refactor(ts): type snowball projection + settings responses (Track C)

Promoted SnowballProjection (+details) and SnowballSettings into @/types;
wired snowball (Bill[]), snowballSettings/saveSnowballSettings, and
snowballProjection with get<T>/_fetch<T>. Removed the projection/settings/
bills casts. Plan-lifecycle SnowballPlan casts kept (component-owned type).
typecheck/lint/build clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

HISTORY.md

@@ -3,6 +3,7 @@
 
 ### 🔌 API response typing cleanup (Track C) — promoting page shapes into `@/types`, endpoint by endpoint
 
+- **[Client] Snowball projection + settings typed.** Promoted `SnowballProjection` (+ `SnowballProjectionDetail`/`AvalancheProjectionDetail`/`SnowballDebtProjection`) and `SnowballSettings` into `@/types`, and wired `snowball` (→ `Bill[]`), `snowballSettings`/`saveSnowballSettings` (→ `SnowballSettings`), and `snowballProjection` (→ `SnowballProjection`). Removed the projection/settings/bills casts. (The plan-lifecycle endpoints still cast to `SnowballPlan`, which is a component-owned type in `PlanHistoryPanel` — left as-is to avoid a cross-file type move for marginal gain.)
 - **[Client] Subscriptions domain typed.** Promoted the `SubscriptionsPage` shapes into `@/types` (`Subscription`, `SubscriptionSummary`/`…TopType`, `SubscriptionsResponse`, `Recommendation` + `RecommendationEvidence`/`…Transaction`/`ExistingBillMatch`/`CatalogMatch`, `SubscriptionTx`) and wired `subscriptions`/`subscriptionRecommendations`/`subscriptionTransactionMatches`/`createSubscriptionFromRecommendation`/`matchRecommendationToBill` with `get<T>`/`post<T>`. Dropped the `(r: any)` in `useSubscriptionRecommendations` (now typed) and the 5 page casts; removed an unused `CatalogMatch` import (Track E).
 - **[Client] Spending domain typed.** Promoted `SpendingPage`'s local response interfaces into `@/types` (`SpendingCategoryEntry`, `SpendingSummary`, `SpendingTransaction`/`…Response`, `SpendingIncomeTx`/`…Response`, `SpendingRule`, `CategoryGroup`, `CopyBudgetsResponse`) and wired `spendingSummary`/`spendingTransactions`/`spendingIncome`/`spendingCategoryRules`/`copySpendingBudgets`/`categoryGroups` with `get<T>`/`post<T>`. `useSpendingSummary`/`useSpendingTransactions`/`useCategoryGroups` now return typed data; the 6 spending `as {…}` casts are gone. Removed 2 now-unused type aliases the cast-removal orphaned (Track E).
 - **[Client] Bank-ledger domain typed end-to-end.** Promoted the `BankTransactionsPage` local interfaces (`Tx`/`Account`/`Ledger`/`LedgerSummary`/`CategoryBreakdown`/auto-categorize preview) into `@/types` as `BankLedgerTransaction` (extends the existing `BankTransaction`, so raw amounts stay branded `Cents`), `BankAccount`, `BankLedger`, `BankLedgerSummary`, `BankCategoryBreakdown`, `AutoCategorizePreview`. Wired the endpoints in `api.ts` (`bankTransactionsLedger` → `get<BankLedger>`, `matchTransaction`/`unmatchTransaction` → `{ transaction }`, `ignoreTransaction`/`unignoreTransaction` → the transaction, `applyTransactionMerchantMatch`/`autoCategorizeTransactions` → their result shapes), so `useBankLedger`'s `data` is now typed and **all 9 `as {…}` casts in the page are gone** — a server field rename now fails in `@/types`, not silently at 9 call sites. Dropped a now-dead `Cents` import (Track E). typecheck/lint/build clean.

