diff --git a/web/AGENTS.md b/web/AGENTS.md
index 327d96af..193ddc14 100644
--- a/web/AGENTS.md
+++ b/web/AGENTS.md
@@ -348,6 +348,8 @@ test context).
   functions.
 - Tailwind utilities by default; custom rules go in `main.css` and are
   applied by class. No `<style>` blocks or static inline `style=`.
+- Lengths are rem or screen proportions (`dvh`, `dvw`, `%`), never `px`,
+  including in arbitrary values: `max-h-[min(90dvh,60rem)]`.
 
 ## PromQL grammar
 
diff --git a/web/app/components/editor/blocks/metrics/MainBlock.nuxt.test.ts b/web/app/components/editor/blocks/metrics/MainBlock.nuxt.test.ts
index 3f9b03f8..f3cd8474 100644
--- a/web/app/components/editor/blocks/metrics/MainBlock.nuxt.test.ts
+++ b/web/app/components/editor/blocks/metrics/MainBlock.nuxt.test.ts
@@ -13,6 +13,7 @@ import {
 	makeEditor,
 	makeNode,
 	mountNodeView,
+	mountNodeViewUnderTooltipProvider,
 } from "../../test-helpers/node-view"
 import { DiffStatus } from "~/components/editor/diff/position-map"
 import {
@@ -20,7 +21,7 @@ import {
 	disposeMockEndpoints,
 	makeXid,
 } from "~/composables/api/test-helpers"
-import { emitFrom } from "~/components/test-helpers"
+import { emitFrom, renderedIconNames } from "~/components/test-helpers"
 
 const DOCUMENT_ID = makeXid("doc")
 const BRANCH_ID = makeXid("branch")
@@ -77,11 +78,15 @@ function mountBlock(
 		getPos?: () => number | undefined
 		nodeAtPos?: { attrs: Record<string, unknown> } | null
 		editing?: { uid: string; name: string; color: string } | null
+		underTooltipProvider?: boolean
 	} = {},
 ) {
 	const uid = options.uid ?? nextUid()
+	const mount = options.underTooltipProvider
+		? mountNodeViewUnderTooltipProvider
+		: mountNodeView
 
-	return mountNodeView(MainBlock, {
+	return mount(MainBlock, {
 		node: makeNode({ uid: uid, ...options.attrs }),
 		editor: makeMetricEditor({
 			nodeAtPos:
@@ -205,6 +210,18 @@ describe("<MetricMainBlock>", { concurrent: false }, () => {
 		expect(storedConfig(uid)?.axisBounds).toEqual({ min: 0, max: 10 })
 	})
 
+	it("reads a block saved without a chart type as a time series", async ({
+		expect,
+	}) => {
+		const uid = nextUid()
+
+		await mountBlock({ uid: uid, attrs: { visualizationType: null } })
+
+		expect(storedConfig(uid)?.visualizationType).toBe(
+			GenericQueryChartType.Line,
+		)
+	})
+
 	it("publishes nothing for a block shown inside a diff", async ({
 		expect,
 	}) => {
@@ -298,6 +315,7 @@ describe("<MetricMainBlock>", { concurrent: false }, () => {
 		await mountBlock({
 			uid: uid,
 			attrs: { simulationPreset: MetricSimulationPreset.DiskUsage },
+			underTooltipProvider: true,
 		})
 
 		expect(storedConfig(uid)?.simulationPreset).toBe(
@@ -305,6 +323,28 @@ describe("<MetricMainBlock>", { concurrent: false }, () => {
 		)
 	})
 
+	it("shows the simulation icon while the visualization simulates", async ({
+		expect,
+	}) => {
+		const wrapper = await mountBlock({ underTooltipProvider: true })
+
+		emitFrom(wrapper, VisualizationContainer, "simulation-visible", true)
+		await nextTick()
+
+		expect(renderedIconNames(wrapper)).toContain("mingcute:test-tube-line")
+	})
+
+	it("hides the simulation icon while the visualization draws real data", async ({
+		expect,
+	}) => {
+		const wrapper = await mountBlock()
+
+		emitFrom(wrapper, VisualizationContainer, "simulation-visible", false)
+		await nextTick()
+
+		expect(renderedIconNames(wrapper)).not.toContain("mingcute:test-tube-line")
+	})
+
 	it("flattens a legacy config on the first edit", async ({ expect }) => {
 		const updateAttributes = vi.fn()
 		const uid = nextUid()
diff --git a/web/app/components/editor/blocks/metrics/MainBlock.vue b/web/app/components/editor/blocks/metrics/MainBlock.vue
index b14f0a43..ecc272f2 100644
--- a/web/app/components/editor/blocks/metrics/MainBlock.vue
+++ b/web/app/components/editor/blocks/metrics/MainBlock.vue
@@ -73,7 +73,8 @@ function migrateLegacyIfNeeded(fieldAttrs: Record<string, any>) {
 	safeUpdateAttributes({
 		title: legacy.title ?? "",
 		dataSourceId: legacy.dataSourceId ?? null,
-		visualizationType: legacy.type ?? legacy.visualizationType ?? null,
+		visualizationType:
+			legacy.type ?? legacy.visualizationType ?? GenericQueryChartType.Line,
 		queries: legacy.queries ?? null,
 		timeRange: legacy.timeRange ?? null,
 		refreshInterval: legacy.refreshInterval ?? null,
@@ -123,9 +124,9 @@ const config = reactive({
 		get: () =>
 			legacyConfig.value?.type ??
 			legacyConfig.value?.visualizationType ??
-			(props.node.attrs
-				.visualizationType as MetricConfig["visualizationType"]) ??
-			null,
+			(props.node.attrs.visualizationType as
+				MetricConfig["visualizationType"] | null) ??
+			GenericQueryChartType.Line,
 		set: (v) => {
 			migrateLegacyIfNeeded({ visualizationType: v })
 		},
@@ -243,6 +244,7 @@ const lastOtherEditingUser = computed(() => {
 })
 
