Review nested message kind groups with exact timer scope

crates/oa-desktop/src/forms.rs

@@ -46,6 +46,7 @@ pub struct Draft {
     pub inputs: BTreeMap<String, Input>,
     pub exact_strings: bool,
     context: Option<Value>,
+    message_timer_draft: Option<Input>,
     port_contract_drafts: BTreeMap<String, Value>,
     pub value_browsers: BTreeMap<String, ValueBrowser>,
 }
@@ -85,6 +86,7 @@ impl Draft {
             inputs: BTreeMap::new(),
             exact_strings: false,
             context: None,
+            message_timer_draft: None,
             port_contract_drafts: BTreeMap::new(),
             value_browsers: BTreeMap::new(),
         };
@@ -248,6 +250,29 @@ impl Draft {
         self.rebuild_retaining(|old| (!within(old, path)).then(|| old.to_owned()));
         Ok(())
     }
+    /// Message-kind selection preserves the timer's exact input/editor state
+    /// while its payload is temporarily hidden by another kind.
+    pub fn message_kind_variant(&mut self, path: &str, value: Value) -> Result<(), String> {
+        serde_json::from_value::<MessageKind>(value.clone()).map_err(|e| e.to_string())?;
+        let current = self
+            .value
+            .pointer(path)
+            .ok_or("Message kind no longer exists.")?;
+        if same_variant(current, &value) {
+            return Ok(());
+        }
+        let timer_path = format!("{path}/Timer/expression");
+        if let Some(input) = self.inputs.remove(&timer_path) {
+            self.message_timer_draft = Some(input);
+        }
+        self.shape_scoped(path, value)?;
+        if self.inputs.contains_key(&timer_path)
+            && let Some(input) = self.message_timer_draft.take()
+        {
+            self.inputs.insert(timer_path, input);
+        }
+        Ok(())
+    }
     fn rebuild_retaining(&mut self, new_path: impl Fn(&str) -> Option<String>) {
         let previous = std::mem::take(&mut self.inputs);
         self.rebuild();

crates/oa-desktop/src/semantic_review.rs

@@ -8,10 +8,13 @@ use oa_core::{transitions::*, *};
 use serde_json::Value;
 use std::collections::{BTreeMap, BTreeSet};
 
+mod message_kind;
 mod scalar;
 mod view;
 pub(crate) use view::summary;
 #[cfg(test)]
+mod message_kind_tests;
+#[cfg(test)]
 mod tests;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -54,6 +57,9 @@ pub struct State {
     pub decisions: BTreeMap<FacetSelector, SemanticDecision>,
     pub references: BTreeMap<Id, Id>,
     pub draft: Option<Draft>,
+    // Group editing cannot reshape the independently authored TimerExpression
+    // scalar draft. Both drafts survive decision changes until this trace closes.
+    pub message_draft: Option<Draft>,
     pub plan: Option<SemanticTransitionPlan>,
     pub proposed: Option<Project>,
     pub error: Option<String>,
@@ -96,6 +102,7 @@ impl State {
             decisions: BTreeMap::new(),
             references: BTreeMap::new(),
             draft: None,
+            message_draft: None,
             plan: None,
             proposed: None,
             error: None,
@@ -128,6 +135,12 @@ impl State {
         self.draft = self
             .target(project)
             .and_then(|id| Draft::from_project(project, id));
+        self.message_draft = self
+            .trace
+            .and_then(|id| project.traces.get(&id))
+            .filter(|trace| message_kind::available(project, trace))
+            .and_then(|_| self.target(project))
+            .and_then(|id| Draft::from_project(project, id));
         if let Some(trace) = self.trace.and_then(|id| project.traces.get(&id)) {
             self.references.insert(trace.oa, trace.sa);
         }
@@ -188,7 +201,10 @@ impl State {
                 self.edit(project, &path, |d| d.shape_scoped(&path, value))
             }
             Event::Variant(path, value) => self.edit(project, &path, |d| {
-                if d.value
+                if path.ends_with("/message_kind") {
+                    d.message_kind_variant(&path, value)
+                } else if d
+                    .value
                     .pointer(&path)
                     .is_some_and(|v| crate::forms::same_variant(v, &value))
                 {
@@ -286,9 +302,15 @@ impl State {
             .and_then(|id| scalar::binding(project, id, facet))
             .ok_or("Selected scalar property is unavailable.")?;
         if path != root && !path.starts_with(&format!("{root}/")) {
-            return Err("Only the selected scalar property can change in this draft.".into());
+            return Err("Only the selected review property can change in this draft.".into());
         }
-        let draft = self.draft.as_mut().ok_or("Choose an existing target.")?;
+        let draft = if message_kind::handles(facet) {
+            &mut self.message_draft
+        } else {
+            &mut self.draft
+        }
+        .as_mut()
+        .ok_or("Choose an existing target.")?;
         // The scoped view sends only descendants of the selected scalar property.
         // Protected identity and top-level body/perspective controls are never exposed.
         if path == "/id" || path == "/alias" || path == "/body" || path == "/layer" {
@@ -301,7 +323,21 @@ impl State {
         self.target(project)
             .and_then(|id| scalar::binding(project, id, facet))
             .is_some()
-            && !scalar::grouped(facet)
+            && (!scalar::grouped(facet)
+                || (message_kind::handles(facet)
+                    && self.message_draft.is_some()
+                    && self
+                        .trace
+                        .and_then(|id| project.traces.get(&id))
+                        .is_some_and(|trace| message_kind::available(project, trace))))
+    }
+
+    fn candidate_draft(&self, facet: &FacetSelector) -> Option<&Draft> {
+        if message_kind::handles(facet) {
+            self.message_draft.as_ref()
+        } else {
+            self.draft.as_ref()
+        }
     }
 
     pub fn can_acknowledge_constructor(&self, project: &Project, facet: &FacetSelector) -> bool {
@@ -319,13 +355,12 @@ impl State {
         {
             return false;
         }
-        self.facts
-            .iter()
-            .find(|f| f.selector == *facet)
-            .is_some_and(|f| {
-                scalar::value(&f.current, Layer::Oa).is_some()
-                    && scalar::observation(&f.current, Layer::Oa)
-                        == scalar::observation(&f.current, Layer::Sa)
+        capture_facet(project, trace.oa, trace.sa, facet)
+            .ok()
+            .is_some_and(|current| {
+                scalar::value(&current, Layer::Oa).is_some()
+                    && scalar::observation(&current, Layer::Oa)
+                        == scalar::observation(&current, Layer::Sa)
             })
     }
 
