diff --git a/frontend/src/api/client.ts b/frontend/src/api/client.ts
index ee06def..329e0b9 100644
--- a/frontend/src/api/client.ts
+++ b/frontend/src/api/client.ts
@@ -134,26 +134,26 @@ async function del<T>(path: string): Promise<T> {
 	return response.json();
 }
 
-// Dashboard
-export const fetchCounts = (machineId?: string) =>
+// Dashboard (Jellyfin-backed; selected via jellyfin_service_id)
+export const fetchCounts = (jellyfinServiceId?: string) =>
 	get<MediaCounts>(
 		"/api/dashboard/counts",
-		machineId ? { machine_id: machineId } : undefined,
+		jellyfinServiceId ? { jellyfin_service_id: jellyfinServiceId } : undefined,
 	);
-export const fetchLibraries = (machineId?: string) =>
+export const fetchLibraries = (jellyfinServiceId?: string) =>
 	get<LibraryCount[]>(
 		"/api/dashboard/libraries",
-		machineId ? { machine_id: machineId } : undefined,
+		jellyfinServiceId ? { jellyfin_service_id: jellyfinServiceId } : undefined,
 	);
-export const fetchActivity = (machineId?: string) =>
+export const fetchActivity = (jellyfinServiceId?: string) =>
 	get<NowPlayingSession[]>(
 		"/api/dashboard/activity",
-		machineId ? { machine_id: machineId } : undefined,
+		jellyfinServiceId ? { jellyfin_service_id: jellyfinServiceId } : undefined,
 	);
-export const fetchUsers = (machineId?: string) =>
+export const fetchUsers = (jellyfinServiceId?: string) =>
 	get<UserDirectoryResponse>(
 		"/api/users",
-		machineId ? { machine_id: machineId } : undefined,
+		jellyfinServiceId ? { jellyfin_service_id: jellyfinServiceId } : undefined,
 	);
 
 // Backward-compatible alias used by older hooks/components.
@@ -293,27 +293,27 @@ export const resetLocalDatabase = (payload: ResetLocalDatabaseInput) =>
 	);
 
 // Media
-export const fetchMediaStatus = (machineId?: string) =>
+export const fetchMediaStatus = (jellyfinServiceId?: string) =>
 	get<MediaIndexStatus>(
 		"/api/media/status",
-		machineId ? { machine_id: machineId } : undefined,
+		jellyfinServiceId ? { jellyfin_service_id: jellyfinServiceId } : undefined,
 	);
-export const buildMediaIndex = (machineId?: string) =>
+export const buildMediaIndex = (jellyfinServiceId?: string) =>
 	post<MediaIndexActionResponse>(
-		machineId
-			? `/api/media/build?machine_id=${encodeURIComponent(machineId)}`
+		jellyfinServiceId
+			? `/api/media/build?jellyfin_service_id=${encodeURIComponent(jellyfinServiceId)}`
 			: "/api/media/build",
 	);
-export const stopMediaIndexBuild = (machineId?: string) =>
+export const stopMediaIndexBuild = (jellyfinServiceId?: string) =>
 	post<MediaIndexActionResponse>(
-		machineId
-			? `/api/media/stop?machine_id=${encodeURIComponent(machineId)}`
+		jellyfinServiceId
+			? `/api/media/stop?jellyfin_service_id=${encodeURIComponent(jellyfinServiceId)}`
 			: "/api/media/stop",
 	);
-export const forceStopMediaIndexBuild = (machineId?: string) =>
+export const forceStopMediaIndexBuild = (jellyfinServiceId?: string) =>
 	post<MediaIndexActionResponse>(
-		machineId
-			? `/api/media/force-stop?machine_id=${encodeURIComponent(machineId)}`
+		jellyfinServiceId
+			? `/api/media/force-stop?jellyfin_service_id=${encodeURIComponent(jellyfinServiceId)}`
 			: "/api/media/force-stop",
 	);
 export const queryMedia = (params: {
@@ -325,7 +325,7 @@ export const queryMedia = (params: {
 	sort_order?: string;
 	limit?: number;
 	offset?: number;
-	machineId?: string;
+	jellyfinServiceId?: string;
 }) =>
 	get<MediaQueryResponse>("/api/media/query", {
 		libraries: params.libraries || "",
@@ -336,7 +336,9 @@ export const queryMedia = (params: {
 		sort_order: params.sort_order || "Ascending",
 		limit: String(params.limit || 100),
 		offset: String(params.offset || 0),
-		...(params.machineId ? { machine_id: params.machineId } : {}),
+		...(params.jellyfinServiceId
+			? { jellyfin_service_id: params.jellyfinServiceId }
+			: {}),
 	});
 