client/api.ts

@@ -4,6 +4,7 @@ import type {
   SpendingSummary, SpendingTransactionsResponse, SpendingIncomeResponse,
   SpendingRule, CopyBudgetsResponse, CategoryGroup,
   SubscriptionsResponse, Recommendation, SubscriptionTx,
+  SnowballProjection, SnowballSettings,
 } from '@/types';
 
 // Fetch CSRF token from the server once and cache in memory.
@@ -323,11 +324,11 @@ export const api = {
   undoAutoMatch:      (id: Id)    => post(`/payments/${id}/undo-auto`),
 
   // Snowball
-  snowball:              ()        => get('/snowball'),
+  snowball:              ()        => get<Bill[]>('/snowball'),
-  snowballSettings:      ()        => get('/snowball/settings'),
+  snowballSettings:      ()        => get<SnowballSettings>('/snowball/settings'),
-  saveSnowballSettings:  (data: Body) => _fetch('PATCH', '/snowball/settings', data),
+  saveSnowballSettings:  (data: Body) => _fetch<SnowballSettings>('PATCH', '/snowball/settings', data),
   saveSnowballOrder:     (items: Body) => _fetch('PATCH', '/snowball/order', items),
-  snowballProjection: (params: QueryParams = {}) => get(`/snowball/projection${queryString(params)}`),
+  snowballProjection: (params: QueryParams = {}) => get<SnowballProjection>(`/snowball/projection${queryString(params)}`),
   snowballPlans:         ()        => get('/snowball/plans'),
   snowballActivePlan:    ()        => get('/snowball/plans/active'),
   startSnowballPlan:     (data: Body) => post('/snowball/plans', data),

client/pages/SnowballPage.tsx

@@ -19,7 +19,13 @@ import PlanStatusBanner, { type ActivePlan } from '@/components/snowball/PlanSta
 import PlanHistoryPanel, { type SnowballPlan } from '@/components/snowball/PlanHistoryPanel';
 import * as AlertDialog from '@radix-ui/react-alert-dialog';
 import { formatUSD, formatUSDWhole, asDollars } from '@/lib/money';
-import type { Bill, Category } from '@/types';
+import type {
+  Bill, Category,
+  SnowballProjection as Projection,
+  SnowballProjectionDetail as SnowballProj,
+  AvalancheProjectionDetail as AvalancheProj,
+  SnowballSettings,
+} from '@/types';
 
 // ── formatters ────────────────────────────────────────────────────────────────
 function fmt(val: number | null | undefined): string {
@@ -51,38 +57,6 @@ function isRamseyOrdered(debts: Bill[]): boolean {
   return debts.every((debt, index) => debt.id === sorted[index]?.id);
 }
 
-interface DebtProj {
-  id: number;
-  name: string;
-  payoff_display?: string;
-  months?: number;
-  total_interest?: number;
-  current_balance?: number;
-}
-interface SnowballProj {
-  debts: DebtProj[];
-  skipped: { name: string }[];
-  payoff_display?: string;
-  months_to_freedom?: number;
-  total_interest_paid?: number;
-  capped?: boolean;
-}
-interface AvalancheProj {
-  months_to_freedom?: number;
-  total_interest_paid?: number;
-  payoff_display?: string;
-}
-interface Projection {
-  snowball?: SnowballProj;
-  avalanche?: AvalancheProj;
-}
-
-interface SnowballSettings {
-  extra_payment?: number;
-  ramsey_mode?: boolean;
-  ready_current_on_bills?: boolean;
-  ready_emergency_fund?: boolean;
-}
 