@@ -399,7 +434,6 @@ impl State {
         let mut final_value = Draft::from_project(project, target)
             .ok_or("Target has no editable record.")?
             .value;
-        let draft = self.draft.as_ref().ok_or("Target draft is unavailable.")?;
         let mut map = BTreeMap::new();
         for (oa, sa) in &self.references {
             let (from, to) = if self.direction == TransitionDirection::OaToSa {
@@ -412,6 +446,7 @@ impl State {
             }
         }
         map.insert(source, target);
+        let mut message_candidate = None;
         for (facet, decision) in &self.decisions {
             if *decision == SemanticDecision::KeepTarget {
                 continue;
@@ -421,6 +456,9 @@ impl State {
             let value = match decision {
                 SemanticDecision::KeepTarget => continue,
                 SemanticDecision::Candidate => {
+                    let draft = self
+                        .candidate_draft(facet)
+                        .ok_or("Target draft is unavailable.")?;
                     let value = match draft.materialize_scopes(std::slice::from_ref(&path)) {
                         Ok(value) => value,
                         Err(_) if form_context => draft.value.clone(),
@@ -431,15 +469,39 @@ impl State {
                         .cloned()
                         .ok_or("Candidate property is no longer available.")?
                 }
+                SemanticDecision::TakeSource if message_kind::handles(facet) => {
+                    // First equal kinds acknowledge only the discriminator.
+                    // An unselected Timer payload must stay at the destination.
+                    message_kind::source_value(
+                        project,
+                        if self.can_acknowledge_constructor(project, facet) {
+                            target
+                        } else {
+                            source
+                        },
+                    )?
+                }
                 SemanticDecision::TakeSource => {
                     let fact = capture_facet(project, trace.oa, trace.sa, facet)?;
                     scalar::source_value(&fact, self.direction.source_layer(), &map)?
                 }
             };
+            if message_kind::handles(facet) && *decision == SemanticDecision::Candidate {
+                message_candidate = Some((path.clone(), value.clone()));
+            }
             *final_value
                 .pointer_mut(&path)
                 .ok_or("Final target property is unavailable.")? = value;
         }
+        if !form_context
+            && let Some((path, candidate)) = message_candidate
+            && let Ok(current) = message_kind::source_value(project, target)
+            && crate::forms::same_variant(&candidate, &current)
+            && candidate != current
+            && final_value.pointer(&path) != Some(&candidate)
+        {
+            return Err("The message-kind candidate and Timer Expression decision propose different timer values. Keep the kind or make their final values agree; both drafts are retained.".into());
+        }
         Ok(final_value)
     }
 
@@ -449,6 +511,9 @@ impl State {
         self.error = None;
         let context = self.combined_value(project, true).ok();
         if let Some(draft) = &mut self.draft {
+            draft.set_context(context.clone());
+        }
+        if let Some(draft) = &mut self.message_draft {
             draft.set_context(context);
         }
         let Some(trace) = self.trace.and_then(|id| project.traces.get(&id)) else {

crates/oa-desktop/src/semantic_review/message_kind.rs

@@ -0,0 +1,32 @@
+//! The first supported constructor group is the closed nested MessageKind.
+//! The core owns its acknowledgment/retirement and validation policies.
+use super::*;
+
+pub(super) fn selector() -> FacetSelector {
+    FacetSelector::Occurrence(OccurrenceFacet::MessageKind)
+}
+pub(super) fn timer_selector() -> FacetSelector {
+    FacetSelector::Occurrence(OccurrenceFacet::TimerExpression)
+}
+pub(super) fn handles(facet: &FacetSelector) -> bool {
+    *facet == selector()
+}
+pub(super) fn value(project: &Project, id: Id) -> Option<&MessageKind> {
+    match project.elements.get(&id)?.shared()? {
+        SharedBody::Occurrence {
+            body: OccurrenceBody::Exchange { message_kind, .. },
+            ..
+        } => Some(message_kind),
+        _ => None,
+    }
+}
+pub(super) fn available(project: &Project, trace: &Trace) -> bool {
+    value(project, trace.oa).is_some() && value(project, trace.sa).is_some()
+}
+/// MessageConstructor observations contain only the discriminator. Taking a
+/// replacing group needs the complete typed payload, including Timer.expression.
+pub(super) fn source_value(project: &Project, id: Id) -> Result<Value, String> {
+    let value =
+        value(project, id).ok_or("Message kind requires an existing Exchange occurrence.")?;
+    serde_json::to_value(value).map_err(|e| e.to_string())
+}