 // Files
diff --git a/frontend/src/hooks/useDashboard.ts b/frontend/src/hooks/useDashboard.ts
index 64a1b5d..d472d6a 100644
--- a/frontend/src/hooks/useDashboard.ts
+++ b/frontend/src/hooks/useDashboard.ts
@@ -9,26 +9,26 @@ import {
 } from "../api/client";
 import type { DashboardShortcutInput } from "../types";
 
-export function useCounts(machineId?: string) {
+export function useCounts(jellyfinServiceId?: string) {
 	return useQuery({
-		queryKey: ["dashboard", "counts", machineId ?? "default"],
-		queryFn: () => fetchCounts(machineId),
+		queryKey: ["dashboard", "counts", jellyfinServiceId ?? "default"],
+		queryFn: () => fetchCounts(jellyfinServiceId),
 		staleTime: 5 * 60 * 1000,
 	});
 }
 
-export function useLibraries(machineId?: string) {
+export function useLibraries(jellyfinServiceId?: string) {
 	return useQuery({
-		queryKey: ["dashboard", "libraries", machineId ?? "default"],
-		queryFn: () => fetchLibraries(machineId),
+		queryKey: ["dashboard", "libraries", jellyfinServiceId ?? "default"],
+		queryFn: () => fetchLibraries(jellyfinServiceId),
 		staleTime: 5 * 60 * 1000,
 	});
 }
 
-export function useActivity(machineId?: string) {
+export function useActivity(jellyfinServiceId?: string) {
 	return useQuery({
-		queryKey: ["dashboard", "activity", machineId ?? "default"],
-		queryFn: () => fetchActivity(machineId),
+		queryKey: ["dashboard", "activity", jellyfinServiceId ?? "default"],
+		queryFn: () => fetchActivity(jellyfinServiceId),
 		refetchInterval: 15_000,
 	});
 }
diff --git a/frontend/src/hooks/useMedia.ts b/frontend/src/hooks/useMedia.ts
index a0f8eb8..bd7b273 100644
--- a/frontend/src/hooks/useMedia.ts
+++ b/frontend/src/hooks/useMedia.ts
@@ -7,10 +7,10 @@ import {
 	forceStopMediaIndexBuild,
 } from "../api/client";
 
-export function useMediaStatus(machineId?: string) {
+export function useMediaStatus(jellyfinServiceId?: string) {
 	return useQuery({
-		queryKey: ["media", "status", machineId ?? "default"],
-		queryFn: () => fetchMediaStatus(machineId),
+		queryKey: ["media", "status", jellyfinServiceId ?? "default"],
+		queryFn: () => fetchMediaStatus(jellyfinServiceId),
 		staleTime: 5_000,
 		refetchInterval: (query) =>
 			query.state.data?.build_running ? 1000 : false,
@@ -27,7 +27,7 @@ export function useMediaQuery(params: {
 	sort_order?: string;
 	limit?: number;
 	offset?: number;
-	machineId?: string;
+	jellyfinServiceId?: string;
 	enabled?: boolean;
 }) {
 	const { enabled = true, ...queryParams } = params;
@@ -44,30 +44,30 @@ function invalidateMedia(queryClient: ReturnType<typeof useQueryClient>) {
 	queryClient.invalidateQueries({ queryKey: ["media"] });
 }
 
-export function useBuildIndex(machineId?: string) {
+export function useBuildIndex(jellyfinServiceId?: string) {
 	const queryClient = useQueryClient();
 	return useMutation({
-		mutationFn: () => buildMediaIndex(machineId),
+		mutationFn: () => buildMediaIndex(jellyfinServiceId),
 		onSuccess: () => {
 			invalidateMedia(queryClient);
 		},
 	});
 }
 