 const disableVisualizationRefresh = ref(false)
+const simulationVisible = ref(false)
 
 watchImmediate(
 	[
@@ -346,7 +348,20 @@ function disableVisualizationRefreshTemporarily() {
 				>
 					{{ lastOtherEditingUser.name }}
 				</div>
-				<div class="absolute top-1 right-1.5 z-1 flex items-center gap-1">
+				<div
+					class="absolute top-1 right-1.5 z-1 flex items-center rounded-md bg-background pl-0.5"
+				>
+					<ShadcnUiTooltip v-if="simulationVisible">
+						<ShadcnUiTooltipTrigger as-child>
+							<Icon
+								name="mingcute:test-tube-line"
+								class="size-3.5 text-foreground"
+							/>
+						</ShadcnUiTooltipTrigger>
+						<ShadcnUiTooltipContent side="bottom">
+							{{ $t("editor.metrics.simulation.tooltip") }}
+						</ShadcnUiTooltipContent>
+					</ShadcnUiTooltip>
 					<ShadcnUiPopoverTrigger as-child>
 						<ShadcnUiButton
 							variant="ghost-plain"
@@ -362,6 +377,7 @@ function disableVisualizationRefreshTemporarily() {
 					:uid="props.node.attrs.uid"
 					:disable-refresh="disableVisualizationRefresh"
 					@simulate="(preset) => (config.simulationPreset = preset)"
+					@simulation-visible="(v) => (simulationVisible = v)"
 				/>
 			</div>
 			<ShadcnUiPopoverContent class="w-50" side="right" side-flip align="start">
diff --git a/web/app/components/editor/blocks/metrics/PopoverConfigBox.vue b/web/app/components/editor/blocks/metrics/PopoverConfigBox.vue
index f587449d..38e21d45 100644
--- a/web/app/components/editor/blocks/metrics/PopoverConfigBox.vue
+++ b/web/app/components/editor/blocks/metrics/PopoverConfigBox.vue
@@ -95,7 +95,9 @@ function openModal() {
 			size="2sm"
 			@click.stop="openModal"
 		>
-			<Icon name="lucide:square-pen" />
+			<Icon
+				:name="isEditingDisabled ? 'mingcute:eye-line' : 'mingcute:pencil-line'"
+			/>
 			{{
 				!isEditingDisabled
 					? $t("editor.metrics.config.modal-trigger-button-normal")
diff --git a/web/app/components/editor/blocks/metrics/VisualizationContainer.nuxt.test.ts b/web/app/components/editor/blocks/metrics/VisualizationContainer.nuxt.test.ts
index 6f848d3c..674ecd33 100644
--- a/web/app/components/editor/blocks/metrics/VisualizationContainer.nuxt.test.ts
+++ b/web/app/components/editor/blocks/metrics/VisualizationContainer.nuxt.test.ts
@@ -109,54 +109,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 
 	afterEach(disposeMockEndpoints)
 
-	it("asks for a visualization type before anything else", async ({
-		expect,
-	}) => {
-		const wrapper = await mountContainer(
-			metricConfig({ visualizationType: null }),
-		)
-
-		expect(wrapper.text()).toContain(
-			t("editor.metrics.status.type-not-selected.title"),
-		)
-		expect(wrapper.text()).toContain(
-			t("editor.metrics.status.type-not-selected.normal-action-button"),
-		)
-	})
-
-	it("offers only to view the metrics in read mode", async ({ expect }) => {
-		useEditorMeta().setEditable(false)
-
-		const wrapper = await mountContainer(
-			metricConfig({ visualizationType: null }),
-		)
-
-		expect(wrapper.text()).toContain(
-			t("editor.metrics.status.type-not-selected.readonly-action-button"),
-		)
-	})
-
-	it("hides the action button when the host asks it to", async ({ expect }) => {
-		const wrapper = await mountContainer(
-			metricConfig({ visualizationType: null }),
-			{ hideEmptyActionButton: true },
-		)
-
-		expect(wrapper.findAll("button")).toHaveLength(0)
-	})
-
-	it("shows a bare placeholder in a simplified host", async ({ expect }) => {
-		const wrapper = await mountContainer(
-			metricConfig({ visualizationType: null }),
-			{ simplifiedEmpty: true },
-		)
-
-		expect(wrapper.text()).toBe(
-			t("editor.metrics.status.simplified-config-in-progress.title"),
-		)
-	})
-
-	it("asks for a data source once a type is chosen", async ({ expect }) => {
+	it("asks for a data source before anything else", async ({ expect }) => {
 		const wrapper = await mountContainer(
 			metricConfig({ dataSourceId: null, queries: [] }),
 		)
@@ -164,6 +117,32 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 		expect(wrapper.text()).toContain(
 			t("editor.metrics.status.data-source-not-selected.title"),
 		)
+		expect(wrapper.text()).toContain(
+			t("editor.metrics.status.data-source-not-selected.normal-action-button"),
+		)
+	})
+
+	it("offers only to view the metrics in read mode", async ({ expect }) => {
+		useEditorMeta().setEditable(false)
+
+		const wrapper = await mountContainer(
+			metricConfig({ dataSourceId: null, queries: [] }),
+		)
+
+		expect(wrapper.text()).toContain(
+			t(
+				"editor.metrics.status.data-source-not-selected.readonly-action-button",
+			),
+		)
+	})
+
+	it("hides the action button when the host asks it to", async ({ expect }) => {
+		const wrapper = await mountContainer(
+			metricConfig({ dataSourceId: null, queries: [] }),
+			{ hideEmptyActionButton: true },
+		)
+
+		expect(wrapper.findAll("button")).toHaveLength(0)
 	})
 
 	it("shows a bare placeholder for a missing data source in a simplified host", async ({
@@ -319,13 +298,13 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 	it("opens the config modal from the action button", async ({ expect }) => {
 		const uid = nextUid()
 		const wrapper = await mountContainer(
-			metricConfig({ visualizationType: null }),
+			metricConfig({ dataSourceId: null, queries: [] }),
 			{ uid: uid },
 		)
 
 		await findButtonByText(
 			wrapper,
-			t("editor.metrics.status.type-not-selected.normal-action-button"),
+			t("editor.metrics.status.data-source-not-selected.normal-action-button"),
 		).trigger("click")
 
 		expect(useEditorStore().activeMetricBlockConfig).toBe(uid)
@@ -512,7 +491,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 			await vi.waitFor(() => {
 				expect(calls.length).toBeGreaterThan(0)
 			}, WAIT_FOR_OPTIONS)
-			expect(wrapper.text()).not.toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(false)
 		})
 
