diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index ba71596ecd..57711362ff 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -605,6 +605,17 @@ dependencies = [
  "tree-sitter-bash",
 ]
 
+[[package]]
+name = "codex-arg0"
+version = "0.0.0"
+dependencies = [
+ "anyhow",
+ "codex-core",
+ "codex-linux-sandbox",
+ "dotenvy",
+ "tokio",
+]
+
 [[package]]
 name = "codex-chatgpt"
 version = "0.0.0"
@@ -628,11 +639,11 @@ dependencies = [
  "anyhow",
  "clap",
  "clap_complete",
+ "codex-arg0",
  "codex-chatgpt",
  "codex-common",
  "codex-core",
  "codex-exec",
- "codex-linux-sandbox",
  "codex-login",
  "codex-mcp-server",
  "codex-tui",
@@ -709,9 +720,9 @@ dependencies = [
  "anyhow",
  "chrono",
  "clap",
+ "codex-arg0",
  "codex-common",
  "codex-core",
- "codex-linux-sandbox",
  "owo-colors",
  "serde_json",
  "shlex",
@@ -761,7 +772,6 @@ dependencies = [
  "clap",
  "codex-common",
  "codex-core",
- "dotenvy",
  "landlock",
  "libc",
  "seccompiler",
@@ -799,8 +809,8 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
+ "codex-arg0",
  "codex-core",
- "codex-linux-sandbox",
  "mcp-types",
  "mcp_test_support",
  "pretty_assertions",
@@ -826,10 +836,10 @@ dependencies = [
  "base64 0.22.1",
  "clap",
  "codex-ansi-escape",
+ "codex-arg0",
  "codex-common",
  "codex-core",
  "codex-file-search",
- "codex-linux-sandbox",
  "codex-login",
  "color-eyre",
  "crossterm",
diff --git a/codex-rs/Cargo.toml b/codex-rs/Cargo.toml
index eba43e548b..190256c211 100644
--- a/codex-rs/Cargo.toml
+++ b/codex-rs/Cargo.toml
@@ -3,6 +3,7 @@ resolver = "2"
 members = [
     "ansi-escape",
     "apply-patch",
+    "arg0",
     "cli",
     "common",
     "core",
diff --git a/codex-rs/arg0/Cargo.toml b/codex-rs/arg0/Cargo.toml
new file mode 100644
index 0000000000..9ad1896746
--- /dev/null
+++ b/codex-rs/arg0/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "codex-arg0"
+version = { workspace = true }
+edition = "2024"
+
+[lib]
+name = "codex_arg0"
+path = "src/lib.rs"
+
+[lints]
+workspace = true
+
+[dependencies]
+anyhow = "1"
+codex-core = { path = "../core" }
+codex-linux-sandbox = { path = "../linux-sandbox" }
+dotenvy = "0.15.7"
+tokio = { version = "1", features = ["rt-multi-thread"] }
diff --git a/codex-rs/linux-sandbox/src/lib.rs b/codex-rs/arg0/src/lib.rs
similarity index 84%
rename from codex-rs/linux-sandbox/src/lib.rs
rename to codex-rs/arg0/src/lib.rs
index 960678467c..221f86f01a 100644
--- a/codex-rs/linux-sandbox/src/lib.rs
+++ b/codex-rs/arg0/src/lib.rs
@@ -1,11 +1,3 @@
-#[cfg(target_os = "linux")]
-mod landlock;
-#[cfg(target_os = "linux")]
-mod linux_run_main;
-
-#[cfg(target_os = "linux")]
-pub use linux_run_main::run_main;
-
 use std::future::Future;
 use std::path::PathBuf;
 
@@ -24,7 +16,7 @@ use std::path::PathBuf;
 ///
 /// This function eliminates duplicated code across the various `main.rs`
 /// entry-points.
-pub fn run_with_sandbox<F, Fut>(main_fn: F) -> anyhow::Result<()>
+pub fn arg0_dispatch_or_else<F, Fut>(main_fn: F) -> anyhow::Result<()>
 where
     F: FnOnce(Option<PathBuf>) -> Fut,
     Fut: Future<Output = anyhow::Result<()>>,
@@ -40,7 +32,7 @@ where
 
     if exe_name == "codex-linux-sandbox" {
         // Safety: [`run_main`] never returns.
-        crate::run_main();
+        codex_linux_sandbox::run_main();
     }
 
