diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index 5dbe03cf9..ac3b50bce 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -69,6 +69,10 @@ class MissingAPIKeyError(ValueError):
 class FinishReasonLength(Exception):
     pass
 
+# Add this new exception
+class AiderAbortException(Exception):
+    pass
+
 
 def wrap_fence(name):
     return f"<{name}>", f"</{name}>"
@@ -864,6 +868,7 @@ class Coder:
         self.test_outcome = None
         self.shell_commands = []
         self.message_cost = 0
+        self.partial_response_function_call = None # Initialize function call attribute
 
         if self.repo:
             self.commit_before_message.append(self.repo.get_head_commit_sha())
@@ -1417,6 +1422,8 @@ class Coder:
         # Notify IO that LLM processing is starting
         self.io.llm_started()
 
+        self.partial_response_function_call = None # Initialize function call attribute here
+
         self.cur_messages += [
             dict(role="user", content=inp),
         ]
@@ -1447,10 +1454,11 @@ class Coder:
 
         self.usage_report = None
         exhausted = False
-        interrupted = False
-        try:
+        interrupted = False # Flag to track if AiderAbortException was caught
+        try: # This try block handles retries and different exception types
             while True:
                 try:
+                    # This is where AiderAbortException can be raised by show_send_output_stream
                     yield from self.send(messages, functions=self.functions)
                     break
                 except litellm_ex.exceptions_tuple() as err:
@@ -1482,8 +1490,14 @@ class Coder:
                     time.sleep(retry_delay)
                     continue
                 except KeyboardInterrupt:
-                    interrupted = True
-                    break
+                    # This handles Ctrl+C from the terminal, which calls io.interrupt_input()
+                    interrupted = True # Mark as interrupted
+                    self.keyboard_interrupt() # Handle the Ctrl+C signal
+                    break # Exit the retry loop
+                except AiderAbortException: # This is the exception raised by show_send_output_stream
+                    # This handles abort signals from the IO layer (e.g., Connector)
+                    interrupted = True # Mark as interrupted
+                    break # Exit the retry loop
                 except FinishReasonLength:
                     # We hit the output limit!
                     if not self.main_model.info.get("supports_assistant_prefill"):
@@ -1506,6 +1520,7 @@ class Coder:
                     self.event("message_send_exception", exception=str(err))
                     return
         finally:
+            # This block always runs, even if an exception occurred or the loop broke (e.g., due to interrupt)
             if self.mdstream:
                 self.live_incremental_response(True)
                 self.mdstream = None
@@ -1513,34 +1528,36 @@ class Coder:
             # Ensure any waiting spinner is stopped
             self._stop_waiting_spinner()
 
+            # Capture the final partial content regardless of how it ended
             self.partial_response_content = self.get_multi_response_content_in_progress(True)
             self.remove_reasoning_content()
             self.multi_response_content = ""
 
-        ###
-        # print()
-        # print("=" * 20)
-        # dump(self.partial_response_content)
+            # Add the assistant's reply (even if partial/interrupted) to cur_messages
+            self.add_assistant_reply_to_cur_messages(interrupted=interrupted) # Pass interrupted status
 
-        self.io.tool_output()
+        # Check the interrupted flag *after* the finally block
+        if interrupted:
+            # If interrupted, we stop here and don't proceed with post-processing
+            self.io.tool_output("Response interrupted.")
+            return # Exit send_message
+
+        # If we reach here, the stream completed without interruption or context exhaustion
+
+        self.io.tool_output() # Add a newline after the assistant output
 
         self.show_usage_report()
 
-        self.add_assistant_reply_to_cur_messages()
+        # The assistant reply was already added to cur_messages in the finally block
 
         if exhausted:
-            if self.cur_messages and self.cur_messages[-1]["role"] == "user":
-                self.cur_messages += [
-                    dict(
-                        role="assistant",
-                        content="FinishReasonLength exception: you sent too many tokens",
-                    ),
-                ]
-
+            # This case should now be handled before the main post-processing
+            # but keeping the check here for safety/clarity.
             self.show_exhausted_error()
             self.num_exhausted_context_windows += 1
             return
 
+        # Proceed with post-processing only if not interrupted
         if self.partial_response_function_call:
             args = self.parse_partial_args()
             if args:
@@ -1552,31 +1569,35 @@ class Coder:
         else:
             content = ""
 
