feat(save): warn before dropping AEC/Civil objects or overwriting on Save-As

Two in-canvas confirmations on the Save-As path:

- AEC/Civil drop warning: when the drawing carries unsupported AEC/Civil
  (application) objects that survive only as verbatim source-version bytes,
  saving to a different version or to DXF would silently drop them. The
  dialog reports the count and offers "Save in source version" (keep) vs
  "Save anyway" (drop). Same-version DWG saves are lossless and skip it.
- Overwrite confirmation: when the chosen filename already exists in the
  target folder, "Replace" / "Cancel" before clobbering it.

The two chain (AEC first, then overwrite) via per-flow acknowledgement flags
reset whenever the Save dialog opens or closes. Detection is a new
io::dropped_on_save_count over the document's Unknown (raw-passthrough)
objects/entities.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/mod.rs

@@ -332,6 +332,13 @@ pub(super) struct OpenCADStudio {
     /// The open in-canvas modal dialog, if any (Plan B: shared overlay instead
     /// of OS windows).
     active_modal: Option<ModalKind>,
+    /// Set once the user acknowledges the AEC-drop warning, so re-entering the
+    /// save path proceeds instead of re-showing the warning.
+    aec_drop_acknowledged: bool,
+    /// Number of unsupported objects shown in the AEC-drop warning modal.
+    aec_drop_count: usize,
+    /// Set once the user confirms overwriting an existing file on Save-As.
+    overwrite_acknowledged: bool,
     /// Pixel offset of the active modal from screen-centre (drag-to-move).
     /// Reset to zero whenever a modal closes so each dialog opens centred.
     modal_offset: iced::Vector,
@@ -923,6 +930,8 @@ pub enum ModalKind {
     DimStyle,
     Unsaved,
     SaveDialog,
+    AecDropWarning,
+    OverwriteWarning,
     #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
     AssocPrompt,
     PointStyle,
@@ -1093,6 +1102,18 @@ pub enum Message {
     UnsavedDialogDiscard,
     /// User clicked "Cancel" in the unsaved-changes dialog.
     UnsavedDialogCancel,
+    // ── AEC / unsupported-object drop warning (lossy Save-As) ──────────────
+    /// Save as the source DWG version so the unsupported objects survive.
+    AecDropSameVersion,
+    /// Proceed with the chosen target format, dropping the unsupported objects.
+    AecDropProceed,
+    /// Go back to the Save dialog from the AEC-drop warning.
+    AecDropBack,
+    // ── Overwrite confirmation (Save-As over an existing file) ────────────
+    /// Replace the existing file and save.
+    OverwriteConfirm,
+    /// Go back to the Save dialog from the overwrite warning.
+    OverwriteCancel,
     /// Save-as path picked for the unsaved-changes → save → close flow.
     UnsavedPickedSavePath(Option<std::path::PathBuf>),
     // ─────────────────────────────────────────────────────────────────────
@@ -1868,6 +1889,9 @@ impl OpenCADStudio {
             main_window: None,
             color_pick_target: None,
             active_modal: None,
+            aec_drop_acknowledged: false,
+            aec_drop_count: 0,
+            overwrite_acknowledged: false,
             modal_offset: iced::Vector::ZERO,
             modal_drag_last: None,
             modal_dragging: false,

src/app/update/dialog.rs

@@ -49,12 +49,16 @@ impl OpenCADStudio {
             self.save_dialog_filename = format!("{}.{ext}", self.tabs[tab_idx].tab_display_name());
         }
         self.save_dialog_entries = crate::io::read_dir_entries(&self.save_dialog_folder.clone());
+        self.aec_drop_acknowledged = false;
+        self.overwrite_acknowledged = false;
         self.active_modal = Some(crate::app::ModalKind::SaveDialog);
         Task::none()
     }
 
 
     pub(in crate::app) fn close_save_dialog_window(&mut self) -> Task<Message> {
+        self.aec_drop_acknowledged = false;
+        self.overwrite_acknowledged = false;
         if self.active_modal == Some(crate::app::ModalKind::SaveDialog) {
             self.active_modal = None;
         }

