feat(trips): trip tracking with analytics, tag conversion, and transaction assignment

Adds trips table usage across API and UI: trip CRUD, per-trip analytics
(category/daily/merchant/tag/participant breakdowns), tag-to-trip
conversion, trip assignment via transaction overrides, and trip filter
in the transactions view. Recovered from working tree after local git
corruption; feature was already live via host-context Docker builds.

src/lib/hooks.ts

@@ -1,7 +1,8 @@
 "use client";
 
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
-import type { TransactionRow, StatementRow, TagRow } from "./queries";
+import type { TransactionRow, StatementRow, TagRow, TripRow, TripAnalytics } from "./queries";
+export type { TripRow, TripAnalytics };
 import type { CurrentUser } from "./auth";
 
 interface TransactionsResponse {
@@ -27,6 +28,7 @@ interface TransactionFilters {
   amount_min?: number;
   amount_max?: number;
   has_split?: string;
+  trip_id?: string;
 }
 
 function buildParams(filters: TransactionFilters): string {
@@ -137,6 +139,7 @@ export function useUpdateTransaction() {
       description?: string;
       amount?: number;
       transaction_date?: string;
+      trip_id?: number | null;
     }) => {
       const res = await fetch(`/api/transactions/${id}`, {
         method: "PATCH",
@@ -801,3 +804,94 @@ export function useMerchantTransactions(merchant: string | null) {
     enabled: !!merchant,
   });
 }
+
+// ─── Trips ───────────────────────────────────────────────────────────────────
+
+export function useTrips() {
+  return useQuery<TripRow[]>({
+    queryKey: ["trips"],
+    queryFn: async () => (await fetch("/api/trips")).json(),
+  });
+}
+
+export function useTrip(id: number) {
+  return useQuery<TripRow>({
+    queryKey: ["trip", id],
+    queryFn: async () => (await fetch(`/api/trips/${id}`)).json(),
+    enabled: id > 0,
+  });
+}
+
+export function useTripAnalytics(id: number) {
+  return useQuery<TripAnalytics>({
+    queryKey: ["trip-analytics", id],
+    queryFn: async () => (await fetch(`/api/trips/${id}/analytics`)).json(),
+    enabled: id > 0,
+  });
+}
+
+export function useCreateTrip() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: async (data: Omit<TripRow, "id" | "owner_id" | "created_at" | "total_spend" | "transaction_count">) => {
+      const res = await fetch("/api/trips", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify(data),
+      });
+      if (!res.ok) throw new Error((await res.json()).error || "Failed");
+      return res.json() as Promise<TripRow>;
+    },
+    onSuccess: () => qc.invalidateQueries({ queryKey: ["trips"] }),
+  });
+}
+
+export function useUpdateTrip() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: async ({ id, ...data }: Partial<TripRow> & { id: number }) => {
+      const res = await fetch(`/api/trips/${id}`, {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify(data),
+      });
+      if (!res.ok) throw new Error((await res.json()).error || "Failed");
+      return res.json() as Promise<TripRow>;
+    },
+    onSuccess: (_d, { id }) => {
+      qc.invalidateQueries({ queryKey: ["trips"] });
+      qc.invalidateQueries({ queryKey: ["trip", id] });
+      qc.invalidateQueries({ queryKey: ["trip-analytics", id] });
+    },
+  });
+}
+
+export function useDeleteTrip() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: async (id: number) => {
+      await fetch(`/api/trips/${id}`, { method: "DELETE" });
+    },
+    onSuccess: () => qc.invalidateQueries({ queryKey: ["trips"] }),
+  });
+}
+
+export function useAssignTransactionsToTrip() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: async ({ tripId, transactionIds }: { tripId: number | null; transactionIds: number[] }) => {
+      const res = await fetch("/api/transactions/bulk", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ action: "assign_trip", ids: transactionIds, trip_id: tripId }),
+      });
+      if (!res.ok) throw new Error("Failed to assign trip");
+      return res.json();
+    },
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["transactions"] });
+      qc.invalidateQueries({ queryKey: ["trips"] });
+      qc.invalidateQueries({ queryKey: ["trip-analytics"] });
+    },
+  });
+}