-        if not interrupted:
-            add_rel_files_message = self.check_for_file_mentions(content)
-            if add_rel_files_message:
-                if self.reflected_message:
-                    self.reflected_message += "\n\n" + add_rel_files_message
-                else:
-                    self.reflected_message = add_rel_files_message
-                return
-
-            try:
-                if self.reply_completed():
-                    return
-            except KeyboardInterrupt:
-                interrupted = True
-
-        if interrupted:
-            if self.cur_messages and self.cur_messages[-1]["role"] == "user":
-                self.cur_messages[-1]["content"] += "\n^C KeyboardInterrupt"
+        # Check for file mentions in the final content
+        add_rel_files_message = self.check_for_file_mentions(content)
+        if add_rel_files_message:
+            # If files were mentioned and added, set reflected_message
+            if self.reflected_message:
+                self.reflected_message += "\n\n" + add_rel_files_message
             else:
-                self.cur_messages += [dict(role="user", content="^C KeyboardInterrupt")]
-            self.cur_messages += [
-                dict(role="assistant", content="I see that you interrupted my previous reply.")
-            ]
+                self.reflected_message = add_rel_files_message
+            # Return here to trigger reflection in run_one
             return
 
+        try:
+            # Check if the reply completed successfully (subclass specific)
+            if self.reply_completed():
+                return
+        except KeyboardInterrupt:
+            # Handle Ctrl+C during reply_completed (less likely but possible)
+            interrupted = True
+            self.keyboard_interrupt()
+            # Fall through to the interrupted handling below
+
+        # If interrupted during reply_completed or file mention check
+        if interrupted:
+             # The message history already has the partial content + "(interrupted)"
+             # No need to add another message here.
+             self.io.tool_output("Response interrupted.")
+             return # Exit send_message
+
+        # Apply edits only if not interrupted and reply completed successfully
         edited = self.apply_updates()
 
         if edited:
@@ -1586,11 +1607,14 @@ class Coder:
             if not saved_message and hasattr(self.gpt_prompts, "files_content_gpt_edits_no_repo"):
                 saved_message = self.gpt_prompts.files_content_gpt_edits_no_repo
 
+            # Move messages back only after successful edits and commit
             self.move_back_cur_messages(saved_message)
 
+        # Check for reflections again after applying edits
         if self.reflected_message:
             return
 
+        # Run lint/test only if edits were applied and not interrupted
         if edited and self.auto_lint:
             lint_errors = self.lint_edited(edited)
             self.auto_commit(edited, context="Ran the linter")
@@ -1601,13 +1625,16 @@ class Coder:
                     self.reflected_message = lint_errors
                     return
 
+        # Run shell commands only if not interrupted
         shared_output = self.run_shell_commands()
         if shared_output:
+            # Add shell command output to chat history
             self.cur_messages += [
                 dict(role="user", content=shared_output),
                 dict(role="assistant", content="Ok"),
             ]
 
+        # Run tests only if edits were applied and not interrupted
         if edited and self.auto_test:
             test_errors = self.commands.cmd_test(self.test_cmd)
             self.test_outcome = not test_errors
@@ -1694,10 +1721,21 @@ class Coder:
         """Cleanup when the Coder object is destroyed."""
         self.ok_to_warm_cache = False
 
-    def add_assistant_reply_to_cur_messages(self):
-        if self.partial_response_content:
-            self.cur_messages += [dict(role="assistant", content=self.partial_response_content)]
-        if self.partial_response_function_call:
+    def add_assistant_reply_to_cur_messages(self, interrupted=False):
+        # Add the partial or complete response content to the current messages
+        # This happens in the finally block, so it includes interrupted content
+        content_to_add = self.partial_response_content
+        if interrupted and content_to_add: # Use the passed interrupted flag
+             content_to_add += " (interrupted)" # Indicate interruption in history
+
+        if content_to_add:
+            self.cur_messages += [dict(role="assistant", content=content_to_add)]
+        # Only add function call if not interrupted, as it implies completion
+        if self.partial_response_function_call and not interrupted:
+            # Note: Function calls are not currently interrupted by the IO layer check
+            # as they don't stream content chunk by chunk in the same way.
+            # If function calls needed interruption, the LiteLLM call itself would need
+            # to be cancellable, which is provider/LiteLLM dependent.
             self.cur_messages += [
                 dict(
                     role="assistant",
@@ -1706,6 +1744,7 @@ class Coder:
                 )
             ]
 
+
     def get_file_mentions(self, content, ignore_current=False):
         words = set(word for word in content.split())
 
