash.connect_clicked(move |button| {
+        let uids = doomed(&toggles.borrow());
+        if uids.is_empty() {
+            return;
+        }
+        trash_photos(&ui_trash, uids, true);
+        if let Some(dialog) = button
+            .ancestor(adw::Dialog::static_type())
+            .and_downcast::<adw::Dialog>()
+        {
+            dialog.close();
+        }
+    });
+
+    let scroll = gtk4::ScrolledWindow::builder()
+        .hscrollbar_policy(gtk4::PolicyType::Never)
+        .vexpand(true)
+        .child(&content)
+        .build();
+    scroll.upcast()
+}
+
+/// The uids of every copy not kept.
+fn doomed(toggles: &SetToggles) -> Vec<String> {
+    toggles
+        .iter()
+        .flatten()
+        .filter(|(_, keep)| !keep.is_active())
+        .map(|(photo, _)| photo.uid.clone())
+        .collect()
+}
+
+/// One copy: its thumbnail, its file name, and whether to keep it.
+fn copy_card(ui: &Rc<Ui>, photo: &PhotoItem, keep: bool) -> (gtk4::Box, gtk4::ToggleButton) {
+    let picture = gtk4::Picture::builder()
+        .content_fit(gtk4::ContentFit::Cover)
+        .can_shrink(true)
+        .build();
+    let placeholder = gtk4::Image::builder()
+        .icon_name("image-x-generic-symbolic")
+        .pixel_size(24)
+        .build();
+    placeholder.add_css_class("photo-placeholder");
+    let overlay = gtk4::Overlay::new();
+    overlay.set_size_request(COPY_SIZE, COPY_SIZE);
+    overlay.set_child(Some(&placeholder));
+    overlay.add_overlay(&picture);
+    overlay.set_overflow(gtk4::Overflow::Hidden);
+    overlay.add_css_class("memory-cover");
+    want_thumb(ui, photo, &picture);
+
+    let name = photo.name.clone().unwrap_or_default();
+    let label = gtk4::Label::builder()
+        .label(&name)
+        .tooltip_text(&name)
+        .ellipsize(gtk4::pango::EllipsizeMode::Middle)
+        .max_width_chars(18)
+        .build();
+    label.add_css_class("caption");
+
+    let toggle = gtk4::ToggleButton::builder()
+        .label(gettext("Keep"))
+        .active(keep)
+        .build();
+    toggle.add_css_class("pill");
+
+    let card = gtk4::Box::new(gtk4::Orientation::Vertical, 6);
+    card.set_size_request(COPY_SIZE, -1);
+    card.append(&overlay);
+    card.append(&label);
+    card.append(&toggle);
+    (card, toggle)
+}

crates/pdfs-gui/src/app/pages/mod.rs

@@ -2,6 +2,7 @@ pub(crate) mod activity;
 pub(crate) mod albums;
 pub(crate) mod browser;
 pub(crate) mod devices;
+pub(crate) mod duplicates;
 pub(crate) mod locations;
 pub(crate) mod login;
 pub(crate) mod photo_viewer;

crates/pdfs-gui/src/app/pages/photo_viewer.rs

@@ -1447,7 +1447,7 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
     delete_btn.connect_clicked(move |_| {
         let uid = viewer_delete.uid.borrow().clone();
         w_delete.close();
-        trash_photos(&ui_delete, vec![uid]);
+        trash_photos(&ui_delete, vec![uid], false);
     });
 
     let ui_group = ui.clone();
@@ -1573,7 +1573,7 @@ pub(crate) fn open_photo_viewer(ui: &Rc<Ui>, initial_uid: String) {
             Some("Delete" | "KP_Delete") => {
                 let uid = viewer_key.uid.borrow().clone();
                 w_key.close();
-                trash_photos(&ui_key, vec![uid]);
+                trash_photos(&ui_key, vec![uid], false);
             }
             Some("Escape" | "q") => w_key.close(),
             Some("w") if ctrl => w_key.close(),

