diff --git a/crates/onyx-core/src/google_tasks.rs b/crates/onyx-core/src/google_tasks.rs
index 8bf3fb1..e13ecd4 100644
--- a/crates/onyx-core/src/google_tasks.rs
+++ b/crates/onyx-core/src/google_tasks.rs
@@ -452,15 +452,7 @@ fn render_task_markdown(task: &Task) -> String {
 
 /// Sanitize a string for use as a filesystem path component.
 fn sanitize_name(name: &str) -> String {
-    let s: String = name.chars()
-        .map(|c| match c {
-            '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
-            '\0'..='\x1f' => '_',
-            _ => c,
-        })
-        .collect::<String>()
-        .trim_matches(|c: char| c == '.' || c == ' ')
-        .to_string();
+    let s = crate::sanitize_filename(name);
     if s.is_empty() { "Untitled".to_string() } else { s }
 }
 
diff --git a/crates/onyx-core/src/lib.rs b/crates/onyx-core/src/lib.rs
index b8c5120..8e85ca0 100644
--- a/crates/onyx-core/src/lib.rs
+++ b/crates/onyx-core/src/lib.rs
@@ -11,3 +11,30 @@ pub use models::{Task, TaskStatus, TaskList};
 pub use repository::TaskRepository;
 pub use config::{AppConfig, WorkspaceConfig};
 pub use error::{Error, Result};
+
+/// Sanitize a string for use as a filesystem path component.
+/// Replaces filesystem-unsafe characters with underscores, trims leading/trailing
+/// dots and spaces, and prefixes Windows reserved device names.
+pub(crate) fn sanitize_filename(name: &str) -> String {
+    let sanitized: String = name.chars()
+        .map(|c| match c {
+            '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
+            '\0'..='\x1f' => '_',
+            _ => c,
+        })
+        .collect::<String>()
+        .trim_matches(|c: char| c == '.' || c == ' ')
+        .to_string();
+    // Reject Windows reserved device names (CON, PRN, AUX, NUL, COM0-9, LPT0-9)
+    let stem = sanitized.split('.').next().unwrap_or("").to_uppercase();
+    let is_reserved = matches!(stem.as_str(),
+        "CON" | "PRN" | "AUX" | "NUL"
+        | "COM0" | "COM1" | "COM2" | "COM3" | "COM4" | "COM5" | "COM6" | "COM7" | "COM8" | "COM9"
+        | "LPT0" | "LPT1" | "LPT2" | "LPT3" | "LPT4" | "LPT5" | "LPT6" | "LPT7" | "LPT8" | "LPT9"
+    );
+    if is_reserved {
+        format!("_{}", sanitized)
+    } else {
+        sanitized
+    }
+}
diff --git a/crates/onyx-core/src/storage.rs b/crates/onyx-core/src/storage.rs
index 42d5801..c966af0 100644
--- a/crates/onyx-core/src/storage.rs
+++ b/crates/onyx-core/src/storage.rs
@@ -237,27 +237,7 @@ impl FileSystemStorage {
     }
 
     fn sanitize_filename(name: &str) -> String {
-        let sanitized: String = name.chars()
-            .map(|c| match c {
-                '/' | '\\' | ':' | '*' | '?' | '"' | '<' | '>' | '|' => '_',
-                '\0'..='\x1f' => '_',
-                _ => c,
-            })
-            .collect::<String>()
-            .trim_matches(|c: char| c == '.' || c == ' ')
-            .to_string();
-        // Reject Windows reserved device names (CON, PRN, AUX, NUL, COM0-9, LPT0-9)
-        let stem = sanitized.split('.').next().unwrap_or("").to_uppercase();
-        let is_reserved = matches!(stem.as_str(),
-            "CON" | "PRN" | "AUX" | "NUL"
-            | "COM0" | "COM1" | "COM2" | "COM3" | "COM4" | "COM5" | "COM6" | "COM7" | "COM8" | "COM9"
-            | "LPT0" | "LPT1" | "LPT2" | "LPT3" | "LPT4" | "LPT5" | "LPT6" | "LPT7" | "LPT8" | "LPT9"
-        );
-        if is_reserved {
-            format!("_{}", sanitized)
-        } else {
-            sanitized
-        }
+        crate::sanitize_filename(name)
     }
 
     fn task_file_path(&self, list_dir: &Path, task: &Task) -> PathBuf {