diff --git a/docs/architecture.md b/docs/architecture.md
index 2acdbdb..03a7b2f 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -107,6 +107,13 @@ registry/{tools,pages}/*.ts
   `registry-schema.ts`, поэтому добавление вида поля не трогает страницы.
 - **Модель превью отделена от вёрстки.** `schema-preview-model.ts` — чистая
   функция, покрыта unit-тестами; `SchemaPreview.svelte` только рисует её вывод.
+- **Цепочка работает над набором файлов (fan-out).** `run-chain.ts`: «ток» между
+  шагами — массив именованных изображений (одиночная загрузка = набор из
+  одного); image-шаг применяется к каждому файлу, files-шаг (split) склеивает
+  имена частей (`<вход>-<часть>`), analyze-шаг (text/verdict) при batch-входе
+  видит первый файл. Шаг роняет цепочку, только если упали все файлы
+  (`ChainStepError`), частичные сбои — warnings. Мультивыбор файлов в drop-зоне;
+  набор на выходе скачивается zip через `zip.ts`.
 
 ## 3. Инструмент и страница
 
diff --git a/docs/backlog.md b/docs/backlog.md
index e9189c3..2f14ae4 100644
--- a/docs/backlog.md
+++ b/docs/backlog.md
@@ -18,33 +18,20 @@
 - [ ] посмотреть реализацию flip animation svelte для анимации переключения
       режима aligned\normal
 - [ ] переделать визуал toggle компонента (которым режим переключается)
-- [ ] **Идея 4. Batch-обработка архивов выбранным chain** — оценка L. Вход —
-      zip-архив картинок (распаковка в браузере), прогон текущего или выбранного
-      сохранённого chain по каждому файлу, сборка результата обратно в zip для
-      скачивания. Зависит от идеи 3 (выбор цепочки) и от экспортного формата
-      pipeline JSON; прогресс и ошибки — пофайлово.
-- [ ] **Идея 15. Набор файлов в пайплайне: 1 → many не должен быть
-      терминальным** — оценка L. **Сейчас** `execute` принимает один
-      `source: PixelImage | undefined` и возвращает один `ToolResult`, а
-      `SchemaToolView` раскладывает вывод в `result` / `fileResult` /
-      `textResult` по `resultKind` — поэтому шаг с `result: "files"` упирается в
-      конец цепочки. **Направление:** следующий инструмент применяется **ко всем
-      картинкам** предыдущего результата (fan-out), а many → 1 (вход = архив или
-      несколько файлов) — обратная сторона того же контракта. Терминальными
-      остаются только результаты, которые не картинка (text, verdict). Что
-      обдумать: - где проходит граница: один вызов `run(ctx)` на файл (имя части
-      склеивается в `FileResult.files`) или батч целиком на стороне исполнителя;
-      `executor/protocol.ts` `files` уже сериализуются, но при батче нужен
-      прогресс и отмена; - частичные ошибки: один битый файл не должен ронять
-      весь шаг — нужен per-file отчёт, а не один `ToolError` на шаг; - имена
-      частей на каждом шаге и Download для набора (сейчас zip по `page.slug`,
-      `SchemaToolView.download()`); - обратная сторона: распаковка zip в
-      браузере, порядок файлов, поведение many → 1 → many в одной цепочке.
-      Зависит от идеи 10 (остальные потребители 1 → many) и идеи 4 (batch по
-      архиву), `docs/roadmap.md` фаза 8 «batch-страница».
+- [ ] **Идея 4. Batch-обработка архивов выбранным chain** — оценка L. Fan-out и
+      мультивыбор уже есть (идея 15: `web/src/lib/run-chain.ts`, zip-выгрузка
+      набора). Осталось: zip на вход (распаковка в браузере, порядок файлов,
+      поведение many → 1 → many), прогресс и отмена пофайлово, запуск по
+      сохранённой цепочке из `/chains`.
+- [ ] **Идея 15. Остатки fan-out** — сделано: 1 → many не терминален,
+      мультизагрузка, склейка имён, per-file ошибки с warning. Отложено:
+      parts-grid на промежуточных тайлах (сейчас первая картинка набора),
+      прогресс/отмена, analyze-шаги пофайлово (сейчас firstOnly-warning).
 
