fix: cross-platform compatibility for Windows support

- Use directories::BaseDirs for config path fallback instead of hardcoded Unix path
- Default to notepad on Windows instead of vi for editor commands
- Skip +N line argument for notepad in todo edit (notepad doesn't support it)

src/cli/commands/edit.rs

@@ -44,7 +44,13 @@ pub fn run(number: i32) -> Result<(), StreamdError> {
     };
 
     if let Some(file_path) = sorted_shards[selected_index].location.get("file") {
-        let editor = std::env::var("EDITOR").unwrap_or_else(|_| "vi".to_string());
+        let editor = std::env::var("EDITOR").unwrap_or_else(|_| {
+            if cfg!(windows) {
+                "notepad".to_string()
+            } else {
+                "vi".to_string()
+            }
+        });
         Command::new(&editor).arg(file_path).status()?;
     }
 

src/cli/commands/new.rs

@@ -24,7 +24,13 @@ pub fn run() -> Result<(), StreamdError> {
     drop(file);
 
     // Open in editor
-    let editor = std::env::var("EDITOR").unwrap_or_else(|_| "vi".to_string());
+    let editor = std::env::var("EDITOR").unwrap_or_else(|_| {
+        if cfg!(windows) {
+            "notepad".to_string()
+        } else {
+            "vi".to_string()
+        }
+    });
     let status = Command::new(&editor).arg(&preliminary_path).status()?;
 
     if !status.success() {

src/cli/commands/todo.rs

@@ -72,13 +72,19 @@ pub fn run_edit(number: usize) -> Result<(), StreamdError> {
         .get("file")
         .ok_or(StreamdError::MissingFilePath)?;
 
-    let editor = std::env::var("EDITOR").unwrap_or_else(|_| "vi".to_string());
-    let line_arg = format!("+{}", task.start_line);
+    let editor = std::env::var("EDITOR").unwrap_or_else(|_| {
+        if cfg!(windows) {
+            "notepad".to_string()
+        } else {
+            "vi".to_string()
+        }
+    });
 
-    let status = Command::new(&editor)
-        .arg(&line_arg)
-        .arg(file_path)
-        .status()?;
+    let mut cmd = Command::new(&editor);
+    if !editor.to_lowercase().contains("notepad") {
+        cmd.arg(format!("+{}", task.start_line));
+    }
+    let status = cmd.arg(file_path).status()?;
 
     if !status.success() {
         return Err(StreamdError::IoError(std::io::Error::other(