     // This modifies the environment, which is not thread-safe, so do this
@@ -61,11 +53,6 @@ where
     })
 }
 
-#[cfg(not(target_os = "linux"))]
-pub fn run_main() -> ! {
-    panic!("codex-linux-sandbox is only supported on Linux");
-}
-
 /// Load env vars from ~/.codex/.env and `$(pwd)/.env`.
 fn load_dotenv() {
     if let Ok(codex_home) = codex_core::config::find_codex_home() {
diff --git a/codex-rs/cli/Cargo.toml b/codex-rs/cli/Cargo.toml
index 943788157b..ab98764bed 100644
--- a/codex-rs/cli/Cargo.toml
+++ b/codex-rs/cli/Cargo.toml
@@ -18,12 +18,12 @@ workspace = true
 anyhow = "1"
 clap = { version = "4", features = ["derive"] }
 clap_complete = "4"
+codex-arg0 = { path = "../arg0" }
 codex-chatgpt = { path = "../chatgpt" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = ["cli"] }
 codex-exec = { path = "../exec" }
 codex-login = { path = "../login" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 codex-mcp-server = { path = "../mcp-server" }
 codex-tui = { path = "../tui" }
 serde_json = "1"
diff --git a/codex-rs/cli/src/main.rs b/codex-rs/cli/src/main.rs
index 7916a7dc79..efda03bda4 100644
--- a/codex-rs/cli/src/main.rs
+++ b/codex-rs/cli/src/main.rs
@@ -2,6 +2,7 @@ use clap::CommandFactory;
 use clap::Parser;
 use clap_complete::Shell;
 use clap_complete::generate;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_chatgpt::apply_command::ApplyCommand;
 use codex_chatgpt::apply_command::run_apply_command;
 use codex_cli::LandlockCommand;
@@ -92,7 +93,7 @@ struct LoginCommand {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         cli_main(codex_linux_sandbox_exe).await?;
         Ok(())
     })
diff --git a/codex-rs/exec/Cargo.toml b/codex-rs/exec/Cargo.toml
index ed01b78ec8..c9d94deb5a 100644
--- a/codex-rs/exec/Cargo.toml
+++ b/codex-rs/exec/Cargo.toml
@@ -18,13 +18,13 @@ workspace = true
 anyhow = "1"
 chrono = "0.4.40"
 clap = { version = "4", features = ["derive"] }
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = [
     "cli",
     "elapsed",
     "sandbox_summary",
 ] }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 owo-colors = "4.2.0"
 serde_json = "1"
 shlex = "1.3.0"
diff --git a/codex-rs/exec/src/main.rs b/codex-rs/exec/src/main.rs
index 3a8e1f9411..03ee533ea9 100644
--- a/codex-rs/exec/src/main.rs
+++ b/codex-rs/exec/src/main.rs
@@ -10,6 +10,7 @@
 //! This allows us to ship a completely separate set of functionality as part
 //! of the `codex-exec` binary.
 use clap::Parser;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_common::CliConfigOverrides;
 use codex_exec::Cli;
 use codex_exec::run_main;
@@ -24,7 +25,7 @@ struct TopCli {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         let top_cli = TopCli::parse();
         // Merge root-level overrides into inner CLI struct so downstream logic remains unchanged.
         let mut inner = top_cli.inner;
diff --git a/codex-rs/linux-sandbox/Cargo.toml b/codex-rs/linux-sandbox/Cargo.toml
index 5c2dea6083..4b173ea17a 100644
--- a/codex-rs/linux-sandbox/Cargo.toml
+++ b/codex-rs/linux-sandbox/Cargo.toml
@@ -14,15 +14,16 @@ path = "src/lib.rs"
 [lints]
 workspace = true
 
-[dependencies]
+[target.'cfg(target_os = "linux")'.dependencies]
 anyhow = "1"
 clap = { version = "4", features = ["derive"] }
 codex-common = { path = "../common", features = ["cli"] }
 codex-core = { path = "../core" }
-dotenvy = "0.15.7"
-tokio = { version = "1", features = ["rt-multi-thread"] }
+libc = "0.2.172"
+landlock = "0.4.1"
+seccompiler = "0.5.0"
 
