diff --git a/codex-rs/core-plugins/src/provider_tests.rs b/codex-rs/core-plugins/src/provider_tests.rs
index e2c22121b..a6a7e2fa7 100644
--- a/codex-rs/core-plugins/src/provider_tests.rs
+++ b/codex-rs/core-plugins/src/provider_tests.rs
@@ -129,6 +129,7 @@ impl ExecutorFileSystem for SyntheticPluginFileSystem {
                 is_directory,
                 is_file,
                 is_symlink: false,
+                size: 0,
                 created_at_ms: 0,
                 modified_at_ms: 0,
             })
diff --git a/codex-rs/exec-server/src/fs_helper.rs b/codex-rs/exec-server/src/fs_helper.rs
index 6f3dc9291..f4db844b5 100644
--- a/codex-rs/exec-server/src/fs_helper.rs
+++ b/codex-rs/exec-server/src/fs_helper.rs
@@ -233,6 +233,7 @@ pub(crate) async fn run_direct_request(
                 is_directory: metadata.is_directory,
                 is_file: metadata.is_file,
                 is_symlink: metadata.is_symlink,
+                size: metadata.size,
                 created_at_ms: metadata.created_at_ms,
                 modified_at_ms: metadata.modified_at_ms,
             }))
diff --git a/codex-rs/exec-server/src/local_file_system.rs b/codex-rs/exec-server/src/local_file_system.rs
index 7b909cc8a..d68c7a013 100644
--- a/codex-rs/exec-server/src/local_file_system.rs
+++ b/codex-rs/exec-server/src/local_file_system.rs
@@ -483,6 +483,7 @@ impl DirectFileSystem {
             is_directory: metadata.is_dir(),
             is_file: metadata.is_file(),
             is_symlink: symlink_metadata.file_type().is_symlink(),
+            size: metadata.len(),
             created_at_ms: metadata.created().ok().map_or(0, system_time_to_unix_ms),
             modified_at_ms: metadata.modified().ok().map_or(0, system_time_to_unix_ms),
         })
diff --git a/codex-rs/exec-server/src/protocol.rs b/codex-rs/exec-server/src/protocol.rs
index 387f48b35..175d23fe0 100644
--- a/codex-rs/exec-server/src/protocol.rs
+++ b/codex-rs/exec-server/src/protocol.rs
@@ -244,6 +244,7 @@ pub struct FsGetMetadataResponse {
     pub is_directory: bool,
     pub is_file: bool,
     pub is_symlink: bool,
+    pub size: u64,
     pub created_at_ms: i64,
     pub modified_at_ms: i64,
 }
diff --git a/codex-rs/exec-server/src/remote_file_system.rs b/codex-rs/exec-server/src/remote_file_system.rs
index f6924d780..1c5b5c8fb 100644
--- a/codex-rs/exec-server/src/remote_file_system.rs
+++ b/codex-rs/exec-server/src/remote_file_system.rs
@@ -132,6 +132,7 @@ impl RemoteFileSystem {
             is_directory: response.is_directory,
             is_file: response.is_file,
             is_symlink: response.is_symlink,
+            size: response.size,
             created_at_ms: response.created_at_ms,
             modified_at_ms: response.modified_at_ms,
         })
diff --git a/codex-rs/exec-server/src/sandboxed_file_system.rs b/codex-rs/exec-server/src/sandboxed_file_system.rs
index 94d18aafc..f1ed02f76 100644
--- a/codex-rs/exec-server/src/sandboxed_file_system.rs
+++ b/codex-rs/exec-server/src/sandboxed_file_system.rs
@@ -164,6 +164,7 @@ impl SandboxedFileSystem {
             is_directory: response.is_directory,
             is_file: response.is_file,
             is_symlink: response.is_symlink,
+            size: response.size,
             created_at_ms: response.created_at_ms,
             modified_at_ms: response.modified_at_ms,
         })
diff --git a/codex-rs/exec-server/src/server/file_system_handler.rs b/codex-rs/exec-server/src/server/file_system_handler.rs
index 211685c13..080d4829d 100644
--- a/codex-rs/exec-server/src/server/file_system_handler.rs
+++ b/codex-rs/exec-server/src/server/file_system_handler.rs
@@ -103,6 +103,7 @@ impl FileSystemHandler {
             is_directory: metadata.is_directory,
             is_file: metadata.is_file,
             is_symlink: metadata.is_symlink,
+            size: metadata.size,
             created_at_ms: metadata.created_at_ms,
             modified_at_ms: metadata.modified_at_ms,
         })
diff --git a/codex-rs/exec-server/tests/file_system/shared.rs b/codex-rs/exec-server/tests/file_system/shared.rs
index 0bef4aa28..27bdb22d8 100644
--- a/codex-rs/exec-server/tests/file_system/shared.rs
+++ b/codex-rs/exec-server/tests/file_system/shared.rs
@@ -2,6 +2,7 @@ use anyhow::Context;
 use anyhow::Result;
 use codex_exec_server::CopyOptions;
 use codex_exec_server::CreateDirectoryOptions;
+use codex_exec_server::FileMetadata;
 use codex_exec_server::ReadDirectoryEntry;
 use codex_exec_server::RemoveOptions;
 use codex_protocol::models::AdditionalPermissionProfile;
@@ -65,18 +66,34 @@ async fn file_system_get_metadata_reports_files_and_directories(
         .get_metadata(&PathUri::from_path(&file_path)?, /*sandbox*/ None)
         .await
         .with_context(|| format!("mode={implementation}"))?;
-    assert_eq!(file_metadata.is_directory, false);
-    assert_eq!(file_metadata.is_file, true);
-    assert_eq!(file_metadata.is_symlink, false);
+    assert_eq!(
+        file_metadata,
+        FileMetadata {
+            is_directory: false,
+            is_file: true,
+            is_symlink: false,
+            size: 5,
+            created_at_ms: file_metadata.created_at_ms,
+            modified_at_ms: file_metadata.modified_at_ms,
+        }
+    );
     assert!(file_metadata.modified_at_ms > 0);
 