 		// a simulation stands in for a metric that has not arrived, not
@@ -535,9 +514,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 				)
 
 				await vi.waitFor(() => {
-					expect(wrapper.text()).not.toContain(
-						t("editor.metrics.simulation.label"),
-					)
+					expect(simulationVisible(wrapper)).toBe(false)
 				}, WAIT_FOR_OPTIONS)
 			},
 		)
@@ -552,7 +529,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 				metricConfig({ simulationPreset: MetricSimulationPreset.CPUUsage }),
 			)
 
-			expect(wrapper.text()).toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(true)
 		})
 
 		it("draws the window the block is configured for", async ({ expect }) => {
@@ -600,7 +577,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 			},
 		)
 
-		it("marks a simulated block for every reader", async ({ expect }) => {
+		it("reports a simulated block for every reader", async ({ expect }) => {
 			useEditorMeta().setEditable(false)
 			mockEndpoint("GET", QUERY_URL, () => seriesResult())
 
@@ -608,15 +585,15 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 				metricConfig({ simulationPreset: MetricSimulationPreset.CPUUsage }),
 			)
 
-			expect(wrapper.text()).toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(true)
 		})
 
-		it("leaves an unsimulated block unmarked", async ({ expect }) => {
+		it("reports an unsimulated block as not simulating", async ({ expect }) => {
 			mockEndpoint("GET", QUERY_URL, () => seriesResult())
 
 			const wrapper = await mountContainer(metricConfig())
 
-			expect(wrapper.text()).not.toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(false)
 		})
 
 		it("asks core whether the real data has arrived", async ({ expect }) => {
@@ -727,7 +704,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 			expect(wrapper.text()).not.toContain(
 				t("editor.metrics.status.no-data-loaded.title"),
 			)
-			expect(wrapper.text()).toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(true)
 			expect(
 				wrapper.findComponent({ name: "LineChart" }).props("seriesData"),
 			).toHaveLength(3)
@@ -739,7 +716,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 					wrapper.findComponent({ name: "LineChart" }).props("seriesData"),
 				).toHaveLength(1)
 			}, WAIT_FOR_OPTIONS)
-			expect(wrapper.text()).not.toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(false)
 		})
 
 		// a block whose queries cannot run is never answered, and holding
@@ -764,7 +741,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 			})
 			await nextTick()
 
-			expect(wrapper.text()).not.toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(false)
 			expect(calls).toHaveLength(0)
 		})
 
@@ -826,7 +803,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 
 			const wrapper = await mountContainer(config, { uid: uid })
 
-			expect(wrapper.text()).toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(true)
 
 			// core removes the attribute on the live document, which reaches
 			// the editor as a node attribute change
@@ -837,7 +814,7 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 			await vi.waitFor(() => {
 				expect(calls.length).toBeGreaterThan(0)
 			}, WAIT_FOR_OPTIONS)
-			expect(wrapper.text()).not.toContain(t("editor.metrics.simulation.label"))
+			expect(simulationVisible(wrapper)).toBe(false)
 		})
 
 		it("keeps drawing when the check fails", async ({ expect }) => {
@@ -859,3 +836,8 @@ describe("<VisualizationContainer>", { concurrent: false }, () => {
 		})
 	})
 })
+
+// whether the container last reported simulated data as visible
+function simulationVisible(wrapper: VueWrapper): boolean | undefined {
+	return wrapper.emitted<[boolean]>("simulation-visible")?.at(-1)?.[0]
+}
diff --git a/web/app/components/editor/blocks/metrics/VisualizationContainer.vue b/web/app/components/editor/blocks/metrics/VisualizationContainer.vue
index 6bb4a0ff..b591962d 100644
--- a/web/app/components/editor/blocks/metrics/VisualizationContainer.vue
+++ b/web/app/components/editor/blocks/metrics/VisualizationContainer.vue
@@ -33,7 +33,7 @@ const props = defineProps<{
 	disableRefresh?: boolean
 }>()
 const emit = defineEmits<{
-	(event: "loading", v: boolean): void
+	(event: "loading" | "simulation-visible", v: boolean): void
 	(event: "simulate", preset: MetricSimulationPreset): void
 }>()
 
@@ -119,7 +119,7 @@ const fetchMetricData = useMultipleGenericQueries(
 			? debouncedConfig.value.visualizationType
 			: props.config.visualizationType
 
-		if (!queries?.length || !timeRange || !visualizationType) {
+		if (!queries?.length || !timeRange) {
 			return null
 		}
 
@@ -163,6 +163,14 @@ const canSimulate = computed(() => {
 	return queryRunnable.value && !dataSourceUnavailable.value
 })
 
+const simulationOffered = computed(() => {
+	return !isEditingDisabled.value && canSimulate.value
+})
+
+const metricsButtonIcon = computed(() => {
+	return isEditingDisabled.value ? "mingcute:eye-line" : "mingcute:pencil-line"
+})
+
 // what the block draws, which outlives the attribute by one load
 const drawnSimulationPreset = computed(() => {
 	return (
@@ -310,6 +318,13 @@ watch(
 	},
 )
 