 ## Инструменты
 
+- [ ] split-to-parts, загружаем картинку, после этого переключаемся на режим by
+      tile - интерфейс начинает тормозить. уже пора переходить на worker\wasm?
 - [ ] remove-alpha-channel - дубль инструмента с выбором цвета на замену, что с
       такими делать вообще? оставить как seo? можно ли под капотом использовать
       другой инструмент с хардкодед настройками?
@@ -54,9 +41,6 @@
       выделенной области
 - [ ] сделать конвертацию в смайлики\награды для твитча (6 размеров или выбор
       какой размер - 112\56\28px или 72\36\18)
-- [ ] сделать несколько проходное сжатие png для получения необходимого размера
-      файлов, посмотреть реализацию в
-      [twitch-emote-resizer](https://github.com/tma02/twitch-emote-resizer)
 - [ ] Font Style - обдумать выбор шрифта (google fonts???) как организовать
       шрифты с кириллицей? сделать галочку "только с кириллицей"??? (решение о
       наборе и лицензиях: `docs/plan-platform.md` §4 — только OFL/Apache с
@@ -134,6 +118,8 @@
 
 ## UI и качество
 
+- [ ] при загрузке нескольких файлов, показывает source не той же высоты, как
+      result
 - [ ] split to parts - посмотреть вариант с toggle component - может будет
       удобнее чем sectioned buttons
 - [ ] чип «Маска» (`resultCard.maskToggle` на тайлах результата) — попробовать
diff --git a/web/src/lib/chains.svelte.ts b/web/src/lib/chains.svelte.ts
index acecf21..166b1bb 100644
--- a/web/src/lib/chains.svelte.ts
+++ b/web/src/lib/chains.svelte.ts
@@ -8,6 +8,7 @@ import {
 	serializeSteps,
 	type ChainStep,
 } from "./pipeline.svelte";
+import type { ToolImageFile } from "./registry";
 
 export interface NamedChain {
 	id: string;
@@ -135,6 +136,7 @@ export function deleteChain(id: string): void {
 /** State that cannot persist across the tool -> pipeline route swap. */
 export interface ChainHandoff {
 	source: PixelImage | null;
+	sourceFiles?: ToolImageFile[];
 	textSource: string;
 	format: OutputMime;
 	limitKb: number | undefined;
diff --git a/web/src/lib/components/schema/Dropzone.svelte b/web/src/lib/components/schema/Dropzone.svelte
index cbffae6..77325d3 100644
--- a/web/src/lib/components/schema/Dropzone.svelte
+++ b/web/src/lib/components/schema/Dropzone.svelte
@@ -5,15 +5,18 @@
 	interface Props {
 		accept?: string;
 		onfile?: (file: File) => void;
+		onfiles?: (files: File[]) => void;
 	}
-	let { accept = "image/*", onfile }: Props = $props();
+	let { accept = "image/*", onfile, onfiles }: Props = $props();
 
 	let dragging = $state(false);
 	let input = $state<HTMLInputElement | null>(null);
 
 	function handleFiles(files: FileList | null | undefined) {
-		const file = files?.[0];
-		if (file) onfile?.(file);
+		const list = Array.from(files ?? []);
+		if (list.length === 0) return;
+		if (list.length > 1 && onfiles) onfiles(list);
+		else if (list[0]) onfile?.(list[0]);
 	}
 