src/app/update/file.rs

@@ -552,6 +552,23 @@ pub(super) fn on_open_file(&mut self) -> Task<Message> {
 
     pub(super) fn on_save_dialog_confirm(&mut self) -> Task<Message> {
                 let (ext, version) = crate::io::parse_save_format(&self.save_dialog_format);
+                // Warn before a lossy Save-As that would drop unsupported
+                // (AEC / application) objects kept only as verbatim
+                // source-version bytes — let the user keep them by saving in the
+                // source version, or proceed and drop them.
+                if !self.aec_drop_acknowledged {
+                    let is_dxf = ext.eq_ignore_ascii_case("dxf");
+                    let n = crate::io::dropped_on_save_count(
+                        &self.tabs[self.active_tab].scene.document,
+                        version,
+                        is_dxf,
+                    );
+                    if n > 0 {
+                        self.aec_drop_count = n;
+                        self.active_modal = Some(crate::app::ModalKind::AecDropWarning);
+                        return Task::none();
+                    }
+                }
                 // The user need not type an extension: append the selected
                 // format's one when the entered name carries none.
                 let name = self.save_dialog_filename.trim();
@@ -563,7 +580,14 @@ pub(super) fn on_open_file(&mut self) -> Task<Message> {
                     name.to_string()
                 };
                 self.save_dialog_filename = filename.clone();
-                self.save_dialog_filename = filename.clone();
+                // Confirm before overwriting an existing file in the folder.
+                #[cfg(not(target_arch = "wasm32"))]
+                if !self.overwrite_acknowledged
+                    && self.save_dialog_folder.join(&filename).exists()
+                {
+                    self.active_modal = Some(crate::app::ModalKind::OverwriteWarning);
+                    return Task::none();
+                }
                 let close = self.close_save_dialog_window();
                 let i = self.active_tab;
                 sync_annotation_scale_header(&mut self.tabs[i].scene);
@@ -609,6 +633,38 @@ pub(super) fn on_open_file(&mut self) -> Task<Message> {
                 }
     }
 
+    /// AEC-drop warning → "Save anyway": accept the loss and proceed with the
+    /// format the user already chose.
+    pub(super) fn on_aec_drop_proceed(&mut self) -> Task<Message> {
+        self.aec_drop_acknowledged = true;
+        self.active_modal = Some(crate::app::ModalKind::SaveDialog);
+        self.on_save_dialog_confirm()
+    }
+
+    /// AEC-drop warning → "Save in source version": switch the target to the
+    /// document's own DWG version (where the unsupported objects round-trip as
+    /// verbatim bytes), then save.
+    pub(super) fn on_aec_drop_same_version(&mut self) -> Task<Message> {
+        let src = self.tabs[self.active_tab].scene.document.version;
+        self.save_dialog_format = crate::io::format_for_version(src, false);
+        // Strip any extension (e.g. .dxf) so the confirm path appends .dwg.
+        let stem = std::path::Path::new(&self.save_dialog_filename)
+            .file_stem()
+            .map(|s| s.to_string_lossy().into_owned())
+            .unwrap_or_else(|| self.save_dialog_filename.clone());
+        self.save_dialog_filename = stem;
+        self.aec_drop_acknowledged = true;
+        self.active_modal = Some(crate::app::ModalKind::SaveDialog);
+        self.on_save_dialog_confirm()
+    }
+
+    /// Overwrite warning → "Replace": save over the existing file.
+    pub(super) fn on_overwrite_confirm(&mut self) -> Task<Message> {
+        self.overwrite_acknowledged = true;
+        self.active_modal = Some(crate::app::ModalKind::SaveDialog);
+        self.on_save_dialog_confirm()
+    }
+
     pub(super) fn on_page_setup_commit(&mut self) -> Task<Message> {
                 let i = self.active_tab;
                 let layout_name = self.tabs[i].scene.current_layout.clone();

src/app/update/mod.rs

@@ -2527,6 +2527,19 @@ impl OpenCADStudio {
 
             Message::UnsavedDialogSave => self.on_unsaved_dialog_save(),
 
+            Message::AecDropSameVersion => self.on_aec_drop_same_version(),
+            Message::AecDropProceed => self.on_aec_drop_proceed(),
+            Message::AecDropBack => {
+                self.active_modal = Some(crate::app::ModalKind::SaveDialog);
+                Task::none()
+            }
+
+            Message::OverwriteConfirm => self.on_overwrite_confirm(),
+            Message::OverwriteCancel => {
+                self.active_modal = Some(crate::app::ModalKind::SaveDialog);
+                Task::none()
+            }
+
             Message::UnsavedPickedSavePath(Some(path)) => {
                 self.on_unsaved_picked_save_path_some(path)
             }

