diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 32b41c0227..d00aa45456 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -1664,6 +1664,7 @@ dependencies = [
  "codex-rmcp-client",
  "codex-state",
  "codex-stdio-to-uds",
+ "codex-terminal-detection",
  "codex-tui",
  "codex-tui-app-server",
  "codex-utils-cargo-bin",
@@ -1858,6 +1859,7 @@ dependencies = [
  "codex-shell-escalation",
  "codex-skills",
  "codex-state",
+ "codex-terminal-detection",
  "codex-test-macros",
  "codex-utils-absolute-path",
  "codex-utils-cache",
@@ -2507,6 +2509,14 @@ dependencies = [
  "uds_windows",
 ]
 
+[[package]]
+name = "codex-terminal-detection"
+version = "0.0.0"
+dependencies = [
+ "pretty_assertions",
+ "tracing",
+]
+
 [[package]]
 name = "codex-test-macros"
 version = "0.0.0"
@@ -2542,6 +2552,7 @@ dependencies = [
  "codex-protocol",
  "codex-shell-command",
  "codex-state",
+ "codex-terminal-detection",
  "codex-tui-app-server",
  "codex-utils-absolute-path",
  "codex-utils-approval-presets",
@@ -2633,6 +2644,7 @@ dependencies = [
  "codex-protocol",
  "codex-shell-command",
  "codex-state",
+ "codex-terminal-detection",
  "codex-utils-absolute-path",
  "codex-utils-approval-presets",
  "codex-utils-cargo-bin",
@@ -5815,6 +5827,7 @@ dependencies = [
  "anyhow",
  "codex-core",
  "codex-mcp-server",
+ "codex-terminal-detection",
  "codex-utils-cargo-bin",
  "core_test_support",
  "os_info",
diff --git a/codex-rs/Cargo.toml b/codex-rs/Cargo.toml
index edcd98fbb1..961c4ef9f9 100644
--- a/codex-rs/Cargo.toml
+++ b/codex-rs/Cargo.toml
@@ -66,6 +66,7 @@ members = [
     "codex-client",
     "codex-api",
     "state",
+    "terminal-detection",
     "codex-experimental-api-macros",
     "test-macros",
     "package-manager",
@@ -131,6 +132,7 @@ codex-skills = { path = "skills" }
 codex-state = { path = "state" }
 codex-stdio-to-uds = { path = "stdio-to-uds" }
 codex-test-macros = { path = "test-macros" }
+codex-terminal-detection = { path = "terminal-detection" }
 codex-tui = { path = "tui" }
 codex-tui-app-server = { path = "tui_app_server" }
 codex-utils-absolute-path = { path = "utils/absolute-path" }
diff --git a/codex-rs/cli/Cargo.toml b/codex-rs/cli/Cargo.toml
index a7e88cd1b4..affc5ef8c2 100644
--- a/codex-rs/cli/Cargo.toml
+++ b/codex-rs/cli/Cargo.toml
@@ -37,6 +37,7 @@ codex-responses-api-proxy = { workspace = true }
 codex-rmcp-client = { workspace = true }
 codex-state = { workspace = true }
 codex-stdio-to-uds = { workspace = true }
+codex-terminal-detection = { workspace = true }
 codex-tui = { workspace = true }
 codex-tui-app-server = { workspace = true }
 libc = { workspace = true }
diff --git a/codex-rs/cli/src/main.rs b/codex-rs/cli/src/main.rs
index 9386398284..e9f4d6f686 100644
--- a/codex-rs/cli/src/main.rs
+++ b/codex-rs/cli/src/main.rs
@@ -50,7 +50,7 @@ use codex_core::config::edit::ConfigEditsBuilder;
 use codex_core::config::find_codex_home;
 use codex_core::features::Stage;
 use codex_core::features::is_known_feature_key;
-use codex_core::terminal::TerminalName;
+use codex_terminal_detection::TerminalName;
 
 /// Codex CLI
 ///
@@ -1049,7 +1049,7 @@ async fn run_interactive_tui(
         interactive.prompt = Some(prompt.replace("\r\n", "\n").replace('\r', "\n"));
     }
 
