Clarify category creation flows

web/src/Registry.tsx

@@ -5,6 +5,7 @@ import {
   GitMerge,
   Trash2,
   FolderTree,
+  FolderPlus,
   Tag as TagIcon,
   Store,
   CandlestickChart,
@@ -32,6 +33,10 @@ import {
 import type { Mutate } from "./ui";
 type Entity = "category" | "tag" | "merchant" | "instrument";
 type Item = Category | Tag | Merchant | Instrument;
+const protectedCategoryIDs = new Set([
+  "cat_expenses_unclassified",
+  "cat_income_unclassified",
+]);
 const titles = {
   category: "Categories",
   tag: "Tags",
@@ -82,7 +87,17 @@ export function Registry({
             ? { id: "", isin: "", name: "", currency: "EUR", symbol: "" }
             : { id: "", name: "" },
     );
-  const row = (item: Item, depth = 0) => (
+  const createChild = (parent: Category) =>
+    setEditing({
+      id: "",
+      name: "",
+      parent_id: parent.id,
+      kind: parent.kind,
+      hint: "",
+    });
+  const row = (item: Item, depth = 0) => {
+    const category = entity === "category" && "kind" in item ? item : null;
+    return (
       <div className="registry-row" key={item.id}>
         <div
           className="registry-label"
@@ -130,6 +145,17 @@ export function Registry({
           </span>
         )}
         <div className="row-actions">
+          {category && !protectedCategoryIDs.has(category.id) && (
+            <button
+              className="button subtle category-child-action"
+              title={`Add a child category under ${category.name}`}
+              aria-label={`Add a child category under ${category.name}`}
+              onClick={() => createChild(category)}
+            >
+              <FolderPlus size={15} />
+              Add child
+            </button>
+          )}
           <button
             className="icon-button"
             title={`Edit ${item.name}`}
@@ -159,6 +185,7 @@ export function Registry({
         </div>
       </div>
     );
+  };
   const tree = (
     parent: string | undefined,
     depth = 0,
@@ -181,7 +208,7 @@ export function Registry({
           <h2>{titles[entity]}</h2>
           <p>
             {entity === "category"
-              ? "A clear home for every transaction. Parent categories roll up their children."
+              ? "Organize spending and income into a tree. Use Add child on any category to create a nested category."
               : entity === "tag"
                 ? "Flexible labels that work across your accounts and categories."
                 : entity === "instrument"
@@ -549,15 +576,18 @@ function RegistryEditor({
                   <option value="income">Income</option>
                 </select>
               </Field>
-              <Field label="Parent category">
+              <Field
+                label="Parent category"
+                hint="Choose an existing category to nest this one. Use Add child on the category list when you want to add a nested category."
+              >
                 <CategoryCombobox
                   data={data}
                   kind={kind}
                   exclude={[...descendants]}
-                  emptyLabel="No parent (root)"
-                  mutate={mutate}
+                  emptyLabel="No parent (top level)"
                   value={parent}
                   onChange={setParent}
+                  placeholder="Choose a parent category"
                 />
               </Field>
               <p className="muted">

web/src/Transactions.tsx

@@ -496,13 +496,17 @@ function TransactionEditor({
             )}
           </div>
           {value.kind !== "transfer" && value.kind !== "investment" && (
-            <Field label="Category">
+            <Field
+              label="Category"
+              hint="Choose a leaf category. To add one now, type a new name and choose “Create category”. Use “Parent / Child” to nest it under an existing category."
+            >
               <CategoryCombobox
                 data={data}
                 kind={value.kind}
                 leavesOnly
                 required
                 mutate={mutate}
+                placeholder="Select or type to add a category"
                 value={value.category_id || ""}
                 onChange={(category_id) =>
                   setValue((v) => ({ ...v, category_id }))

web/src/styles.css

@@ -903,6 +903,11 @@ tbody tr:hover {
   gap: 5px;
   align-items: center;
 }
+.category-child-action {
+  min-height: 32px;
+  padding: 6px 9px;
+  font-size: 11px;
+}
 .modal {
   border: 1px solid #dce5eb;
   border-radius: 12px;

web/src/ui.tsx

@@ -730,9 +730,9 @@ export function CategoryOptions({
 }
 // CategoryCombobox is the one category picker: options are full paths, and
 // with a mutate handle an unmatched name can be created in place. A bare name
-// lands under the kind's root; "Parent / Name" creates under that parent.
-// leavesOnly matches the server rule that assigned categories must be leaves;
-// a freshly created category is always a leaf.
+// is offered under each matching root; "Parent / Name" creates under that
+// existing parent. leavesOnly matches the server rule that assigned categories
+// must be leaves; a freshly created category is always a leaf.
 export function CategoryCombobox({
   data,
   value,
@@ -782,7 +782,7 @@ export function CategoryCombobox({
     const name = segments[segments.length - 1];
     const row = (parent: Category): ComboCreate => ({
       key: parent.id,
-      label: `Create "${name}" in ${categoryPath(data, parent.id)}`,
+      label: `Create category "${name}" in ${categoryPath(data, parent.id)}`,
       run: async () =>
         onChange(
           await createCategory(mutate, data, {
@@ -813,7 +813,7 @@ export function CategoryCombobox({
       placeholder={placeholder}
       emptyText={
         mutate
-          ? "No matching category. Type a name to create it."
+          ? "No match. Type a category name and choose Create category."
           : "No matching category."
       }
       create={create}