src/app/view/mod.rs

@@ -1358,6 +1358,8 @@ impl OpenCADStudio {
             DimStyle => (720, 560),
             AssocPrompt => (440, 210),
             Unsaved => (420, 160),
+            AecDropWarning => (480, 230),
+            OverwriteWarning => (420, 180),
             SaveDialog => (560, 480),
             PointStyle => (360, 470),
         };

src/app/view/modal.rs

@@ -466,6 +466,25 @@ impl OpenCADStudio {
             ), 720, 560)
             }
             super::super::ModalKind::AssocPrompt => sized(default_assoc_dialog_window(), 440, 210),
+            super::super::ModalKind::AecDropWarning => {
+                let src_label = self
+                    .tabs
+                    .get(self.active_tab)
+                    .map(|t| crate::io::format_for_version(t.scene.document.version, false))
+                    .unwrap_or_else(|| "DWG".to_string());
+                sized(
+                    aec_drop_dialog_window(
+                        self.aec_drop_count,
+                        &self.save_dialog_format,
+                        &src_label,
+                    ),
+                    480,
+                    230,
+                )
+            }
+            super::super::ModalKind::OverwriteWarning => {
+                sized(overwrite_dialog_window(&self.save_dialog_filename), 420, 180)
+            }
             super::super::ModalKind::Unsaved => {
                 let tab_name = match &self.pending_close {
                     Some(super::super::PendingClose::Tab(idx)) => self
@@ -880,6 +899,123 @@ fn unsaved_changes_dialog_window(name: &str) -> Element<'static, Message> {
     .into()
 }
 
