diff --git a/app/javascript/controllers/list_filter_controller.js b/app/javascript/controllers/list_filter_controller.js
index b012f26e5..b7362232a 100644
--- a/app/javascript/controllers/list_filter_controller.js
+++ b/app/javascript/controllers/list_filter_controller.js
@@ -11,7 +11,12 @@ export default class extends Controller {
   }
 
   filter() {
-    const filterValue = this.inputTarget.value.toLowerCase();
+    // Only a genuinely empty query means "show everything". A non-empty
+    // query that normalizes away to "" (e.g. a lone combining mark) must
+    // still match nothing — "".includes("") is true, so without this split
+    // it would show every row instead of filtering.
+    const rawFilterValue = this.inputTarget.value;
+    const filterValue = this.normalize(rawFilterValue);
     const items = this.listTarget.querySelectorAll(".filterable-item");
     let noMatchFound = true;
 
@@ -33,13 +38,10 @@ export default class extends Controller {
     }
 
     items.forEach((item) => {
-      if (filterValue.length > 0 && recentItems.has(item)) {
-        item.style.display = "none";
-        return;
-      }
-
-      const text = item.getAttribute("data-filter-name").toLowerCase();
-      const shouldDisplay = text.includes(filterValue);
+      const text = this.normalize(item.getAttribute("data-filter-name"));
+      const shouldDisplay =
+        rawFilterValue.length === 0 ||
+        (filterValue.length > 0 && text.includes(filterValue));
       item.style.display = shouldDisplay ? "" : "none";
 
       if (shouldDisplay) {
@@ -56,6 +58,21 @@ export default class extends Controller {
     this.updateAriaActiveDescendant();
   }
 
+  // Case- and diacritic-insensitive: "prestecs" should match "Prèstecs".
+  // NFD splits each accented char into base char + combining mark, then
+  // \p{Mark} strips the marks, so both sides compare on bare base characters.
+  // Not \p{Diacritic}: that property is broader than combining marks — it
+  // also covers standalone characters like "^", "`", the middot, and
+  // modifier letters (e.g. the Hawaiian ʻokina) — so a query of just one of
+  // those would normalize to "", and "".includes() matches everything,
+  // silently showing every row instead of filtering.
+  normalize(value) {
+    return value
+      .normalize("NFD")
+      .replace(/\p{Mark}/gu, "")
+      .toLowerCase();
+  }
+
   handleKeydown(event) {
     if (event.key === "ArrowDown") {
       event.preventDefault();
@@ -74,7 +91,10 @@ export default class extends Controller {
     if (items.length === 0) return;
 
     this.clearHighlights();
-    this.highlightedIndex = Math.min(this.highlightedIndex + 1, items.length - 1);
+    this.highlightedIndex = Math.min(
+      this.highlightedIndex + 1,
+      items.length - 1,
+    );
     this.highlightItem(items[this.highlightedIndex]);
     this.updateAriaActiveDescendant();
   }
@@ -104,7 +124,8 @@ export default class extends Controller {
 
   selectHighlighted() {
     const items = this.visibleItems;
-    if (this.highlightedIndex < 0 || this.highlightedIndex >= items.length) return;
+    if (this.highlightedIndex < 0 || this.highlightedIndex >= items.length)
+      return;
 
     const item = items[this.highlightedIndex];
     const form = item.querySelector("form");
@@ -124,8 +145,8 @@ export default class extends Controller {
   }
 
   get visibleItems() {
-    return Array.from(this.listTarget.querySelectorAll(".filterable-item")).filter(
-      (item) => item.style.display !== "none"
-    );
+    return Array.from(
+      this.listTarget.querySelectorAll(".filterable-item"),
+    ).filter((item) => item.style.display !== "none");
   }
 }