crates/oa-desktop/src/semantic_review/message_kind_tests.rs

@@ -0,0 +1,691 @@
+use super::{tests::*, *};
+use crate::{app::App, document::Document};
+use serde_json::json;
+
+fn fixture(oa_kind: MessageKind, sa_kind: MessageKind) -> (Project, Id, Id, Id) {
+    let mut p = Project::empty();
+    let mut ids = vec![];
+    for (layer, message_kind) in [(Layer::Oa, oa_kind), (Layer::Sa, sa_kind)] {
+        let scenario = p
+            .add_element(Kind::Scenario, layer, "Scenario", None)
+            .unwrap();
+        let id = p
+            .add_element(Kind::Occurrence, layer, "Message", Some(scenario))
+            .unwrap();
+        *p.elements.get_mut(&id).unwrap().shared_mut().unwrap() = SharedBody::Occurrence {
+            body: OccurrenceBody::Exchange {
+                exchange: None,
+                sender: None,
+                receiver: None,
+                message_kind,
+                reply_to: None,
+                values: vec![],
+            },
+            precondition: "retain precondition".into(),
+            postcondition: "retain postcondition".into(),
+        };
+        p.elements
+            .get_mut(&scenario)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .push(id);
+        ids.push(id);
+    }
+    let trace = add_trace(&mut p, ids[0], ids[1], "Message-kind review");
+    (p, ids[0], ids[1], trace)
+}
+fn timer(value: &str) -> MessageKind {
+    MessageKind::Timer {
+        expression: value.into(),
+    }
+}
+fn path(layer: &str) -> String {
+    format!("/body/{layer}/Shared/Occurrence/body/Exchange/message_kind")
+}
+fn set_kind(p: &mut Project, id: Id, kind: MessageKind) {
+    let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange { message_kind, .. },
+        ..
+    }) = p.elements.get_mut(&id).unwrap().shared_mut()
+    else {
+        panic!()
+    };
+    *message_kind = kind;
+}
+fn seed_history(p: &mut Project, trace: Id) {
+    let t = &p.traces[&trace];
+    let baseline = TraceBaseline {
+        oa: p.properties(t.oa).unwrap(),
+        sa: p.properties(t.sa).unwrap(),
+        semantic: Some(SemanticBaseline {
+            facets: [message_kind::selector(), message_kind::timer_selector()]
+                .iter()
+                .map(|selector| capture_facet(p, t.oa, t.sa, selector).unwrap())
+                .collect(),
+        }),
+    };
+    p.traces.get_mut(&trace).unwrap().baseline = Some(baseline);
+}
+fn acknowledged(app: &App) -> BTreeSet<FacetSelector> {
+    state(app).plan.as_ref().unwrap().reviews[0]
+        .acknowledged
+        .iter()
+        .cloned()
+        .collect()
+}
+fn failures(app: &App) -> String {
+    state(app)
+        .error
+        .iter()
+        .chain(state(app).plan.iter().flat_map(|p| &p.conflicts))
+        .cloned()
+        .collect::<Vec<_>>()
+        .join("; ")
+}
+
+#[test]
+fn message_group_take_full_timer_and_scalar_candidate_are_one_source_history_change_both_directions()
+ {
+    for reverse in [false, true] {
+        let expression = "  after β ≥ 5 s\n\tkeep exact whitespace  ";
+        let (p, oa, sa, trace) = if reverse {
+            fixture(MessageKind::Asynchronous, timer(expression))
+        } else {
+            fixture(timer(expression), MessageKind::Asynchronous)
+        };
+        let (source, target) = if reverse { (sa, oa) } else { (oa, sa) };
+        let mut app = App::with_project(p);
+        let mut bundle = app.document.bundle().clone();
+        bundle
+            .files
+            .get_mut(&bundle.entry)
+            .unwrap()
+            .insert_str(0, "// Keep the engineering review rationale.\r\n");
+        app.document.apply_bundle(bundle).unwrap();
+        let before = app.document.snapshot();
+        let revision = app.document.revision();
+        start(&mut app, source);
+        decide(
+            &mut app,
+            message_kind::selector(),
+            SemanticDecision::TakeSource,
+        );
+        decide(
+            &mut app,
+            FacetSelector::Header(HeaderFacet::Name),
+            SemanticDecision::Candidate,
+        );
+        send(
+            &mut app,
+            Event::Input("/name".into(), "Reviewed message".into()),
+        );
+        assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+        assert_eq!(
+            acknowledged(&app),
+            BTreeSet::from([
+                message_kind::selector(),
+                message_kind::timer_selector(),
+                FacetSelector::Header(HeaderFacet::Name)
+            ])
+        );
+        assert!(
+            state(&app).plan.as_ref().unwrap().reviews[0]
+                .retired
+                .is_empty()
+        );
+        assert!(state(&app).plan.as_ref().unwrap().impacts.is_empty());
+        let expected = state(&app).proposed.clone().unwrap();
+        assert_eq!(
+            message_kind::value(&expected, target),
+            Some(&timer(expression))
+        );
+        assert_eq!(app.document.bundle(), &before.bundle);
+        apply(&mut app);
+        assert_eq!(app.project(), &expected);
+        assert_eq!(app.document.revision(), revision + 1);
+        assert_eq!(
+            app.project().elements[&source],
+            before.decoded.project.elements[&source]
+        );
+        let saved = app.document.bundle().clone();
+        assert!(saved.files[&saved.entry].starts_with("// Keep the engineering review rationale."));
+        assert_eq!(
+            Document::from_bundle(saved.clone(), source_project::ProjectLimits::default())
+                .unwrap()
+                .snapshot()
+                .decoded
+                .project,
+            expected
+        );
+        let facts = &app.project().traces[&trace]
+            .baseline
+            .as_ref()
+            .unwrap()
+            .semantic
+            .as_ref()
+            .unwrap()
+            .facets;
+        assert_eq!(facts.len(), 3);
+        let _ = app.update(Message::Undo);
+        assert_eq!(app.document.bundle(), &before.bundle);
+        let _ = app.update(Message::Redo);
+        assert_eq!(app.document.bundle(), &saved);
+    }
+}
+
+#[test]
+fn message_group_candidate_timer_switches_preserve_both_drafts_and_overlap_is_explicit() {
+    let (p, oa, _, _) = fixture(MessageKind::Asynchronous, timer("original target"));
+    let mut app = App::with_project(p);
+    let before = app.document.snapshot();
+    let kind = path("Sa");
+    let expression = format!("{kind}/Timer/expression");
+    start(&mut app, oa);
+    decide(
+        &mut app,
+        message_kind::timer_selector(),
+        SemanticDecision::Candidate,
+    );
+    send(
+        &mut app,
+        Event::Input(expression.clone(), "independent scalar timer".into()),
+    );
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::Candidate,
+    );
+    assert_eq!(state(&app).decisions.len(), 2);
+    assert!(!state(&app).can_apply());
+    send(
+        &mut app,
+        Event::Input(expression.clone(), "  group β timer\n\t  ".into()),
+    );
+    send(
+        &mut app,
+        Event::Text(expression.clone(), text_editor::Action::SelectAll),
+    );
+    let cursor = state(&app).message_draft.as_ref().unwrap().inputs[&expression]
+        .editor
+        .cursor();
+    let selection = state(&app).message_draft.as_ref().unwrap().inputs[&expression]
+        .editor
+        .selection();
+    send(
+        &mut app,
+        Event::Variant(kind.clone(), json!("Asynchronous")),
+    );
+    send(
+        &mut app,
+        Event::Variant(kind, json!({"Timer":{"expression":""}})),
+    );
+    assert_eq!(
+        state(&app).message_draft.as_ref().unwrap().inputs[&expression].raw,
+        "  group β timer\n\t  "
+    );
+    assert_eq!(