crates/pdfs-gui/src/app/pages/photos.rs

@@ -361,6 +361,7 @@ pub(crate) struct GalleryWidgets {
     pub(crate) empty_upload: gtk4::Button,
     pub(crate) empty_import: gtk4::Button,
     pub(crate) refresh: gtk4::Button,
+    pub(crate) duplicates: gtk4::Button,
     /// The Select toggle and the bar it reveals.
     pub(crate) select_btn: gtk4::ToggleButton,
     pub(crate) select_bar: gtk4::Revealer,
@@ -520,6 +521,15 @@ pub(crate) fn build_gallery_page() -> (gtk4::Widget, GalleryWidgets) {
     import.add_css_class("circular");
     let refresh = refresh_button();
 
+    // The duplicate finder opens over the page: a review, not a view of it.
+    let duplicates = gtk4::Button::builder()
+        .icon_name("edit-copy-symbolic")
+        .tooltip_text(gettext("Find duplicates"))
+        .valign(gtk4::Align::Center)
+        .build();
+    duplicates.add_css_class("flat");
+    duplicates.add_css_class("circular");
+
     // Picking photos is a mode, so its control is a toggle rather than a button.
     let select_btn = gtk4::ToggleButton::builder()
         .icon_name("selection-mode-symbolic")
@@ -749,6 +759,7 @@ pub(crate) fn build_gallery_page() -> (gtk4::Widget, GalleryWidgets) {
     header.pack_end(&refresh);
     header.pack_end(&select_btn);
     header.pack_end(&import);
+    header.pack_end(&duplicates);
 
     (
         frame.upcast(),
@@ -770,6 +781,7 @@ pub(crate) fn build_gallery_page() -> (gtk4::Widget, GalleryWidgets) {
             empty_upload,
             empty_import,
             refresh,
+            duplicates,
             select_btn,
             select_bar,
             select_label,
@@ -1849,7 +1861,7 @@ pub(crate) fn confirm_trash_photos(ui: &Rc<Ui>, uids: Vec<String>) {
     let ui = ui.clone();
     dialog.connect_response(None, move |_, response| {
         if response == "trash" {
-            trash_photos(&ui, uids.clone());
+            trash_photos(&ui, uids.clone(), false);
         }
     });
     dialog.present(win.as_ref());
@@ -1861,13 +1873,19 @@ pub(crate) fn confirm_trash_photos(ui: &Rc<Ui>, uids: Vec<String>) {
 /// photos the user just deleted until a refresh lands — reads as a failure. What
 /// the server refuses comes back, so the grid still ends up telling the truth,
 /// and what succeeded is one Undo away for as long as the toast is up.
-pub(crate) fn trash_photos(ui: &Rc<Ui>, uids: Vec<String>) {
+///
+/// `files_only` trashes exactly `uids` and leaves the rest of their groups, for
+/// the duplicate finder; otherwise each photo takes its whole group along.
+pub(crate) fn trash_photos(ui: &Rc<Ui>, uids: Vec<String>, files_only: bool) {
     let removed = remove_photos(ui, &uids);
     set_selection_mode(ui, false);
     ui.busy_begin();
     let rx = spawn_request(
         ui.dirs.control_socket(),
-        Request::TrashNodes { uids: uids.clone() },
+        Request::TrashNodes {
+            uids: uids.clone(),
+            files_only,
+        },
     );
     let ui = ui.clone();
     glib::spawn_future_local(async move {

po/POTFILES.in

@@ -4,6 +4,7 @@ crates/pdfs-gui/src/app/pages/activity.rs
 crates/pdfs-gui/src/app/pages/albums.rs
 crates/pdfs-gui/src/app/pages/browser.rs
 crates/pdfs-gui/src/app/pages/devices.rs
+crates/pdfs-gui/src/app/pages/duplicates.rs
 crates/pdfs-gui/src/app/pages/locations.rs
 crates/pdfs-gui/src/app/pages/login.rs
 crates/pdfs-gui/src/app/pages/photo_viewer.rs