Add category management UI and service layer

Users can now create, edit, and delete custom categories from Settings → Categories. System categories (45 built-in) are shown read-only. Backend adds update_category() and delete_category() service functions; frontend has a new categories API module and a full CRUD section in SettingsPage with filter tabs, colour picker, and delete confirmation.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -23,6 +23,7 @@ Runs entirely on your own hardware via Docker Compose. Designed for LAN access w
 - Per-category budget tracking with rollover support
 - Visual radial gauges showing spend vs. budget
 - Configurable alert threshold (default 80%)
+- Edit existing budgets (amount, period, alert threshold) without losing history
 
 ### Investments
 - Portfolio tracking with holdings and buy/sell/dividend/split transactions
@@ -31,10 +32,17 @@ Runs entirely on your own hardware via Docker Compose. Designed for LAN access w
 - Hourly FX rates for multi-currency conversion to GBP base
 - TWRR and MWRR performance metrics
 - Capital gains reporting (short/long-term by tax year)
-- OHLCV candlestick charts per asset
+- OHLCV candlestick charts per asset with buy/sell transaction history overlay
 - Portfolio visualisations: allocation donut by holding, allocation donut by asset type, cost basis vs current value bar chart, return % per holding bar chart
 - Investment account balances include holding market values in net worth, balance sheet, and accounts list — supports both simple (holdings only) and full cash-flow tracking workflows
 
+### Reports
+### Categories
+- 45 built-in system categories across income, expense, and transfer types
+- Create custom categories with a name, type, and colour
+- Rename and recolour existing custom categories
+- Managed in **Settings → Categories**
+
 ### Reports
 Seven report views:
 1. Net Worth over time (area chart with time slider)

backend/app/api/v1/categories.py

@@ -1,14 +1,28 @@
 import uuid
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel, Field
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.dependencies import get_current_user, get_db
-from app.services.category_service import create_category, list_categories
+from app.services.category_service import create_category, list_categories, update_category, delete_category
 
 router = APIRouter()
 
 
+class CategoryCreate(BaseModel):
+    name: str = Field(..., min_length=1, max_length=100)
+    type: str = Field(..., pattern="^(income|expense|transfer)$")
+    color: str | None = Field(default=None, max_length=7)
+    icon: str | None = Field(default=None, max_length=50)
+
+
+class CategoryUpdate(BaseModel):
+    name: str | None = Field(default=None, min_length=1, max_length=100)
+    color: str | None = None
+    icon: str | None = None
+
+
 @router.get("")
 async def get_categories(
     db: AsyncSession = Depends(get_db),
@@ -19,18 +33,43 @@ async def get_categories(
 
 @router.post("", status_code=201)
 async def create(
-    body: dict,
+    body: CategoryCreate,
     db: AsyncSession = Depends(get_db),
     user=Depends(get_current_user),
 ):
     result = await create_category(
         db,
         user_id=user.id,
-        name=body["name"],
+        name=body.name,
-        type_=body["type"],
+        type_=body.type,
-        icon=body.get("icon"),
+        icon=body.icon,
-        color=body.get("color"),
+        color=body.color,
-        parent_id=uuid.UUID(body["parent_id"]) if body.get("parent_id") else None,
     )
     await db.commit()
     return result
+
+
+@router.put("/{category_id}", status_code=200)
+async def update(
+    category_id: uuid.UUID,
+    body: CategoryUpdate,
+    db: AsyncSession = Depends(get_db),
+    user=Depends(get_current_user),
+):
+    result = await update_category(db, user.id, category_id, body.name, body.color, body.icon)
+    if result is None:
+        raise HTTPException(status_code=404, detail="Category not found or is a system category")
+    await db.commit()
+    return result
+
+
+@router.delete("/{category_id}", status_code=204)
+async def delete(
+    category_id: uuid.UUID,
+    db: AsyncSession = Depends(get_db),
+    user=Depends(get_current_user),
+):
+    ok = await delete_category(db, user.id, category_id)
+    if not ok:
+        raise HTTPException(status_code=404, detail="Category not found or is a system category")
+    await db.commit()