+        state(&app).message_draft.as_ref().unwrap().inputs[&expression]
+            .editor
+            .cursor(),
+        cursor
+    );
+    assert_eq!(
+        state(&app).message_draft.as_ref().unwrap().inputs[&expression]
+            .editor
+            .selection(),
+        selection
+    );
+    assert_eq!(
+        state(&app).draft.as_ref().unwrap().inputs[&expression].raw,
+        "independent scalar timer"
+    );
+    assert!(!state(&app).can_apply());
+    assert_eq!(app.document.bundle(), &before.bundle);
+    // The visible overlap-resolution actions only change the explicitly chosen
+    // decision. Neither independent candidate buffer is discarded.
+    send(&mut app, Event::Decide(message_kind::selector(), None));
+    assert!(state(&app).can_apply());
+    send(
+        &mut app,
+        Event::Decide(message_kind::timer_selector(), None),
+    );
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::Candidate,
+    );
+    assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+    assert_eq!(
+        acknowledged(&app),
+        BTreeSet::from([message_kind::selector(), message_kind::timer_selector()])
+    );
+    let _ = state(&app).view(app.project());
+    let expected = state(&app).proposed.clone().unwrap();
+    apply(&mut app);
+    assert_eq!(app.project(), &expected);
+}
+
+#[test]
+fn message_group_keep_historical_switch_retires_timer_and_completed_no_switch_rejects() {
+    let (mut p, oa, sa, trace) = fixture(timer("old OA"), timer("old SA"));
+    seed_history(&mut p, trace);
+    set_kind(&mut p, oa, MessageKind::Asynchronous);
+    set_kind(&mut p, sa, MessageKind::Asynchronous);
+    let mut app = App::with_project(p);
+    start(&mut app, oa);
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::KeepTarget,
+    );
+    assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+    assert_eq!(
+        acknowledged(&app),
+        BTreeSet::from([message_kind::selector()])
+    );
+    assert_eq!(
+        state(&app).plan.as_ref().unwrap().reviews[0].retired,
+        vec![message_kind::timer_selector()]
+    );
+    apply(&mut app);
+    assert_eq!(
+        app.project().traces[&trace]
+            .baseline
+            .as_ref()
+            .unwrap()
+            .semantic
+            .as_ref()
+            .unwrap()
+            .facets
+            .len(),
+        1
+    );
+    start(&mut app, oa);
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::KeepTarget,
+    );
+    assert!(!state(&app).can_apply());
+    assert!(
+        failures(&app).contains("No constructor switch"),
+        "{}",
+        failures(&app)
+    );
+}
+
+#[test]
+fn message_group_reply_and_reference_take_require_explicit_call_mapping_both_directions() {
+    for reverse in [false, true] {
+        let (mut p, oa, sa, _) = if reverse {
+            fixture(MessageKind::Asynchronous, MessageKind::Reply)
+        } else {
+            fixture(MessageKind::Reply, MessageKind::Asynchronous)
+        };
+        let (source, target, layer) = if reverse {
+            (sa, oa, "Oa")
+        } else {
+            (oa, sa, "Sa")
+        };
+        let mut calls = vec![];
+        for message in [oa, sa] {
+            let scenario = p.elements[&message].parent.unwrap();
+            let layer = p.elements[&message].layer();
+            let call = p
+                .add_element(Kind::Occurrence, layer, "Correlated call", Some(scenario))
+                .unwrap();
+            *p.elements.get_mut(&call).unwrap().shared_mut().unwrap() = SharedBody::Occurrence {
+                body: OccurrenceBody::Exchange {
+                    exchange: None,
+                    sender: None,
+                    receiver: None,
+                    message_kind: MessageKind::Call,
+                    reply_to: None,
+                    values: vec![],
+                },
+                precondition: String::new(),
+                postcondition: String::new(),
+            };
+            p.elements
+                .get_mut(&scenario)
+                .unwrap()
+                .steps_mut()
+                .unwrap()
+                .insert(0, call);
+            if message == source {
+                let Some(SharedBody::Occurrence {
+                    body: OccurrenceBody::Exchange { reply_to, .. },
+                    ..
+                }) = p.elements.get_mut(&message).unwrap().shared_mut()
+                else {
+                    panic!()
+                };
+                *reply_to = Some(call);
+            }
+            calls.push(call);
+        }
+        let target_call = if reverse { calls[0] } else { calls[1] };
+        let mut app = App::with_project(p);
+        let before = app.document.snapshot();
+        start(&mut app, source);
+        decide(
+            &mut app,
+            message_kind::selector(),
+            SemanticDecision::Candidate,
+        );
+        send(&mut app, Event::Variant(path(layer), json!("Reply")));
+        decide(
+            &mut app,
+            FacetSelector::Occurrence(OccurrenceFacet::ReplyTo),
+            SemanticDecision::TakeSource,
+        );
+        assert!(!state(&app).can_apply());
+        assert!(
+            failures(&app).contains("reference counterparts"),
+            "{}",
+            failures(&app)
+        );
+        send(
+            &mut app,
+            Event::ReferenceOa(Choice {
+                id: calls[0],
+                label: "OA call".into(),
+            }),
+        );
+        send(
+            &mut app,
+            Event::ReferenceSa(Choice {
+                id: calls[1],
+                label: "SA call".into(),
+            }),
+        );
+        send(&mut app, Event::AddReference);
+        assert!(state(&app).can_apply(), "{}", failures(&app));
+        assert_eq!(
+            acknowledged(&app),
+            BTreeSet::from([
+                message_kind::selector(),
+                FacetSelector::Occurrence(OccurrenceFacet::ReplyTo)
+            ])
+        );
+        let final_value =
+            serde_json::to_value(&state(&app).proposed.as_ref().unwrap().elements[&target])
+                .unwrap();
+        assert_eq!(
+            final_value.pointer(&format!(
+                "/body/{layer}/Shared/Occurrence/body/Exchange/reply_to"
+            )),
+            Some(&json!(target_call))
+        );
+        assert_eq!(app.document.bundle(), &before.bundle);
+        apply(&mut app);
+        assert_eq!(
+            message_kind::value(app.project(), target),
+            Some(&MessageKind::Reply)
+        );
+        for call in calls {
+            assert_eq!(
+                app.project().elements[&call],
+                before.decoded.project.elements[&call]
+            );
+        }
+    }
+}
+
+#[test]
+fn message_group_candidate_closed_kinds_are_core_validated_in_both_directions() {
+    for reverse in [false, true] {
+        for kind in [
+            MessageKind::Asynchronous,
+            MessageKind::Call,
+            MessageKind::Reply,
+            MessageKind::Create,
+            MessageKind::Delete,
+            timer("after 2 s"),
+        ] {
+            let (p, oa, sa, _) = fixture(MessageKind::Asynchronous, MessageKind::Asynchronous);
+            let (source, target, layer) = if reverse {
+                (sa, oa, "Oa")
+            } else {
+                (oa, sa, "Sa")
+            };
+            let mut app = App::with_project(p);
+            start(&mut app, source);
+            decide(
+                &mut app,
+                message_kind::selector(),
+                SemanticDecision::Candidate,
+            );
+            send(
+                &mut app,
+                Event::Variant(path(layer), serde_json::to_value(&kind).unwrap()),