-export function useStopBuildIndex(machineId?: string) {
+export function useStopBuildIndex(jellyfinServiceId?: string) {
 	const queryClient = useQueryClient();
 	return useMutation({
-		mutationFn: () => stopMediaIndexBuild(machineId),
+		mutationFn: () => stopMediaIndexBuild(jellyfinServiceId),
 		onSuccess: () => {
 			invalidateMedia(queryClient);
 		},
 	});
 }
 
-export function useForceStopBuildIndex(machineId?: string) {
+export function useForceStopBuildIndex(jellyfinServiceId?: string) {
 	const queryClient = useQueryClient();
 	return useMutation({
-		mutationFn: () => forceStopMediaIndexBuild(machineId),
+		mutationFn: () => forceStopMediaIndexBuild(jellyfinServiceId),
 		onSuccess: () => {
 			invalidateMedia(queryClient);
 		},
diff --git a/frontend/src/hooks/useUsers.ts b/frontend/src/hooks/useUsers.ts
index d8bbd07..4d31114 100644
--- a/frontend/src/hooks/useUsers.ts
+++ b/frontend/src/hooks/useUsers.ts
@@ -2,10 +2,10 @@ import { useQuery } from "@tanstack/react-query";
 import { fetchUsers } from "../api/client";
 import type { UserDirectoryResponse } from "../types";
 
-export function useUsers(machineId?: string) {
+export function useUsers(jellyfinServiceId?: string) {
 	return useQuery<UserDirectoryResponse>({
-		queryKey: ["users", machineId ?? "default"],
-		queryFn: () => fetchUsers(machineId),
+		queryKey: ["users", jellyfinServiceId ?? "default"],
+		queryFn: () => fetchUsers(jellyfinServiceId),
 		staleTime: 30_000,
 	});
 }
diff --git a/frontend/src/pages/Applications.tsx b/frontend/src/pages/Applications.tsx
index e00b72e..e002554 100644
--- a/frontend/src/pages/Applications.tsx
+++ b/frontend/src/pages/Applications.tsx
@@ -1,28 +1,23 @@
-import { useMemo, useState } from "react";
+import { useState } from "react";
 import { useSearchParams } from "react-router-dom";
 import { Alert, AlertDescription } from "@/components/ui/alert";
 import { Badge } from "@/components/ui/badge";
 import { TabsTrigger } from "@/components/ui/tabs";
 import { Media } from "./Media";
 import { useCounts, useLibraries } from "../hooks/useDashboard";
-import { useMonitoringSettings } from "../hooks/useSettings";
+import { useServiceInstances } from "../hooks/useServices";
 import { SectionCard } from "../components/SectionCard";
 import { TabbedCard } from "../components/TabbedCard";
 
 function JellyfinLibraryStats() {
 	const [searchParams] = useSearchParams();
-	const { data: machines = [] } = useMonitoringSettings();
-	const jellyfinMachines = useMemo(
-		() =>
-			machines.filter(
-				(machine) => machine.enabled && machine.services.includes("jellyfin"),
-			),
-		[machines],
-	);
-	const selectedMachineId =
-		searchParams.get("machine_id") || jellyfinMachines[0]?.id || "";
-	const { data: counts } = useCounts(selectedMachineId || undefined);
-	const { data: libraries } = useLibraries(selectedMachineId || undefined);
+	const { data: jellyfinServices = [] } = useServiceInstances("jellyfin");
+	const selectedServiceId =
+		searchParams.get("jellyfin_service_id") ||
+		jellyfinServices.find((s) => s.enabled)?.id ||
+		"";
+	const { data: counts } = useCounts(selectedServiceId || undefined);
+	const { data: libraries } = useLibraries(selectedServiceId || undefined);
 
 	return (
 		<SectionCard
@@ -30,7 +25,7 @@ function JellyfinLibraryStats() {
 			description="Compact Jellyfin summary for the selected machine."
 			action={
 				<Badge variant="outline">
-					{selectedMachineId ? "Selected machine" : "Default machine"}
+					{selectedServiceId ? "Selected service" : "Default service"}
 				</Badge>
 			}
 		>
diff --git a/frontend/src/pages/Media.tsx b/frontend/src/pages/Media.tsx
index 0808431..e6dd536 100644
--- a/frontend/src/pages/Media.tsx
+++ b/frontend/src/pages/Media.tsx
@@ -32,7 +32,7 @@ import {
 } from "../hooks/useMedia";
 import { usePersistentState } from "../hooks/usePersistentState";
 import type { MediaItem } from "../types";
-import { useMonitoringSettings } from "../hooks/useSettings";
+import { useServiceInstances } from "../hooks/useServices";
 import { useCounts, useLibraries } from "../hooks/useDashboard";
 
