fix: preserve tab identity across restored sessions

1 files changed, 33 insertions, 2 deletions

diff --git a/src/workspace/aggregate.rs b/src/workspace/aggregate.rs
index c9c1266d..bf4c9408 100644
--- a/src/workspace/aggregate.rs
+++ b/src/workspace/aggregate.rs
@@ -48,7 +48,7 @@ impl Tab {
                 let presentation = terminal.effective_presentation();
                 Some(PaneDetail {
                     pane_id: *id,
-                    tab_idx: self.number.saturating_sub(1),
+                    tab_idx: 0,
                     tab_label: self.display_name(),
                     label: agent_label.clone(),
                     agent_label,
@@ -98,7 +98,15 @@ impl Workspace {
         let multi_tab = self.tabs.len() > 1;
         self.tabs
             .iter()
-            .flat_map(|tab| tab.pane_details(terminals))
+            .enumerate()
+            .flat_map(|(tab_idx, tab)| {
+                tab.pane_details(terminals)
+                    .into_iter()
+                    .map(move |mut detail| {
+                        detail.tab_idx = tab_idx;
+                        detail
+                    })
+            })
             .map(|mut detail| {
                 if multi_tab {
                     detail.label = format!("{}·{}", detail.tab_label, detail.agent_label);
@@ -245,4 +253,27 @@ mod tests {
             ]
         );
     }
+
+    #[test]
+    fn pane_details_use_tab_vector_index_not_stable_public_tab_number() {
+        let mut ws = Workspace::test_new("test");
+        let removed_tab = ws.test_add_tab(Some("removed"));
+        let survivor_tab = ws.test_add_tab(Some("survivor"));
+        let survivor_pane = ws.tabs[survivor_tab].root_pane;
+        assert!(ws.close_tab(removed_tab));
+
+        let mut terminals = HashMap::new();
+        let mut terminal = terminal_for_pane(&ws, survivor_pane);
+        terminal.detected_agent = Some(Agent::Codex);
+        terminals.insert(terminal.id.clone(), terminal);
+
+        let details = ws.pane_details(&terminals);
+        let survivor = details
+            .iter()
+            .find(|detail| detail.pane_id == survivor_pane)
+            .expect("surviving tab agent should be listed");
+
+        assert_eq!(ws.tabs[1].number, 3);
+        assert_eq!(survivor.tab_idx, 1);
+    }
 }