autocomplete: key results by extension filter and reject the placeholder

1 files changed, 18 insertions, 6 deletions

diff --git a/src/commands/autocomplete.rs b/src/commands/autocomplete.rs
index d05a48b..4cefd67 100644
--- a/src/commands/autocomplete.rs
+++ b/src/commands/autocomplete.rs
@@ -20,7 +20,7 @@ const AC_SEARCH_TIMEOUT: Duration = Duration::from_secs(2);
 
 /// Value used for the mock "searching" placeholder — recognisable by the
 /// command handler as a no-op.
-const MOCK_SEARCHING: &str = "\u{231B}...";
+pub(crate) const MOCK_SEARCHING: &str = "\u{231B}...";
 
 fn truncate_choice(s: &str) -> String {
     if s.chars().count() <= MAX_CHOICE_LEN {
@@ -98,6 +98,12 @@ type SearchCache = Arc<
     tokio::sync::Mutex<HashMap<String, (Vec<copyparty::SearchHit>, std::time::Instant)>>,
 >;
 
+fn search_cache_key(partial: &str, extensions: &[&str]) -> String {
+    // The extension filter changes the result set, so it must be part of the
+    // key; otherwise `/music` and `/upload` poison each other's cache.
+    format!("{partial}\u{1f}{}", extensions.join(","))
+}
+
 fn spawn_search(
     cache: SearchCache,
     client: copyparty::CopypartyClient,
@@ -114,10 +120,10 @@ fn spawn_search(
             Ok(hits) => {
                 debug!(%query, count = hits.len(), "background search completed");
                 // Always fill the shared search cache
-                cache
-                    .lock()
-                    .await
-                    .insert(query, (hits.clone(), std::time::Instant::now()));
+                cache.lock().await.insert(
+                    search_cache_key(&query, &exts),
+                    (hits.clone(), std::time::Instant::now()),
+                );
                 // Send to foreground (ignores error if receiver was dropped)
                 let _ = tx.send(hits);
             }
@@ -143,8 +149,14 @@ async fn timed_search(
     partial: &str,
     extensions: &[&str],
 ) -> Vec<serenity::AutocompleteChoice> {
+    // The placeholder is a UI hint, not a real query.
+    if partial == MOCK_SEARCHING {
+        return vec![];
+    }
+
     // 1. Shared search cache hit?
-    if let Some(hits) = ctx.data().ac_search_cache_lookup(partial).await
+    let cache_key = search_cache_key(partial, extensions);
+    if let Some(hits) = ctx.data().ac_search_cache_lookup(&cache_key).await
         && !hits.is_empty() {
             debug!(%partial, count = hits.len(), "autocomplete cache hit");
             let pairs = build_choices(&hits);