From 2fea115fc227a38d04a0ce0bff8b4ca1172c8f34 Mon Sep 17 00:00:00 2001
From: Tristan Simas <tristan.simas@mail.mcgill.ca>
Date: Fri, 16 Oct 2026 01:21:53 -0400
Subject: [PATCH] Own tail-follow transition notifications (Toad #64)

---
 src/textual/widget.py | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/textual/widget.py b/src/textual/widget.py
index ca337c54d7..d354ff6c6b 100644
--- a/src/textual/widget.py
+++ b/src/textual/widget.py
@@ -688,6 +688,20 @@ def is_anchored(self) -> bool:
         """
         return self._anchored
 
+    @property
+    def follows_tail(self) -> bool:
+        """Whether anchoring currently follows the latest content."""
+        return self._anchored and not self._anchor_released
+
+    def tail_follow_changed(self) -> None:
+        """React to entering or leaving tail-follow, not to each scroll offset."""
+
+    def _set_anchor_state(self, *, anchored: bool, released: bool) -> None:
+        following = self.follows_tail
+        self._anchored, self._anchor_released = anchored, released
+        if self.follows_tail != following:
+            self.tail_follow_changed()
+
     @property
     def is_mouse_over(self) -> bool:
         """Is the mouse currently over this widget?
@@ -863,7 +877,7 @@ def anchor(self, anchor: bool = True) -> None:
             anchor: Anchor the widget if `True`, clear the anchor if `False`.
 
         """
-        self._anchored = anchor
+        self._set_anchor_state(anchored=anchor, released=self._anchor_released)
         if anchor:
             self.scroll_end(immediate=True, animate=False)
 
@@ -874,7 +888,7 @@ def release_anchor(self) -> None:
 
         """
         self.scroll_target_y = self.scroll_y
-        self._anchor_released = True
+        self._set_anchor_state(anchored=self._anchored, released=True)
 
     def _check_anchor(self) -> None:
         """Check if the scroll position is near enough to the bottom to restore anchor."""
@@ -883,7 +897,7 @@ def _check_anchor(self) -> None:
             and self._anchor_released
             and self.scroll_y >= self.max_scroll_y
         ):
-            self._anchor_released = False
+            self._set_anchor_state(anchored=True, released=False)
 
     def _check_disabled(self) -> bool:
         """Check if the widget is disabled either explicitly by setting `disabled`,
@@ -2951,7 +2965,7 @@ def _lazily_scroll_end() -> None:
             )
 
         if self._anchored and self._anchor_released:
-            self._anchor_released = False
+            self._set_anchor_state(anchored=True, released=False)
 
         if immediate:
             _lazily_scroll_end()