fix: reconcile client locations after no-focus pane moves (#4171)

refs #4153

Root cause:
A no-focus pane move can remove the source tab without changing the
server's numeric workspace and tab coordinates. PaneMove is not classified
as a topology change, so a client viewing that tab retains its deleted ID.
Its target lookup falls back to the server default and can follow a later,
unrelated focus change instead of staying in the source workspace.

Fix:
Include PaneMove in the existing client-location reconciliation path.
Extend the existing focus-guard test with a client on the removed tab and
verify that a later server-default change cannot move its view. Preserve
the other client's view and existing error, no-op and zoom assertions.

Validation:
The minimized regression fails five times on PR #4159's unchanged head and
passes five times with the one-line fix. All 19 pane-move tests, native
lint, maintenance, architecture and integration-asset checks pass.
Full native just ci on the publication branch, including the unchanged
prerequisites from #4159 and #4168, passes 3585 Rust tests with six default
skips plus lint, 106 maintenance, six architecture and 39 integration-asset
tests. All seven docs contract tests pass. Local Windows cross-lint was
not run because its SDK is unavailable.

No geometry policy, protocol or periodic rendering behavior is changed.

2 files changed, 11 insertions, 0 deletions

diff --git a/src/server/headless/client_views.rs b/src/server/headless/client_views.rs
index bb697b9a..d6030f74 100644
--- a/src/server/headless/client_views.rs
+++ b/src/server/headless/client_views.rs
@@ -230,6 +230,7 @@ impl HeadlessServer {
             Method::CommandInvoke(_)
                 | Method::PaneClose(_)
                 | Method::PaneEditScrollback(_)
+                | Method::PaneMove(_)
                 | Method::PaneSplit(_)
                 | Method::TabClose(_)
                 | Method::TabCreate(_)
diff --git a/src/server/headless/tests/pane_move.rs b/src/server/headless/tests/pane_move.rs
index 93bff0c9..c18d0f1f 100644
--- a/src/server/headless/tests/pane_move.rs
+++ b/src/server/headless/tests/pane_move.rs
@@ -185,6 +185,7 @@ async fn public_pane_move_without_effective_focus_preserves_client_views() {
         let remaining_tab = server.app.public_tab_id(0, 1).unwrap();
         let destination_tab = server.app.public_tab_id(1, 0).unwrap();
         let (_control, _render) = connect_test_shell(&mut server, 9, 80, 23);
+        let (_source_control, _source_render) = connect_test_shell(&mut server, 10, 80, 23);
         // Keep a valid view distinct from the server default in every case.
         assert!(server.focus_shell_client_on_tab(9, &remaining_tab));
         let location_before = server.clients[&9].shell_location.clone();
@@ -221,6 +222,15 @@ async fn public_pane_move_without_effective_focus_preserves_client_views() {
             "{case}"
         );
         assert_eq!(server.app.state.active, Some(0));
+        if case == "no-focus" {
+            // A later change to the server default must not move this client.
+            server.app.state.switch_workspace_tab(1, 0);
+            assert_eq!(
+                server.shell_tab_id_for_client(10).as_deref(),
+                Some(remaining_tab.as_str()),
+                "the removed source tab must be reconciled to the remaining source tab"
+            );
+        }
         shutdown_test_runtimes(&mut server);
     }
 }