+watchImmediate(
+	() => !!drawnSimulationPreset.value,
+	(visible) => {
+		emit("simulation-visible", visible)
+	},
+)
+
 // labels series the query gave no legend format for, counting up per
 // merge call ("Line A", "Line B", ...)
 function orderedLegendLabel() {
@@ -416,13 +431,6 @@ function openModal() {
 </script>
 <template>
 	<div class="relative flex size-full min-w-0 items-center justify-center">
-		<div
-			v-if="drawnSimulationPreset"
-			class="pointer-events-none absolute top-2.5 left-1/2 z-1 flex -translate-x-1/2 items-center gap-1 text-2sm text-foreground/70"
-		>
-			<Icon name="lucide:hourglass" class="size-3" />
-			{{ $t("editor.metrics.simulation.label") }}
-		</div>
 		<template v-if="data.status === GenericQueryResultStatus.Ok && data.data">
 			<LineChart
 				v-if="props.config.visualizationType === GenericQueryChartType.Line"
@@ -480,8 +488,12 @@ function openModal() {
 							{{ $t("editor.metrics.status.no-data-loaded.description") }}
 						</ShadcnUiEmptyDescription>
 					</ShadcnUiEmptyHeader>
-					<ShadcnUiEmptyContent v-if="!props.hideEmptyActionButton">
-						<ShadcnUiButton variant="outline" size="2sm" @click="openModal">
+					<ShadcnUiEmptyContent
+						v-if="!props.hideEmptyActionButton"
+						:class="simulationOffered && 'grid w-auto grid-cols-2'"
+					>
+						<ShadcnUiButton size="2sm" @click="openModal">
+							<Icon :name="metricsButtonIcon" class="size-3.5" />
 							{{
 								!isEditingDisabled
 									? $t(
@@ -493,11 +505,13 @@ function openModal() {
 							}}
 						</ShadcnUiButton>
 						<ShadcnUiButton
-							v-if="!isEditingDisabled && canSimulate"
+							v-if="simulationOffered"
 							variant="outline"
 							size="2sm"
+							class="gap-0.5"
 							@click="startSimulation"
 						>
+							<Icon name="mingcute:test-tube-line" class="size-3.5" />
 							{{
 								$t(
 									"editor.metrics.status.no-data-loaded.simulate-action-button",
@@ -521,7 +535,8 @@ function openModal() {
 						</ShadcnUiEmptyDescription>
 					</ShadcnUiEmptyHeader>
 					<ShadcnUiEmptyContent v-if="!props.hideEmptyActionButton">
-						<ShadcnUiButton variant="outline" size="2sm" @click="openModal">
+						<ShadcnUiButton size="2sm" @click="openModal">
+							<Icon :name="metricsButtonIcon" class="size-3.5" />
 							{{
 								!isEditingDisabled
 									? $t(
@@ -548,8 +563,14 @@ function openModal() {
 				</ShadcnUiEmptyHeader>
 				<!-- editing the block is what the simplified state is already
 				inside of, but simulating it is not offered anywhere else -->
-				<ShadcnUiEmptyContent v-if="!isEditingDisabled && canSimulate">
-					<ShadcnUiButton variant="outline" size="2sm" @click="startSimulation">
+				<ShadcnUiEmptyContent v-if="simulationOffered">
+					<ShadcnUiButton
+						variant="outline"
+						size="2sm"
+						class="gap-0.5"
+						@click="startSimulation"
+					>
+						<Icon name="mingcute:test-tube-line" class="size-3.5" />
 						{{
 							$t("editor.metrics.status.no-data-loaded.simulate-action-button")
 						}}
@@ -557,49 +578,6 @@ function openModal() {
 				</ShadcnUiEmptyContent>
 			</ShadcnUiEmpty>
 		</div>
-		<div
-			v-else-if="data.status === GenericQueryResultStatus.TypeNotSelected"
-			class="text-foreground"
-		>
-			<ShadcnUiEmpty v-if="!props.simplifiedEmpty">
-				<ShadcnUiEmptyHeader>
-					<ShadcnUiEmptyMedia variant="icon" class="size-9">
-						<Icon name="lucide:chart-line" class="size-6" />
-					</ShadcnUiEmptyMedia>
-					<ShadcnUiEmptyTitle>
-						{{ $t("editor.metrics.status.type-not-selected.title") }}
-					</ShadcnUiEmptyTitle>
-					<ShadcnUiEmptyDescription>
-						{{ $t("editor.metrics.status.type-not-selected.description") }}
-					</ShadcnUiEmptyDescription>
-				</ShadcnUiEmptyHeader>
-				<ShadcnUiEmptyContent v-if="!props.hideEmptyActionButton">
-					<ShadcnUiButton variant="outline" size="2sm" @click="openModal">
-						{{
-							!isEditingDisabled
-								? $t(
-										"editor.metrics.status.type-not-selected.normal-action-button",
-									)
-								: $t(
-										"editor.metrics.status.type-not-selected.readonly-action-button",
-									)
-						}}
-					</ShadcnUiButton>
-				</ShadcnUiEmptyContent>
-			</ShadcnUiEmpty>
-			<ShadcnUiEmpty v-else>
-				<ShadcnUiEmptyHeader>
-					<ShadcnUiEmptyMedia variant="icon" class="size-9">
-						<Icon name="lucide:chart-line" class="size-6" />
-					</ShadcnUiEmptyMedia>
-					<ShadcnUiEmptyTitle>
-						{{
-							$t("editor.metrics.status.simplified-config-in-progress.title")
-						}}
-					</ShadcnUiEmptyTitle>
-				</ShadcnUiEmptyHeader>
-			</ShadcnUiEmpty>
-		</div>
 		<div
 			v-else-if="
 				data.status === GenericQueryResultStatus.QueryError &&
@@ -638,7 +616,8 @@ function openModal() {
 					</ShadcnUiEmptyDescription>
 				</ShadcnUiEmptyHeader>
 				<ShadcnUiEmptyContent v-if="!props.hideEmptyActionButton">
-					<ShadcnUiButton variant="outline" size="2sm" @click="openModal">
+					<ShadcnUiButton size="2sm" @click="openModal">
+						<Icon :name="metricsButtonIcon" class="size-3.5" />
 						{{
 							!isEditingDisabled
 								? $t("editor.metrics.status.invalid-data.normal-action-button")
@@ -664,7 +643,8 @@ function openModal() {
 					</ShadcnUiEmptyDescription>
 				</ShadcnUiEmptyHeader>
 				<ShadcnUiEmptyContent v-if="!props.hideEmptyActionButton">
-					<ShadcnUiButton variant="outline" size="2sm" @click="openModal">
+					<ShadcnUiButton size="2sm" @click="openModal">
+						<Icon :name="metricsButtonIcon" class="size-3.5" />
 						{{
 							!isEditingDisabled
 								? $t("editor.metrics.status.invalid-data.normal-action-button")
diff --git a/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.nuxt.test.ts b/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.nuxt.test.ts
index af4ed67e..b4711766 100644
--- a/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.nuxt.test.ts
+++ b/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.nuxt.test.ts
@@ -1,4 +1,3 @@
-import { mountSuspended } from "@nuxt/test-utils/runtime"
 import { enableAutoUnmount } from "@vue/test-utils"
 import { afterEach, beforeEach, describe, it } from "vitest"
 import BaseModal from "./BaseModal.client.vue"
@@ -20,6 +19,7 @@ import {
 } from "~/composables/api/test-helpers"
 import {
 	emitFrom,
+	mountUnderTooltipProvider,
 	stubViewportMatches,
 	t,
 	teleportedButton,
@@ -67,7 +67,7 @@ function activateBlock(
 }
 
