diff --git a/aider/__init__.py b/aider/__init__.py
index 478a2f82558..935725a74c0 100644
--- a/aider/__init__.py
+++ b/aider/__init__.py
@@ -1,6 +1,6 @@
 from packaging import version
 
-__version__ = "0.90.4.dev"
+__version__ = "0.90.5.dev"
 safe_version = __version__
 
 try:
diff --git a/aider/args.py b/aider/args.py
index 1453cca90a1..005fe0a0d04 100644
--- a/aider/args.py
+++ b/aider/args.py
@@ -332,7 +332,7 @@ def get_parser(default_config_files, git_root):
     )
     group.add_argument(
         "--context-compaction-max-tokens",
-        type=int,
+        type=float,
         default=None,
         help=(
             "The maximum number of tokens in the conversation before context compaction is"
diff --git a/aider/coders/agent_prompts.py b/aider/coders/agent_prompts.py
index 0aa2bb771f6..136a961a999 100644
--- a/aider/coders/agent_prompts.py
+++ b/aider/coders/agent_prompts.py
@@ -19,6 +19,7 @@ class AgentPrompts(CoderPrompts):
 - **Act Proactively**: Autonomously use file discovery and context management tools (`ViewFilesAtGlob`, `ViewFilesMatching`, `Ls`, `View`, `Remove`) to gather information and fulfill the user's request. Chain tool calls across multiple turns to continue exploration.
 - **Be Decisive**: Trust that your initial findings are valid. Refrain from asking the same question or searching for the same term in multiple similar ways.
 - **Be Concise**: Keep all responses brief and direct (1-3 sentences). Avoid preamble, postamble, and unnecessary explanations. Do not repeat yourself.
+- **Be Careful**: Break updates down into smaller, more manageable chunks. Focus on one thing at a time.
 </context>
 
 <context name="workflow_and_tool_usage">
diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index fc74626e096..47c7d765130 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -306,7 +306,6 @@ def __init__(
         context_compaction_summary_tokens=8192,
         map_cache_dir=".",
         repomap_in_memory=False,
-        preserve_todo_list=False,
         linear_output=False,
     ):
         # initialize from args.map_cache_dir
@@ -321,13 +320,6 @@ def __init__(
 
         self.auto_copy_context = auto_copy_context
         self.auto_accept_architect = auto_accept_architect
-        self.preserve_todo_list = preserve_todo_list
-
-        if self.preserve_todo_list:
-            self.io.tool_warning(
-                "--preserve-todo-list is deprecated; todo lists are now saved and restored with"
-                " sessions. The flag will be removed in a future release."
-            )
 
         self.ignore_mentions = ignore_mentions
         if not self.ignore_mentions:
@@ -2344,6 +2336,8 @@ async def send_message(self, inp):
                         return
             except Exception as e:
                 self.io.tool_error(f"Error processing tool calls: {str(e)}")
+                self.reflected_message = True
+                return
                 # Continue without tool processing
 
             self.num_tool_calls = 0
diff --git a/aider/io.py b/aider/io.py
index 2b8a6ed55a7..b2d5d811197 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -1414,7 +1414,11 @@ def replace_json(match):
 
         # Match b'{...}', b"[...]", '{...}', "[...]"
         # Handle escaped quotes with (?<!\\)
-        text = re.sub(r"b?(['\"])([\{\[].*?)(?<!\\)\1", replace_json, text, flags=re.DOTALL)
+        try:
+            new_text = re.sub(r"b?(['\"])([\{\[].*?)(?<!\\)\1", replace_json, text, flags=re.DOTALL)
+            return new_text
+        except Exception:
+            pass
 
         return text
 
diff --git a/aider/main.py b/aider/main.py
index a8a2209efec..03ea584a6e9 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -1193,10 +1193,17 @@ def apply_model_overrides(model_name):
     else:
         map_tokens = args.map_tokens
 
