docs: Add comprehensive documentation for modes, services, and plugins

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/filter_plugin/grep.rs

@@ -3,6 +3,9 @@ use std::io::{Result, Read, Write, BufRead};
 use regex::Regex;
 
 /// A filter that matches lines against a regular expression pattern.
+///
+/// Outputs only lines that match the given regex.
+#[derive(Debug, Clone)]
 pub struct GrepFilter {
     regex: Regex,
 }
@@ -16,7 +19,7 @@ impl GrepFilter {
     ///
     /// # Errors
     ///
-    /// Returns an `io::Error` if the regex pattern is invalid.
+    /// Returns an `io::Error` with `InvalidInput` if the regex pattern is invalid.
     pub fn new(pattern: String) -> Result<Self> {
         let regex = Regex::new(&pattern)
             .map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidInput, e))?;
@@ -29,6 +32,8 @@ impl GrepFilter {
 impl FilterPlugin for GrepFilter {
     /// Filters the input by writing only lines that match the regex pattern.
     ///
+    /// Reads lines from the input and writes matching lines to the output, preserving newlines.
+    ///
     /// # Arguments
     ///
     /// * `reader` - A boxed mutable reference to the input reader providing the data stream.
@@ -37,6 +42,10 @@ impl FilterPlugin for GrepFilter {
     /// # Returns
     ///
     /// Returns `Ok(())` on success, or an `io::Error` if reading or writing fails.
+    ///
+    /// # Errors
+    ///
+    /// Propagates `io::Error` from reading lines or writing output.
     fn filter(&mut self, mut reader: Box<&mut dyn Read>, mut writer: Box<&mut dyn Write>) -> Result<()> {
         let mut buf_reader = std::io::BufReader::new(&mut *reader);
         for line in buf_reader.by_ref().lines() {
@@ -50,6 +59,8 @@ impl FilterPlugin for GrepFilter {
 
     /// Clones this filter into a new boxed instance.
     ///
+    /// Creates a new GrepFilter with the same regex pattern.
+    ///
     /// # Returns
     ///
     /// A new `Box<dyn FilterPlugin>` representing a clone of this filter.
@@ -61,6 +72,8 @@ impl FilterPlugin for GrepFilter {
     
     /// Returns the configuration options for this filter.
     ///
+    /// The only option is the required "pattern" for the regex.
+    ///
     /// # Returns
     ///
     /// A vector of `FilterOption` describing the filter's configurable parameters.