@@ -1896,6 +1935,11 @@ class Coder:
         received_content = False
 
         for chunk in completion:
+            # Check for interruption at the start of processing each chunk
+            if self.io.is_interrupted():
+                self._stop_waiting_spinner() # Stop spinner on abort
+                raise AiderAbortException("Stream interrupted by user.")
+
             if len(chunk.choices) == 0:
                 continue
 
diff --git a/aider/io.py b/aider/io.py
index f28a1c86d..0161c58a4 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -514,6 +514,13 @@ class InputOutput:
             self.interrupted = True
             self.prompt_session.app.exit()
 
+    def is_interrupted(self):
+        """
+        Check if the current operation should be interrupted.
+        Implementations should override this based on their environment.
+        """
+        return False # Default implementation
+
     def get_input(
         self,
         root,
diff --git a/tests/basic/test_coder.py b/tests/basic/test_coder.py
index 9dd0ce37a..fe0faf0fc 100644
--- a/tests/basic/test_coder.py
+++ b/tests/basic/test_coder.py
@@ -7,7 +7,7 @@ from unittest.mock import MagicMock, patch
 import git
 
 from aider.coders import Coder
-from aider.coders.base_coder import FinishReasonLength, UnknownEditFormat
+from aider.coders.base_coder import AiderAbortException, FinishReasonLength, UnknownEditFormat
 from aider.dump import dump  # noqa: F401
 from aider.io import InputOutput
 from aider.models import Model
@@ -1433,6 +1433,257 @@ This command will print 'Hello, World!' to the console."""
                     # (because user rejected the changes)
                     mock_editor.run.assert_not_called()
 