backend/app/services/category_service.py

@@ -133,3 +133,51 @@ async def create_category(
     db.add(cat)
     await db.flush()
     return {"id": str(cat.id), "name": cat.name, "type": cat.type, "icon": cat.icon, "color": cat.color, "is_system": False}
+
+
+async def update_category(
+    db: AsyncSession,
+    user_id: uuid.UUID,
+    category_id: uuid.UUID,
+    name: str | None,
+    color: str | None,
+    icon: str | None,
+) -> dict | None:
+    result = await db.execute(
+        select(Category).where(
+            Category.id == category_id,
+            Category.user_id == user_id,
+            Category.is_system == False,
+        )
+    )
+    cat = result.scalar_one_or_none()
+    if cat is None:
+        return None
+    if name is not None:
+        cat.name = name
+    if color is not None:
+        cat.color = color
+    if icon is not None:
+        cat.icon = icon
+    await db.flush()
+    return {"id": str(cat.id), "name": cat.name, "type": cat.type, "icon": cat.icon, "color": cat.color, "is_system": False}
+
+
+async def delete_category(
+    db: AsyncSession,
+    user_id: uuid.UUID,
+    category_id: uuid.UUID,
+) -> bool:
+    result = await db.execute(
+        select(Category).where(
+            Category.id == category_id,
+            Category.user_id == user_id,
+            Category.is_system == False,
+        )
+    )
+    cat = result.scalar_one_or_none()
+    if cat is None:
+        return False
+    await db.delete(cat)
+    await db.flush()
+    return True

frontend/src/api/categories.ts

@@ -0,0 +1,37 @@
+import { api } from "./client";
+
+export interface Category {
+  id: string;
+  name: string;
+  type: "income" | "expense" | "transfer";
+  icon: string | null;
+  color: string | null;
+  is_system: boolean;
+  parent_id: string | null;
+  sort_order: number;
+}
+
+export interface CategoryCreate {
+  name: string;
+  type: "income" | "expense" | "transfer";
+  color?: string | null;
+  icon?: string | null;
+}
+
+export interface CategoryUpdate {
+  name?: string | null;
+  color?: string | null;
+  icon?: string | null;
+}
+
+export const listCategories = (): Promise<Category[]> =>
+  api.get("/categories").then((r: { data: Category[] }) => r.data);
+
+export const createCategory = (data: CategoryCreate): Promise<Category> =>
+  api.post("/categories", data).then((r: { data: Category }) => r.data);
+
+export const updateCategory = (id: string, data: CategoryUpdate): Promise<Category> =>
+  api.put(`/categories/${id}`, data).then((r: { data: Category }) => r.data);
+
+export const deleteCategory = (id: string): Promise<void> =>
+  api.delete(`/categories/${id}`).then(() => undefined);

frontend/src/pages/settings/SettingsPage.tsx

@@ -9,6 +9,8 @@ import {
 } from "@/api/auth";
 import { listBackups, triggerBackup, downloadBackup, restoreBackup } from "@/api/admin";
 import { getAiSettings, saveAiSettings, clearAiSettings, testAiSettings } from "@/api/settings";
+import { listCategories, createCategory, updateCategory, deleteCategory } from "@/api/categories";
+import type { Category } from "@/api/categories";
 import type { AiSettings } from "@/api/settings";
 import type { BackupFile } from "@/api/admin";
 import { cn } from "@/utils/cn";
@@ -16,13 +18,14 @@ import { format } from "date-fns";
 import {
   User, Shield, MonitorSmartphone, Download, HardDrive,
   Loader2, CheckCircle, Eye, EyeOff, Trash2,
-  LogOut, QrCode, KeyRound, AlertTriangle, RefreshCw, RotateCcw, Sparkles,
+  LogOut, QrCode, KeyRound, AlertTriangle, RefreshCw, RotateCcw, Sparkles, Tag, Plus, Pencil, X,
 } from "lucide-react";
 
