review-classifier: skip draft prs, classify once when they leave draft

swarm-controller/src/forge.rs

@@ -157,6 +157,9 @@ pub struct PullForReview {
     /// Why `diff` is the forge's `.diff`, with 3 lines of context, rather
     /// than [`pull_diff::wide`]'s. `None` when it is the wide one.
     pub narrowed: Option<String>,
+    /// The forge calls the PR a draft (a title starting with a
+    /// work-in-progress prefix).
+    pub draft: bool,
 }
 
 /// Files on a repo's branch, as [`Client::default_branch_files`] and
@@ -1382,6 +1385,7 @@ impl Client {
             .await
             .with_context(|| format!("read PR {number} of {owner}/{repo}"))?;
         let changed_files = pull.changed_files;
+        let draft = pull.draft.unwrap_or(false);
         let head_sha = pull
             .head
             .and_then(|h| h.sha)
@@ -1443,6 +1447,7 @@ impl Client {
             commits,
             diff,
             narrowed,
+            draft,
         })
     }