-    if args.enable_context_compaction and args.context_compaction_max_tokens is None:
+    if args.enable_context_compaction and (
+        args.context_compaction_max_tokens is None or args.context_compaction_max_tokens < 1
+    ):
         max_input_tokens = main_model.info.get("max_input_tokens")
+        ratio = 0.8
+
+        if args.context_compaction_max_tokens:
+            ratio = args.context_compaction_max_tokens
+
         if max_input_tokens:
-            args.context_compaction_max_tokens = int(max_input_tokens * 0.8)
+            args.context_compaction_max_tokens = int(max_input_tokens * ratio)
 
     try:
         # Load MCP servers from config string or file
@@ -1249,7 +1256,6 @@ def apply_model_overrides(model_name):
             context_compaction_summary_tokens=args.context_compaction_summary_tokens,
             map_cache_dir=args.map_cache_dir,
             repomap_in_memory=args.map_memory_cache,
-            preserve_todo_list=args.preserve_todo_list,
             linear_output=args.linear_output,
         )
 
diff --git a/aider/models.py b/aider/models.py
index 60fb51ea107..86c46fd4178 100644
--- a/aider/models.py
+++ b/aider/models.py
@@ -112,7 +112,7 @@
 class ModelSettings:
     # Model class needs to have each of these as well
     name: str
-    edit_format: str = "whole"
+    edit_format: str = "diff"
     weak_model_name: Optional[str] = None
     use_repo_map: bool = False
     send_undo_reply: bool = False
diff --git a/aider/tools/insert_block.py b/aider/tools/insert_block.py
index 1c27811ec89..9105dc7e998 100644
--- a/aider/tools/insert_block.py
+++ b/aider/tools/insert_block.py
@@ -23,8 +23,8 @@ class Tool(BaseTool):
         "function": {
             "name": "InsertBlock",
             "description": (
-                "Insert a block of content into a file. Only use one of: after_pattern,"
-                " before_pattern, position."
+                "Insert a block of content into a file. Mutually Exclusive Parameters:"
+                " after_pattern, before_pattern, position."
             ),
             "parameters": {
                 "type": "object",
diff --git a/aider/tools/show_numbered_context.py b/aider/tools/show_numbered_context.py
index 90c61b97e71..21285062f09 100644
--- a/aider/tools/show_numbered_context.py
+++ b/aider/tools/show_numbered_context.py
@@ -16,8 +16,8 @@ class Tool(BaseTool):
         "function": {
             "name": "ShowNumberedContext",
             "description": (
-                "Show numbered lines of context around a pattern or line number. Only use one of:"
-                " pattern, line_number"
+                "Show numbered lines of context around a pattern or line number. Mutually Exclusive"
+                " Parameters: pattern, line_number"
             ),
             "parameters": {
                 "type": "object",
diff --git a/aider/tui/app.py b/aider/tui/app.py
index 6e7fe1a5580..8cbca5bd286 100644
--- a/aider/tui/app.py
+++ b/aider/tui/app.py
@@ -69,40 +69,51 @@ def __init__(self, coder_worker, output_queue, input_queue, args):
         )
 
         self.bind(
-            self.tui_config["key_bindings"]["newline"], "noop", description="New Line", show=True
+            self._encode_keys(self.get_keys_for("newline")),
+            "noop",
+            description="New Line",
+            show=True,
         )
         self.bind(
-            self.tui_config["key_bindings"]["submit"], "noop", description="Submit", show=True
+            self._encode_keys(self.get_keys_for("submit")), "noop", description="Submit", show=True
         )
         self.bind(
-            self.tui_config["key_bindings"]["cycle_forward"],
+            self._encode_keys(self.get_keys_for("cycle_forward")),
             "noop",
             description="Cycle Forward",
             show=True,
         )
         self.bind(
-            self.tui_config["key_bindings"]["cycle_backward"],
+            self._encode_keys(self.get_keys_for("cycle_backward")),
             "noop",
             description="Cycle Backward",
             show=True,
         )
         self.bind(
-            self.tui_config["key_bindings"]["cancel"], "noop", description="Cancel", show=True
+            self._encode_keys(self.get_keys_for("cancel")), "noop", description="Cancel", show=True
         )
 
