Improve [rendered-link] guess of the relevant file to point to

src/config.rs

@@ -496,7 +496,11 @@ pub(crate) struct BotPullRequests {}
 #[serde(rename_all = "kebab-case")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct RenderedLinkConfig {
+    /// List of paths to watch for modifications
     pub(crate) trigger_files: Vec<String>,
+    /// List of paths to exclude from watching for modifications
+    #[serde(default)]
+    pub(crate) exclude_files: Vec<String>,
 }
 
 #[derive(PartialEq, Eq, Debug, serde::Deserialize)]
@@ -720,7 +724,8 @@ mod tests {
                 merge_conflicts: None,
                 bot_pull_requests: None,
                 rendered_link: Some(RenderedLinkConfig {
-                    trigger_files: vec!["posts/".to_string()]
+                    trigger_files: vec!["posts/".to_string()],
+                    exclude_files: vec![],
                 }),
                 issue_links: Some(IssueLinksConfig {
                     check_commits: true,

src/github.rs

@@ -1100,6 +1100,9 @@ pub struct PullRequestFile {
     pub sha: String,
     pub filename: String,
     pub blob_url: String,
+    pub additions: u64,
+    pub deletions: u64,
+    pub changes: u64,
 }
 
 #[derive(Debug, serde::Deserialize)]

src/handlers/rendered_link.rs

@@ -42,13 +42,20 @@ async fn add_rendered_link(
 
         let rendered_link = files
             .iter()
-            .find(|f| {
+            .filter(|f| {
                 config
                     .trigger_files
                     .iter()
                     .any(|tf| f.filename.starts_with(tf))
+                    && !config
+                        .exclude_files
+                        .iter()
+                        .any(|tf| f.filename.starts_with(tf))
             })
-            .and_then(|file| {
+            // Sort the relavant files by the total number of lines changed, as to
+            // improve our guess for the relevant file to show the link to.
+            .max_by_key(|f| f.additions + f.deletions + f.changes)
+            .map(|file| {
                 let head = e.issue.head.as_ref()?;
                 let base = e.issue.base.as_ref()?;
 
@@ -84,7 +91,8 @@ async fn add_rendered_link(
                     },
                     file.filename
                 ))
-            });
+            })
+            .flatten();
 
         let new_body: Cow<'_, str> = if !e.issue.body.contains("[Rendered]") {
             if let Some(rendered_link) = rendered_link {