From 06dcb20d03ea7353a0254d60630ce2fc9204495f Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Fri, 8 Dec 2023 12:50:31 +0000
Subject: [PATCH] Properly indicate whether we can extend backwards.

---
 client.py       | 13 ++++++++-----
 cursesclient.py |  7 ++++---
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/client.py b/client.py
index 2a58bda..6b171a4 100644
--- a/client.py
+++ b/client.py
@@ -187,6 +187,12 @@ class Feed:
     """
     def __init__(self, client):
         self.client = client
+    def can_extend(self):
+        return False
+    def extend_past(self):
+        return False
+    def extend_future(self):
+        return False
 
 class IncrementalServerFeed(Feed):
     """A Feed that fetches something from the server via get_incremental."""
@@ -214,6 +220,8 @@ class IncrementalServerFeed(Feed):
     def __getitem__(self, n):
         return self.data[n + self.origin]
 
+    def can_extend(self):
+        return True
     def extend_past(self):
         if not self.started:
             return None
@@ -267,11 +275,6 @@ class ThreadFeed(Feed):
     def __getitem__(self, n):
         return self.data[n]
 
-    def extend_past(self):
-        return False
-    def extend_future(self):
-        return False
-
 class EgoFeed(IncrementalServerFeed):
     def __init__(self, client):
         super().__init__(client, "notifications", {
diff --git a/cursesclient.py b/cursesclient.py
index 946b618..5e7455f 100644
--- a/cursesclient.py
+++ b/cursesclient.py
@@ -484,7 +484,7 @@ class ObjectFile(File):
         self.header = text.FileHeader(title)
         self.constructor = constructor
 
-        self.history_closed = False
+        self.history_closed = not self.feed.can_extend()
         self.minpos = self.feed.min_index()
         self.maxpos = self.feed.max_index()
         self.statuses = {i: self.constructor(self.feed[i], cc)
@@ -719,11 +719,12 @@ class ObjectFile(File):
 
     def up_screen(self):
         success = self.move_by(-max(1, self.cc.scr_h - 3))
-        if not success:
+        if not success and not self.history_closed:
             if not self.primed_to_extend:
                 self.primed_to_extend = True
             else:
-                self.feed.extend_past()
+                if self.feed.extend_past() is False: # None does not count
+                    self.history_closed = True
                 self.primed_to_extend = False
     def unprime(self):
         self.primed_to_extend = False
-- 
2.30.2