         self.bind(
-            self.tui_config["key_bindings"]["focus"],
+            self._encode_keys(self.get_keys_for("focus")),
             "focus_input",
             description="Focus Input",
             show=True,
         )
         self.bind(
-            self.tui_config["key_bindings"]["stop"], "interrupt", description="Interrupt", show=True
+            self._encode_keys(self.get_keys_for("stop")),
+            "interrupt",
+            description="Interrupt",
+            show=True,
         )
         self.bind(
-            self.tui_config["key_bindings"]["clear"], "clear_output", description="Clear", show=True
+            self._encode_keys(self.get_keys_for("clear")),
+            "clear_output",
+            description="Clear",
+            show=True,
+        )
+        self.bind(
+            self._encode_keys(self.get_keys_for("focus")), "quit", description="Quit", show=True
         )
-        self.bind(self.tui_config["key_bindings"]["focus"], "quit", description="Quit", show=True)
 
         self.register_theme(BASE_THEME)
         self.theme = "aider"
@@ -267,10 +278,10 @@ def update_key_hints(self, generating=False):
         try:
             hints = self.query_one(KeyHints)
             if generating:
-                stop = self.app._decode_keys(self.app.tui_config["key_bindings"]["stop"])
+                stop = self.app.get_keys_for("stop")
                 hints.update(f"{stop} to cancel")
             else:
-                submit = self.app._decode_keys(self.app.tui_config["key_bindings"]["submit"])
+                submit = self.app.get_keys_for("submit")
                 hints.update(f"{submit} to submit")
         except Exception:
             pass
@@ -486,17 +497,26 @@ def action_noop(self):
         pass
 
     def _encode_keys(self, key):
-        if key == "shift+enter":
-            return "ctrl+j"
+        key = key.replace("shift+enter", "ctrl+j")
 
         return key
 
     def _decode_keys(self, key):
-        if key == "ctrl+j":
-            return "shift+enter"
+        key = key.replace("ctrl+j", "shift+enter")
 
         return key
 
+    def is_key_for(self, type, key):
+        allowed_keys = self.tui_config["key_bindings"][type].split(",")
+        if key in allowed_keys:
+            return True
+
+        return False
+
+    def get_keys_for(self, type):
+        allowed_keys = self.tui_config["key_bindings"][type]
+        return self._decode_keys(allowed_keys)
+
     def _do_quit(self):
         """Perform the actual quit after UI updates."""
         self.worker.stop()
@@ -644,7 +664,16 @@ def _get_suggestions(self, text: str) -> list[str]:
         suggestions = []
         commands = self.worker.coder.commands
 
-        if text.startswith("/"):
+        if len(text) and text[-1] == " ":
+            return
+
+        if "@" in text:
+            # Symbol completion triggered by @
+            # Find the @ and get the prefix after it
+            at_index = text.rfind("@")
+            prefix = text[at_index + 1 :]
+            suggestions = self._get_symbol_completions(prefix)
+        elif text.startswith("/"):
             # Command completion
             parts = text.split(maxsplit=1)
             cmd_part = parts[0]
@@ -661,7 +690,7 @@ def _get_suggestions(self, text: str) -> list[str]:
                 cmd_name = cmd_part
                 end_lookup = text.rsplit(maxsplit=1)
 
-                arg_prefix = end_lookup[1]
+                arg_prefix = end_lookup[-1]
                 arg_prefix_lower = arg_prefix.lower()
 
                 # Check if this command needs path-based completion
@@ -689,12 +718,6 @@ def _get_suggestions(self, text: str) -> list[str]:
                                 suggestions = list(cmd_completions)
                     except Exception:
                         pass
-        elif "@" in text:
-            # Symbol completion triggered by @
-            # Find the @ and get the prefix after it
-            at_index = text.rfind("@")
-            prefix = text[at_index + 1 :]
-            suggestions = self._get_symbol_completions(prefix)
         else:
             # Check if last contiguous, no-space separated string contains a forward slash
             # This allows path completions even without a leading slash
@@ -708,6 +731,34 @@ def _get_suggestions(self, text: str) -> list[str]:
 
         return [str(s) for s in suggestions[:50]]
 
