Workspace(fix[synchronize-panes]): Restore sync state on setup failure

why: Window setup temporarily disables tmux pane synchronization so pane setup commands do not broadcast across panes. If pane creation or layout application fails, that temporary state must still be restored so partial windows and existing/global tmux state are not left with an unintended local override.
what:
- Restore synchronize-panes from a build-level finally block when pane setup aborts
- Preserve and restore pane-local synchronize-panes overrides while setup is isolated
- Cover raw options, inherited global state, options_after, and plugin-set synchronization state in regression tests

Author: tony

src/tmuxp/workspace/builder/classic.py

@@ -9,6 +9,7 @@
 import typing as t
 
 from libtmux._internal.query_list import ObjectDoesNotExist
+from libtmux.constants import OptionScope
 from libtmux.pane import Pane
 from libtmux.server import Server
 from libtmux.session import Session
@@ -32,6 +33,7 @@
 SYNCHRONIZE_PANES_OPTION = "synchronize-panes"
 SYNCHRONIZE_PANES_FINAL_OPTION = "_synchronize_panes"
 SYNCHRONIZE_PANES_FORCED_OFF_OPTION = "_synchronize_panes_forced_off"
+SYNCHRONIZE_PANES_PANE_RESTORE_OPTION = "_synchronize_panes_pane_restore"
 SYNCHRONIZE_PANES_RESTORE_OPTION = "_synchronize_panes_restore"
 _MISSING = object()
 
@@ -619,17 +621,24 @@ def build(self, session: Session | None = None, append: bool = False) -> None:
             self.prepare_window_synchronize_panes(window, window_config)
 
             focus_pane = None
-            for pane, pane_config in self.iter_create_panes(window, window_config):
-                assert isinstance(pane, Pane)
-                pane = pane
+            try:
+                for pane, pane_config in self.iter_create_panes(window, window_config):
+                    assert isinstance(pane, Pane)
+                    pane = pane
 
-                if pane_config.get("focus"):
-                    focus_pane = pane
+                    if pane_config.get("focus"):
+                        focus_pane = pane
 
-            if window_config.get("focus"):
-                focus = window
+                if window_config.get("focus"):
+                    focus = window
 
-            self.config_after_window(window, window_config)
+                self.config_after_window(window, window_config)
+            finally:
+                self.restore_window_synchronize_panes(
+                    window,
+                    window_config,
+                    apply_options_after=False,
+                )
 
             for plugin in self.plugins:
                 plugin.after_window_finished(window)
@@ -763,7 +772,7 @@ def prepare_window_synchronize_panes(
         Examples
         --------
         >>> cfg = {}
-        >>> builder = WorkspaceBuilder(
+        >>> builder = ClassicWorkspaceBuilder(
         ...     session_config={"session_name": session.name, "windows": []},
         ...     server=session.server,
         ... )
@@ -788,17 +797,38 @@ def prepare_window_synchronize_panes(
             window.set_option(SYNCHRONIZE_PANES_OPTION, False)
             window_config[SYNCHRONIZE_PANES_FORCED_OFF_OPTION] = True
 
+        pane_restores = []
+        for pane in window.panes:
+            local_pane_sync = pane.show_option(
+                SYNCHRONIZE_PANES_OPTION,
+                scope=OptionScope.Pane,
+            )
+            if local_pane_sync is True:
+                pane_restores.append((pane, local_pane_sync))
+                pane.set_option(
+                    SYNCHRONIZE_PANES_OPTION,
+                    False,
+                    scope=OptionScope.Pane,
+                    ignore_errors=True,
+                )
+
+        if pane_restores:
+            window_config[SYNCHRONIZE_PANES_PANE_RESTORE_OPTION] = pane_restores
+            window_config[SYNCHRONIZE_PANES_FORCED_OFF_OPTION] = True
+
     def restore_window_synchronize_panes(
         self,
         window: Window,
         window_config: dict[str, t.Any],
+        *,
+        apply_options_after: bool = True,
     ) -> None:
         """Restore the configured final tmux pane synchronization state.
 
         Examples
         --------
         >>> cfg = {"options_after": {"synchronize-panes": "off"}}
-        >>> builder = WorkspaceBuilder(
+        >>> builder = ClassicWorkspaceBuilder(
         ...     session_config={"session_name": session.name, "windows": []},
         ...     server=session.server,
         ... )
@@ -809,26 +839,49 @@ def restore_window_synchronize_panes(
         False
         >>> _ = scratch.kill()
         """
-        after_sync = _get_window_option_value(
-            window_config,
-            "options_after",
-            SYNCHRONIZE_PANES_OPTION,
-        )
-        if after_sync is not _MISSING:
-            window.set_option(SYNCHRONIZE_PANES_OPTION, after_sync)
-            return
-
-        if not window_config.get(SYNCHRONIZE_PANES_FORCED_OFF_OPTION):
-            return
+        after_sync = _MISSING
+        if apply_options_after:
+            after_sync = _get_window_option_value(
+                window_config,
+                "options_after",
+                SYNCHRONIZE_PANES_OPTION,
+            )
 
-        restore_sync = window_config.get(
+        pane_restores = window_config.pop(
+            SYNCHRONIZE_PANES_PANE_RESTORE_OPTION,
+            [],
+        )
+        forced_off = window_config.pop(SYNCHRONIZE_PANES_FORCED_OFF_OPTION, False)
+        restore_sync = window_config.pop(
             SYNCHRONIZE_PANES_RESTORE_OPTION,
             _MISSING,
         )
-        if restore_sync is _MISSING or restore_sync is None:
-            window.unset_option(SYNCHRONIZE_PANES_OPTION, ignore_errors=True)
-        else:
-            window.set_option(SYNCHRONIZE_PANES_OPTION, restore_sync)
+
+        if after_sync is not _MISSING:
+            window.set_option(SYNCHRONIZE_PANES_OPTION, t.cast(int | str, after_sync))
+        elif forced_off and restore_sync is not _MISSING:
+            if restore_sync is None:
+                window.unset_option(SYNCHRONIZE_PANES_OPTION, ignore_errors=True)
+            else:
+                window.set_option(
+                    SYNCHRONIZE_PANES_OPTION,
+                    t.cast(int | str, restore_sync),
+                )
+
+        for pane, restore_pane_sync in pane_restores:
+            if restore_pane_sync is _MISSING or restore_pane_sync is None:
+                pane.unset_option(
+                    SYNCHRONIZE_PANES_OPTION,
+                    scope=OptionScope.Pane,
+                    ignore_errors=True,
+                )
+            else:
+                pane.set_option(
+                    SYNCHRONIZE_PANES_OPTION,
+                    t.cast(int | str, restore_pane_sync),
+                    scope=OptionScope.Pane,
+                    ignore_errors=True,
+                )
 
     def iter_create_panes(
         self,