Checkpoint source 7 workflows and in-progress diagram authoring redesign

Preserve current core, source, REST, desktop, recovery, documentation and validation work, including AGENTS.md and the development summary. This is a work-in-progress checkpoint: the new compact palette has outstanding compilation errors and native acceptance; earlier passing gates retain their documented scope.

crates/oa-desktop/src/app.rs

@@ -1,3 +1,6 @@
+pub(crate) mod architecture_authoring;
+#[cfg(test)]
+mod architecture_authoring_tests;
 mod checkpoints;
 #[cfg(test)]
 mod diagram_selection_tests;
@@ -314,6 +317,7 @@ pub struct FilePrompt {
 
 #[derive(Debug, Clone)]
 pub enum Message {
+    Architecture(architecture_authoring::Event),
     Home(crate::home::Event),
     CheckpointTick,
     CheckpointWritten(Id, Result<(), String>),
@@ -329,6 +333,7 @@ pub enum Message {
     ExactStrings(bool),
     Page(Page),
     Guide(crate::guide::Event),
+    Traceability(crate::views::traceability::Event),
     Behavior(crate::behavior::Event),
     Layer(Layer),
     Select(Id),
@@ -450,6 +455,7 @@ pub struct App {
     /// Home resumes this page; explicit Architecture navigation remains separate.
     last_workspace_page: Page,
     pub guide: crate::guide::State,
+    pub traceability: crate::views::traceability::State,
     pub behavior: crate::behavior::State,
     pub data_state: crate::data_view::State,
     pub inspector_tab: crate::navigation::InspectorTab,
@@ -460,6 +466,8 @@ pub struct App {
     pub active_diagram: Option<Id>,
     pub search: String,
     pub create_kind: Kind,
+    pub architecture: Option<architecture_authoring::State>,
+    pub architecture_palette_expanded: bool,
     pub status: String,
     pub busy: bool,
     pub pending: Option<Pending>,
@@ -548,6 +556,7 @@ impl App {
             page: Page::Diagram,
             last_workspace_page: Page::Diagram,
             guide: crate::guide::State::default(),
+            traceability: Default::default(),
             behavior: Default::default(),
             data_state: Default::default(),
             inspector_tab: Default::default(),
@@ -557,6 +566,8 @@ impl App {
             draft,
             active_diagram,
             search: String::new(),
+            architecture: None,
+            architecture_palette_expanded: false,
             create_kind: if layer == Layer::Sa {
                 Kind::Function
             } else {
@@ -623,6 +634,7 @@ impl App {
     }
     pub fn dirty(&self) -> bool {
         self.document.dirty()
+            || self.architecture.is_some()
             || self.workflow.is_some()
             || self.draft_dirty()
             || self.source_dirty()
@@ -1051,6 +1063,39 @@ impl App {
         ])
     }
     pub fn update(&mut self, message: Message) -> Task<Message> {
+        if matches!(&message, Message::Connection(_))
+            && self
+                .architecture
+                .as_ref()
+                .is_some_and(architecture_authoring::State::unnamed_tool)
+        {
+            self.architecture = None;
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        }
+        // Named placement owns input. Passive geometry/checkpoints continue;
+        // navigation and close retain raw input until explicit completion/cancel.
+        if self.architecture.is_some() {
+            if matches!(message, Message::Escape) {
+                self.architecture = None;
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                return Task::none();
+            }
+            let placing = self.architecture.as_ref().is_some_and(|s| s.saved.placing);
+            if !matches!(
+                &message,
+                Message::Architecture(_)
+                    | Message::CheckpointTick
+                    | Message::CheckpointWritten(..)
+                    | Message::Lint(_)
+                    | Message::Linted(..)
+                    | Message::WindowResized(_)
+                    | Message::CanvasResized(_)
+            ) && !(placing && matches!(&message, Message::Pan(_) | Message::Zoom(_)))
+            {
+                self.status = "Finish placing this element or Cancel (Esc) before leaving. Your name is retained.".into();
+                return Task::none();
+            }
+        }
         // Scrollable geometry can change while async work or an overlay blocks
         // commands. Keep the observed translation current; its passive handler
         // still validates document, scenario and revision before accepting it.
@@ -1303,6 +1348,7 @@ impl App {
     }
     fn handle(&mut self, message: Message) -> Task<Message> {
         match message {
+            Message::Architecture(event) => return self.architecture_event(event),
             Message::Home(event) => return self.home_event(event),
             Message::CheckpointTick => return self.checkpoint_tick(),
             Message::CheckpointWritten(id, result) => {
@@ -1718,6 +1764,13 @@ impl App {
                     self.refresh_draft();
                 }
             }
+            Message::Traceability(event) => {
+                self.traceability.update(event);
+                return iced::widget::operation::snap_to(
+                    "traceability-list",
+                    iced::widget::scrollable::RelativeOffset::START,
+                );
+            }
             Message::Search(value) => {
                 self.search = value;
                 self.explorer_page = 0;
@@ -1910,6 +1963,10 @@ impl App {
                             if t.request.sources.first().is_some_and(|source|
                                 crate::behavior::selected_behavior(self.project(), *source).is_some()));
                     let previous_behavior_context = self.state_view_identity();
+                    let requested_destination = match &workflow {
+                        crate::workflow::Workflow::Transition(t) => t.request.destination_diagram,
+                        _ => None,
+                    };
                     match workflow.update(self.project(), event) {
                         Ok(Some(mut candidate)) => {
                             let focus = transition_focus
@@ -1932,7 +1989,24 @@ impl App {
                                 .and_then(|id| crate::behavior::selected_behavior(&candidate, id));
                             let destination = focus.and_then(|id| {
                                 candidate.layer_of(id).and_then(|layer| {
-                                    preferred_diagram(&candidate, self.active_diagram, layer, id)
+                                    requested_destination
+                                        .filter(|view| {
+                                            candidate.diagrams.get(view).is_some_and(|d| {
+                                                (d.layer == layer
+                                                    || d.projection == ProjectionKind::Traceability)
+                                                    && d.nodes
+                                                        .values()
+                                                        .any(|node| node.element == id)
+                                            })
+                                        })
+                                        .or_else(|| {
+                                            preferred_diagram(
+                                                &candidate,
+                                                self.active_diagram,
+                                                layer,
+                                                id,
+                                            )
+                                        })
                                 })
                             });
                             if let (None, Some(id), Some(diagram)) =