+            );
+            assert!(state(&app).can_apply(), "{kind:?}: {}", failures(&app));
+            assert_eq!(
+                message_kind::value(state(&app).proposed.as_ref().unwrap(), target),
+                Some(&kind)
+            );
+            assert_eq!(
+                acknowledged(&app).contains(&message_kind::timer_selector()),
+                matches!(kind, MessageKind::Timer { .. })
+            );
+            assert!(state(&app).plan.as_ref().unwrap().impacts.is_empty());
+        }
+    }
+    let (mut p, oa, _, _) = fixture(MessageKind::Asynchronous, MessageKind::Asynchronous);
+    let mut review = State::new(&p, oa).unwrap();
+    let Some(SharedBody::Occurrence { body, .. }) = p.elements.get_mut(&oa).unwrap().shared_mut()
+    else {
+        panic!()
+    };
+    *body = OccurrenceBody::Action {
+        action: None,
+        lifeline: None,
+    };
+    review.refresh(&p);
+    assert!(
+        !review.editable(&p, &message_kind::selector()),
+        "An externally changed outer occurrence requires its own constructor review"
+    );
+    review.update(
+        &p,
+        Event::Decide(message_kind::selector(), Some(SemanticDecision::Candidate)),
+    );
+    assert!(review.decisions.is_empty());
+    assert!(!review.can_apply());
+}
+
+#[test]
+fn message_group_timer_does_not_erase_exchange_without_its_own_selected_decision() {
+    let (mut p, oa, sa, _) = fixture(MessageKind::Asynchronous, MessageKind::Asynchronous);
+    let sender = p
+        .add_element(Kind::Function, Layer::Sa, "Sender", None)
+        .unwrap();
+    let receiver = p
+        .add_element(Kind::Function, Layer::Sa, "Receiver", None)
+        .unwrap();
+    let exchange = p.relate(
+        RelationKind::FunctionalExchange,
+        "Message exchange",
+        sender,
+        receiver,
+    );
+    let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange {
+            exchange: selected, ..
+        },
+        ..
+    }) = p.elements.get_mut(&sa).unwrap().shared_mut()
+    else {
+        panic!()
+    };
+    *selected = Some(exchange);
+    let mut app = App::with_project(p);
+    let before = app.document.snapshot();
+    start(&mut app, oa);
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::Candidate,
+    );
+    send(
+        &mut app,
+        Event::Variant(path("Sa"), json!({"Timer":{"expression":"after 2 s"}})),
+    );
+    assert!(!state(&app).can_apply());
+    assert!(
+        failures(&app).contains("timer_contract"),
+        "{}",
+        failures(&app)
+    );
+    assert_eq!(state(&app).decisions.len(), 1);
+    assert_eq!(app.document.bundle(), &before.bundle);
+    decide(
+        &mut app,
+        FacetSelector::Occurrence(OccurrenceFacet::Exchange),
+        SemanticDecision::Candidate,
+    );
+    send(
+        &mut app,
+        Event::Shape(
+            "/body/Sa/Shared/Occurrence/body/Exchange/exchange".into(),
+            Value::Null,
+        ),
+    );
+    assert!(state(&app).can_apply(), "{}", failures(&app));
+    assert_eq!(
+        acknowledged(&app),
+        BTreeSet::from([
+            message_kind::selector(),
+            message_kind::timer_selector(),
+            FacetSelector::Occurrence(OccurrenceFacet::Exchange)
+        ])
+    );
+    assert!(state(&app).plan.as_ref().unwrap().impacts.is_empty());
+    apply(&mut app);
+    assert_eq!(
+        app.project().relations[&exchange],
+        before.decoded.project.relations[&exchange]
+    );
+}
+
+#[test]
+fn message_group_initial_equal_take_acknowledges_only_kind_and_checks_authored_timer_agreement() {
+    let (p, oa, sa, _) = fixture(timer("source timer"), timer("target timer"));
+    let mut app = App::with_project(p);
+    start(&mut app, oa);
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::TakeSource,
+    );
+    decide(
+        &mut app,
+        FacetSelector::Header(HeaderFacet::Name),
+        SemanticDecision::Candidate,
+    );
+    send(&mut app, Event::Input("/name".into(), "Final name".into()));
+    assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+    assert_eq!(
+        message_kind::value(state(&app).proposed.as_ref().unwrap(), sa),
+        Some(&timer("target timer"))
+    );
+    assert!(!acknowledged(&app).contains(&message_kind::timer_selector()));
+    let expression = format!("{}/Timer/expression", path("Sa"));
+    decide(
+        &mut app,
+        message_kind::selector(),
+        SemanticDecision::Candidate,
+    );
+    send(
+        &mut app,
+        Event::Input(expression.clone(), "authored group timer".into()),
+    );
+    assert!(
+        !state(&app).can_apply(),
+        "An unchanged initial kind cannot silently authorize a timer edit"
+    );
+    decide(
+        &mut app,
+        message_kind::timer_selector(),
+        SemanticDecision::Candidate,
+    );
+    send(
+        &mut app,
+        Event::Input(expression.clone(), "different scalar timer".into()),
+    );
+    assert!(!state(&app).can_apply());
+    assert!(
+        state(&app)
+            .error
+            .as_ref()
+            .unwrap()
+            .contains("different timer values")
+    );
+    send(
+        &mut app,
+        Event::Input(expression, "authored group timer".into()),
+    );
+    assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+    assert!(acknowledged(&app).contains(&message_kind::timer_selector()));
+    assert_eq!(
+        message_kind::value(state(&app).proposed.as_ref().unwrap(), sa),
+        Some(&timer("authored group timer"))
+    );
+}
+
+#[test]
+fn message_group_rejects_protected_edits_stale_plan_and_source_failure_without_losing_timer() {
+    for source_failure in [false, true] {
+        let (p, oa, _, _) = fixture(MessageKind::Asynchronous, timer("target"));
+        let mut app = App::with_project(p);
+        if source_failure {
+            let bundle = app.document.bundle().clone();
+            let mut limits = source_project::ProjectLimits::default();
+            limits.model.max_source_bytes =
+                bundle.files.values().map(String::len).sum::<usize>() + 10;
+            app.document = Document::from_bundle(bundle, limits).unwrap();
+        }
+        start(&mut app, oa);
+        decide(
+            &mut app,
+            message_kind::selector(),
+            SemanticDecision::Candidate,
+        );
+        let expression = format!("{}/Timer/expression", path("Sa"));
+        let raw = "retain exact timer β\n".repeat(40);
+        send(&mut app, Event::Input(expression.clone(), raw.clone()));
+        assert!(state(&app).can_apply(), "{:?}", state(&app).error);
+        send(
+            &mut app,
+            Event::Input("/name".into(), "Unselected protected scope".into()),
+        );
+        assert!(!state(&app).can_apply());
+        assert!(
+            state(&app)
+                .error
+                .as_ref()
+                .unwrap()
+                .contains("selected review")
+        );
+        send(&mut app, Event::Preview);
+        assert!(state(&app).can_apply());
+        if !source_failure {
+            app.document
+                .execute(Command::Rename(oa, "External source edit".into()))
+                .unwrap();
+        }
+        let before = app.document.snapshot();
+        let revision = app.document.revision();
+        apply(&mut app);
+        assert!(state(&app).error.is_some());
+        assert_eq!(state(&app).decisions.len(), 1);
+        assert_eq!(
+            state(&app).message_draft.as_ref().unwrap().inputs[&expression].raw,
+            raw
+        );
+        assert_eq!(app.document.bundle(), &before.bundle);
+        assert_eq!(app.document.revision(), revision);
+    }
+}

