feat: emit layout update events for runtime layout changes

3 files changed, 50 insertions, 4 deletions

diff --git a/src/api/schema/events.rs b/src/api/schema/events.rs
index 2fbce4d0..aff3d2a2 100644
--- a/src/api/schema/events.rs
+++ b/src/api/schema/events.rs
@@ -72,6 +72,8 @@ pub enum Subscription {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         agent_status: Option<AgentStatus>,
     },
+    #[serde(rename = "layout.updated")]
+    LayoutUpdated {},
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, schemars::JsonSchema)]
@@ -204,6 +206,7 @@ pub enum EventKind {
     PaneExited,
     PaneAgentDetected,
     PaneAgentStatusChanged,
+    LayoutUpdated,
 }
 
 impl EventKind {
@@ -231,6 +234,7 @@ impl EventKind {
             EventKind::PaneExited => "pane.exited",
             EventKind::PaneAgentDetected => "pane.agent_detected",
             EventKind::PaneAgentStatusChanged => "pane.agent_status_changed",
+            EventKind::LayoutUpdated => "layout.updated",
         }
     }
 }
@@ -259,6 +263,7 @@ pub const KNOWN_EVENT_KINDS: &[EventKind] = &[
     EventKind::PaneExited,
     EventKind::PaneAgentDetected,
     EventKind::PaneAgentStatusChanged,
+    EventKind::LayoutUpdated,
 ];
 
 pub const PLUGIN_HOOK_EVENT_KINDS: &[EventKind] = &[
@@ -325,14 +330,15 @@ mod known_event_name_tests {
     }
 
     #[test]
-    fn plugin_hook_event_names_exclude_unemitted_output_change() {
+    fn plugin_hook_event_names_exclude_high_volume_events() {
         let names = plugin_hook_event_names();
         assert!(!names.contains(&"pane.output_changed"));
+        assert!(!names.contains(&"layout.updated"));
         assert!(names.contains(&"pane.moved"));
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, schemars::JsonSchema)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, schemars::JsonSchema)]
 pub struct EventEnvelope {
     pub event: EventKind,
     pub data: EventData,
@@ -383,7 +389,7 @@ pub struct PaneAgentStatusChangedEvent {
     pub state_labels: HashMap<String, String>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, schemars::JsonSchema)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, schemars::JsonSchema)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum EventData {
     WorkspaceCreated {
@@ -502,4 +508,7 @@ pub enum EventData {
         #[serde(default, skip_serializing_if = "HashMap::is_empty")]
         state_labels: HashMap<String, String>,
     },
+    LayoutUpdated {
+        layout: super::panes::PaneLayoutSnapshot,
+    },
 }
diff --git a/src/api/schema/tests.rs b/src/api/schema/tests.rs
index 5106fafe..abd96656 100644
--- a/src/api/schema/tests.rs
+++ b/src/api/schema/tests.rs
@@ -374,6 +374,34 @@ fn event_envelope_round_trips() {
                 tabs: vec![],
             },
         },
+        EventEnvelope {
+            event: EventKind::LayoutUpdated,
+            data: EventData::LayoutUpdated {
+                layout: PaneLayoutSnapshot {
+                    workspace_id: "w_1".into(),
+                    tab_id: "w_1:1".into(),
+                    zoomed: false,
+                    area: PaneLayoutRect {
+                        x: 0,
+                        y: 0,
+                        width: 100,
+                        height: 24,
+                    },
+                    focused_pane_id: "w_1-1".into(),
+                    panes: vec![PaneLayoutPane {
+                        pane_id: "w_1-1".into(),
+                        focused: true,
+                        rect: PaneLayoutRect {
+                            x: 0,
+                            y: 0,
+                            width: 100,
+                            height: 24,
+                        },
+                    }],
+                    splits: vec![],
+                },
+            },
+        },
     ];
 
     for event in events {
@@ -934,12 +962,17 @@ fn authority_mutation_requests_round_trip() {
     let subscription = Request {
         id: "sub_moves".into(),
         method: Method::EventsSubscribe(EventsSubscribeParams {
-            subscriptions: vec![Subscription::WorkspaceMoved {}, Subscription::TabMoved {}],
+            subscriptions: vec![
+                Subscription::WorkspaceMoved {},
+                Subscription::TabMoved {},
+                Subscription::LayoutUpdated {},
+            ],
         }),
     };
     let json = serde_json::to_string(&subscription).unwrap();
     assert!(json.contains("\"type\":\"workspace.moved\""));
     assert!(json.contains("\"type\":\"tab.moved\""));
+    assert!(json.contains("\"type\":\"layout.updated\""));
     let restored: Request = serde_json::from_str(&json).unwrap();
     assert_eq!(restored, subscription);
 }
diff --git a/src/api/subscriptions.rs b/src/api/subscriptions.rs
index f3b82090..73586b99 100644
--- a/src/api/subscriptions.rs
+++ b/src/api/subscriptions.rs
@@ -188,6 +188,10 @@ impl ActiveSubscription {
                 event_kind: crate::api::schema::EventKind::PaneAgentDetected,
                 last_sequence: 0,
             })),
+            Subscription::LayoutUpdated {} => Ok(Self::Event(ActiveEventSubscription {
+                event_kind: crate::api::schema::EventKind::LayoutUpdated,
+                last_sequence: 0,
+            })),
             Subscription::PaneOutputMatched {
                 pane_id,
                 source,