diff --git a/src/admin/components/PlanCellModal.tsx b/src/admin/components/PlanCellModal.tsx
index e910f59..bad9f29 100644
--- a/src/admin/components/PlanCellModal.tsx
+++ b/src/admin/components/PlanCellModal.tsx
@@ -122,7 +122,11 @@ function EditForm(props: Props) {
         date_to: mode.date,
         is_range: false,
         project_id: null as number | null,
-        category: "work",
+        // Default to "work" when it's active, otherwise the first active
+        // category, so a new entry never starts on a retired key.
+        category: activeCategories.some((c) => c.key === "work")
+          ? "work"
+          : (activeCategories[0]?.key ?? "work"),
         note: "",
       };
     }
@@ -294,6 +298,19 @@ function EditForm(props: Props) {
             value={category}
             onChange={(e) => setCategory(e.target.value)}
           >
+            {/* If the row's current category was retired/hidden, still show it
+                (marked) so the select reflects reality instead of silently
+                snapping to the first active option. The server only re-checks
+                the category if it changes, so keeping it saves fine. */}
+            {category && !activeCategories.some((c) => c.key === category) && (
+              <option value={category}>
+                {planCategoryLabel(
+                  category,
+                  Object.fromEntries(props.categories.map((x) => [x.key, x])),
+                )}{" "}
+                (skrytá)
+              </option>
+            )}
             {activeCategories.map((c) => (
               <option key={c.key} value={c.key}>
                 {c.label}
diff --git a/src/services/plan.service.ts b/src/services/plan.service.ts
index 5f4af09..9d99be7 100644
--- a/src/services/plan.service.ts
+++ b/src/services/plan.service.ts
@@ -502,7 +502,9 @@ export async function updateEntry(
     return { error: "Datum do musí být stejné nebo po datumu od", status: 400 };
   }
 
-  if (input.category) {
+  // Only validate the category when it actually changes — so editing just the
+  // note of an entry whose category was later retired/hidden still saves.
+  if (input.category && input.category !== existing.category) {
     const catErr = await assertActiveCategory(input.category);
     if (catErr) return catErr;
   }
@@ -695,7 +697,8 @@ export async function updateOverride(
   const lock = assertNotPastDate(dateStr, force);
   if (lock) return lock;
 
-  if (input.category) {
+  // Only validate the category when it actually changes (see updateEntry).
+  if (input.category && input.category !== existing.category) {
     const catErr = await assertActiveCategory(input.category);
     if (catErr) return catErr;
   }