 function formatDuration(seconds: number | null | undefined): string {
@@ -178,23 +178,18 @@ export function Media() {
 	const navigate = useNavigate();
 	const [searchParams, setSearchParams] = useSearchParams();
 	const isSmall = usePrefersSmallScreen();
-	const { data: machines } = useMonitoringSettings();
-	const jellyfinMachines = useMemo(
-		() =>
-			(machines ?? []).filter(
-				(machine) => machine.enabled && machine.services.includes("jellyfin"),
-			),
-		[machines],
-	);
-	const selectedMachineId =
-		searchParams.get("machine_id") || jellyfinMachines[0]?.id || "";
-	const { data: counts } = useCounts(selectedMachineId || undefined);
-	const { data: libraries } = useLibraries(selectedMachineId || undefined);
-	const { data: status } = useMediaStatus(selectedMachineId || undefined);
-	const buildIndex = useBuildIndex(selectedMachineId || undefined);
-	const stopBuildIndex = useStopBuildIndex(selectedMachineId || undefined);
+	const { data: jellyfinServices = [] } = useServiceInstances("jellyfin");
+	const selectedServiceId =
+		searchParams.get("jellyfin_service_id") ||
+		jellyfinServices.find((s) => s.enabled)?.id ||
+		"";
+	const { data: counts } = useCounts(selectedServiceId || undefined);
+	const { data: libraries } = useLibraries(selectedServiceId || undefined);
+	const { data: status } = useMediaStatus(selectedServiceId || undefined);
+	const buildIndex = useBuildIndex(selectedServiceId || undefined);
+	const stopBuildIndex = useStopBuildIndex(selectedServiceId || undefined);
 	const forceStopBuildIndex = useForceStopBuildIndex(
-		selectedMachineId || undefined,
+		selectedServiceId || undefined,
 	);
 
 	const [rawMediaState, setMediaState] = usePersistentState<MediaTabState>(
@@ -215,17 +210,17 @@ export function Media() {
 	const [rowSelection, setRowSelection] = useState<RowSelectionState>({});
 
 	useEffect(() => {
-		if (!searchParams.get("machine_id") && selectedMachineId) {
+		if (!searchParams.get("jellyfin_service_id") && selectedServiceId) {
 			setSearchParams(
 				(current) => {
 					const next = new URLSearchParams(current);
-					next.set("machine_id", selectedMachineId);
+					next.set("jellyfin_service_id", selectedServiceId);
 					return next;
 				},
 				{ replace: true },
 			);
 		}
-	}, [searchParams, selectedMachineId, setSearchParams]);
+	}, [searchParams, selectedServiceId, setSearchParams]);
 
 	const { data: queryResult, isLoading } = useMediaDataQuery({
 		types,
@@ -235,7 +230,7 @@ export function Media() {
 		sort_order: sortOrder,
 		limit: pageSize,
 		offset,
-		machineId: selectedMachineId || undefined,
+		jellyfinServiceId: selectedServiceId || undefined,
 		enabled: status?.exists ?? false,
 	});
 
@@ -323,27 +318,27 @@ export function Media() {
 			<div className="flex flex-row flex-wrap items-center gap-2">
 				<h2 className="text-lg font-semibold">Jellyfin</h2>
 				<div className="flex flex-col gap-1.5">
-					<Label htmlFor="media-machine">Machine</Label>
+					<Label htmlFor="media-service">Service</Label>
 					<Select
-						value={selectedMachineId}
+						value={selectedServiceId}
 						onValueChange={(value) =>
 							setSearchParams(
 								(current) => {
 									const next = new URLSearchParams(current);
-									next.set("machine_id", value);
+									next.set("jellyfin_service_id", value);
 									return next;
 								},
 								{ replace: true },
 							)
 						}
 					>
-						<SelectTrigger id="media-machine" className="w-full md:w-[220px]">
-							<SelectValue placeholder="Select a machine" />
+						<SelectTrigger id="media-service" className="w-full md:w-[220px]">
+							<SelectValue placeholder="Select a service" />
 						</SelectTrigger>
 						<SelectContent>
-							{jellyfinMachines.map((machine) => (
-								<SelectItem key={machine.id} value={machine.id}>
-									{machine.name}
+							{jellyfinServices.map((service) => (
+								<SelectItem key={service.id} value={service.id}>
+									{service.name}
 								</SelectItem>
 							))}
 						</SelectContent>
diff --git a/frontend/src/pages/__tests__/Applications.test.tsx b/frontend/src/pages/__tests__/Applications.test.tsx
index 693e323..6b151b5 100644
--- a/frontend/src/pages/__tests__/Applications.test.tsx
+++ b/frontend/src/pages/__tests__/Applications.test.tsx
@@ -26,6 +26,12 @@ vi.mock("../../hooks/useSettings", () => ({
 	}),
 }));
 