-    let terminal_info = codex_core::terminal::terminal_info();
+    let terminal_info = codex_terminal_detection::terminal_info();
     if terminal_info.name == TerminalName::Dumb {
         if !(std::io::stdin().is_terminal() && std::io::stderr().is_terminal()) {
             return Ok(AppExitInfo::fatal(
diff --git a/codex-rs/core/Cargo.toml b/codex-rs/core/Cargo.toml
index a44da5e111..869f9dd9f4 100644
--- a/codex-rs/core/Cargo.toml
+++ b/codex-rs/core/Cargo.toml
@@ -48,6 +48,7 @@ codex-artifacts = { workspace = true }
 codex-protocol = { workspace = true }
 codex-rmcp-client = { workspace = true }
 codex-state = { workspace = true }
+codex-terminal-detection = { workspace = true }
 codex-utils-absolute-path = { workspace = true }
 codex-utils-cache = { workspace = true }
 codex-utils-image = { workspace = true }
diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index 9e76297a0d..c248c0f0de 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -49,7 +49,6 @@ use crate::stream_events_utils::handle_output_item_done;
 use crate::stream_events_utils::last_assistant_message_from_item;
 use crate::stream_events_utils::raw_assistant_output_text_from_item;
 use crate::stream_events_utils::record_completed_response_item;
-use crate::terminal;
 use crate::truncate::TruncationPolicy;
 use crate::turn_metadata::TurnMetadataState;
 use crate::util::error_or_panic;
@@ -118,6 +117,7 @@ use codex_protocol::request_user_input::RequestUserInputArgs;
 use codex_protocol::request_user_input::RequestUserInputResponse;
 use codex_rmcp_client::ElicitationResponse;
 use codex_rmcp_client::OAuthCredentialsStoreMode;
+use codex_terminal_detection::user_agent;
 use codex_utils_stream_parser::AssistantTextChunk;
 use codex_utils_stream_parser::AssistantTextStreamParser;
 use codex_utils_stream_parser::ProposedPlanSegment;
@@ -1594,7 +1594,7 @@ impl Session {
         let account_id = auth.and_then(CodexAuth::get_account_id);
         let account_email = auth.and_then(CodexAuth::get_account_email);
         let originator = crate::default_client::originator().value;
-        let terminal_type = terminal::user_agent();
+        let terminal_type = user_agent();
         let session_model = session_configuration.collaboration_mode.model().to_string();
         let auth_env_telemetry = collect_auth_env_telemetry(
             &session_configuration.provider,
diff --git a/codex-rs/core/src/default_client.rs b/codex-rs/core/src/default_client.rs
index 3ca653ba46..59c7bd2fb9 100644
--- a/codex-rs/core/src/default_client.rs
+++ b/codex-rs/core/src/default_client.rs
@@ -4,6 +4,7 @@ use codex_client::BuildCustomCaTransportError;
 use codex_client::CodexHttpClient;
 pub use codex_client::CodexRequestBuilder;
 use codex_client::build_reqwest_client_with_custom_ca;
+use codex_terminal_detection::user_agent;
 use reqwest::header::HeaderMap;
 use reqwest::header::HeaderValue;
 use std::sync::LazyLock;
@@ -130,7 +131,7 @@ pub fn get_codex_user_agent() -> String {
         os_info.os_type(),
         os_info.version(),
         os_info.architecture().unwrap_or("unknown"),
-        crate::terminal::user_agent()
+        user_agent()
     );
     let suffix = USER_AGENT_SUFFIX
         .lock()
diff --git a/codex-rs/core/src/lib.rs b/codex-rs/core/src/lib.rs
index 10a51b23ec..6d519f488f 100644
--- a/codex-rs/core/src/lib.rs
+++ b/codex-rs/core/src/lib.rs
@@ -120,7 +120,6 @@ pub mod shell_snapshot;
 pub mod skills;
 pub mod spawn;
 pub mod state_db;
-pub mod terminal;
 mod tools;
 pub mod turn_diff_tracker;
 mod turn_metadata;
diff --git a/codex-rs/core/src/tools/spec.rs b/codex-rs/core/src/tools/spec.rs
index 8992eb4456..a91e95bbe5 100644
--- a/codex-rs/core/src/tools/spec.rs
+++ b/codex-rs/core/src/tools/spec.rs
@@ -587,6 +587,12 @@ fn create_request_permissions_schema() -> JsonSchema {
     }
 }
 