+    def _get_completed_text(self, current_text: str, completion: str) -> str:
+        """Calculate the new text after applying completion."""
+        if current_text.startswith("/"):
+            parts = current_text.rsplit(maxsplit=1)
+            if len(parts) == 1:
+                # Replace entire command
+                # Only add space if command takes arguments
+                commands = self.worker.coder.commands
+                has_completions = commands.get_completions(completion) is not None
+                if has_completions:
+                    return completion + " "
+                else:
+                    return completion
+            else:
+                # Replace argument
+                return parts[0] + " " + completion
+        elif "@" in current_text:
+            # Replace from @ onwards with the symbol
+            at_index = current_text.rfind("@")
+            return current_text[:at_index] + completion + " "
+        else:
+            # Replace last word with completion
+            words = current_text.rsplit(maxsplit=1)
+            if len(words) > 1:
+                return words[0] + " " + completion
+            else:
+                return completion
+
     def on_input_area_completion_requested(self, message: InputArea.CompletionRequested):
         """Handle completion request - show or update completion bar."""
         input_area = self.query_one("#input", InputArea)
@@ -743,6 +794,13 @@ def on_input_area_completion_cycle(self, message: InputArea.CompletionCycle):
         try:
             completion_bar = self.query_one("#completion-bar", CompletionBar)
             completion_bar.cycle_next()
+            selected = completion_bar.current_selection
+            if selected:
+                input_area = self.query_one("#input", InputArea)
+                # Use completion_prefix as base
+                base_text = input_area.completion_prefix
+                new_text = self._get_completed_text(base_text, selected)
+                input_area.set_completion_preview(new_text)
         except Exception:
             pass
 
@@ -751,6 +809,13 @@ def on_input_area_completion_cycle_previous(self, message: InputArea.CompletionC
         try:
             completion_bar = self.query_one("#completion-bar", CompletionBar)
             completion_bar.cycle_previous()
+            selected = completion_bar.current_selection
+            if selected:
+                input_area = self.query_one("#input", InputArea)
+                # Use completion_prefix as base
+                base_text = input_area.completion_prefix
+                new_text = self._get_completed_text(base_text, selected)
+                input_area.set_completion_preview(new_text)
         except Exception:
             pass
 
@@ -775,37 +840,17 @@ def on_input_area_completion_dismiss(self, message: InputArea.CompletionDismiss)
     def on_completion_bar_selected(self, message: CompletionBar.Selected):
         """Handle completion selection."""
         input_area = self.query_one("#input", InputArea)
-        input_area.completion_active = False
 
-        # Insert the completion
-        current = input_area.value
+        # Use stored prefix as base for completion
+        current = input_area.completion_prefix
         selected = message.value
 
-        if current.startswith("/"):
-            parts = current.split(maxsplit=1)
-            if len(parts) == 1:
-                # Replace entire command
-                # Only add space if command takes arguments
-                commands = self.worker.coder.commands
-                has_completions = commands.get_completions(selected) is not None
-                if has_completions:
-                    input_area.value = selected + " "
-                else:
-                    input_area.value = selected
-            else:
-                # Replace argument
-                input_area.value = parts[0] + " " + selected
-        elif "@" in current:
-            # Replace from @ onwards with the symbol
-            at_index = current.rfind("@")
-            input_area.value = current[:at_index] + selected + " "
-        else:
-            # Replace last word with completion
-            words = current.rsplit(maxsplit=1)
-            if len(words) > 1:
-                input_area.value = words[0] + " " + selected
-            else:
-                input_area.value = selected
+        new_text = self._get_completed_text(current, selected)
+
+        # Reset cycling state so the new value is registered as the new prefix
+        input_area._cycling = False
+        input_area.value = new_text
+        input_area.completion_active = False
 
         input_area.focus()
         input_area.cursor_position = len(input_area.value)
@@ -813,5 +858,11 @@ def on_completion_bar_selected(self, message: CompletionBar.Selected):
     def on_completion_bar_dismissed(self, message: CompletionBar.Dismissed):
         """Handle completion bar dismissal."""
         input_area = self.query_one("#input", InputArea)
+
+        # Restore original text if we were cycling
+        if input_area._cycling:
+            input_area.value = input_area.completion_prefix
+            input_area._cycling = False
+
         input_area.completion_active = False
         input_area.focus()
diff --git a/aider/tui/io.py b/aider/tui/io.py
index 382453651f2..cf06f45012e 100644
--- a/aider/tui/io.py
+++ b/aider/tui/io.py
@@ -19,6 +19,9 @@ def __init__(self, output_queue, input_queue, **kwargs):
             input_queue: queue.Queue for receiving input from TUI
             **kwargs: Passed to InputOutput parent class
         """
+        # Lazy-initialized console for TUI rendering
+        self._tui_console = None
+
         # Initialize parent (fancy_input should already be False from caller)
         super().__init__(**kwargs)
 