 const SECTIONS = [
   { id: "profile",    label: "Profile",    icon: User },
   { id: "security",   label: "Security",   icon: Shield },
   { id: "sessions",   label: "Sessions",   icon: MonitorSmartphone },
+  { id: "categories", label: "Categories", icon: Tag },
   { id: "data",       label: "Data",       icon: Download },
   { id: "backups",    label: "Backups",    icon: HardDrive },
   { id: "ai",         label: "AI",         icon: Sparkles },
@@ -65,6 +68,7 @@ export default function SettingsPage() {
           {section === "profile"    && <ProfileSection />}
           {section === "security"   && <SecuritySection />}
           {section === "sessions"   && <SessionsSection />}
+          {section === "categories" && <CategoriesSection />}
           {section === "data"       && <DataSection />}
           {section === "backups"    && <BackupsSection />}
           {section === "ai"         && <AiSection />}
@@ -875,6 +879,303 @@ function AiSection() {
   );
 }
 
+// ─── Categories ───────────────────────────────────────────────────────────────
+
+const TYPE_LABELS: Record<string, string> = { income: "Income", expense: "Expense", transfer: "Transfer" };
+const TYPE_COLORS: Record<string, string> = { income: "text-success", expense: "text-destructive", transfer: "text-muted-foreground" };
+
+function CategoryRow({
+  cat,
+  onEdit,
+  onDelete,
+}: {
+  cat: Category;
+  onEdit: (c: Category) => void;
+  onDelete: (c: Category) => void;
+}) {
+  return (
+    <div className="flex items-center gap-3 px-3 py-2.5 rounded-lg hover:bg-secondary/40 transition-colors group">
+      <div className="w-3 h-3 rounded-full shrink-0" style={{ backgroundColor: cat.color ?? "#94a3b8" }} />
+      <span className="flex-1 text-sm truncate">{cat.name}</span>
+      <span className={cn("text-xs", TYPE_COLORS[cat.type])}>{TYPE_LABELS[cat.type]}</span>
+      {!cat.is_system && (
+        <div className="flex gap-1 opacity-0 group-hover:opacity-100 transition-opacity">
+          <button
+            type="button"
+            onClick={() => onEdit(cat)}
+            className="p-1 rounded text-muted-foreground hover:text-foreground hover:bg-secondary transition-colors"
+          >
+            <Pencil className="w-3.5 h-3.5" />
+          </button>
+          <button
+            type="button"
+            onClick={() => onDelete(cat)}
+            className="p-1 rounded text-muted-foreground hover:text-destructive hover:bg-destructive/10 transition-colors"
+          >
+            <Trash2 className="w-3.5 h-3.5" />
+          </button>
+        </div>
+      )}
+    </div>
+  );
+}
+
+function CategoryFormModal({
+  editing,
+  onClose,
+}: {
+  editing: Category | null;
+  onClose: () => void;
+}) {
+  const qc = useQueryClient();
+  const [name, setName]   = useState(editing?.name ?? "");
+  const [type, setType]   = useState<"income" | "expense" | "transfer">(editing?.type ?? "expense");
+  const [color, setColor] = useState(editing?.color ?? "#6366f1");
+  const [error, setError] = useState("");
+
+  const isEdit = editing !== null;
+
+  const mutation = useMutation({
+    mutationFn: () =>
+      isEdit
+        ? updateCategory(editing!.id, { name, color })
+        : createCategory({ name, type, color }),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["categories"] });
+      onClose();
+    },
+    onError: (e: any) => setError(e?.response?.data?.detail ?? "Failed to save category"),
+  });
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm p-4">
+      <div className="bg-card border border-border rounded-2xl w-full max-w-sm shadow-xl p-6 space-y-4">
+        <div className="flex items-center justify-between">
+          <h3 className="font-semibold text-base">{isEdit ? "Edit category" : "New category"}</h3>
+          <button type="button" onClick={onClose} className="p-1 rounded text-muted-foreground hover:text-foreground hover:bg-secondary transition-colors">
+            <X className="w-4 h-4" />
+          </button>
+        </div>
+
+        {error && <ErrorBanner message={error} />}
+
+        <div>
+          <label className="text-sm font-medium block mb-1.5">Name</label>