+    @patch("aider.coders.base_coder.Coder.apply_updates")
+    @patch("aider.coders.base_coder.Coder.run_shell_commands")
+    @patch("aider.coders.base_coder.Coder.check_for_file_mentions")
+    @patch("aider.coders.base_coder.Coder.reply_completed")
+    @patch("aider.coders.base_coder.Coder.show_usage_report")
+    @patch("aider.coders.base_coder.Coder._stop_waiting_spinner")
+    def test_send_message_handles_abort_exception(
+        self,
+        mock_stop_spinner,
+        mock_show_usage,
+        mock_reply_completed,
+        mock_check_mentions,
+        mock_run_shell,
+        mock_apply_updates,
+    ):
+        """Test that send_message handles AiderAbortException correctly."""
+        with GitTemporaryDirectory():
+            io = InputOutput(yes=True)
+            coder = Coder.create(self.GPT35, "diff", io=io)
+
+            # Mock the send method to raise AiderAbortException
+            def mock_send(*args, **kwargs):
+                # Simulate some partial content before abort
+                coder.partial_response_content = "Partial content received."
+                raise AiderAbortException("Test abort")
+
+            coder.send = MagicMock(side_effect=mock_send)
+
+            # Mock post-processing methods to ensure they are NOT called
+            mock_apply_updates.return_value = set()
+            mock_run_shell.return_value = ""
+            mock_check_mentions.return_value = None
+            mock_reply_completed.return_value = False
+            mock_show_usage.return_value = None
+
+            # Run send_message (it's a generator, so iterate through it)
+            list(coder.send_message("Test message"))
+
+            # Assert that the partial content was captured and added to history
+            self.assertIn("Partial content received. (interrupted)", coder.cur_messages[-1]["content"])
+            self.assertEqual(coder.cur_messages[-1]["role"], "assistant")
+
+            # Assert that post-processing methods were NOT called
+            mock_apply_updates.assert_not_called()
+            mock_run_shell.assert_not_called()
+            mock_check_mentions.assert_not_called()
+            mock_reply_completed.assert_not_called()
+            mock_show_usage.assert_not_called() # show_usage_report should be skipped on interruption
+
+            # Assert spinner was stopped
+            mock_stop_spinner.assert_called()
+
+    @patch("aider.coders.base_coder.Coder.apply_updates")
+    @patch("aider.coders.base_coder.Coder.run_shell_commands")
+    @patch("aider.coders.base_coder.Coder.check_for_file_mentions")
+    @patch("aider.coders.base_coder.Coder.reply_completed")
+    @patch("aider.coders.base_coder.Coder.show_usage_report")
+    @patch("aider.coders.base_coder.Coder._stop_waiting_spinner")
+    @patch("aider.io.InputOutput.is_interrupted", return_value=True) # Simulate IO signal
+    def test_streaming_interruption_raises_exception(
+        self,
+        mock_is_interrupted,
+        mock_stop_spinner,
+        mock_show_usage,
+        mock_reply_completed,
+        mock_check_mentions,
+        mock_run_shell,
+        mock_apply_updates,
+    ):
+        """Test that streaming is interrupted when io.is_interrupted() is True."""
+        with GitTemporaryDirectory():
+            io = InputOutput(yes=True)
+            coder = Coder.create(self.GPT35, "diff", io=io, stream=True)
+
+            # Mock the underlying LiteLLM completion stream
+            mock_completion_stream = MagicMock()
+            # Simulate a few chunks before interruption
+            mock_completion_stream.__iter__.return_value = [
+                MagicMock(choices=[MagicMock(delta=MagicMock(content="chunk1"))]),
+                MagicMock(choices=[MagicMock(delta=MagicMock(content="chunk2"))]),
+                # The third iteration will check io.is_interrupted() and raise
+            ]
+
+            # Mock the send method to return the mock stream
+            coder.send = MagicMock(return_value=mock_completion_stream)
+
+            # Mock post-processing methods to ensure they are NOT called
+            mock_apply_updates.return_value = set()
+            mock_run_shell.return_value = ""
+            mock_check_mentions.return_value = None
+            mock_reply_completed.return_value = False
+            mock_show_usage.return_value = None
+
+            # Run send_message (it's a generator, so iterate through it)
+            # Expect AiderAbortException to be raised by show_send_output_stream
+            # which is called by send, which is yielded from by send_message.
+            # The exception should be caught within send_message.
+            list(coder.send_message("Test streaming interruption"))
+
+            # Assert that the interrupted flag was set within send_message's exception handler
+            # We can't directly check the local 'interrupted' flag in send_message,
+            # but we can check that the io object's flag was used (which we mocked)
+            # and that post-processing was skipped.
+            self.assertTrue(mock_is_interrupted.called) # Verify the mock was checked
+
+            # Assert that the partial content was captured and added to history
+            # The content should include chunks received before the interrupt
+            self.assertIn("chunk1chunk2 (interrupted)", coder.cur_messages[-1]["content"])
+            self.assertEqual(coder.cur_messages[-1]["role"], "assistant")
+
+            # Assert that post-processing methods were NOT called
+            mock_apply_updates.assert_not_called()
+            mock_run_shell.assert_not_called()
+            mock_check_mentions.assert_not_called()
+            mock_reply_completed.assert_not_called()
+            mock_show_usage.assert_called_once() # show_usage_report is called after the finally block, but before the interrupted check
+
+            # Assert spinner was stopped
+            mock_stop_spinner.assert_called()
+
+    @patch("aider.coders.base_coder.Coder.apply_updates")
+    @patch("aider.coders.base_coder.Coder.run_shell_commands")
+    @patch("aider.coders.base_coder.Coder.check_for_file_mentions")
+    @patch("aider.coders.base_coder.Coder.reply_completed")
+    @patch("aider.coders.base_coder.Coder.show_usage_report")
+    @patch("aider.coders.base_coder.Coder._stop_waiting_spinner")
+    @patch("aider.coders.base_coder.Coder.keyboard_interrupt") # Mock the handler
+    def test_send_message_handles_keyboard_interrupt(
+        self,
+        mock_keyboard_interrupt,
+        mock_stop_spinner,
+        mock_show_usage,
+        mock_reply_completed,