 function mountModal() {
-	return mountSuspended(BaseModal)
+	return mountUnderTooltipProvider(BaseModal, {})
 }
 
 function dialogText(): string {
@@ -275,6 +275,30 @@ describe("<MetricConfigBaseModal>", { concurrent: false }, () => {
 		).toBe(MetricSimulationPreset.HTTPLatency)
 	})
 
+	it("shows the simulation icon while the preview simulates", async ({
+		expect,
+	}) => {
+		activateBlock()
+		const wrapper = await mountModal()
+
+		emitFrom(wrapper, VisualizationContainer, "simulation-visible", true)
+		await nextTick()
+
+		expect(simulationIconShown()).toBe(true)
+	})
+
+	it("hides the simulation icon while the preview draws real data", async ({
+		expect,
+	}) => {
+		activateBlock()
+		const wrapper = await mountModal()
+
+		emitFrom(wrapper, VisualizationContainer, "simulation-visible", false)
+		await nextTick()
+
+		expect(simulationIconShown()).toBe(false)
+	})
+
 	it("stands aside when the reader asks for the data source settings", async ({
 		expect,
 	}) => {
@@ -285,6 +309,15 @@ describe("<MetricConfigBaseModal>", { concurrent: false }, () => {
 		await nextTick()
 
 		expect(useEditorStore().activeMetricBlockConfig).toBeNull()
-		expect(wrapper.emitted("open-settings")).toHaveLength(1)
+		expect(
+			wrapper.findComponent(BaseModal).emitted("open-settings"),
+		).toHaveLength(1)
 	})
 })
+
+// the modal teleports to the body, out of the wrapper's reach
+function simulationIconShown(): boolean {
+	return (
+		document.body.querySelector('[class~="i-mingcute:test-tube-line"]') !== null
+	)
+}
diff --git a/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.vue b/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.vue
index b4712320..6621d0f7 100644
--- a/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.vue
+++ b/web/app/components/editor/blocks/metrics/config-modal/BaseModal.client.vue
@@ -82,6 +82,7 @@ const isRefreshIntervalModified = computed(() => {
 })
 const chartTopOptionElem = useTemplateRef<HTMLDivElement>("chart-top-options")
 const { width: chartTopOptionWidth } = useElementSize(chartTopOptionElem)
+const simulationVisible = ref(false)
 