+          <input
+            value={name}
+            onChange={e => setName(e.target.value)}
+            className={inputCls}
+            placeholder="Category name"
+            maxLength={100}
+            autoFocus
+          />
+        </div>
+
+        {!isEdit && (
+          <div>
+            <label className="text-sm font-medium block mb-1.5">Type</label>
+            <select
+              value={type}
+              onChange={e => setType(e.target.value as any)}
+              className={inputCls}
+            >
+              <option value="expense">Expense</option>
+              <option value="income">Income</option>
+              <option value="transfer">Transfer</option>
+            </select>
+          </div>
+        )}
+
+        <div>
+          <label className="text-sm font-medium block mb-1.5">Colour</label>
+          <div className="flex items-center gap-3">
+            <input
+              type="color"
+              value={color}
+              onChange={e => setColor(e.target.value)}
+              className="h-9 w-16 rounded-lg border border-input bg-background cursor-pointer p-0.5"
+            />
+            <input
+              value={color}
+              onChange={e => setColor(e.target.value)}
+              className={cn(inputCls, "flex-1 font-mono")}
+              placeholder="#6366f1"
+              maxLength={7}
+            />
+          </div>
+        </div>
+
+        <div className="flex gap-3 pt-1">
+          <button type="button" onClick={onClose} className="flex-1 py-2 rounded-lg border border-border text-sm hover:bg-secondary transition-colors">
+            Cancel
+          </button>
+          <button
+            type="button"
+            onClick={() => mutation.mutate()}
+            disabled={!name.trim() || mutation.isPending}
+            className="flex-1 flex items-center justify-center gap-2 bg-primary text-primary-foreground rounded-lg py-2 text-sm font-medium hover:bg-primary/90 disabled:opacity-50 transition-colors"
+          >
+            {mutation.isPending && <Loader2 className="w-4 h-4 animate-spin" />}
+            {isEdit ? "Save" : "Create"}
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function CategoriesSection() {
+  const qc = useQueryClient();
+  const [modal, setModal]       = useState<"create" | Category | null>(null);
+  const [deleting, setDeleting] = useState<Category | null>(null);
+  const [filter, setFilter]     = useState<"all" | "income" | "expense" | "transfer">("all");
+
+  const { data: categories = [], isLoading } = useQuery({
+    queryKey: ["categories"],
+    queryFn: listCategories,
+  });
+
+  const deleteMutation = useMutation({
+    mutationFn: (id: string) => deleteCategory(id),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["categories"] });
+      setDeleting(null);
+    },
+  });
+
+  const userCats   = categories.filter(c => !c.is_system);
+  const systemCats = categories.filter(c => c.is_system);
+
+  const filtered = (list: Category[]) =>
+    filter === "all" ? list : list.filter(c => c.type === filter);
+
+  return (
+    <div className="space-y-4">
+      <div className={cardCls}>
+        <div className="flex items-center justify-between gap-2 flex-wrap">
+          <SectionTitle>Categories</SectionTitle>
+          <button
+            type="button"
+            onClick={() => setModal("create")}
+            className="flex items-center gap-1.5 bg-primary text-primary-foreground px-3 py-1.5 rounded-lg text-sm font-medium hover:bg-primary/90 transition-colors"
+          >
+            <Plus className="w-3.5 h-3.5" />
+            Add category
+          </button>
+        </div>
+
+        <p className="text-sm text-muted-foreground">
+          System categories are built-in and cannot be edited. Custom categories can be freely created, renamed, and coloured.
+        </p>
+
+        {/* Filter tabs */}
+        <div className="flex gap-1">
+          {(["all", "income", "expense", "transfer"] as const).map(t => (
+            <button
+              key={t}
+              type="button"
+              onClick={() => setFilter(t)}
