Implement multiline-mode, swaps Enter & Meta-Enter

aider/args.py

@@ -795,6 +795,12 @@ def get_parser(default_config_files, git_root):
         default=True,
         help="Enable/disable fancy input with history and completion (default: True)",
     )
+    group.add_argument(
+        "--multiline",
+        action=argparse.BooleanOptionalAction,
+        default=False,
+        help="Enable/disable multi-line input mode with Meta-Enter to submit (default: False, env: AIDER_MULTILINE)",
+    )
     group.add_argument(
         "--detect-urls",
         action=argparse.BooleanOptionalAction,

aider/coders/base_coder.py

@@ -248,6 +248,9 @@ class Coder:
         if self.done_messages:
             lines.append("Restored previous conversation history.")
 
+        if self.io.multiline_mode:
+            lines.append("Multiline mode: Enabled. Enter inserts newline, Alt-Enter submits text")
+
         return lines
 
     def __init__(

aider/commands.py

@@ -1363,6 +1363,10 @@ class Commands:
         except Exception as e:
             self.io.tool_error(f"Error saving commands to file: {e}")
 
+    def cmd_multiline_mode(self, args):
+        "Toggle multiline mode (swaps behavior of Enter and Meta+Enter)"
+        self.io.toggle_multiline_mode()
+
     def cmd_copy(self, args):
         "Copy the last assistant message to the clipboard"
         all_messages = self.coder.done_messages + self.coder.cur_messages

aider/io.py

@@ -202,11 +202,19 @@ class InputOutput:
         editingmode=EditingMode.EMACS,
         fancy_input=True,
         file_watcher=None,
+        multiline_mode=False,
     ):
         self.placeholder = None
         self.interrupted = False
         self.never_prompts = set()
         self.editingmode = editingmode
+        # Base multiline setting that can be temporarily overridden
+        # Command line argument takes precedence over environment variable
+        self.base_multiline_mode = multiline_mode if multiline_mode is not None else (
+            os.environ.get('AIDER_MULTILINE', '').lower() in ('true', '1', 'yes', 'on')
+        )
+        # Current multiline state that can be temporarily disabled for prompts
+        self.multiline_mode = self.base_multiline_mode
         no_color = os.environ.get("NO_COLOR")
         if no_color is not None and no_color != "":
             pretty = False
@@ -412,6 +420,8 @@ class InputOutput:
             show = self.format_files_for_input(rel_fnames, rel_read_only_fnames)
         if edit_format:
             show += edit_format
+        if self.multiline_mode:
+            show += (" " if edit_format else "") + "multi"
         show += "> "
 
         inp = ""
@@ -456,9 +466,25 @@ class InputOutput:
             "Navigate forward through history"
             event.current_buffer.history_forward()
 
-        @kb.add("escape", "c-m", eager=True)
+        @kb.add("enter", eager=True)
         def _(event):
-            event.current_buffer.insert_text("\n")
+            "Handle Enter key press"
+            if self.multiline_mode:
+                # In multiline mode, Enter adds a newline
+                event.current_buffer.insert_text("\n")
+            else:
+                # In normal mode, Enter submits
+                event.current_buffer.validate_and_handle()
+
+        @kb.add("escape", "enter", eager=True)  # This is Alt+Enter
+        def _(event):
+            "Handle Alt+Enter key press"
+            if self.multiline_mode:
+                # In multiline mode, Alt+Enter submits
+                event.current_buffer.validate_and_handle()
+            else:
+                # In normal mode, Alt+Enter adds a newline
+                event.current_buffer.insert_text("\n")
 
         while True:
             if multiline_input:
@@ -629,6 +655,9 @@ class InputOutput:
         group=None,
         allow_never=False,
     ):
+        # Temporarily disable multiline mode for yes/no prompts
+        orig_multiline = self.multiline_mode
+        self.multiline_mode = False
         self.num_user_asks += 1
 
         question_id = (question, subject)
@@ -726,9 +755,15 @@ class InputOutput:
         hist = f"{question.strip()} {res}"
         self.append_chat_history(hist, linebreak=True, blockquote=True)
 
+        # Restore original multiline mode
+        self.multiline_mode = orig_multiline
+
         return is_yes
 
     def prompt_ask(self, question, default="", subject=None):
+        # Temporarily disable multiline mode for prompts
+        orig_multiline = self.multiline_mode
+        self.multiline_mode = False
         self.num_user_asks += 1
 
         if subject:
@@ -752,6 +787,9 @@ class InputOutput:
         if self.yes in (True, False):
             self.tool_output(hist)
 
+        # Restore original multiline mode
+        self.multiline_mode = orig_multiline
+
         return res
 
     def _tool_message(self, message="", strip=True, color=None):
@@ -821,6 +859,14 @@ class InputOutput:
     def print(self, message=""):
         print(message)
 
+    def toggle_multiline_mode(self):
+        """Toggle between normal and multiline input modes"""
+        self.multiline_mode = not self.multiline_mode
+        if self.multiline_mode:
+            self.tool_output("Multiline mode: Enabled. Enter inserts newline, Alt-Enter submits text")
+        else:
+            self.tool_output("Multiline mode: Disabled. Alt-Enter inserts newline, Enter submits text")
+
     def append_chat_history(self, text, linebreak=False, blockquote=False, strip=True):
         if blockquote:
             if strip:

aider/main.py

@@ -515,6 +515,7 @@ def main(argv=None, input=None, output=None, force_git_root=None, return_coder=F
             llm_history_file=args.llm_history_file,
             editingmode=editing_mode,
             fancy_input=args.fancy_input,
+            multiline_mode=args.multiline,
         )
 
     io = get_io(args.pretty)

aider/website/_includes/multi-line.md

@@ -5,6 +5,10 @@ You can send long, multi-line messages in the chat in a few ways:
   - Use Meta-ENTER to start a new line without sending the message (Esc+ENTER in some environments).
   - Use `/paste` to paste text from the clipboard into the chat.
   - Use the `/editor` command to open your editor to create the next chat message. See [editor configuration docs](/docs/config/editor.html) for more info.
+  - Use multiline-mode, which swaps the function of Meta-Enter and Enter, so that Enter inserts a newline, and Meta-Enter submits your command. You can enable multiline mode in three ways:
+    - Use the `/multiline-mode` command to toggle it during a session
+    - Start aider with the `--multiline` flag
+    - Start aider with the environment variable AIDER\_MULTILINE=true
 
 Example with a tag:
 ```