 function updateOpenStatus(v: boolean) {
 	if (v) {
@@ -147,10 +148,10 @@ function openSettings() {
 				</ShadcnUiDialogHeader>
 				<div
 					v-if="config"
-					class="flex flex-col rounded-md border bg-muted/50 lg:flex-row"
+					class="flex flex-col rounded-md border bg-muted/50 lg:h-126 lg:flex-row"
 				>
 					<div class="flex min-w-0 flex-1 flex-col self-stretch">
-						<div class="relative h-70 min-w-0 border-b">
+						<div class="relative h-70 min-w-0 shrink-0 border-b">
 							<div
 								ref="chart-top-options"
 								:class="
@@ -159,6 +160,17 @@ function openSettings() {
 									)
 								"
 							>
+								<ShadcnUiTooltip v-if="simulationVisible">
+									<ShadcnUiTooltipTrigger as-child>
+										<Icon
+											name="mingcute:test-tube-line"
+											class="size-3.5 text-foreground"
+										/>
+									</ShadcnUiTooltipTrigger>
+									<ShadcnUiTooltipContent side="bottom">
+										{{ $t("editor.metrics.simulation.tooltip") }}
+									</ShadcnUiTooltipContent>
+								</ShadcnUiTooltip>
 								<div class="flex flex-col gap-0.5 md:gap-1">
 									<ShadcnUiSelect v-model="config.timeRange">
 										<ShadcnUiSelectTrigger
@@ -297,6 +309,7 @@ function openSettings() {
 								simplified-empty
 								:uid="editorStore.activeMetricBlockConfig!"
 								@simulate="(preset) => (config!.simulationPreset = preset)"
+								@simulation-visible="(v) => (simulationVisible = v)"
 							/>
 						</div>
 						<div v-if="!isMinWidth1024px" class="self-stretch border-b">
@@ -307,7 +320,7 @@ function openSettings() {
 								@open-settings="openSettings"
 							/>
 						</div>
-						<div>
+						<div class="lg:min-h-0 lg:flex-1 lg:overflow-y-auto">
 							<BottomConfig
 								:model-value="config"
 								:diff-status="diffStatus"
@@ -315,7 +328,10 @@ function openSettings() {
 							/>
 						</div>
 					</div>
-					<div v-if="isMinWidth1024px" class="w-70 self-stretch border-l">
+					<div
+						v-if="isMinWidth1024px"
+						class="w-70 self-stretch border-l lg:overflow-y-auto"
+					>
 						<ConfigSidebar
 							:model-value="config"
 							:diff-status="diffStatus"
diff --git a/web/app/components/editor/blocks/metrics/config-modal/ConfigSidebar.vue b/web/app/components/editor/blocks/metrics/config-modal/ConfigSidebar.vue
index b3f26d7a..f5271b08 100644
--- a/web/app/components/editor/blocks/metrics/config-modal/ConfigSidebar.vue
+++ b/web/app/components/editor/blocks/metrics/config-modal/ConfigSidebar.vue
@@ -287,6 +287,34 @@ function removeThreshold(index: number) {
 			</div>
 			<div class="mt-1 h-px bg-border" />
 		</div>
+		<div v-if="config.simulationPreset">
+			<div class="flex flex-col gap-1 px-1.75">
+				<span class="text-2sm font-medium">
+					{{ $t("editor.metrics.simulation.section-title") }}
+				</span>
+				<span class="mb-1 text-2xs text-muted-foreground">
+					{{ $t("editor.metrics.simulation.section-description") }}
+				</span>
+				<ConfigField>
+					<template #label>
+						<span>
+							{{ $t("editor.metrics.simulation.preset-label") }}
+						</span>
+					</template>
+					<SimulationPresetSelect v-model="config.simulationPreset" />
+				</ConfigField>
+				<ShadcnUiButton
+					v-if="!isEditingDisabled"
+					variant="outline-transparent"
+					size="custom"
+					class="h-[1.775rem]! justify-center px-1.5 text-2sm font-normal"
+					@click="config.simulationPreset = null"
+				>
+					{{ $t("editor.metrics.simulation.stop-button") }}
+				</ShadcnUiButton>
+			</div>
+			<div class="mt-2 h-px bg-border" />
+		</div>
 		<div class="px-1.75">
 			<ConfigField>
 				<template #label>
@@ -595,33 +623,5 @@ function removeThreshold(index: number) {
 				/>
 			</ConfigField>
 		</div>
-		<div v-if="config.simulationPreset">
-			<div class="mb-2 h-px bg-border" />
-			<div class="flex flex-col gap-1 px-1.75">
-				<span class="text-2sm font-medium">
-					{{ $t("editor.metrics.simulation.section-title") }}
-				</span>
-				<span class="text-2xs text-muted-foreground">
-					{{ $t("editor.metrics.simulation.section-description") }}
-				</span>
-				<ConfigField>
-					<template #label>
-						<span>
-							{{ $t("editor.metrics.simulation.preset-label") }}
-						</span>
-					</template>
-					<SimulationPresetSelect v-model="config.simulationPreset" />
-				</ConfigField>
-				<ShadcnUiButton
-					v-if="!isEditingDisabled"
-					variant="outline-transparent"
-					size="custom"
-					class="h-[1.775rem]! justify-center px-1.5 text-2sm font-normal"
-					@click="config.simulationPreset = null"
-				>
-					{{ $t("editor.metrics.simulation.stop-button") }}
-				</ShadcnUiButton>
-			</div>
-		</div>
 	</div>
 </template>
diff --git a/web/app/components/editor/blocks/metrics/config-modal/VisualizationTypeSelect.nuxt.test.ts b/web/app/components/editor/blocks/metrics/config-modal/VisualizationTypeSelect.nuxt.test.ts
index f04e0107..9deb4ce7 100644
--- a/web/app/components/editor/blocks/metrics/config-modal/VisualizationTypeSelect.nuxt.test.ts
+++ b/web/app/components/editor/blocks/metrics/config-modal/VisualizationTypeSelect.nuxt.test.ts
@@ -34,7 +34,9 @@ describe("<VisualizationTypeSelect>", { concurrent: false }, () => {
 	})
 
 	it("offers the three visualization types", async ({ expect }) => {
-		const wrapper = await mountTypeSelect({ modelValue: configWith(null) })
+		const wrapper = await mountTypeSelect({
+			modelValue: configWith(GenericQueryChartType.Line),
+		})
 
 		expect(tiles(wrapper).map((t) => t.text())).toEqual([
 			t("editor.metrics.config.type-options.line-chart.title"),
@@ -52,22 +54,26 @@ describe("<VisualizationTypeSelect>", { concurrent: false }, () => {
 		expect(at(tiles(wrapper), LINE).classes()).not.toContain("border-primary")
 	})
 