+              className={cn(
+                "px-3 py-1 rounded-lg text-xs font-medium transition-colors capitalize",
+                filter === t ? "bg-primary/15 text-primary" : "text-muted-foreground hover:text-foreground hover:bg-secondary"
+              )}
+            >
+              {t}
+            </button>
+          ))}
+        </div>
+
+        {isLoading ? (
+          <div className="space-y-1">
+            {[1,2,3,4].map(i => <div key={i} className="h-9 bg-secondary/30 rounded-lg animate-pulse" />)}
+          </div>
+        ) : (
+          <>
+            {/* User categories */}
+            {filtered(userCats).length > 0 && (
+              <div>
+                <p className="text-xs font-medium text-muted-foreground uppercase tracking-wider mb-1 px-1">Custom</p>
+                <div className="space-y-0.5">
+                  {filtered(userCats).map(c => (
+                    <CategoryRow
+                      key={c.id}
+                      cat={c}
+                      onEdit={setModal}
+                      onDelete={setDeleting}
+                    />
+                  ))}
+                </div>
+              </div>
+            )}
+
+            {/* System categories */}
+            {filtered(systemCats).length > 0 && (
+              <div>
+                <p className="text-xs font-medium text-muted-foreground uppercase tracking-wider mb-1 px-1">System</p>
+                <div className="space-y-0.5">
+                  {filtered(systemCats).map(c => (
+                    <CategoryRow key={c.id} cat={c} onEdit={() => {}} onDelete={() => {}} />
+                  ))}
+                </div>
+              </div>
+            )}
+
+            {filtered([...userCats, ...systemCats]).length === 0 && (
+              <p className="text-sm text-muted-foreground text-center py-4">No categories for this type yet.</p>
+            )}
+          </>
+        )}
+      </div>
+
+      {/* Create / Edit modal */}
+      {modal !== null && (
+        <CategoryFormModal
+          editing={modal === "create" ? null : modal}
+          onClose={() => setModal(null)}
+        />
+      )}
+
+      {/* Delete confirmation */}
+      {deleting && (
+        <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm p-4">
+          <div className="bg-card border border-border rounded-2xl w-full max-w-sm shadow-xl p-6 space-y-4">
+            <div className="flex items-start gap-4">
+              <div className="w-10 h-10 rounded-full bg-destructive/15 flex items-center justify-center shrink-0">
+                <AlertTriangle className="w-5 h-5 text-destructive" />
+              </div>
+              <div>
+                <h3 className="font-semibold text-base">Delete "{deleting.name}"?</h3>
+                <p className="text-sm text-muted-foreground mt-1">
+                  Transactions using this category will remain but their category will be unset. This cannot be undone.
+                </p>
+              </div>
+            </div>
+            <div className="flex gap-3">
+              <button
+                type="button"
+                onClick={() => setDeleting(null)}
+                disabled={deleteMutation.isPending}
+                className="flex-1 py-2.5 rounded-lg border border-border text-sm hover:bg-secondary transition-colors disabled:opacity-50"
+              >
+                Cancel
+              </button>
+              <button
+                type="button"
+                onClick={() => deleteMutation.mutate(deleting.id)}
+                disabled={deleteMutation.isPending}
+                className="flex-1 flex items-center justify-center gap-2 py-2.5 rounded-lg bg-destructive text-destructive-foreground text-sm font-medium hover:bg-destructive/90 disabled:opacity-50 transition-colors"
+              >
+                {deleteMutation.isPending && <Loader2 className="w-4 h-4 animate-spin" />}
+                Delete
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}
+
 // ─── Data ─────────────────────────────────────────────────────────────────────
 
 function DataSection() {