-[dev-dependencies]
+[target.'cfg(target_os = "linux")'.dev-dependencies]
 tempfile = "3"
 tokio = { version = "1", features = [
     "io-std",
@@ -31,8 +32,3 @@ tokio = { version = "1", features = [
     "rt-multi-thread",
     "signal",
 ] }
-
-[target.'cfg(target_os = "linux")'.dependencies]
-libc = "0.2.172"
-landlock = "0.4.1"
-seccompiler = "0.5.0"
diff --git a/codex-rs/mcp-server/Cargo.toml b/codex-rs/mcp-server/Cargo.toml
index 1088b92481..488ee6a67c 100644
--- a/codex-rs/mcp-server/Cargo.toml
+++ b/codex-rs/mcp-server/Cargo.toml
@@ -16,8 +16,8 @@ workspace = true
 
 [dependencies]
 anyhow = "1"
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 mcp-types = { path = "../mcp-types" }
 schemars = "0.8.22"
 serde = { version = "1", features = ["derive"] }
diff --git a/codex-rs/mcp-server/src/main.rs b/codex-rs/mcp-server/src/main.rs
index 51c46c44d2..60ddeeab41 100644
--- a/codex-rs/mcp-server/src/main.rs
+++ b/codex-rs/mcp-server/src/main.rs
@@ -1,7 +1,8 @@
+use codex_arg0::arg0_dispatch_or_else;
 use codex_mcp_server::run_main;
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         run_main(codex_linux_sandbox_exe).await?;
         Ok(())
     })
diff --git a/codex-rs/tui/Cargo.toml b/codex-rs/tui/Cargo.toml
index 9d73e3b386..9161cfbb35 100644
--- a/codex-rs/tui/Cargo.toml
+++ b/codex-rs/tui/Cargo.toml
@@ -19,6 +19,7 @@ anyhow = "1"
 base64 = "0.22.1"
 clap = { version = "4", features = ["derive"] }
 codex-ansi-escape = { path = "../ansi-escape" }
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = [
     "cli",
@@ -26,7 +27,6 @@ codex-common = { path = "../common", features = [
     "sandbox_summary",
 ] }
 codex-file-search = { path = "../file-search" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 codex-login = { path = "../login" }
 color-eyre = "0.6.3"
 crossterm = { version = "0.28.1", features = ["bracketed-paste"] }
diff --git a/codex-rs/tui/src/bottom_pane/chat_composer.rs b/codex-rs/tui/src/bottom_pane/chat_composer.rs
index bdfb6a23e2..6a1bb526ce 100644
--- a/codex-rs/tui/src/bottom_pane/chat_composer.rs
+++ b/codex-rs/tui/src/bottom_pane/chat_composer.rs
@@ -127,10 +127,6 @@ impl ChatComposer<'_> {
             .on_entry_response(log_id, offset, entry, &mut self.textarea)
     }
 
-    pub fn set_input_focus(&mut self, has_focus: bool) {
-        self.update_border(has_focus);
-    }
-
     pub fn handle_paste(&mut self, pasted: String) -> bool {
         let char_count = pasted.chars().count();
         if char_count > LARGE_PASTE_CHAR_THRESHOLD {
@@ -638,13 +634,6 @@ impl ChatComposer<'_> {
                 .border_style(bs.border_style),
         );
     }
-
-    pub(crate) fn is_popup_visible(&self) -> bool {
-        match self.active_popup {
-            ActivePopup::Command(_) | ActivePopup::File(_) => true,
-            ActivePopup::None => false,
-        }
-    }
 }
 
 impl WidgetRef for &ChatComposer<'_> {
diff --git a/codex-rs/tui/src/bottom_pane/mod.rs b/codex-rs/tui/src/bottom_pane/mod.rs
index ebec534f21..0ddb36f635 100644
--- a/codex-rs/tui/src/bottom_pane/mod.rs
+++ b/codex-rs/tui/src/bottom_pane/mod.rs
@@ -104,12 +104,6 @@ impl BottomPane<'_> {
         }
     }
 