 	function onDrop(e: DragEvent) {
@@ -50,6 +53,7 @@
 		bind:this={input}
 		type="file"
 		{accept}
+		multiple
 		hidden
 		onchange={(e) => handleFiles((e.target as HTMLInputElement).files)}
 	/>
diff --git a/web/src/lib/components/schema/PartsGrid.svelte b/web/src/lib/components/schema/PartsGrid.svelte
new file mode 100644
index 0000000..fbaa27c
--- /dev/null
+++ b/web/src/lib/components/schema/PartsGrid.svelte
@@ -0,0 +1,70 @@
+<script lang="ts">
+	import { toDataUrl } from "$lib/core/io";
+	import type { ToolImageFile } from "$lib/registry";
+
+	interface Props {
+		files: ToolImageFile[];
+	}
+	let { files }: Props = $props();
+
+	const parts = $derived(
+		files.map((file) => ({ name: file.name, url: toDataUrl(file.image) })),
+	);
+</script>
+
+<div class="parts-wrap">
+	<div class="parts-grid">
+		{#each parts as part (part.name)}
+			<figure class="part">
+				<img src={part.url} alt={part.name} loading="lazy" />
+				<figcaption>{part.name}</figcaption>
+			</figure>
+		{/each}
+	</div>
+</div>
+
+<style>
+	/* Own scrollbox: usable inside any tile without extra canvas classes. */
+	.parts-wrap {
+		width: 100%;
+		max-height: 60vh;
+		overflow: auto;
+		align-self: flex-start;
+	}
+	.parts-grid {
+		display: grid;
+		grid-template-columns: repeat(
+			auto-fill,
+			minmax(var(--size-parts-grid-min), 1fr)
+		);
+		gap: var(--space-m);
+		width: 100%;
+		padding: var(--space-l);
+		box-sizing: border-box;
+		align-content: start;
+	}
+	.part {
+		margin: 0;
+		display: flex;
+		flex-direction: column;
+		gap: var(--space-s);
+	}
+	.part img {
+		width: 100%;
+		height: auto;
+		display: block;
+		border: var(--size-border) solid var(--color-border);
+		border-radius: var(--radius-s);
+		background: repeating-conic-gradient(
+				var(--color-checker-main) 0 25%,
+				var(--color-checker-alt) 0 50%
+			)
+			50% / 16px 16px;
+	}
+	.part figcaption {
+		font: var(--font-size-s) var(--font-mono);
+		color: var(--color-text-muted);
+		text-align: center;
+		overflow-wrap: anywhere;
+	}
+</style>
diff --git a/web/src/lib/components/schema/SchemaPreview.svelte b/web/src/lib/components/schema/SchemaPreview.svelte
index 50de80c..f94be22 100644
--- a/web/src/lib/components/schema/SchemaPreview.svelte
+++ b/web/src/lib/components/schema/SchemaPreview.svelte
@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { hasPreviewResult } from "./schema-preview-model";
 	import SchemaActions from "./SchemaActions.svelte";
+	import PartsGrid from "./PartsGrid.svelte";
 	import SchemaResultTile from "./SchemaResultTile.svelte";
 	import SchemaSourceTile from "./SchemaSourceTile.svelte";
 	import PreviewTile from "./PreviewTile.svelte";
@@ -15,6 +16,7 @@
 		InputMode,
 		ResultKind,
 		ResultNote,
+		ToolImageFile,
 	} from "$lib/registry";
 
 	interface Props {
@@ -22,6 +24,8 @@
 		resultKind?: ResultKind;
 		toolId: string;
 		source: PixelImage | null;
+		sources?: ToolImageFile[];
+		fileCount?: number;
 		result: PixelImage | null;
 		resultNote?: ResultNote | null;
 		fileResult?: FileResult | null;
@@ -34,6 +38,7 @@
 		running?: boolean;
 		error?: string;
 		stepResults?: (PixelImage | null)[];
+		stepFileSets?: ToolImageFile[][];
 		stepMaskable?: boolean[];
 		stepMaskOn?: boolean[];
 		stepMasks?: (PixelImage | null)[];
@@ -45,6 +50,7 @@
 		limitKb?: number;
 		alphaLoss?: boolean;
 		onupload: (file: File) => void;
+		onuploadmany?: (files: File[]) => void;
 		ontextsource?: (text: string) => void;
 		onrendertext?: () => void;
 		oncopytext?: () => void;
@@ -59,6 +65,8 @@
 		resultKind = "image",
 		toolId,
 		source,
+		sources = [],
+		fileCount = 0,
 		result,
 		resultNote = null,
 		fileResult = null,
@@ -71,6 +79,7 @@
 		running = false,
 		error = "",
 		stepResults = [],
+		stepFileSets = [],
 		stepMaskable = [],
 		stepMaskOn = [],
 		stepMasks = [],
@@ -82,6 +91,7 @@
 		limitKb = undefined,
 		alphaLoss = false,
 		onupload,
+		onuploadmany,
 		ontextsource,
 		onrendertext,
 		oncopytext,
@@ -134,14 +144,36 @@
 	<SchemaSourceTile
 		mode={inputMode}
 		{source}
+		{sources}
 		{textSource}
 		{running}
+		{fileCount}
 		ontextinput={ontextsource}
 		{onrendertext}
 		{onupload}
+		{onuploadmany}
 	/>
 	{#each stepResults.slice(0, -1) as img, i (i)}
-		{#if img}
+		{@const set = stepFileSets[i] ?? []}
+		{#if set.length > 1 && !stepMaskOn[i]}
+			<PreviewTile
+				label={t("chain.stepResult", { n: i + 1 })}
+				viewMode="image"
+				parts={set.length}
+				partsDims={`${set[0].image.width} × ${set[0].image.height}`}
+			>
+				{#snippet actions()}
+					{#if stepMaskable[i]}
+						<ChipButton
+							label={t("resultCard.maskToggle")}
+							active={stepMaskOn[i] ?? false}
+							onclick={() => ontogglestepmask?.(i)}
+						/>
+					{/if}
+				{/snippet}
+				<PartsGrid files={set} />
+			</PreviewTile>
+		{:else if img}
 			<PreviewTile
 				label={t("chain.stepResult", { n: i + 1 })}
 				viewMode="image"
diff --git a/web/src/lib/components/schema/SchemaResultTile.svelte b/web/src/lib/components/schema/SchemaResultTile.svelte
index 5fc746e..69d62f8 100644
--- a/web/src/lib/components/schema/SchemaResultTile.svelte
+++ b/web/src/lib/components/schema/SchemaResultTile.svelte
@@ -5,6 +5,7 @@
 	import type { FileResult, ResultKind, ResultNote } from "$lib/registry";
 	import { Check } from "@lucide/svelte";
 	import ChipButton from "$lib/components/ui/ChipButton.svelte";
+	import PartsGrid from "./PartsGrid.svelte";
 	import SchemaTextResult from "./SchemaTextResult.svelte";
 	import PreviewTile from "./PreviewTile.svelte";
 