@@ -26,9 +29,6 @@ def __init__(self, output_queue, input_queue, **kwargs):
         self.output_queue = output_queue
         self.input_queue = input_queue
 
-        # Lazy-initialized console for TUI rendering
-        self._tui_console = None
-
         # Current task tracking
         self.current_task_id = None
 
diff --git a/aider/tui/widgets/completion_bar.py b/aider/tui/widgets/completion_bar.py
index d4de302be37..a516f147f3e 100644
--- a/aider/tui/widgets/completion_bar.py
+++ b/aider/tui/widgets/completion_bar.py
@@ -93,6 +93,13 @@ def __init__(self, suggestions: list[str] = None, prefix: str = "", **kwargs):
         self._display_names: list[str] = []
         self._compute_display_names()
 
+    @property
+    def current_selection(self) -> str | None:
+        """Get currently selected suggestion."""
+        if self.suggestions and 0 <= self.selected_index < len(self.suggestions):
+            return self.suggestions[self.selected_index]
+        return None
+
     def _compute_display_names(self) -> None:
         """Compute common directory prefix and short display names."""
         if not self.suggestions:
diff --git a/aider/tui/widgets/input_area.py b/aider/tui/widgets/input_area.py
index 83a31002203..67b8da021bd 100644
--- a/aider/tui/widgets/input_area.py
+++ b/aider/tui/widgets/input_area.py
@@ -59,8 +59,8 @@ def __init__(self, history_file: str = None, **kwargs):
         # Let's assume kwargs might handle it or we set it.
         # Actually, let's just set the default if it's empty.
         if not self.placeholder:
-            submit = self.app._decode_keys(self.app.tui_config["key_bindings"]["submit"])
-            newline = self.app._decode_keys(self.app.tui_config["key_bindings"]["newline"])
+            submit = self.app.get_keys_for("submit")
+            newline = self.app.get_keys_for("newline")
 
             self.placeholder = (
                 f"> Type your message... ({submit} to submit, {newline} for new line)"
@@ -70,6 +70,9 @@ def __init__(self, history_file: str = None, **kwargs):
         self.commands = []
         self.completion_active = False
 
+        self._cycling = False
+        self._completion_prefix = ""
+
         # History support - lazy loaded
         self.history_file = history_file
         self._history: list[str] | None = None  # None = not loaded yet
@@ -81,10 +84,9 @@ def value(self) -> str:
         """Alias for text property to maintain compatibility."""
         return self.text
 
-    @value.setter
-    def value(self, new_value: str):
-        """Alias for text property to maintain compatibility."""
-        self.text = new_value
+    @property
+    def completion_prefix(self) -> str:
+        return self._completion_prefix
 
     @property
     def cursor_position(self) -> int:
@@ -100,6 +102,11 @@ def cursor_position(self) -> int:
         # So it uses setter.
         return 0  # Dummy getter
 
+    @value.setter
+    def value(self, new_value: str):
+        """Alias for text property to maintain compatibility."""
+        self.text = new_value
+
     @cursor_position.setter
     def cursor_position(self, pos: int):
         """
@@ -203,12 +210,28 @@ def _history_next(self) -> None:
 
         self.cursor_position = len(self.text)  # Will move to end
 
+    def set_completion_preview(self, text: str):
+        self._cycling = True
+        self.value = text
+        self.cursor_position = len(text)
+
     def on_key(self, event) -> None:
         """Handle keys for completion and history navigation."""
         if self.disabled:
             return
 
