fix: make finish method public and fix ringbuf method names

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/filter_plugin/mod.rs

@@ -41,7 +41,7 @@ impl FilterChain {
         Ok(current_data)
     }
 
-    fn finish(&mut self) -> Result<Vec<u8>> {
+    pub fn finish(&mut self) -> Result<Vec<u8>> {
         let mut result = Vec::new();
         
         // Process each plugin's finish method and collect results

src/filter_plugin/tail.rs

@@ -68,7 +68,7 @@ impl FilterPlugin for TailLinesFilter {
         
         // Iterate backwards to find the starting point
         for i in (0..self.ring_buffer.len()).rev() {
-            let index = (self.ring_buffer.write_index() as isize - 1 - i as isize)
+            let index = (self.ring_buffer.write_pos() as isize - 1 - i as isize)
                 .rem_euclid(self.ring_buffer.capacity() as isize) as usize;
             let byte = self.ring_buffer[index];
             
@@ -85,7 +85,7 @@ impl FilterPlugin for TailLinesFilter {
         let start_index = self.ring_buffer.len() - bytes_to_keep;
         let mut result = Vec::with_capacity(bytes_to_keep);
         for i in start_index..self.ring_buffer.len() {
-            let index = (self.ring_buffer.write_index() as isize - (self.ring_buffer.len() - i) as isize)
+            let index = (self.ring_buffer.write_pos() as isize - (self.ring_buffer.len() - i) as isize)
                 .rem_euclid(self.ring_buffer.capacity() as isize) as usize;
             result.push(self.ring_buffer[index]);
         }