-    /// Update the UI to reflect whether this `BottomPane` has input focus.
-    pub(crate) fn set_input_focus(&mut self, has_focus: bool) {
-        self.has_input_focus = has_focus;
-        self.composer.set_input_focus(has_focus);
-    }
-
     pub(crate) fn show_ctrl_c_quit_hint(&mut self) {
         self.ctrl_c_quit_hint = true;
         self.composer
@@ -203,11 +197,6 @@ impl BottomPane<'_> {
         self.app_event_tx.send(AppEvent::RequestRedraw)
     }
 
-    /// Returns true when a popup inside the composer is visible.
-    pub(crate) fn is_popup_visible(&self) -> bool {
-        self.active_view.is_none() && self.composer.is_popup_visible()
-    }
-
     // --- History helpers ---
 
     pub(crate) fn set_history_metadata(&mut self, log_id: u64, entry_count: usize) {
diff --git a/codex-rs/tui/src/chatwidget.rs b/codex-rs/tui/src/chatwidget.rs
index 6ca8d4c4be..5e839d1419 100644
--- a/codex-rs/tui/src/chatwidget.rs
+++ b/codex-rs/tui/src/chatwidget.rs
@@ -45,7 +45,6 @@ pub(crate) struct ChatWidget<'a> {
     codex_op_tx: UnboundedSender<Op>,
     conversation_history: ConversationHistoryWidget,
     bottom_pane: BottomPane<'a>,
-    input_focus: InputFocus,
     config: Config,
     initial_user_message: Option<UserMessage>,
     token_usage: TokenUsage,
@@ -56,12 +55,6 @@ pub(crate) struct ChatWidget<'a> {
     answer_buffer: String,
 }
 
-#[derive(Clone, Copy, Eq, PartialEq)]
-enum InputFocus {
-    HistoryPane,
-    BottomPane,
-}
-
 struct UserMessage {
     text: String,
     image_paths: Vec<PathBuf>,
@@ -137,7 +130,6 @@ impl ChatWidget<'_> {
                 app_event_tx,
                 has_input_focus: true,
             }),
-            input_focus: InputFocus::BottomPane,
             config,
             initial_user_message: create_initial_user_message(
                 initial_prompt.unwrap_or_default(),
@@ -151,44 +143,17 @@ impl ChatWidget<'_> {
 
     pub(crate) fn handle_key_event(&mut self, key_event: KeyEvent) {
         self.bottom_pane.clear_ctrl_c_quit_hint();
-        // Special-case <Tab>: normally toggles focus between history and bottom panes.
-        // However, when the slash-command popup is visible we forward the key
-        // to the bottom pane so it can handle auto-completion.
-        if matches!(key_event.code, crossterm::event::KeyCode::Tab)
-            && !self.bottom_pane.is_popup_visible()
-        {
-            self.input_focus = match self.input_focus {
-                InputFocus::HistoryPane => InputFocus::BottomPane,
-                InputFocus::BottomPane => InputFocus::HistoryPane,
-            };
-            self.conversation_history
-                .set_input_focus(self.input_focus == InputFocus::HistoryPane);
-            self.bottom_pane
-                .set_input_focus(self.input_focus == InputFocus::BottomPane);
-            self.request_redraw();
-            return;
-        }
 
-        match self.input_focus {
-            InputFocus::HistoryPane => {
-                let needs_redraw = self.conversation_history.handle_key_event(key_event);
-                if needs_redraw {
-                    self.request_redraw();
-                }
+        match self.bottom_pane.handle_key_event(key_event) {
+            InputResult::Submitted(text) => {
+                self.submit_user_message(text.into());
             }
-            InputFocus::BottomPane => match self.bottom_pane.handle_key_event(key_event) {
-                InputResult::Submitted(text) => {
-                    self.submit_user_message(text.into());
-                }
-                InputResult::None => {}
-            },
+            InputResult::None => {}
         }
     }
 
     pub(crate) fn handle_paste(&mut self, text: String) {
-        if matches!(self.input_focus, InputFocus::BottomPane) {
-            self.bottom_pane.handle_paste(text);
-        }
+        self.bottom_pane.handle_paste(text);
     }
 
