diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 662bd7912..f6c8f7174 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -48,6 +48,7 @@ class Coder:
     abs_fnames = None
     repo = None
     last_aider_commit_hash = None
+    aider_commit_hashes = set()
     aider_edited_files = None
     last_asked_for_commit_time = 0
     repo_map = None
@@ -115,6 +116,7 @@ class Coder:
                 fnames=from_coder.get_inchat_relative_files(),
                 done_messages=done_messages,
                 cur_messages=from_coder.cur_messages,
+                aider_commit_hashes=from_coder.aider_commit_hashes,
             )
 
             use_kwargs.update(update)  # override to complete the switch
@@ -222,6 +224,7 @@ class Coder:
         attribute_author=True,
         attribute_committer=True,
         attribute_commit_message=False,
+        aider_commit_hashes=None,
     ):
         if not fnames:
             fnames = []
@@ -229,6 +232,11 @@ class Coder:
         if io is None:
             io = InputOutput()
 
+        if aider_commit_hashes:
+            self.aider_commit_hashes = aider_commit_hashes
+        else:
+            self.aider_commit_hashes = set()
+
         self.chat_completion_call_hashes = []
         self.chat_completion_response_hashes = []
         self.need_commit_before_edits = set()
@@ -1451,6 +1459,7 @@ class Coder:
         if res:
             commit_hash, commit_message = res
             self.last_aider_commit_hash = commit_hash
+            self.aider_commit_hashes.add(commit_hash)
             self.last_aider_commit_message = commit_message
             if self.show_diffs:
                 self.commands.cmd_diff()
diff --git a/aider/commands.py b/aider/commands.py
index 2cc18ab54..b50138c2b 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -346,16 +346,12 @@ class Commands:
         # Move the HEAD back before the latest commit
         self.coder.repo.repo.git.reset("--soft", "HEAD~1")
 
-        self.io.tool_output(
-            f"Commit `{last_commit_hash}` with message '{last_commit_message}' was reset and removed from git."
-        )
+        self.io.tool_output(f"Removed: {last_commit_hash} {last_commit_message}")
 
         # Get the current HEAD after undo
         current_head_hash = self.coder.repo.repo.head.commit.hexsha[:7]
         current_head_message = self.coder.repo.repo.head.commit.message.strip()
-        self.io.tool_output(
-            f"Current HEAD is now `{current_head_hash}` with message '{current_head_message}'."
-        )
+        self.io.tool_output(f"HEAD is: {current_head_hash} {current_head_message}")
 
         if self.coder.main_model.send_undo_reply:
             return prompts.undo_command_reply
@@ -375,8 +371,8 @@ class Commands:
 
         diff = self.coder.repo.diff_commits(
             self.coder.pretty,
-            'HEAD^',
-            'HEAD',
+            "HEAD^",
+            "HEAD",
         )
 
         # don't use io.tool_output() because we don't want to log or further colorize