crates/oa-desktop/src/semantic_review/tests.rs

@@ -2,13 +2,13 @@ use super::*;
 use crate::{app::App, document::Document, workflow::Workflow};
 use serde_json::json;
 
-fn send(app: &mut App, event: Event) {
+pub(super) fn send(app: &mut App, event: Event) {
     let _ = app.update(Message::Workflow(crate::workflow::Event::Semantic(event)));
 }
-fn apply(app: &mut App) {
+pub(super) fn apply(app: &mut App) {
     let _ = app.update(Message::Workflow(crate::workflow::Event::Apply));
 }
-fn state(app: &App) -> &State {
+pub(super) fn state(app: &App) -> &State {
     let Some(Workflow::Semantic(state)) = &app.workflow else {
         panic!("Semantic workflow missing: {}", app.status)
     };
@@ -35,7 +35,7 @@ fn fixture() -> (Project, Id, Id, Id) {
     let trace = add_trace(&mut p, oa, sa, "Range rationale");
     (p, oa, sa, trace)
 }
-fn add_trace(p: &mut Project, oa: Id, sa: Id, name: &str) -> Id {
+pub(super) fn add_trace(p: &mut Project, oa: Id, sa: Id, name: &str) -> Id {
     let id = Id::new_v4();
     p.traces.insert(
         id,
@@ -52,7 +52,7 @@ fn add_trace(p: &mut Project, oa: Id, sa: Id, name: &str) -> Id {
     );
     id
 }
-fn start(app: &mut App, source: Id) {
+pub(super) fn start(app: &mut App, source: Id) {
     let _ = app.update(Message::StartSemanticReview(source));
 }
 fn facet(value: DataFacet) -> FacetSelector {
@@ -262,7 +262,7 @@ fn independent_review_keyed_fact_titles_keep_live_deleted_and_qualified_identity
     assert!(second_title.contains(&b.to_string()));
     assert_ne!(super::view::title(&p, &annotation(vec![])), first_title);
 }
-fn decide(app: &mut App, selected: FacetSelector, decision: SemanticDecision) {
+pub(super) fn decide(app: &mut App, selected: FacetSelector, decision: SemanticDecision) {
     send(app, Event::Select(selected.clone()));
     send(app, Event::Decide(selected, Some(decision)));
 }
@@ -386,7 +386,7 @@ fn invalid_numeric_draft_and_protected_edits_retain_workflow_and_source() {
             .error
             .as_ref()
             .unwrap()
-            .contains("selected scalar")
+            .contains("selected review")
     );
     assert_eq!(app.project(), &before.decoded.project);
     send(&mut app, Event::Preview);