     let directory_metadata = file_system
         .get_metadata(&PathUri::from_path(&directory_path)?, /*sandbox*/ None)
         .await
         .with_context(|| format!("mode={implementation}"))?;
-    assert_eq!(directory_metadata.is_directory, true);
-    assert_eq!(directory_metadata.is_file, false);
-    assert_eq!(directory_metadata.is_symlink, false);
+    assert_eq!(
+        directory_metadata,
+        FileMetadata {
+            is_directory: true,
+            is_file: false,
+            is_symlink: false,
+            size: std::fs::metadata(&directory_path)?.len(),
+            created_at_ms: directory_metadata.created_at_ms,
+            modified_at_ms: directory_metadata.modified_at_ms,
+        }
+    );
     assert!(directory_metadata.modified_at_ms > 0);
 
     Ok(())
@@ -395,7 +412,7 @@ async fn file_system_copy_rejects_directory_without_recursive(
 #[test_case(FileSystemImplementation::Local ; "local")]
 #[test_case(FileSystemImplementation::Remote ; "remote")]
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn file_system_sandboxed_read_allows_readable_root(
+async fn file_system_sandboxed_metadata_and_read_allow_readable_root(
     implementation: FileSystemImplementation,
 ) -> Result<()> {
     let context = create_file_system_context(implementation).await?;
@@ -408,6 +425,22 @@ async fn file_system_sandboxed_read_allows_readable_root(
     std::fs::write(&file_path, "sandboxed hello")?;
     let sandbox = read_only_sandbox(allowed_dir);
 