+        mock_check_mentions,
+        mock_run_shell,
+        mock_apply_updates,
+    ):
+        """Test that send_message handles KeyboardInterrupt correctly."""
+        with GitTemporaryDirectory():
+            io = InputOutput(yes=True)
+            coder = Coder.create(self.GPT35, "diff", io=io)
+
+            # Mock the send method to raise KeyboardInterrupt
+            def mock_send(*args, **kwargs):
+                # Simulate some partial content before interrupt
+                coder.partial_response_content = "Partial content received."
+                raise KeyboardInterrupt("Test interrupt")
+
+            coder.send = MagicMock(side_effect=mock_send)
+
+            # Mock post-processing methods to ensure they are NOT called
+            mock_apply_updates.return_value = set()
+            mock_run_shell.return_value = ""
+            mock_check_mentions.return_value = None
+            mock_reply_completed.return_value = False
+            mock_show_usage.return_value = None
+
+            # Run send_message (it's a generator, so iterate through it)
+            list(coder.send_message("Test message"))
+
+            # Assert that keyboard_interrupt handler was called
+            mock_keyboard_interrupt.assert_called_once()
+
+            # Assert that the partial content was captured and added to history
+            self.assertIn("Partial content received. (interrupted)", coder.cur_messages[-1]["content"])
+            self.assertEqual(coder.cur_messages[-1]["role"], "assistant")
+
+            # Assert that post-processing methods were NOT called
+            mock_apply_updates.assert_not_called()
+            mock_run_shell.assert_not_called()
+            mock_check_mentions.assert_not_called()
+            mock_reply_completed.assert_not_called()
+            mock_show_usage.assert_called_once() # show_usage_report is called after the finally block, but before the interrupted check
+
+            # Assert spinner was stopped
+            mock_stop_spinner.assert_called()
+
+    def test_add_assistant_reply_to_cur_messages_interrupted(self):
+        """Test that add_assistant_reply_to_cur_messages marks content as interrupted."""
+        with GitTemporaryDirectory():
+            io = InputOutput(yes=True)
+            coder = Coder.create(self.GPT35, "diff", io=io)
+
+            # Simulate partial content and interrupted state
+            coder.partial_response_content = "This is partial content."
+            coder.partial_response_function_call = None # No function call
+
+            # Add the reply, simulating interruption
+            coder.add_assistant_reply_to_cur_messages(interrupted=True)
+
+            # Check the last message in cur_messages
+            self.assertEqual(len(coder.cur_messages), 1)
+            last_msg = coder.cur_messages[-1]
+            self.assertEqual(last_msg["role"], "assistant")
+            self.assertEqual(last_msg["content"], "This is partial content. (interrupted)")
+            self.assertNotIn("function_call", last_msg)
+
+            # Simulate partial content with function call and interrupted state
+            coder.cur_messages = [] # Reset messages
+            coder.partial_response_content = "This is partial content before func call."
+            coder.partial_response_function_call = {"name": "test_func", "arguments": "{}"}
+
+            # Add the reply, simulating interruption
+            coder.add_assistant_reply_to_cur_messages(interrupted=True)
+
+            # Check the last message in cur_messages
+            self.assertEqual(len(coder.cur_messages), 1)
+            last_msg = coder.cur_messages[-1]
+            self.assertEqual(last_msg["role"], "assistant")
+            # Content should be marked as interrupted
+            self.assertEqual(last_msg["content"], "This is partial content before func call. (interrupted)")
+            # Function call should NOT be added if interrupted
+            self.assertNotIn("function_call", last_msg)
+
+    def test_add_assistant_reply_to_cur_messages_not_interrupted(self):
+        """Test that add_assistant_reply_to_cur_messages works normally when not interrupted."""
+        with GitTemporaryDirectory():
+            io = InputOutput(yes=True)
+            coder = Coder.create(self.GPT35, "diff", io=io)
+
+            # Simulate complete content and no interruption
+            coder.partial_response_content = "This is the final content."
+            coder.partial_response_function_call = None # No function call
+
+            # Add the reply, not interrupted
+            coder.add_assistant_reply_to_cur_messages(interrupted=False)
+
+            # Check the last message in cur_messages
+            self.assertEqual(len(coder.cur_messages), 1)
+            last_msg = coder.cur_messages[-1]
+            self.assertEqual(last_msg["role"], "assistant")
+            self.assertEqual(last_msg["content"], "This is the final content.")
+            self.assertNotIn("function_call", last_msg)
+
+            # Simulate complete content with function call and no interruption
+            coder.cur_messages = [] # Reset messages
+            coder.partial_response_content = "This is content before func call."
+            coder.partial_response_function_call = {"name": "test_func", "arguments": '{"arg": "val"}'}
+
+            # Add the reply, not interrupted
+            coder.add_assistant_reply_to_cur_messages(interrupted=False)
+
+            # Check the last message in cur_messages
+            self.assertEqual(len(coder.cur_messages), 1)
+            last_msg = coder.cur_messages[-1]
+            self.assertEqual(last_msg["role"], "assistant")
+            self.assertEqual(last_msg["content"], "This is content before func call.")
+            # Function call SHOULD be added if not interrupted
+            self.assertIn("function_call", last_msg)
+            self.assertEqual(last_msg["function_call"], {"name": "test_func", "arguments": '{"arg": "val"}'})
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/basic/test_io.py b/tests/basic/test_io.py
index 270a3c247..54f84ecd8 100644
--- a/tests/basic/test_io.py
+++ b/tests/basic/test_io.py
@@ -341,6 +341,11 @@ class TestInputOutput(unittest.TestCase):
         self.assertEqual(mock_input.call_count, 2)
         self.assertNotIn(("Do you want to proceed?", None), io.never_prompts)
 
+    def test_is_interrupted_default(self):
+        """Test that is_interrupted returns False by default."""
+        io = InputOutput()
+        self.assertFalse(io.is_interrupted())
+
 
 class TestInputOutputMultilineMode(unittest.TestCase):
     def setUp(self):