-	it("marks nothing while no type is chosen", async ({ expect }) => {
-		const wrapper = await mountTypeSelect({ modelValue: configWith(null) })
-
-		expect(
-			tiles(wrapper).filter((t) => t.classes().includes("border-primary")),
-		).toHaveLength(0)
-	})
-
 	it.for([
-		{ index: LINE, expected: GenericQueryChartType.Line },
-		{ index: BAR, expected: GenericQueryChartType.Bar },
-		{ index: GAUGE, expected: GenericQueryChartType.Gauge },
+		{
+			index: LINE,
+			input: GenericQueryChartType.Gauge,
+			expected: GenericQueryChartType.Line,
+		},
+		{
+			index: BAR,
+			input: GenericQueryChartType.Line,
+			expected: GenericQueryChartType.Bar,
+		},
+		{
+			index: GAUGE,
+			input: GenericQueryChartType.Line,
+			expected: GenericQueryChartType.Gauge,
+		},
 	])(
 		"stores the $expected type when picked",
-		async ({ index, expected }, { expect }) => {
-			const config = configWith(null)
+		async ({ index, input, expected }, { expect }) => {
+			const config = configWith(input)
 			const wrapper = await mountTypeSelect({ modelValue: config })
 
 			await at(tiles(wrapper), index).trigger("click")
@@ -78,22 +84,22 @@ describe("<VisualizationTypeSelect>", { concurrent: false }, () => {
 
 	it("changes nothing in read mode", async ({ expect }) => {
 		useEditorMeta().setEditable(false)
-		const config = configWith(null)
+		const config = configWith(GenericQueryChartType.Line)
 		const wrapper = await mountTypeSelect({ modelValue: config })
 
 		await at(tiles(wrapper), BAR).trigger("click")
 
-		expect(config.visualizationType).toBeNull()
+		expect(config.visualizationType).toBe(GenericQueryChartType.Line)
 	})
 
 	it("changes nothing while a reviewable diff is shown", async ({ expect }) => {
 		useEditorStore().setReviewableDiffActive(true)
-		const config = configWith(null)
+		const config = configWith(GenericQueryChartType.Line)
 		const wrapper = await mountTypeSelect({ modelValue: config })
 
 		await at(tiles(wrapper), BAR).trigger("click")
 
-		expect(config.visualizationType).toBeNull()
+		expect(config.visualizationType).toBe(GenericQueryChartType.Line)
 	})
 
 	it("changes nothing when there is no config to edit", async ({ expect }) => {
diff --git a/web/app/components/editor/blocks/metrics/index.test.ts b/web/app/components/editor/blocks/metrics/index.test.ts
index 08e4b1a0..a7efbb79 100644
--- a/web/app/components/editor/blocks/metrics/index.test.ts
+++ b/web/app/components/editor/blocks/metrics/index.test.ts
@@ -226,7 +226,7 @@ describe("MetricBlock", () => {
 				config: null,
 				title: "",
 				dataSourceId: null,
-				visualizationType: null,
+				visualizationType: GenericQueryChartType.Line,
 				queries: [{ name: "Query 1", query: "", legendFormat: "" }],
 				timeRange: TimeRangePreset.Last5Minutes,
 				refreshInterval: RefreshInterval.M5,
diff --git a/web/app/components/editor/blocks/metrics/utils.test.ts b/web/app/components/editor/blocks/metrics/utils.test.ts
index cdeb63fd..a182b1c7 100644
--- a/web/app/components/editor/blocks/metrics/utils.test.ts
+++ b/web/app/components/editor/blocks/metrics/utils.test.ts
@@ -29,7 +29,7 @@ describe("defaultMetricConfig", () => {
 		expect(defaultMetricConfig()).toEqual({
 			title: "",
 			dataSourceId: null,
-			visualizationType: null,
+			visualizationType: GenericQueryChartType.Line,
 			queries: [{ name: "Query 1", query: "", legendFormat: "" }],
 			timeRange: TimeRangePreset.Last5Minutes,
 			refreshInterval: RefreshInterval.M5,
@@ -103,7 +103,7 @@ describe("buildConfigFromNodeAttrs", () => {
 		expect(buildConfigFromNodeAttrs({ config: {} })).toEqual({
 			title: "",
 			dataSourceId: null,
-			visualizationType: null,
+			visualizationType: GenericQueryChartType.Line,
 			queries: null,
 			timeRange: null,
 			refreshInterval: null,
@@ -161,7 +161,7 @@ describe("buildConfigFromNodeAttrs", () => {
 		expect(buildConfigFromNodeAttrs({})).toEqual({
 			title: "",
 			dataSourceId: null,
-			visualizationType: null,
+			visualizationType: GenericQueryChartType.Line,
 			queries: null,
 			timeRange: null,
 			refreshInterval: null,
diff --git a/web/app/components/editor/blocks/metrics/utils.ts b/web/app/components/editor/blocks/metrics/utils.ts
index 5a72ff30..86cd06c5 100644
--- a/web/app/components/editor/blocks/metrics/utils.ts
+++ b/web/app/components/editor/blocks/metrics/utils.ts
@@ -79,7 +79,7 @@ export enum MetricSimulationPreset {
 export interface MetricConfig {
 	title: string
 	dataSourceId: string | null
-	visualizationType: GenericQueryChartType | null
+	visualizationType: GenericQueryChartType
 	queries:
 		| {
 				name: string
@@ -118,7 +118,7 @@ export function defaultMetricConfig(): MetricConfig {
 	return {
 		title: "",
 		dataSourceId: null,
-		visualizationType: null,
+		visualizationType: GenericQueryChartType.Line,
 		// NOTE: this doesn't use i18n because this isn't a reactive context
 		queries: [{ name: "Query 1", query: "", legendFormat: "" }],
 		timeRange: TimeRangePreset.Last5Minutes,
@@ -153,7 +153,8 @@ export function buildConfigFromNodeAttrs(
 		return {
 			title: legacy.title ?? "",
 			dataSourceId: legacy.dataSourceId ?? null,
-			visualizationType: legacy.type ?? legacy.visualizationType ?? null,
+			visualizationType:
+				legacy.type ?? legacy.visualizationType ?? GenericQueryChartType.Line,
 			queries: legacy.queries ?? null,
 			timeRange: legacy.timeRange ?? null,
 			refreshInterval: legacy.refreshInterval ?? null,
@@ -178,7 +179,7 @@ export function buildConfigFromNodeAttrs(
 		dataSourceId: (attrs.dataSourceId as string | null | undefined) ?? null,
 		visualizationType:
 			(attrs.visualizationType as GenericQueryChartType | null | undefined) ??
-			null,
+			GenericQueryChartType.Line,
 		queries: (attrs.queries as MetricConfig["queries"] | undefined) ?? null,
 		timeRange: (attrs.timeRange as TimeRangePreset | null | undefined) ?? null,
 		refreshInterval:
diff --git a/web/app/components/editor/blocks/metrics/visualizations/index.test.ts b/web/app/components/editor/blocks/metrics/visualizations/index.test.ts
index 7c73a440..a63c1896 100644
--- a/web/app/components/editor/blocks/metrics/visualizations/index.test.ts
+++ b/web/app/components/editor/blocks/metrics/visualizations/index.test.ts
@@ -174,23 +174,6 @@ describe("indexToAlphabeticLabel", () => {
 })
 