+fn windows_destructive_filesystem_guidance() -> &'static str {
+    r#"Windows safety rules:
+- Do not compose destructive filesystem commands across shells. Do not enumerate paths in PowerShell and then pass them to `cmd /c`, batch builtins, or another shell for deletion or moving. Use one shell end-to-end, prefer native PowerShell cmdlets such as `Remove-Item` / `Move-Item` with `-LiteralPath`, and avoid string-built shell commands for file operations.
+- Before any recursive delete or move on Windows, verify the resolved absolute target paths stay within the intended workspace or explicitly named target directory. Never issue a recursive delete or move against a computed path if the final target has not been checked."#
+}
+
 fn create_approval_parameters(
     exec_permission_approvals_enabled: bool,
 ) -> BTreeMap<String, JsonSchema> {
@@ -709,9 +715,15 @@ fn create_exec_command_tool(
 
     ToolSpec::Function(ResponsesApiTool {
         name: "exec_command".to_string(),
-        description:
+        description: if cfg!(windows) {
+            format!(
+                "Runs a command in a PTY, returning output or a session ID for ongoing interaction.\n\n{}",
+                windows_destructive_filesystem_guidance()
+            )
+        } else {
             "Runs a command in a PTY, returning output or a session ID for ongoing interaction."
-                .to_string(),
+                .to_string()
+        },
         strict: false,
         defer_loading: None,
         parameters: JsonSchema::Object {
@@ -848,22 +860,28 @@ fn create_shell_tool(exec_permission_approvals_enabled: bool) -> ToolSpec {
         exec_permission_approvals_enabled,
     ));
 
-    let description  = if cfg!(windows) {
-        r#"Runs a Powershell command (Windows) and returns its output. Arguments to `shell` will be passed to CreateProcessW(). Most commands should be prefixed with ["powershell.exe", "-Command"].
+    let description = if cfg!(windows) {
+        format!(
+            r#"Runs a Powershell command (Windows) and returns its output. Arguments to `shell` will be passed to CreateProcessW(). Most commands should be prefixed with ["powershell.exe", "-Command"].
 
 Examples of valid command strings:
 
 - ls -a (show hidden): ["powershell.exe", "-Command", "Get-ChildItem -Force"]
 - recursive find by name: ["powershell.exe", "-Command", "Get-ChildItem -Recurse -Filter *.py"]
 - recursive grep: ["powershell.exe", "-Command", "Get-ChildItem -Path C:\\myrepo -Recurse | Select-String -Pattern 'TODO' -CaseSensitive"]
-- ps aux | grep python: ["powershell.exe", "-Command", "Get-Process | Where-Object { $_.ProcessName -like '*python*' }"]
+- ps aux | grep python: ["powershell.exe", "-Command", "Get-Process | Where-Object {{ $_.ProcessName -like '*python*' }}"]
 - setting an env var: ["powershell.exe", "-Command", "$env:FOO='bar'; echo $env:FOO"]
-- running an inline Python script: ["powershell.exe", "-Command", "@'\\nprint('Hello, world!')\\n'@ | python -"]"#
+- running an inline Python script: ["powershell.exe", "-Command", "@'\\nprint('Hello, world!')\\n'@ | python -"]
+
+{}"#,
+            windows_destructive_filesystem_guidance()
+        )
     } else {
         r#"Runs a shell command and returns its output.
 - The arguments to `shell` will be passed to execvp(). Most terminal commands should be prefixed with ["bash", "-lc"].
 - Always set the `workdir` param when using the shell function. Do not use `cd` unless absolutely necessary."#
-    }.to_string();
+            .to_string()
+    };
 
     ToolSpec::Function(ResponsesApiTool {
         name: "shell".to_string(),
@@ -921,20 +939,26 @@ fn create_shell_command_tool(
     ));
 
     let description = if cfg!(windows) {
-        r#"Runs a Powershell command (Windows) and returns its output.
+        format!(
+            r#"Runs a Powershell command (Windows) and returns its output.
 