crates/oa-desktop/src/semantic_review/view.rs

@@ -266,7 +266,7 @@ impl State {
             .iter()
             .filter(|f| f.drift == Drift::Unreviewed)
             .count();
-        content = content.push(text(format!("{} selected decisions · {unreviewed} currently unreviewed facts · Constructors and structured collections require further review.", self.decisions.len())).size(10).color(style::MUTED));
+        content = content.push(text(format!("{} selected decisions · {unreviewed} currently unreviewed facts · Other constructor groups and structured collections require further review.", self.decisions.len())).size(10).color(style::MUTED));
         if let Some(trace) = trace {
             content = content.push(text(summary(project, trace)).size(10).color(style::MUTED));
         }
@@ -364,7 +364,32 @@ impl State {
             .and_then(|t| t.baseline.as_ref())
             .and_then(|b| b.semantic.as_ref())
             .and_then(|b| b.facets.iter().find(|f| f.selector() == fact.selector));
+        let is_message_kind = message_kind::handles(&fact.selector);
+        let timer_previous = trace
+            .and_then(|t| t.baseline.as_ref())
+            .and_then(|b| b.semantic.as_ref())
+            .and_then(|b| {
+                b.facets
+                    .iter()
+                    .find(|f| f.selector() == message_kind::timer_selector())
+            });
+        let timer_current = self
+            .facts
+            .iter()
+            .find(|f| f.selector == message_kind::timer_selector());
         let side = |layer, label: &str| {
+            let mut before = observed(project, previous, layer);
+            let mut current = observed(project, Some(&fact.current), layer);
+            if is_message_kind {
+                before.push_str(&format!(
+                    "\nTimer expression: {}",
+                    observed(project, timer_previous, layer)
+                ));
+                current.push_str(&format!(
+                    "\nTimer expression: {}",
+                    observed(project, timer_current.map(|f| &f.current), layer)
+                ));
+            }
             column![
                 text(format!(
                     "{label}{}",
@@ -377,9 +402,9 @@ impl State {
                 .size(12)
                 .color(style::TEAL),
                 text("Previously reviewed").size(10).color(style::MUTED),
-                text(observed(project, previous, layer)).size(12),
+                text(before).size(12),
                 text("Current").size(10).color(style::MUTED),
-                text(observed(project, Some(&fact.current), layer)).size(12),
+                text(current).size(12),
             ]
             .spacing(5)
             .width(Fill)
@@ -401,11 +426,14 @@ impl State {
                         .color(style::TEAL),
                 )
                 .push(
-                    text(observed(
-                        proposed,
-                        Some(&after),
-                        self.direction.target_layer(),
-                    ))
+                    text(if is_message_kind {
+                        self.target(project)
+                            .and_then(|id| message_kind::source_value(proposed, id).ok())
+                            .map(|value| formatted(proposed, &value, &BTreeSet::new()))
+                            .unwrap_or_else(|| "Message kind is not applicable.".into())
+                    } else {
+                        observed(proposed, Some(&after), self.direction.target_layer())
+                    })
                     .size(12),
                 );
         } else {
@@ -416,6 +444,12 @@ impl State {
             );
         }
         if self.editable(project, &fact.selector) {
+            if is_message_kind {
+                detail = detail.push(text("A replacing message-kind decision reviews its Timer Expression as a group. The exact acknowledgment and retirement appear below.").size(12));
+                if self.can_acknowledge_constructor(project, &fact.selector) {
+                    detail = detail.push(text("These initial kinds are equal. Keep or Take acknowledges only the kind; an unchanged final kind also needs a separate Timer Expression decision for expression edits.").size(11).color(style::MUTED));
+                }
+            }
             let destination = if self.direction.target_layer() == Layer::Sa {
                 "System"
             } else {
@@ -438,15 +472,19 @@ impl State {
             ]
             .spacing(5);
             buttons = buttons.push(action(
-                "Set final value…",
+                if is_message_kind {
+                    "Set final message kind…"
+                } else {
+                    "Set final value…"
+                },
                 Event::Decide(fact.selector.clone(), Some(SemanticDecision::Candidate)),
             ));
-            detail = detail.push(buttons).push(action(
+            detail = detail.push(buttons.wrap()).push(action(
                 "Leave unselected",
                 Event::Decide(fact.selector.clone(), None),
             ));
             if self.decisions.get(&fact.selector) == Some(&SemanticDecision::Candidate)
-                && let Some(draft) = &self.draft
+                && let Some(draft) = self.candidate_draft(&fact.selector)
                 && let Some(path) = self
                     .target(project)
                     .and_then(|id| scalar::binding(project, id, &fact.selector))
@@ -463,6 +501,38 @@ impl State {
         } else {
             detail = detail.push(text(if scalar::grouped(&fact.selector) { "Constructor groups are shown for comparison. Group replacement and its complete descendant review are a later milestone." } else { "This structured or inapplicable fact is read-only here. Its review history is retained." }).size(12).color(style::MUTED));
         }
+        if is_message_kind || fact.selector == message_kind::timer_selector() {
+            if self.decisions.contains_key(&message_kind::selector())
+                && self.decisions.contains_key(&message_kind::timer_selector())
+            {
+                detail = detail.push(text("Both kind and timer decisions are selected. An initial equal-kind acknowledgment can coexist with a timer decision; a replacing group requires one combined decision. Resolve any overlap explicitly; both drafts are retained.").size(11))
+                    .push(action("Replace timer decision with message-kind group", Event::Decide(message_kind::timer_selector(), None)))
+                    .push(action("Leave message kind unselected; use timer decision", Event::Decide(message_kind::selector(), None)));
+            }
+            if let Some(review) = self.plan.as_ref().and_then(|p| p.reviews.first()) {
+                detail = detail.push(text("Exact review scope from preview").size(13));
+                for (label, selectors) in [
+                    ("Acknowledge", &review.acknowledged),
+                    ("Retire previous observation", &review.retired),
+                ] {
+                    detail = detail.push(
+                        text(format!(
+                            "{label}: {}",
+                            if selectors.is_empty() {
+                                "None".into()
+                            } else {
+                                selectors
+                                    .iter()
+                                    .map(|s| title(project, s))
+                                    .collect::<Vec<_>>()
+                                    .join(", ")
+                            }
+                        ))
+                        .size(11),
+                    );
+                }
+            }
+        }
         if matches!(
             fact.selector,
             FacetSelector::Child(_)

crates/oa-desktop/src/views.rs

@@ -744,6 +744,7 @@ fn traces(app: &App) -> View<'_, Message> {
             action("+ Artifact", Message::AddArtifact)
         ]
         .spacing(8)
+        .wrap()
     ]
     .spacing(16);
     for t in p.traces.values() {

harness/release-semantic-gui.md

@@ -1,7 +1,8 @@
-# Semantic desktop review — milestones 1 and 2
+# Semantic desktop review — scalars and nested message kind
 
-Status: milestones 1–2 implemented and desktop tests/build verified; not full GUI
-parity, native acceptance or release acceptance.
+Status: milestones 1–2 implemented; the bounded MessageKind/TimerExpression
+constructor slice is implemented. Full milestone 3, GUI parity, native acceptance
+and release acceptance remain outstanding.
 Base: `d130013`. Dedicated build target:
 `D:/CodexBuilds/Capella2-semantic-desktop-target`. Native verification is root-owned.
 