     /// Emits the last entry's plain lines from conversation_history, if any.
diff --git a/codex-rs/tui/src/conversation_history_widget.rs b/codex-rs/tui/src/conversation_history_widget.rs
index d8035eff64..dede0caf5f 100644
--- a/codex-rs/tui/src/conversation_history_widget.rs
+++ b/codex-rs/tui/src/conversation_history_widget.rs
@@ -5,8 +5,6 @@ use crate::history_cell::PatchEventType;
 use codex_core::config::Config;
 use codex_core::protocol::FileChange;
 use codex_core::protocol::SessionConfiguredEvent;
-use crossterm::event::KeyCode;
-use crossterm::event::KeyEvent;
 use ratatui::prelude::*;
 use ratatui::style::Style;
 use ratatui::widgets::*;
@@ -47,33 +45,6 @@ impl ConversationHistoryWidget {
         }
     }
 
-    pub(crate) fn set_input_focus(&mut self, has_input_focus: bool) {
-        self.has_input_focus = has_input_focus;
-    }
-
-    /// Returns true if it needs a redraw.
-    pub(crate) fn handle_key_event(&mut self, key_event: KeyEvent) -> bool {
-        match key_event.code {
-            KeyCode::Up | KeyCode::Char('k') => {
-                self.scroll_up(1);
-                true
-            }
-            KeyCode::Down | KeyCode::Char('j') => {
-                self.scroll_down(1);
-                true
-            }
-            KeyCode::PageUp | KeyCode::Char('b') => {
-                self.scroll_page_up();
-                true
-            }
-            KeyCode::PageDown | KeyCode::Char(' ') => {
-                self.scroll_page_down();
-                true
-            }
-            _ => false,
-        }
-    }
-
     /// Negative delta scrolls up; positive delta scrolls down.
     pub(crate) fn scroll(&mut self, delta: i32) {
         match delta.cmp(&0) {
@@ -122,53 +93,6 @@ impl ConversationHistoryWidget {
         }
     }
 
-    /// Scroll up by one full viewport height (Page Up).
-    fn scroll_page_up(&mut self) {
-        let viewport_height = self.last_viewport_height.get().max(1);
-
-        // If we are currently in the "stick to bottom" mode, first convert the
-        // implicit scroll position (`usize::MAX`) into an explicit offset that
-        // represents the very bottom of the scroll region.  This mirrors the
-        // logic from `scroll_up()`.
-        if self.scroll_position == usize::MAX {
-            self.scroll_position = self
-                .num_rendered_lines
-                .get()
-                .saturating_sub(viewport_height);
-        }
-
-        // Move up by a full page.
-        self.scroll_position = self.scroll_position.saturating_sub(viewport_height);
-    }
-
-    /// Scroll down by one full viewport height (Page Down).
-    fn scroll_page_down(&mut self) {
-        // Nothing to do if we're already stuck to the bottom.
-        if self.scroll_position == usize::MAX {
-            return;
-        }
-
-        let viewport_height = self.last_viewport_height.get().max(1);
-        let num_lines = self.num_rendered_lines.get();
-
-        // Calculate the maximum explicit scroll offset that is still within
-        // range. This matches the logic in `scroll_down()` and the render
-        // method.
-        let max_scroll = num_lines.saturating_sub(viewport_height);
-
-        // Attempt to move down by a full page.
-        let new_pos = self.scroll_position.saturating_add(viewport_height);
-
-        if new_pos >= max_scroll {
-            // We have reached (or passed) the bottom – switch back to
-            // automatic stick‑to‑bottom mode so that subsequent output keeps
-            // the viewport pinned.
-            self.scroll_position = usize::MAX;
-        } else {
-            self.scroll_position = new_pos;
-        }
-    }
-
     pub fn scroll_to_bottom(&mut self) {
         self.scroll_position = usize::MAX;
     }
diff --git a/codex-rs/tui/src/main.rs b/codex-rs/tui/src/main.rs
index fdb3cdaf82..480e56e88e 100644
--- a/codex-rs/tui/src/main.rs
+++ b/codex-rs/tui/src/main.rs
@@ -1,4 +1,5 @@
 use clap::Parser;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_common::CliConfigOverrides;
 use codex_tui::Cli;
 use codex_tui::run_main;
@@ -13,7 +14,7 @@ struct TopCli {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         let top_cli = TopCli::parse();
         let mut inner = top_cli.inner;
         inner