feat(prometheus-direct-charting): slice 1 — prom range query + chart rebrand

Add PrometheusWidgetSource._fetch_chart hitting /api/v1/query_range directly
(SC-101..104). New shared helpers in widgets/prometheus_range.py:
step_for_window (window preset -> step, ~200pts) and normalize_prometheus_matrix
(extracted label/dedup rule, retargeted at Prom matrix, robust to malformed
data). Chart widget kind moved grafana->prometheus in both registries;
GrafanaChartWidget renamed -> PrometheusChartWidget (git mv, recharts body
preserved). Grafana binding/service untouched (removed in slice 3).

Backend: 298 pytest pass, ruff clean. Frontend: 128 vitest pass, build+lint green.

frontend/src/integrations/registry.test.ts

@@ -23,6 +23,9 @@ describe("service registry", () => {
 	it("binds widget kinds per service", () => {
 		expect(SERVICE_REGISTRY.grafana.widgets.map((w) => w.kind)).toEqual([
 			"link",
+		]);
+		expect(SERVICE_REGISTRY.prometheus.widgets.map((w) => w.kind)).toEqual([
+			"metric",
 			"chart",
 		]);
 		expect(SERVICE_REGISTRY.alertmanager.widgets.map((w) => w.kind)).toEqual([

frontend/src/integrations/registry.ts

@@ -2,7 +2,7 @@ import type { ComponentType } from "react";
 import { AlertmanagerAlertsWidget } from "../widgets/AlertmanagerAlertsWidget";
 import { BackupsWidget } from "../widgets/BackupsWidget";
 import { GrafanaLinkWidget } from "../widgets/GrafanaLinkWidget";
-import { GrafanaChartWidget } from "../widgets/GrafanaChartWidget";
+import { PrometheusChartWidget } from "../widgets/PrometheusChartWidget";
 import { JellyfinWidget } from "../widgets/JellyfinWidget";
 import { JellyfinNowPlayingWidget } from "../widgets/JellyfinNowPlayingWidget";
 import { PrometheusMetricWidget } from "../widgets/PrometheusMetricWidget";
@@ -88,39 +88,6 @@ export const SERVICE_REGISTRY: Record<string, ServiceBinding> = {
 				},
 				component: GrafanaLinkWidget,
 			},
-			{
-				kind: "chart",
-				name: "Chart",
-				description: "Live time-series chart from a Grafana datasource query.",
-				refreshIntervalMs: 60_000,
-				defaultConfig: {
-					datasource_uid: "prometheus",
-					query: "",
-					from_ts: "now-1h",
-					to_ts: "now",
-					interval_ms: 30_000,
-					max_data_points: 100,
-				},
-				configSchema: {
-					type: "object",
-					properties: {
-						datasource_uid: {
-							type: "string",
-							description: "Grafana datasource UID (e.g. 'prometheus')",
-						},
-						query: {
-							type: "string",
-							description: "Query expression (e.g. PromQL)",
-						},
-						from_ts: { type: "string" },
-						to_ts: { type: "string" },
-						interval_ms: { type: "integer" },
-						max_data_points: { type: "integer" },
-					},
-					required: ["query"],
-				},
-				component: GrafanaChartWidget,
-			},
 		],
 	},
 	prometheus: {
@@ -141,6 +108,28 @@ export const SERVICE_REGISTRY: Record<string, ServiceBinding> = {
 				},
 				component: PrometheusMetricWidget,
 			},
+			{
+				kind: "chart",
+				name: "Chart",
+				description: "Multi-series line chart from a PromQL range query.",
+				refreshIntervalMs: 60_000,
+				defaultConfig: { promql: "", window: "1h" },
+				configSchema: {
+					type: "object",
+					properties: {
+						promql: {
+							type: "string",
+							description: "PromQL range query expression",
+						},
+						window: {
+							type: "string",
+							description: "Time window preset (1h, 6h, 24h, 7d)",
+						},
+					},
+					required: ["promql"],
+				},
+				component: PrometheusChartWidget,
+			},
 		],
 	},
 	jellyfin: {

frontend/src/widgets/PrometheusChartWidget.tsx

@@ -59,7 +59,7 @@ const CHART_COLORS = [
 	"var(--color-chart-5)",
 ];
 
-export function GrafanaChartWidget({
+export function PrometheusChartWidget({
 	widget,
 	refreshIntervalMs,
 	description,
@@ -111,7 +111,7 @@ export function GrafanaChartWidget({
 			) : (
 				<Alert>
 					<AlertDescription>
-						No data. Check your query and datasource_uid in the widget config.
+						No data. Check your PromQL query and window in the widget config.
 					</AlertDescription>
 				</Alert>
 			)}

frontend/src/widgets/__tests__/PrometheusChartWidget.test.tsx

@@ -1,6 +1,6 @@
 import { describe, it, expect, vi } from "vitest";
 import { render, screen } from "@testing-library/react";
-import { GrafanaChartWidget } from "../GrafanaChartWidget";
+import { PrometheusChartWidget } from "../PrometheusChartWidget";
 import type { WidgetInstance } from "../../types";
 import * as useWidgets from "../../hooks/useWidgets";
 
@@ -29,7 +29,7 @@ function mockData(data: unknown, error?: string) {
 	} as unknown as ReturnType<typeof useWidgets.useWidgetData>);
 }
 
-describe("GrafanaChartWidget", () => {
+describe("PrometheusChartWidget", () => {
 	it("renders a chart with series data", () => {
 		mockData({
 			series: [
@@ -42,20 +42,20 @@ describe("GrafanaChartWidget", () => {
 				},
 			],
 		});
-		render(<GrafanaChartWidget widget={widget} refreshIntervalMs={60000} />);
+		render(<PrometheusChartWidget widget={widget} refreshIntervalMs={60000} />);
 		// recharts renders an SVG; the title from SectionCard should be present.
 		expect(screen.getByText("CPU Usage")).toBeInTheDocument();
 	});
 
 	it("shows error Alert on error", () => {
-		mockData(null, "Grafana api_key is required for chart queries");
-		render(<GrafanaChartWidget widget={widget} refreshIntervalMs={60000} />);
-		expect(screen.getByText(/api_key is required/i)).toBeInTheDocument();
+		mockData(null, "promql is required");
+		render(<PrometheusChartWidget widget={widget} refreshIntervalMs={60000} />);
+		expect(screen.getByText(/promql is required/i)).toBeInTheDocument();
 	});
 
 	it("shows empty state when no series", () => {
 		mockData({ series: [] });
-		render(<GrafanaChartWidget widget={widget} refreshIntervalMs={60000} />);
+		render(<PrometheusChartWidget widget={widget} refreshIntervalMs={60000} />);
 		expect(screen.getByText(/No data/i)).toBeInTheDocument();
 	});
 });

frontend/src/widgets/index.ts

@@ -1,7 +1,7 @@
 export { AlertmanagerAlertsWidget } from "./AlertmanagerAlertsWidget";
 export { BackupsWidget } from "./BackupsWidget";
 export { GrafanaLinkWidget } from "./GrafanaLinkWidget";
-export { GrafanaChartWidget } from "./GrafanaChartWidget";
+export { PrometheusChartWidget } from "./PrometheusChartWidget";
 export { JellyfinWidget } from "./JellyfinWidget";
 export { PrometheusMetricWidget } from "./PrometheusMetricWidget";
 export { SshTaskWidget } from "./SshTaskWidget";