 Examples of valid command strings:
 
 - ls -a (show hidden): "Get-ChildItem -Force"
 - recursive find by name: "Get-ChildItem -Recurse -Filter *.py"
 - recursive grep: "Get-ChildItem -Path C:\\myrepo -Recurse | Select-String -Pattern 'TODO' -CaseSensitive"
-- ps aux | grep python: "Get-Process | Where-Object { $_.ProcessName -like '*python*' }"
+- ps aux | grep python: "Get-Process | Where-Object {{ $_.ProcessName -like '*python*' }}"
 - setting an env var: "$env:FOO='bar'; echo $env:FOO"
-- running an inline Python script: "@'\\nprint('Hello, world!')\\n'@ | python -"#
+- running an inline Python script: "@'\\nprint('Hello, world!')\\n'@ | python -"
+
+{}"#,
+            windows_destructive_filesystem_guidance()
+        )
     } else {
         r#"Runs a shell command and returns its output.
 - Always set the `workdir` param when using the shell_command function. Do not use `cd` unless absolutely necessary."#
-    }.to_string();
+            .to_string()
+    };
 
     ToolSpec::Function(ResponsesApiTool {
         name: "shell_command".to_string(),
diff --git a/codex-rs/core/src/tools/spec_tests.rs b/codex-rs/core/src/tools/spec_tests.rs
index 2d0a23431c..3142dd46a3 100644
--- a/codex-rs/core/src/tools/spec_tests.rs
+++ b/codex-rs/core/src/tools/spec_tests.rs
@@ -50,6 +50,10 @@ fn discoverable_connector(id: &str, name: &str, description: &str) -> Discoverab
     }))
 }
 
+fn windows_shell_safety_description() -> String {
+    format!("\n\n{}", super::windows_destructive_filesystem_guidance())
+}
+
 fn search_capable_model_info() -> ModelInfo {
     let config = test_config();
     let mut model_info =
@@ -2363,7 +2367,7 @@ fn test_shell_tool() {
     assert_eq!(name, "shell");
 
     let expected = if cfg!(windows) {
-            r#"Runs a Powershell command (Windows) and returns its output. Arguments to `shell` will be passed to CreateProcessW(). Most commands should be prefixed with ["powershell.exe", "-Command"].
+        r#"Runs a Powershell command (Windows) and returns its output. Arguments to `shell` will be passed to CreateProcessW(). Most commands should be prefixed with ["powershell.exe", "-Command"].
 
 Examples of valid command strings:
 
@@ -2373,11 +2377,37 @@ Examples of valid command strings:
 - ps aux | grep python: ["powershell.exe", "-Command", "Get-Process | Where-Object { $_.ProcessName -like '*python*' }"]
 - setting an env var: ["powershell.exe", "-Command", "$env:FOO='bar'; echo $env:FOO"]
 - running an inline Python script: ["powershell.exe", "-Command", "@'\\nprint('Hello, world!')\\n'@ | python -"]"#
-        } else {
-            r#"Runs a shell command and returns its output.
+                .to_string()
+                + &windows_shell_safety_description()
+    } else {
+        r#"Runs a shell command and returns its output.
 - The arguments to `shell` will be passed to execvp(). Most terminal commands should be prefixed with ["bash", "-lc"].
 - Always set the `workdir` param when using the shell function. Do not use `cd` unless absolutely necessary."#
-        }.to_string();
+                .to_string()
+    };
+    assert_eq!(description, &expected);
+}
+
+#[test]
+fn test_exec_command_tool_windows_description_includes_shell_safety_guidance() {
+    let tool = super::create_exec_command_tool(true, false);
+    let ToolSpec::Function(ResponsesApiTool {
+        description, name, ..
+    }) = &tool
+    else {
+        panic!("expected function tool");
+    };
+    assert_eq!(name, "exec_command");
+
+    let expected = if cfg!(windows) {
+        format!(
+            "Runs a command in a PTY, returning output or a session ID for ongoing interaction.{}",
+            windows_shell_safety_description()
+        )
+    } else {
+        "Runs a command in a PTY, returning output or a session ID for ongoing interaction."
+            .to_string()
+    };
     assert_eq!(description, &expected);
 }
 