+vi.mock("../../hooks/useServices", () => ({
+	useServiceInstances: () => ({
+		data: [{ id: "jfs1", service_type: "jellyfin", name: "Main", enabled: true }],
+	}),
+}));
+
 vi.mock("../../hooks/useDashboard", () => ({
 	useCounts: () => ({
 		data: { movies: 10, series: 5, episodes: 100 },
diff --git a/frontend/src/pages/__tests__/Media.test.tsx b/frontend/src/pages/__tests__/Media.test.tsx
index 40e74af..2960016 100644
--- a/frontend/src/pages/__tests__/Media.test.tsx
+++ b/frontend/src/pages/__tests__/Media.test.tsx
@@ -103,7 +103,7 @@ let queryResult: MediaQueryResponse;
 
 vi.mock("react-router-dom", () => ({
 	useNavigate: () => navigate,
-	useSearchParams: () => [new URLSearchParams("machine_id=local"), vi.fn()],
+	useSearchParams: () => [new URLSearchParams("jellyfin_service_id=jfs1"), vi.fn()],
 }));
 
 vi.mock("../../hooks/useMedia", () => ({
@@ -118,6 +118,12 @@ vi.mock("../../hooks/useSettings", () => ({
 	useMonitoringSettings: () => ({ data: [machineFixture()] }),
 }));
 
+vi.mock("../../hooks/useServices", () => ({
+	useServiceInstances: () => ({
+		data: [{ id: "jfs1", service_type: "jellyfin", name: "Main", enabled: true }],
+	}),
+}));
+
 vi.mock("../../hooks/useDashboard", () => ({
 	useCounts: () => ({ data: undefined }),
 	useLibraries: () => ({ data: undefined }),
diff --git a/openspec/changes/service-registry/apply-progress.md b/openspec/changes/service-registry/apply-progress.md
index 536a31e..8740dbf 100644
--- a/openspec/changes/service-registry/apply-progress.md
+++ b/openspec/changes/service-registry/apply-progress.md
@@ -88,6 +88,26 @@ both.
 - Remove machine app fields from `settings_store.py` + `routers/settings.py`
   once the UI no longer writes them.
 
+### Frontend half (this PR)
+
+- [x] `api/client.ts`: Jellyfin-backed calls (`fetchCounts`, `fetchLibraries`,
+      `fetchActivity`, `fetchUsers`, Media status/build/stop/force-stop, and
+      `queryMedia`) now send `jellyfin_service_id` instead of `machine_id`.
+- [x] `hooks/useDashboard.ts`, `hooks/useUsers.ts`, `hooks/useMedia.ts`: renamed
+      the selector param to `jellyfinServiceId`.
+- [x] `pages/Media.tsx` + `pages/Applications.tsx`: select a `jellyfin` service
+      instance via `useServiceInstances("jellyfin")` and persist
+      `jellyfin_service_id` in the URL.
+- [x] Dashboard (widget-based) and Users (default-instance) need no selector
+      change.
+- [x] Updated Applications + Media tests for the new hook/param.
+
+### Deferred (explicit follow-up)
+
+- Remove machine-level Jellyfin/Jellyseerr fields from `settings_store.py`,
+  `routers/settings.py`, and the Settings UI. Low urgency now that the runtime
+  reads from services; the machine fields are simply unused for Jellyfin.
+
 ### Verification (backend half)
 
 ```bash