 describe("mergeVisualizationResults", () => {
-	it.for([
-		{ name: "null", type: null },
-		{ name: "undefined", type: undefined },
-	])(
-		"reports type-not-selected when the chart type is $name",
-		({ type }, { expect }) => {
-			expect(
-				mergeVisualizationResults(
-					type,
-					[queryItem(okResult([]))],
-					null,
-					orderedLabel,
-				),
-			).toEqual({ status: GenericQueryResultStatus.TypeNotSelected })
-		},
-	)
-
 	it.for([
 		{ name: "null", results: null },
 		{ name: "undefined", results: undefined },
diff --git a/web/app/components/editor/blocks/metrics/visualizations/index.ts b/web/app/components/editor/blocks/metrics/visualizations/index.ts
index 9c3cf079..cb7002be 100644
--- a/web/app/components/editor/blocks/metrics/visualizations/index.ts
+++ b/web/app/components/editor/blocks/metrics/visualizations/index.ts
@@ -102,7 +102,7 @@ function truncToDecimals(num: number, decimals: number | null) {
 }
 
 function extractVisualizationData(
-	visualizationType: GenericQueryChartType | null | undefined,
+	visualizationType: GenericQueryChartType,
 	input: GenericQueryResult | null | undefined,
 	legendLabelFormat: string,
 	decimals: number | null,
@@ -112,10 +112,6 @@ function extractVisualizationData(
 	queryErrorMessage?: string
 	data?: MultipleLineChartData | MultipleBarChartData | MultipleGaugeChartData
 } {
-	if (!visualizationType) {
-		return { status: GenericQueryResultStatus.TypeNotSelected }
-	}
-
 	if (!input) {
 		return { status: GenericQueryResultStatus.NoData }
 	}
@@ -227,7 +223,7 @@ export interface QueryResultItem {
 }
 
 export function mergeVisualizationResults(
-	visualizationType: GenericQueryChartType | null | undefined,
+	visualizationType: GenericQueryChartType,
 	queryResults: QueryResultItem[] | null | undefined,
 	decimals: number | null,
 	orderedLegendLabelFn: (type: GenericQueryChartType) => string,
@@ -236,10 +232,6 @@ export function mergeVisualizationResults(
 	queryErrorMessage?: string
 	data?: MultipleLineChartData | MultipleBarChartData | MultipleGaugeChartData
 } {
-	if (!visualizationType) {
-		return { status: GenericQueryResultStatus.TypeNotSelected }
-	}
-
 	if (!queryResults?.length) {
 		return { status: GenericQueryResultStatus.NoData }
 	}
diff --git a/web/app/stores/editor.nuxt.test.ts b/web/app/stores/editor.nuxt.test.ts
index 58ba24d5..3ce7aee7 100644
--- a/web/app/stores/editor.nuxt.test.ts
+++ b/web/app/stores/editor.nuxt.test.ts
@@ -20,7 +20,7 @@ function metricConfig(title: string): MetricConfig {
 	return {
 		title,
 		dataSourceId: null,
-		visualizationType: null,
+		visualizationType: GenericQueryChartType.Line,
 		queries: null,
 		timeRange: null,
 		refreshInterval: null,
diff --git a/web/i18n/locales/en/editor.json b/web/i18n/locales/en/editor.json
index 840e7be3..5dbaa97e 100644
--- a/web/i18n/locales/en/editor.json
+++ b/web/i18n/locales/en/editor.json
@@ -437,12 +437,6 @@
 				"simplified-config-in-progress": {
 					"title": "No Data"
 				},
-				"type-not-selected": {
-					"title": "No Visualization Selected",
-					"description": "Start configuring metrics by selecting a visualization type",
-					"normal-action-button": "Edit Metrics",
-					"readonly-action-button": "View Metrics"
-				},
 				"data-source-not-selected": {
 					"title": "No Data Source Selected",
 					"description": "Choose a data source to see metric data",
@@ -464,7 +458,7 @@
 					"description": "The current configuration returned no data. Please adjust your queries or data sources",
 					"normal-action-button": "Edit Metrics",
 					"readonly-action-button": "View Metrics",
-					"simulate-action-button": "Simulate data"
+					"simulate-action-button": "Simulate Data"
 				}
 			},
 			"config": {
@@ -783,12 +777,12 @@
 				}
 			},
 			"simulation": {
-				"label": "Simulation",
+				"tooltip": "Showing simulated data until real data is available",
 				"section-title": "Simulated data",
-				"section-description": "Simulate the shape this chart will take until the metric it documents becomes available.",
-				"preset-label": "Chart",
-				"preset-placeholder": "Select a chart",
-				"stop-button": "Stop simulating",
+				"section-description": "The chart shows sample data in the pattern below until real data is available.",
+				"preset-label": "Data pattern",
+				"preset-placeholder": "Select a pattern",
+				"stop-button": "Remove Simulated Data",
 				"preset-options": {
 					"cpu_usage": "CPU usage",
 					"memory_usage": "Memory usage",