@@ -2482,7 +2512,9 @@ Examples of valid command strings:
 - recursive grep: "Get-ChildItem -Path C:\\myrepo -Recurse | Select-String -Pattern 'TODO' -CaseSensitive"
 - ps aux | grep python: "Get-Process | Where-Object { $_.ProcessName -like '*python*' }"
 - setting an env var: "$env:FOO='bar'; echo $env:FOO"
-- running an inline Python script: "@'\\nprint('Hello, world!')\\n'@ | python -"#.to_string()
+- running an inline Python script: "@'\\nprint('Hello, world!')\\n'@ | python -""#
+            .to_string()
+            + &windows_shell_safety_description()
     } else {
         r#"Runs a shell command and returns its output.
 - Always set the `workdir` param when using the shell_command function. Do not use `cd` unless absolutely necessary."#.to_string()
diff --git a/codex-rs/exec-server/src/server/filesystem.rs b/codex-rs/exec-server/src/server/filesystem.rs
index bc3d22a4da..a263bb1fee 100644
--- a/codex-rs/exec-server/src/server/filesystem.rs
+++ b/codex-rs/exec-server/src/server/filesystem.rs
@@ -36,7 +36,7 @@ pub(crate) struct ExecServerFileSystem {
 impl Default for ExecServerFileSystem {
     fn default() -> Self {
         Self {
-            file_system: Arc::new(Environment.get_filesystem()),
+            file_system: Arc::new(Environment::default().get_filesystem()),
         }
     }
 }
diff --git a/codex-rs/mcp-server/tests/common/Cargo.toml b/codex-rs/mcp-server/tests/common/Cargo.toml
index 1dec2d09ac..83f2c53697 100644
--- a/codex-rs/mcp-server/tests/common/Cargo.toml
+++ b/codex-rs/mcp-server/tests/common/Cargo.toml
@@ -11,6 +11,7 @@ path = "lib.rs"
 anyhow = { workspace = true }
 codex-core = { workspace = true }
 codex-mcp-server = { workspace = true }
+codex-terminal-detection = { workspace = true }
 codex-utils-cargo-bin = { workspace = true }
 rmcp = { workspace = true }
 os_info = { workspace = true }
diff --git a/codex-rs/mcp-server/tests/common/mcp_process.rs b/codex-rs/mcp-server/tests/common/mcp_process.rs
index 92b5caa65a..53925ca396 100644
--- a/codex-rs/mcp-server/tests/common/mcp_process.rs
+++ b/codex-rs/mcp-server/tests/common/mcp_process.rs
@@ -11,6 +11,7 @@ use tokio::process::ChildStdout;
 
 use anyhow::Context;
 use codex_mcp_server::CodexToolCallParam;
+use codex_terminal_detection::user_agent;
 