+/// Warning shown before a lossy Save-As: the drawing carries unsupported
+/// (AEC / application) objects that survive only as verbatim source-version
+/// bytes, so saving to a different version or to DXF would drop them. Offers to
+/// save in the source version (keep them) or proceed (drop them).
+fn aec_drop_dialog_window(count: usize, target: &str, src_version: &str) -> Element<'static, Message> {
+    const BG: Color = Color { r: 0.18, g: 0.18, b: 0.20, a: 1.0 };
+    const BORDER_COL: Color = Color { r: 0.38, g: 0.38, b: 0.42, a: 1.0 };
+    const TEXT_COL: Color = Color { r: 0.90, g: 0.90, b: 0.90, a: 1.0 };
+    const BTN_SAVE: Color = Color { r: 0.20, g: 0.46, b: 0.80, a: 1.0 };
+    const BTN_HOVER: Color = Color { r: 0.26, g: 0.55, b: 0.92, a: 1.0 };
+    const BTN_DISC: Color = Color { r: 0.28, g: 0.28, b: 0.30, a: 1.0 };
+    const BTN_DHOV: Color = Color { r: 0.36, g: 0.36, b: 0.40, a: 1.0 };
+
+    let body_text = format!(
+        "This drawing contains {count} AEC/Civil objects that \"{target}\" \
+         cannot store, so they will not be saved.\n\n\
+         To keep them, save in the source version ({src_version})."
+    );
+
+    let btn = |label: &'static str, msg: Message, base: Color, hov: Color| {
+        button(text(label).size(13).color(TEXT_COL))
+            .on_press(msg)
+            .style(move |_: &Theme, status| button::Style {
+                background: Some(Background::Color(match status {
+                    button::Status::Hovered | button::Status::Pressed => hov,
+                    _ => base,
+                })),
+                text_color: TEXT_COL,
+                border: Border {
+                    color: BORDER_COL,
+                    width: 1.0,
+                    radius: 4.0.into(),
+                },
+                shadow: iced::Shadow::default(),
+                snap: false,
+            })
+            .padding([6, 14])
+    };
+
+    container(
+        column![
+            text(body_text).size(13).color(TEXT_COL),
+            iced::widget::Space::new().height(20),
+            row![
+                btn("Save in source version", Message::AecDropSameVersion, BTN_SAVE, BTN_HOVER),
+                iced::widget::Space::new().width(8),
+                btn("Save anyway", Message::AecDropProceed, BTN_DISC, BTN_DHOV),
+                iced::widget::Space::new().width(8),
+                btn("Back", Message::AecDropBack, BTN_DISC, BTN_DHOV),
+            ],
+        ]
+        .spacing(0),
+    )
+    .style(move |_: &Theme| container::Style {
+        background: Some(Background::Color(BG)),
+        ..Default::default()
+    })
+    .center(Fill)
+    .padding([24, 28])
+    .into()
+}
+
+/// Confirmation shown when the chosen Save-As filename already exists in the
+/// target folder. "Replace" overwrites; "Cancel" returns to the Save dialog.
+fn overwrite_dialog_window(filename: &str) -> Element<'static, Message> {
+    const BG: Color = Color { r: 0.18, g: 0.18, b: 0.20, a: 1.0 };
+    const BORDER_COL: Color = Color { r: 0.38, g: 0.38, b: 0.42, a: 1.0 };
+    const TEXT_COL: Color = Color { r: 0.90, g: 0.90, b: 0.90, a: 1.0 };
+    const BTN_SAVE: Color = Color { r: 0.20, g: 0.46, b: 0.80, a: 1.0 };
+    const BTN_HOVER: Color = Color { r: 0.26, g: 0.55, b: 0.92, a: 1.0 };
+    const BTN_DISC: Color = Color { r: 0.28, g: 0.28, b: 0.30, a: 1.0 };
+    const BTN_DHOV: Color = Color { r: 0.36, g: 0.36, b: 0.40, a: 1.0 };
+
+    let body_text =
+        format!("\"{filename}\" already exists in this folder.\n\nDo you want to replace it?");
+
+    let btn = |label: &'static str, msg: Message, base: Color, hov: Color| {
+        button(text(label).size(13).color(TEXT_COL))
+            .on_press(msg)
+            .style(move |_: &Theme, status| button::Style {
+                background: Some(Background::Color(match status {
+                    button::Status::Hovered | button::Status::Pressed => hov,
+                    _ => base,
+                })),
+                text_color: TEXT_COL,
+                border: Border {
+                    color: BORDER_COL,
+                    width: 1.0,
+                    radius: 4.0.into(),
+                },
+                shadow: iced::Shadow::default(),
+                snap: false,
+            })
+            .padding([6, 18])
+    };
+
+    container(
+        column![
+            text(body_text).size(13).color(TEXT_COL),
+            iced::widget::Space::new().height(20),
+            row![
+                btn("Replace", Message::OverwriteConfirm, BTN_SAVE, BTN_HOVER),
+                iced::widget::Space::new().width(8),
+                btn("Cancel", Message::OverwriteCancel, BTN_DISC, BTN_DHOV),
+            ],
+        ]
+        .spacing(0),
+    )
+    .style(move |_: &Theme| container::Style {
+        background: Some(Background::Color(BG)),
+        ..Default::default()
+    })
+    .center(Fill)
+    .padding([24, 28])
+    .into()
+}
+
 /// First-launch prompt offering to register Open CAD Studio as the default
 /// handler for .dwg / .dxf. "Yes" runs the platform association call; "Not now"
 /// just dismisses. Either answer flips the persisted `default_assoc_prompted`

src/io/mod.rs

@@ -442,6 +442,37 @@ pub fn format_for_version(version: acadrust::DxfVersion, is_dxf: bool) -> String
     format!("{} {}", if is_dxf { "DXF" } else { "DWG" }, year)
 }
 
+/// Count of unsupported "raw passthrough" objects/entities — AEC / application
+/// objects with no native representation, kept only as verbatim source-version
+/// bytes — that would be DROPPED when saving `doc` to `target_version` (or to
+/// DXF). Returns 0 for a same-version DWG save, where they round-trip verbatim.
+/// Used to warn the user before a lossy Save-As.
+pub fn dropped_on_save_count(
+    doc: &acadrust::CadDocument,
+    target_version: acadrust::DxfVersion,
+    is_dxf: bool,
+) -> usize {
+    if !is_dxf && target_version == doc.version {
+        return 0;
+    }
+    let mut n = doc
+        .objects
+        .values()
+        .filter(|o| {
+            matches!(
+                o,
+                acadrust::objects::ObjectType::Unknown { raw_dwg_data: Some(_), .. }
+            )
+        })
+        .count();
+    for e in doc.entities() {
+        if matches!(e, acadrust::EntityType::Unknown(_)) {
+            n += 1;
+        }
+    }
+    n
+}
+
 // ── Plot Style Table ──────────────────────────────────────────────────────
 
 /// Show a file-open dialog and load the selected CTB or STB file.