+    let metadata = file_system
+        .get_metadata(&PathUri::from_path(&file_path)?, Some(&sandbox))
+        .await
+        .with_context(|| format!("mode={implementation}"))?;
+    assert_eq!(
+        metadata,
+        FileMetadata {
+            is_directory: false,
+            is_file: true,
+            is_symlink: false,
+            size: 15,
+            created_at_ms: metadata.created_at_ms,
+            modified_at_ms: metadata.modified_at_ms,
+        }
+    );
+
     let contents = file_system
         .read_file(&PathUri::from_path(&file_path)?, Some(&sandbox))
         .await
diff --git a/codex-rs/exec-server/tests/file_system_unix.rs b/codex-rs/exec-server/tests/file_system_unix.rs
index 3538f3236..3c4dfa99a 100644
--- a/codex-rs/exec-server/tests/file_system_unix.rs
+++ b/codex-rs/exec-server/tests/file_system_unix.rs
@@ -21,6 +21,7 @@ use codex_exec_server::CopyOptions;
 use codex_exec_server::CreateDirectoryOptions;
 #[cfg(target_os = "linux")]
 use codex_exec_server::Environment;
+use codex_exec_server::FileMetadata;
 use codex_exec_server::RemoveOptions;
 use codex_utils_path_uri::PathUri;
 use pretty_assertions::assert_eq;
@@ -222,9 +223,17 @@ async fn file_system_get_metadata_reports_symlink_targets(
         .get_metadata(&PathUri::from_path(&symlink_path)?, /*sandbox*/ None)
         .await
         .with_context(|| format!("mode={implementation}"))?;
-    assert_eq!(symlink_metadata.is_directory, false);
-    assert_eq!(symlink_metadata.is_file, true);
-    assert_eq!(symlink_metadata.is_symlink, true);
+    assert_eq!(
+        symlink_metadata,
+        FileMetadata {
+            is_directory: false,
+            is_file: true,
+            is_symlink: true,
+            size: 5,
+            created_at_ms: symlink_metadata.created_at_ms,
+            modified_at_ms: symlink_metadata.modified_at_ms,
+        }
+    );
     assert!(symlink_metadata.modified_at_ms > 0);
 
     let dir_path = tmp.path().join("notes");
@@ -238,9 +247,17 @@ async fn file_system_get_metadata_reports_symlink_targets(
         )
         .await
         .with_context(|| format!("mode={implementation}"))?;
-    assert_eq!(dir_symlink_metadata.is_directory, true);
-    assert_eq!(dir_symlink_metadata.is_file, false);
-    assert_eq!(dir_symlink_metadata.is_symlink, true);
+    assert_eq!(
+        dir_symlink_metadata,
+        FileMetadata {
+            is_directory: true,
+            is_file: false,
+            is_symlink: true,
+            size: std::fs::metadata(&dir_path)?.len(),
+            created_at_ms: dir_symlink_metadata.created_at_ms,
+            modified_at_ms: dir_symlink_metadata.modified_at_ms,
+        }
+    );
 
     Ok(())
 }
diff --git a/codex-rs/ext/skills/tests/executor_file_system_authority.rs b/codex-rs/ext/skills/tests/executor_file_system_authority.rs
index d5387abce..b57f1db6b 100644
--- a/codex-rs/ext/skills/tests/executor_file_system_authority.rs
+++ b/codex-rs/ext/skills/tests/executor_file_system_authority.rs
@@ -85,6 +85,7 @@ impl SyntheticFileSystem {
             is_directory,
             is_file,
             is_symlink: false,
+            size: 0,
             created_at_ms: 0,
             modified_at_ms: 0,
         })
diff --git a/codex-rs/file-system/src/lib.rs b/codex-rs/file-system/src/lib.rs
index 929162b10..429c2ead5 100644
--- a/codex-rs/file-system/src/lib.rs
+++ b/codex-rs/file-system/src/lib.rs
@@ -34,6 +34,8 @@ pub struct FileMetadata {
     pub is_directory: bool,
     pub is_file: bool,
     pub is_symlink: bool,
+    /// Size in bytes.
+    pub size: u64,
     pub created_at_ms: i64,
     pub modified_at_ms: i64,
 }