diff --git a/web/src/lib/components/ToolPage.svelte b/web/src/lib/components/ToolPage.svelte
index 3b9daaf..0f73902 100644
--- a/web/src/lib/components/ToolPage.svelte
+++ b/web/src/lib/components/ToolPage.svelte
@@ -21,6 +21,10 @@
 	const isInfo = $derived(tool.resultType === 'info');
 	const sanitized = $derived(sanitizeParams(tool, values));
 
+	let runToken = 0;
+	let lastRunSource: PixelImage | null = null;
+	let lastRunValuesJson = '';
+
 	async function handleFile(file: File) {
 		errorText = '';
 		status = 'processing';
@@ -41,20 +45,27 @@
 
 	async function runTool() {
 		if (!source || isInfo) return;
+		const token = ++runToken;
+		lastRunSource = source;
+		lastRunValuesJson = JSON.stringify(sanitized);
 		try {
-			result = await tool.run(source, sanitized);
+			const next = await tool.run(source, sanitized);
+			if (token !== runToken) return;
+			result = next;
 			status = 'loaded';
 		} catch (e) {
+			if (token !== runToken) return;
 			showError(e);
 		}
 	}
 
-	function apply() {
-		if (!source || isInfo || status === 'processing') return;
-		errorText = '';
-		status = 'processing';
-		runTool();
-	}
+	$effect(() => {
+		const valuesJson = JSON.stringify(sanitized);
+		if (source === lastRunSource && valuesJson === lastRunValuesJson) return;
+		if (!source || isInfo) return;
+		const timer = setTimeout(() => void runTool(), 300);
+		return () => clearTimeout(timer);
+	});
 
 	function showError(e: unknown) {
 		status = source ? 'loaded' : 'idle';
@@ -123,7 +134,7 @@
 	</div>
 
 	{#if source && !isInfo}
-		<ParamsCard params={tool.params} bind:values busy={status === 'processing'} onApply={apply} />
+		<ParamsCard params={tool.params} bind:values />
 	{/if}
 </section>
 
diff --git a/web/src/lib/components/tool/ParamsCard.svelte b/web/src/lib/components/tool/ParamsCard.svelte
index 63ef5d3..2fb6e7a 100644
--- a/web/src/lib/components/tool/ParamsCard.svelte
+++ b/web/src/lib/components/tool/ParamsCard.svelte
@@ -1,23 +1,19 @@
 <script lang="ts">
-	import type { ParamDef } from '$lib/registry';
 	import ParamForm from '../ParamForm.svelte';
-	import Button from '../ui/Button.svelte';
+	import type { ParamDef } from '$lib/registry';
 
 	interface Props {
 		params: ParamDef[];
 		values: Record<string, any>;
-		busy: boolean;
-		onApply: () => void;
 	}
 
-	let { params, values = $bindable(), busy, onApply }: Props = $props();
+	let { params, values = $bindable() }: Props = $props();
 </script>
 
 <div class="panel root">
 	<h2 class="heading-section">Параметры</h2>
 	{#if params.length > 0}
 		<ParamForm {params} bind:values />
-		<Button onclick={onApply} {busy} busyText="Обработка…" fullWidth>Применить</Button>
 	{:else}
 		<p class="hint text-caption text-muted">
 			У этого инструмента нет параметров — результат уже готов.
diff --git a/web/src/lib/components/tool/ResultCard.svelte b/web/src/lib/components/tool/ResultCard.svelte
index 613ffb1..e091271 100644
--- a/web/src/lib/components/tool/ResultCard.svelte
+++ b/web/src/lib/components/tool/ResultCard.svelte
@@ -57,6 +57,9 @@
 	{:else}
 		<div class="media">
 			<Preview image={result} />
+			{#if status === 'processing'}
+				<span class="recalc" aria-live="polite">Пересчёт…</span>
+			{/if}
 		</div>
 		<DownloadButton
 			image={result}
@@ -88,5 +91,17 @@
 		align-items: center;
 		justify-content: center;
 		min-height: 16rem;
+		position: relative;
+	}
+
+	.recalc {
+		position: absolute;
+		top: var(--space-2);
+		right: var(--space-2);
+		padding: 2px var(--space-2);
+		border-radius: var(--radius-s);
+		background: color-mix(in srgb, var(--accent) 12%, var(--surface));
+		color: var(--accent);
+		font-size: var(--text-xs);
 	}
 </style>