 use pretty_assertions::assert_eq;
 use rmcp::model::CallToolRequestParams;
@@ -156,7 +157,7 @@ impl McpProcess {
             os_info.os_type(),
             os_info.version(),
             os_info.architecture().unwrap_or("unknown"),
-            codex_core::terminal::user_agent()
+            user_agent()
         );
         let JsonRpcMessage::Response(JsonRpcResponse {
             jsonrpc,
diff --git a/codex-rs/terminal-detection/BUILD.bazel b/codex-rs/terminal-detection/BUILD.bazel
new file mode 100644
index 0000000000..a41a762c18
--- /dev/null
+++ b/codex-rs/terminal-detection/BUILD.bazel
@@ -0,0 +1,6 @@
+load("//:defs.bzl", "codex_rust_crate")
+
+codex_rust_crate(
+    name = "terminal-detection",
+    crate_name = "codex_terminal_detection",
+)
diff --git a/codex-rs/terminal-detection/Cargo.toml b/codex-rs/terminal-detection/Cargo.toml
new file mode 100644
index 0000000000..f75e649d36
--- /dev/null
+++ b/codex-rs/terminal-detection/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "codex-terminal-detection"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lib]
+name = "codex_terminal_detection"
+path = "src/lib.rs"
+
+[lints]
+workspace = true
+
+[dependencies]
+tracing = { workspace = true }
+
+[dev-dependencies]
+pretty_assertions = { workspace = true }
diff --git a/codex-rs/core/src/terminal.rs b/codex-rs/terminal-detection/src/lib.rs
similarity index 100%
rename from codex-rs/core/src/terminal.rs
rename to codex-rs/terminal-detection/src/lib.rs
diff --git a/codex-rs/core/src/terminal_tests.rs b/codex-rs/terminal-detection/src/terminal_tests.rs
similarity index 100%
rename from codex-rs/core/src/terminal_tests.rs
rename to codex-rs/terminal-detection/src/terminal_tests.rs
diff --git a/codex-rs/tui/Cargo.toml b/codex-rs/tui/Cargo.toml
index 03c3a03dd0..d4b6f25f01 100644
--- a/codex-rs/tui/Cargo.toml
+++ b/codex-rs/tui/Cargo.toml
@@ -43,6 +43,7 @@ codex-otel = { workspace = true }
 codex-protocol = { workspace = true }
 codex-shell-command = { workspace = true }
 codex-state = { workspace = true }
+codex-terminal-detection = { workspace = true }
 codex-tui-app-server = { workspace = true }
 codex-utils-approval-presets = { workspace = true }
 codex-utils-absolute-path = { workspace = true }
diff --git a/codex-rs/tui/src/app.rs b/codex-rs/tui/src/app.rs
index 09776f0f77..50b663162d 100644
--- a/codex-rs/tui/src/app.rs
+++ b/codex-rs/tui/src/app.rs
@@ -80,6 +80,7 @@ use codex_protocol::protocol::SessionConfiguredEvent;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::SkillErrorInfo;
 use codex_protocol::protocol::TokenUsage;
+use codex_terminal_detection::user_agent;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use color_eyre::eyre::Result;
 use color_eyre::eyre::WrapErr;
@@ -2079,7 +2080,7 @@ impl App {
             auth_mode,
             codex_core::default_client::originator().value,
             config.otel.log_user_prompt,
-            codex_core::terminal::user_agent(),
+            user_agent(),
             SessionSource::Cli,
         );
         if config
diff --git a/codex-rs/tui/src/chatwidget.rs b/codex-rs/tui/src/chatwidget.rs
index a1736171cf..897ec389ec 100644
--- a/codex-rs/tui/src/chatwidget.rs
+++ b/codex-rs/tui/src/chatwidget.rs
@@ -76,8 +76,6 @@ use codex_core::models_manager::manager::ModelsManager;
 use codex_core::plugins::PluginsManager;
 use codex_core::project_doc::DEFAULT_PROJECT_DOC_FILENAME;
 use codex_core::skills::model::SkillMetadata;
-use codex_core::terminal::TerminalName;
-use codex_core::terminal::terminal_info;
 #[cfg(target_os = "windows")]
 use codex_core::windows_sandbox::WindowsSandboxLevelExt;
 use codex_otel::RuntimeMetricsSummary;
@@ -155,6 +153,8 @@ use codex_protocol::request_permissions::RequestPermissionsEvent;
 use codex_protocol::request_user_input::RequestUserInputEvent;
 use codex_protocol::user_input::TextElement;
 use codex_protocol::user_input::UserInput;
+use codex_terminal_detection::TerminalName;
+use codex_terminal_detection::terminal_info;
 use codex_utils_sleep_inhibitor::SleepInhibitor;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
diff --git a/codex-rs/tui/src/chatwidget/tests.rs b/codex-rs/tui/src/chatwidget/tests.rs
index 05adf3d307..97cdf7eeef 100644
--- a/codex-rs/tui/src/chatwidget/tests.rs
+++ b/codex-rs/tui/src/chatwidget/tests.rs
@@ -38,7 +38,6 @@ use codex_core::features::Feature;
 use codex_core::models_manager::collaboration_mode_presets::CollaborationModesConfig;
 use codex_core::models_manager::manager::ModelsManager;
 use codex_core::skills::model::SkillMetadata;
-use codex_core::terminal::TerminalName;
 use codex_otel::RuntimeMetricsSummary;
 use codex_otel::SessionTelemetry;
 use codex_protocol::ThreadId;
@@ -121,6 +120,7 @@ use codex_protocol::request_user_input::RequestUserInputQuestion;
 use codex_protocol::request_user_input::RequestUserInputQuestionOption;
 use codex_protocol::user_input::TextElement;
 use codex_protocol::user_input::UserInput;
+use codex_terminal_detection::TerminalName;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_approval_presets::builtin_approval_presets;
 use crossterm::event::KeyCode;
diff --git a/codex-rs/tui/src/diff_render.rs b/codex-rs/tui/src/diff_render.rs
index dd39901651..684d76b1e0 100644
--- a/codex-rs/tui/src/diff_render.rs
+++ b/codex-rs/tui/src/diff_render.rs
@@ -93,9 +93,9 @@ use crate::terminal_palette::indexed_color;
 use crate::terminal_palette::rgb_color;
 use crate::terminal_palette::stdout_color_level;
 use codex_core::git_info::get_git_repo_root;
-use codex_core::terminal::TerminalName;
-use codex_core::terminal::terminal_info;
 use codex_protocol::protocol::FileChange;
+use codex_terminal_detection::TerminalName;
+use codex_terminal_detection::terminal_info;
 