 interface ReadinessItem {
   id: string;
@@ -347,11 +321,11 @@ function ReadinessStrip({ items, readyCount, totalCount, allReady, onToggle, dis
 export default function SnowballPage() {
   const queryClient = useQueryClient();
   const { data: billsRaw = [], isPending: billsPending, error: snowballError } = useSnowball();
-  const bills = (billsRaw ?? []) as Bill[];
+  const bills = billsRaw ?? [];
   const { data: categoriesRaw = [] } = useCategories();
   const categories = (categoriesRaw ?? []) as Category[];
   const { data: settingsRaw } = useSnowballSettings();
-  const settings = settingsRaw as SnowballSettings | undefined;
+  const settings = settingsRaw;
   const { data: activePlanRaw = null } = useSnowballActivePlan();
   const activePlan = (activePlanRaw ?? null) as SnowballPlan | null;
   const { data: allPlansRaw = [] } = useSnowballPlans();
@@ -395,7 +369,7 @@ export default function SnowballPage() {
     try {
       const extra = parseFloat(typedExtraRef.current);
       const params = Number.isFinite(extra) && extra >= 0 ? { extra } : {};
-      setProjection(await api.snowballProjection(params) as Projection);
+      setProjection(await api.snowballProjection(params));
       setProjectionError(false);
     } catch {
       setProjectionError(true);
@@ -491,7 +465,7 @@ export default function SnowballPage() {
     if (val === extraPaymentRef.current) return;
     setSavingSettings(true);
     try {
-      const result = await api.saveSnowballSettings({ extra_payment: val === '' ? 0 : parseFloat(val) }) as SnowballSettings;
+      const result = await api.saveSnowballSettings({ extra_payment: val === '' ? 0 : parseFloat(val) });
       const saved = Number(result.extra_payment) > 0 ? String(result.extra_payment) : '';
       extraPaymentRef.current = saved;
       setExtraPayment(saved);
@@ -504,7 +478,7 @@ export default function SnowballPage() {
   const handleRamseyModeChange = async (checked: boolean) => {
     setSavingSettings(true);
     try {
-      const result = await api.saveSnowballSettings({ ramsey_mode: checked }) as SnowballSettings;
+      const result = await api.saveSnowballSettings({ ramsey_mode: checked });
       const nextMode = result.ramsey_mode !== false;
       setRamseyMode(nextMode);
       setDirty(false);
@@ -530,7 +504,7 @@ export default function SnowballPage() {
 
     setSavingSettings(true);
     try {
-      const result = await api.saveSnowballSettings(payload) as SnowballSettings;
+      const result = await api.saveSnowballSettings(payload);
       setReadyCurrentOnBills(!!result.ready_current_on_bills);
       setReadyEmergencyFund(!!result.ready_emergency_fund);
     } catch (err) {
@@ -583,7 +557,7 @@ export default function SnowballPage() {
       const params = Number.isFinite(extra) && extra >= 0 ? { extra } : {};
       try {
         setProjectionLoading(true);
-        const result = await api.snowballProjection(params) as Projection;
+        const result = await api.snowballProjection(params);
         setProjection(result);
         setProjectionError(false);
       } catch {

client/types.ts

@@ -203,6 +203,40 @@ export interface Recommendation {
   transactions?: RecommendationTransaction[];
   [key: string]: unknown;
 }
+// The snowball projection (GET /snowball/projection) and settings
+// (PATCH /snowball/settings). Amounts are dollars kept as plain `number`.
+export interface SnowballDebtProjection {
+  id: number;
+  name: string;
+  payoff_display?: string;
+  months?: number;
+  total_interest?: number;
+  current_balance?: number;
+}
+export interface SnowballProjectionDetail {
+  debts: SnowballDebtProjection[];
+  skipped: { name: string }[];
+  payoff_display?: string;
+  months_to_freedom?: number;
+  total_interest_paid?: number;
+  capped?: boolean;
+}
+export interface AvalancheProjectionDetail {
+  months_to_freedom?: number;
+  total_interest_paid?: number;
+  payoff_display?: string;
+}
+export interface SnowballProjection {
+  snowball?: SnowballProjectionDetail;
+  avalanche?: AvalancheProjectionDetail;
+}
+export interface SnowballSettings {
+  extra_payment?: number;
+  ramsey_mode?: boolean;
+  ready_current_on_bills?: boolean;
+  ready_emergency_fund?: boolean;
+}
+
 // A raw bank transaction on the subscription-match search — amount in CENTS.
 export interface SubscriptionTx {
   id: number;