-        if event.key == self.app.tui_config["key_bindings"]["cancel"]:
+        # Reset cycling if not a cycle command
+        is_cycle = self.app.is_key_for("cycle_forward", event.key) or self.app.is_key_for(
+            "cycle_backward", event.key
+        )
+        if not is_cycle:
+            self._cycling = False
+
+        if event.key == "space" and self.completion_active:
+            self.completion_active = False
+            self.post_message(self.CompletionDismiss())
+
+        if self.app.is_key_for("cancel", event.key):
             event.stop()
             event.prevent_default()
             if self.text.strip():
@@ -216,30 +239,23 @@ def on_key(self, event) -> None:
             self.text = ""
             return
 
-        if event.key == self.app.tui_config["key_bindings"]["submit"]:
+        if self.app.is_key_for("submit", event.key):
             # Submit message
             event.stop()
             event.prevent_default()
             self.post_message(self.Submit(self.text))
             return
 
-        if event.key == self.app.tui_config["key_bindings"]["newline"]:
-            if self.completion_active:
-                # Accept completion
-                self.post_message(self.CompletionAccept())
-                event.stop()
-                event.prevent_default()
-                return
-            else:
-                if self.app.tui_config["key_bindings"]["newline"] != "enter":
-                    self.insert("\n")
+        if self.app.is_key_for("newline", event.key):
+            if self.app.get_keys_for("newline") != "enter":
+                self.insert("\n")
 
-                    current_row, current_col = self.cursor_location
-                    self.cursor_location = (current_row + 1, 0)
+                current_row, current_col = self.cursor_location
+                self.cursor_location = (current_row + 1, 0)
 
-                return
+            return
 
-        if event.key == self.app.tui_config["key_bindings"]["cycle_forward"]:
+        if self.app.is_key_for("cycle_forward", event.key):
             event.stop()
             event.prevent_default()
             if self.completion_active:
@@ -248,7 +264,7 @@ def on_key(self, event) -> None:
             else:
                 # Request completions
                 self.post_message(self.CompletionRequested(self.text))
-        elif event.key == self.app.tui_config["key_bindings"]["cycle_backward"]:
+        elif self.app.is_key_for("cycle_backward", event.key):
             event.stop()
             event.prevent_default()
             if self.completion_active:
@@ -257,7 +273,7 @@ def on_key(self, event) -> None:
             else:
                 # Request completions
                 self.post_message(self.CompletionRequested(self.text))
-        elif event.key == self.app.tui_config["key_bindings"]["stop"] and self.completion_active:
+        elif self.app.is_key_for("stop", event.key) and self.completion_active:
             event.stop()
             event.prevent_default()
             self.post_message(self.CompletionDismiss())
@@ -280,6 +296,14 @@ def on_key(self, event) -> None:
     def on_text_area_changed(self, event) -> None:
         """Update completions as user types."""
         # Note: Event name for TextArea change is 'Changed' but handler is on_text_area_changed
+        if self.disabled:
+            return
+
+        if self._cycling:
+            return
+
+        self._completion_prefix = self.text
+
         if not self.disabled:
             val = self.text
             possible_path = False
diff --git a/aider/website/docs/config/tui.md b/aider/website/docs/config/tui.md
index f394afc41e1..7843a3681cb 100644
--- a/aider/website/docs/config/tui.md
+++ b/aider/website/docs/config/tui.md
@@ -48,6 +48,7 @@ tui-config:
   key_bindings:
     newline: "enter"
     submit: "shift+enter"
+    completion: "tab"
     stop: "escape"
     cycle_forward: "tab"
     cycle_backward: "shift+tab"
diff --git a/tests/basic/test_sessions.py b/tests/basic/test_sessions.py
index 2b24607e831..c08e123ab5a 100644
--- a/tests/basic/test_sessions.py
+++ b/tests/basic/test_sessions.py
@@ -252,7 +252,7 @@ async def test_preserve_todo_list_deprecated(self):
 
             io = InputOutput(pretty=False, fancy_input=False, yes=True)
             with mock.patch.object(io, "tool_warning") as mock_tool_warning:
-                await Coder.create(self.GPT35, None, io, preserve_todo_list=True)
+                await Coder.create(self.GPT35, None, io)
 
             self.assertFalse(todo_path.exists())
             self.assertTrue(