 /// Classifies a diff line for gutter sign rendering and style selection.
 ///
diff --git a/codex-rs/tui/src/lib.rs b/codex-rs/tui/src/lib.rs
index b4841a7797..8f015981c0 100644
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -33,7 +33,6 @@ use codex_core::format_exec_policy_error_with_source;
 use codex_core::path_utils;
 use codex_core::read_session_meta_line;
 use codex_core::state_db::get_state_db;
-use codex_core::terminal::Multiplexer;
 use codex_core::windows_sandbox::WindowsSandboxLevelExt;
 use codex_protocol::ThreadId;
 use codex_protocol::config_types::AltScreenMode;
@@ -43,6 +42,8 @@ use codex_protocol::protocol::AskForApproval;
 use codex_protocol::protocol::RolloutItem;
 use codex_protocol::protocol::RolloutLine;
 use codex_state::log_db;
+use codex_terminal_detection::Multiplexer;
+use codex_terminal_detection::terminal_info;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_oss::ensure_oss_provider_ready;
 use codex_utils_oss::get_default_model_for_oss_provider;
@@ -1138,7 +1139,7 @@ fn determine_alt_screen_mode(no_alt_screen: bool, tui_alternate_screen: AltScree
             AltScreenMode::Always => true,
             AltScreenMode::Never => false,
             AltScreenMode::Auto => {
-                let terminal_info = codex_core::terminal::terminal_info();
+                let terminal_info = terminal_info();
                 !matches!(terminal_info.multiplexer, Some(Multiplexer::Zellij { .. }))
             }
         }
diff --git a/codex-rs/tui_app_server/Cargo.toml b/codex-rs/tui_app_server/Cargo.toml
index 9ab33202c6..4d9b268895 100644
--- a/codex-rs/tui_app_server/Cargo.toml
+++ b/codex-rs/tui_app_server/Cargo.toml
@@ -48,6 +48,7 @@ codex-otel = { workspace = true }
 codex-protocol = { workspace = true }
 codex-shell-command = { workspace = true }
 codex-state = { workspace = true }
+codex-terminal-detection = { workspace = true }
 codex-utils-approval-presets = { workspace = true }
 codex-utils-absolute-path = { workspace = true }
 codex-utils-cli = { workspace = true }
diff --git a/codex-rs/tui_app_server/src/app.rs b/codex-rs/tui_app_server/src/app.rs
index 8f8092eac6..52b6db48bb 100644
--- a/codex-rs/tui_app_server/src/app.rs
+++ b/codex-rs/tui_app_server/src/app.rs
@@ -96,6 +96,7 @@ use codex_protocol::protocol::SandboxPolicy;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::SkillErrorInfo;
 use codex_protocol::protocol::TokenUsage;
+use codex_terminal_detection::user_agent;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use color_eyre::eyre::Result;
 use color_eyre::eyre::WrapErr;
@@ -2965,7 +2966,7 @@ impl App {
             auth_mode,
             codex_core::default_client::originator().value,
             config.otel.log_user_prompt,
-            codex_core::terminal::user_agent(),
+            user_agent(),
             SessionSource::Cli,
         );
         if config
diff --git a/codex-rs/tui_app_server/src/chatwidget.rs b/codex-rs/tui_app_server/src/chatwidget.rs
index d76751c146..eaf9ca1159 100644
--- a/codex-rs/tui_app_server/src/chatwidget.rs
+++ b/codex-rs/tui_app_server/src/chatwidget.rs
@@ -94,8 +94,6 @@ use codex_core::git_info::local_git_branches;
 use codex_core::plugins::PluginsManager;
 use codex_core::project_doc::DEFAULT_PROJECT_DOC_FILENAME;
 use codex_core::skills::model::SkillMetadata;
-use codex_core::terminal::TerminalName;
-use codex_core::terminal::terminal_info;
 #[cfg(target_os = "windows")]
 use codex_core::windows_sandbox::WindowsSandboxLevelExt;
 use codex_otel::RuntimeMetricsSummary;
@@ -199,6 +197,8 @@ use codex_protocol::request_user_input::RequestUserInputEvent;
 use codex_protocol::request_user_input::RequestUserInputQuestionOption;
 use codex_protocol::user_input::TextElement;
 use codex_protocol::user_input::UserInput;
+use codex_terminal_detection::TerminalName;
+use codex_terminal_detection::terminal_info;
 use codex_utils_sleep_inhibitor::SleepInhibitor;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
diff --git a/codex-rs/tui_app_server/src/chatwidget/tests.rs b/codex-rs/tui_app_server/src/chatwidget/tests.rs
index bae556d51a..a08d56da8f 100644
--- a/codex-rs/tui_app_server/src/chatwidget/tests.rs
+++ b/codex-rs/tui_app_server/src/chatwidget/tests.rs
@@ -61,7 +61,6 @@ use codex_core::features::FEATURES;
 use codex_core::features::Feature;
 use codex_core::models_manager::collaboration_mode_presets::CollaborationModesConfig;
 use codex_core::skills::model::SkillMetadata;
-use codex_core::terminal::TerminalName;
 use codex_otel::RuntimeMetricsSummary;
 use codex_otel::SessionTelemetry;
 use codex_protocol::ThreadId;
@@ -144,6 +143,7 @@ use codex_protocol::request_user_input::RequestUserInputQuestion;
 use codex_protocol::request_user_input::RequestUserInputQuestionOption;
 use codex_protocol::user_input::TextElement;
 use codex_protocol::user_input::UserInput;
+use codex_terminal_detection::TerminalName;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_approval_presets::builtin_approval_presets;
 use crossterm::event::KeyCode;
diff --git a/codex-rs/tui_app_server/src/diff_render.rs b/codex-rs/tui_app_server/src/diff_render.rs
index dd39901651..684d76b1e0 100644
--- a/codex-rs/tui_app_server/src/diff_render.rs
+++ b/codex-rs/tui_app_server/src/diff_render.rs
@@ -93,9 +93,9 @@ use crate::terminal_palette::indexed_color;
 use crate::terminal_palette::rgb_color;
 use crate::terminal_palette::stdout_color_level;
 use codex_core::git_info::get_git_repo_root;
-use codex_core::terminal::TerminalName;
-use codex_core::terminal::terminal_info;
 use codex_protocol::protocol::FileChange;
+use codex_terminal_detection::TerminalName;
+use codex_terminal_detection::terminal_info;
 