@@ -16,7 +17,8 @@ Base: `d130013`. Dedicated build target:
 - Support every applicable scalar leaf through Keep, Take and typed final-value
   forms. Candidate records contain the complete combined selected result. Identity,
   alias and layer are protected. The closed core remains the validation boundary.
-- State.Kind is a single structural scalar. Other constructor switches, keyed
+- State.Kind is a single structural scalar. Occurrence.MessageKind now supports
+  its complete nested group, including TimerExpression. Other constructor switches, keyed
   membership/order/annotation/binding/attachment decisions and pairing resets belong
   to milestone 3; show them read-only with an honest explanation.
 - Core `6bb2583` permits first equal constructor acknowledgment without descendant
@@ -36,14 +38,16 @@ Base: `d130013`. Dedicated build target:
 2. Scalar decisions and typed candidates; immutable initial observations; combined
    final records; exact impact acceptance; atomic document/source commit. Focused
    App event/source/history tests, strict Clippy and a dedicated desktop build.
-3. Constructor closure, keyed and ordered facts, reset, complete artifact lifecycle,
-   multi-source review and remaining source/REST parity cases. Still outstanding.
+3. Nested MessageKind/TimerExpression closure is implemented. Other constructor
+   groups, keyed and ordered facts, reset, complete artifact lifecycle, multi-source
+   review and remaining source/REST parity cases are outstanding.
 4. Root-owned native review, cross-surface fixtures, package/release acceptance.
 
 ## Verification
 
-Verified after the independent scalar review fixes on SEM `6ad3cb`, using only the
-dedicated desktop target (core behavior remains based on `6bb2583`):
+Scalar fixes were verified on SEM `6ad3cb`; the nested message-kind slice builds
+on scalar commit `5a51a75`. Verification uses only the dedicated desktop target
+(core behavior remains based on `6bb2583`):
 
 ```powershell
 $env:CARGO_TARGET_DIR='D:/CodexBuilds/Capella2-semantic-desktop-target'
@@ -52,8 +56,8 @@ cargo clippy --locked -p oa-desktop --all-targets -- -D warnings
 cargo build --locked -p oa-desktop
 ```
 
-All **277 desktop tests passed**, including **11 original semantic review tests**
-and **5 scalar review regression tests**.
+All **285 desktop tests passed**, including **11 original semantic review tests**,
+**5 scalar review regression tests**, and **8 nested message-kind tests**.
 Strict Clippy and the desktop build passed. The existing migration test's header
 assertion now follows `SCHEMA_VERSION` instead of expecting schema 4.
 
@@ -85,19 +89,56 @@ The independent scalar review found three gaps, now corrected:
 The regression tests exercise App events, the actual default-form helpers and
 button availability, exact source retention before Apply, and one-step undo.
 
+## Bounded constructor slice
+
+Occurrence.MessageKind is a complete closed nested family: Asynchronous, Call,
+Reply, Create, Delete and Timer. It is available only when both traced counterparts
+are Exchange occurrences. The only constructor-specific payload is the timer
+expression. Outer occurrence replacement remains read-only.
+
+- Keep/Take/Candidate use the core's switch and first-equal acknowledgment policy.
+  Taking a replacing group copies the typed MessageKind, including its expression.
+  Taking an initial equal discriminator does not copy an unselected timer value.
+- Candidate MessageKind has its own scoped draft. The independent TimerExpression
+  scalar draft survives group decisions; the group timer's exact raw text, editor
+  cursor and selection survive switching away from Timer and back.
+- An overlapping kind/timer draft retains both decisions and blocks Apply until
+  explicitly resolved. The dialog offers **Replace timer decision with message-kind
+  group** and **Leave message kind unselected; use timer decision**. First equal-kind
+  acknowledgment can coexist with an independent timer decision. Divergent authored
+  candidate values reject; neither candidate silently overwrites the other.
+- The kind detail includes baseline/current timer observations and the complete
+  proposed kind. It displays the exact plan-provided acknowledged/retired lists.
+  Exchange, reply-to, lifelines, annotations and pre/postconditions stay separately
+  scoped. Incompatible Timer contracts remain core errors; no dependency or payload
+  is silently removed. Existing additional-impact approval remains in force.
+- Group changes compose with scalar choices and execute the exact prepared Document
+  batch. Tests cover both directions, all six kinds, mapped reply correlation,
+  historical retirement, repeated no-switch rejection, invalid combinations,
+  protected scopes, stale preview, source failure, comments and one-step undo/redo.
+- The Traceability contextual toolbar now wraps at the available width so +Artifact
+  remains reachable in the compact layout. This is a single `row.wrap()` change in
+  `views.rs`; other toolbars are outside this slice.
+
+Root reported native scalar coverage on frozen integrated `e7fa061`: mixed numeric
+Keep/Take/Candidate, invalid default retention/repair, zero additional changes,
+atomic Apply, comment/value inspection, Undo/Redo and Save All at 1440×900 and
+1100×700. Reverse/type/reference/history/reopen native checks were still continuing
+when this slice was implemented. This task launched no native application.
+
 Built executable:
 `D:/CodexBuilds/Capella2-semantic-desktop-target/debug/arcadia-studio.exe`.
 The build target is idle. No native application was launched by this task.
 
 ## Remaining work
 
-Milestone 3 must add explicit constructor closure/replacement, keyed and ordered
+Milestone 3 must add the remaining constructor closure/replacement, keyed and ordered
 decisions, historical pairing reset, complete artifact lifecycle and multi-source
 review. These facts are currently inspectable, with unsupported writes visibly
 identified. The reference table supplies explicit mappings for scalar reference
 Take; it does not claim to complete a reset or establish keyed acknowledgments.
 
-Fresh independent scalar GUI review and root-owned native verification are still
-required before merging this milestone into release acceptance. In particular,
-validate the 1100×700 layout, keyboard/focus continuity, long historical values,
-reference selection, source reopening and prepared-impact inspection in the app.
+Fresh independent requirements/correctness review and root-owned native checks of
+the message-kind slice are required before release acceptance. Verify the compact
+kind picker, timer text/focus retention, overlap choices, exact closure/retirement,
+mapped Reply, blocked Timer contract, source reopening and toolbar wrapping.