diff --git a/.github/workflows/rust-ci.yml b/.github/workflows/rust-ci.yml
index 25394d6a..03a42223 100644
--- a/.github/workflows/rust-ci.yml
+++ b/.github/workflows/rust-ci.yml
@@ -83,6 +83,15 @@ jobs:
       - name: cargo clippy
         run: cargo clippy --target ${{ matrix.target }} --all-features -- -D warnings || echo "FAILED=${FAILED:+$FAILED, }cargo clippy" >> $GITHUB_ENV
 
+      # Running `cargo build` from the workspace root builds the workspace using
+      # the union of all features from third-party crates. This can mask errors
+      # where individual crates have underspecified features. To avoid this, we
+      # run `cargo build` for each crate individually, though because this is
+      # slower, we only do this for the x86_64-unknown-linux-gnu target.
+      - name: cargo build individual crates
+        if: ${{ matrix.target == 'x86_64-unknown-linux-gnu' }}
+        run: find . -name Cargo.toml -mindepth 2 -maxdepth 2 -print0 | xargs -0 -n1 -I{} bash -c 'cd "$(dirname "{}")" && cargo build' || echo "FAILED=${FAILED:+$FAILED, }cargo build individual crates" >> $GITHUB_ENV
+
       - name: cargo test
         run: cargo test --target ${{ matrix.target }} || echo "FAILED=${FAILED:+$FAILED, }cargo test" >> $GITHUB_ENV
 
diff --git a/codex-rs/core/src/approval_mode_cli_arg.rs b/codex-rs/core/src/approval_mode_cli_arg.rs
index f4e64feb..6aadbd92 100644
--- a/codex-rs/core/src/approval_mode_cli_arg.rs
+++ b/codex-rs/core/src/approval_mode_cli_arg.rs
@@ -1,12 +1,11 @@
 //! Standard type to use with the `--approval-mode` CLI option.
 //! Available when the `cli` feature is enabled for the crate.
 
-use std::path::PathBuf;
-
 use clap::ArgAction;
 use clap::Parser;
 use clap::ValueEnum;
 
+use crate::config::parse_sandbox_permission_with_base_path;
 use crate::protocol::AskForApproval;
 use crate::protocol::SandboxPermission;
 
@@ -72,49 +71,3 @@ fn parse_sandbox_permission(raw: &str) -> std::io::Result<SandboxPermission> {
     let base_path = std::env::current_dir()?;
     parse_sandbox_permission_with_base_path(raw, base_path)
 }
-
-pub(crate) fn parse_sandbox_permission_with_base_path(
-    raw: &str,
-    base_path: PathBuf,
-) -> std::io::Result<SandboxPermission> {
-    use SandboxPermission::*;
-
-    if let Some(path) = raw.strip_prefix("disk-write-folder=") {
-        return if path.is_empty() {
-            Err(std::io::Error::new(
-                std::io::ErrorKind::InvalidInput,
-                "--sandbox-permission disk-write-folder=<PATH> requires a non-empty PATH",
-            ))
-        } else {
-            use path_absolutize::*;
-
-            let file = PathBuf::from(path);
-            let absolute_path = if file.is_relative() {
-                file.absolutize_from(base_path)
-            } else {
-                file.absolutize()
-            }
-            .map(|path| path.into_owned())?;
-            Ok(DiskWriteFolder {
-                folder: absolute_path,
-            })
-        };
-    }
-
-    match raw {
-        "disk-full-read-access" => Ok(DiskFullReadAccess),
-        "disk-write-platform-user-temp-folder" => Ok(DiskWritePlatformUserTempFolder),
-        "disk-write-platform-global-temp-folder" => Ok(DiskWritePlatformGlobalTempFolder),
-        "disk-write-cwd" => Ok(DiskWriteCwd),
-        "disk-full-write-access" => Ok(DiskFullWriteAccess),
-        "network-full-access" => Ok(NetworkFullAccess),
-        _ => Err(
-            std::io::Error::new(
-                std::io::ErrorKind::InvalidInput,
-                format!(
-                    "`{raw}` is not a recognised permission.\nRun with `--help` to see the accepted values."
-                ),
-            )
-        ),
-    }
-}
diff --git a/codex-rs/core/src/config.rs b/codex-rs/core/src/config.rs
index 1557ce27..554173c5 100644
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -1,4 +1,3 @@
-use crate::approval_mode_cli_arg::parse_sandbox_permission_with_base_path;
 use crate::flags::OPENAI_DEFAULT_MODEL;
 use crate::protocol::AskForApproval;
 use crate::protocol::SandboxPermission;
@@ -257,6 +256,52 @@ pub fn log_dir() -> std::io::Result<PathBuf> {
     Ok(p)
 }
 
+pub(crate) fn parse_sandbox_permission_with_base_path(
+    raw: &str,
+    base_path: PathBuf,
+) -> std::io::Result<SandboxPermission> {
+    use SandboxPermission::*;
+
+    if let Some(path) = raw.strip_prefix("disk-write-folder=") {
+        return if path.is_empty() {
+            Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                "--sandbox-permission disk-write-folder=<PATH> requires a non-empty PATH",
+            ))
+        } else {
+            use path_absolutize::*;
+
+            let file = PathBuf::from(path);
+            let absolute_path = if file.is_relative() {
+                file.absolutize_from(base_path)
+            } else {
+                file.absolutize()
+            }
+            .map(|path| path.into_owned())?;
+            Ok(DiskWriteFolder {
+                folder: absolute_path,
+            })
+        };
+    }
+
+    match raw {
+        "disk-full-read-access" => Ok(DiskFullReadAccess),
+        "disk-write-platform-user-temp-folder" => Ok(DiskWritePlatformUserTempFolder),
+        "disk-write-platform-global-temp-folder" => Ok(DiskWritePlatformGlobalTempFolder),
+        "disk-write-cwd" => Ok(DiskWriteCwd),
+        "disk-full-write-access" => Ok(DiskFullWriteAccess),
+        "network-full-access" => Ok(NetworkFullAccess),
+        _ => Err(
+            std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                format!(
+                    "`{raw}` is not a recognised permission.\nRun with `--help` to see the accepted values."
+                ),
+            )
+        ),
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/codex-rs/mcp-client/Cargo.toml b/codex-rs/mcp-client/Cargo.toml
index b3792922..562675c8 100644
--- a/codex-rs/mcp-client/Cargo.toml
+++ b/codex-rs/mcp-client/Cargo.toml
@@ -11,11 +11,11 @@ serde_json = "1"
 tracing = { version = "0.1.41", features = ["log"] }
 tracing-subscriber = { version = "0.3", features = ["fmt", "env-filter"] }
 tokio = { version = "1", features = [
-    "io-std",
+    "io-util",
     "macros",
     "process",
     "rt-multi-thread",
-    "signal",
+    "sync",
 ] }
 
 [dev-dependencies]