 /// Classifies a diff line for gutter sign rendering and style selection.
 ///
diff --git a/codex-rs/tui_app_server/src/lib.rs b/codex-rs/tui_app_server/src/lib.rs
index 19cf079f54..5677806576 100644
--- a/codex-rs/tui_app_server/src/lib.rs
+++ b/codex-rs/tui_app_server/src/lib.rs
@@ -38,7 +38,6 @@ use codex_core::format_exec_policy_error_with_source;
 use codex_core::path_utils;
 use codex_core::read_session_meta_line;
 use codex_core::state_db::get_state_db;
-use codex_core::terminal::Multiplexer;
 use codex_core::windows_sandbox::WindowsSandboxLevelExt;
 use codex_protocol::ThreadId;
 use codex_protocol::config_types::AltScreenMode;
@@ -49,6 +48,8 @@ use codex_protocol::protocol::RolloutItem;
 use codex_protocol::protocol::RolloutLine;
 use codex_protocol::protocol::TurnContextItem;
 use codex_state::log_db;
+use codex_terminal_detection::Multiplexer;
+use codex_terminal_detection::terminal_info;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_oss::ensure_oss_provider_ready;
 use codex_utils_oss::get_default_model_for_oss_provider;
@@ -1485,7 +1486,7 @@ fn determine_alt_screen_mode(no_alt_screen: bool, tui_alternate_screen: AltScree
             AltScreenMode::Always => true,
             AltScreenMode::Never => false,
             AltScreenMode::Auto => {
-                let terminal_info = codex_core::terminal::terminal_info();
+                let terminal_info = terminal_info();
                 !matches!(terminal_info.multiplexer, Some(Multiplexer::Zellij { .. }))
             }
         }