From 780b4337e43df5d0fe664366c7304f0e50cb39f2 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 16 Mar 2026 11:18:13 +0000
Subject: [PATCH] Fix move_tab_forward/backward with tab_bar_filter

When tab_bar_filter is used (e.g. with sessions), move_tab() was using
self.active_tab_idx (index in the full tabs list) as an index into the
filtered tabs list, causing incorrect behavior.

Also fix the same bug in tab_at_location() for left/right locations.

Fixes #9672
Fixes #9673
---
 kitty/tabs.py | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/kitty/tabs.py b/kitty/tabs.py
index 7174bd744..720f3f4cc 100644
--- a/kitty/tabs.py
+++ b/kitty/tabs.py
@@ -1337,8 +1337,13 @@ class TabManager:  # {{{
                 return self.tab_for_id(self.active_tab_history[-1])
         elif loc in ('left', 'right'):
             delta = -1 if loc == 'left' else 1
-            idx = (len(tabs) + self.active_tab_idx + delta) % len(tabs)
-            return tabs[idx]
+            if (at := self.active_tab) is not None:
+                try:
+                    active_idx = tabs.index(at)
+                except ValueError:
+                    return None
+                idx = (len(tabs) + active_idx + delta) % len(tabs)
+                return tabs[idx]
         return None
 
     def goto_tab(self, tab_num: int) -> None:
@@ -1439,8 +1444,14 @@ class TabManager:  # {{{
     def move_tab(self, delta: int = 1) -> None:
         tabs = tuple(self.tabs_to_be_shown_in_tab_bar)
         if len(tabs) > 1:
-            idx = self.active_tab_idx
-            new_active_tab = tabs[(idx + len(tabs) + delta) % len(tabs)]
+            if (at := self.active_tab) is None:
+                return
+            try:
+                filtered_idx = tabs.index(at)
+            except ValueError:
+                return
+            new_active_tab = tabs[(filtered_idx + len(tabs) + delta) % len(tabs)]
+            idx = self.tabs.index(at)
             nidx = self.tabs.index(new_active_tab)
             step = 1 if idx < nidx else -1
             for i in range(idx, nidx, step):