@@ -46,14 +47,6 @@
 			? `${result.width} × ${result.height}`
 			: undefined,
 	);
-	const partUrls = $derived(
-		resultKind === "files" && fileResult
-			? fileResult.files.map((file) => ({
-					name: file.name,
-					url: toDataUrl(file.image),
-				}))
-			: [],
-	);
 
 	let parts = $derived(
 		resultKind === "files" && fileResult ? fileResult.files.length : undefined,
@@ -85,11 +78,7 @@
 			/>
 		{/if}
 	{/snippet}
-	<div
-		class="canvas"
-		class:checker={resultKind === "image"}
-		class:files={resultKind === "files"}
-	>
+	<div class="canvas" class:checker={resultKind === "image"}>
 		{#if resultKind === "text" && textResult}
 			<div class="text-result-wrap">
 				<SchemaTextResult
@@ -110,15 +99,8 @@
 					ondownload={ondownloadtxt ?? (() => {})}
 				/>
 			</div>
-		{:else if resultKind === "files" && partUrls.length > 0}
-			<div class="parts-grid">
-				{#each partUrls as part (part.name)}
-					<figure class="part">
-						<img src={part.url} alt={part.name} loading="lazy" />
-						<figcaption>{part.name}</figcaption>
-					</figure>
-				{/each}
-			</div>
+		{:else if resultKind === "files" && fileResult && fileResult.files.length > 0}
+			<PartsGrid files={fileResult.files} />
 		{:else if resultKind === "image" && resultUrl}
 			<img
 				data-testid="result-image"
@@ -166,51 +148,9 @@
 			)
 			50% / 28px 28px;
 	}
-	/* Сетка частей: без потолка 1024 плитки растягивали страницу бесконечно. */
-	.canvas.files {
-		max-height: 60vh;
-		align-items: flex-start;
-	}
 	.empty {
 		font: var(--font-size-s) var(--font-mono);
 	}
-	.parts-grid {
-		display: grid;
-		grid-template-columns: repeat(
-			auto-fill,
-			minmax(var(--size-parts-grid-min), 1fr)
-		);
-		gap: var(--space-m);
-		width: 100%;
-		height: 100%;
-		padding: var(--space-l);
-		box-sizing: border-box;
-		align-content: start;
-	}
-	.part {
-		margin: 0;
-		display: flex;
-		flex-direction: column;
-		gap: var(--space-s);
-	}
-	.part img {
-		width: 100%;
-		height: auto;
-		display: block;
-		border: var(--size-border) solid var(--color-border);
-		border-radius: var(--radius-s);
-		background: repeating-conic-gradient(
-				var(--color-checker-main) 0 25%,
-				var(--color-checker-alt) 0 50%
-			)
-			50% / 16px 16px;
-	}
-	.part figcaption {
-		font: var(--font-size-s) var(--font-mono);
-		color: var(--color-text-muted);
-		text-align: center;
-		overflow-wrap: anywhere;
-	}
 	.text-result-wrap {
 		width: 100%;
 		padding: var(--space-l);
diff --git a/web/src/lib/components/schema/SchemaSourceTile.svelte b/web/src/lib/components/schema/SchemaSourceTile.svelte
index f9d69cf..d23e3af 100644
--- a/web/src/lib/components/schema/SchemaSourceTile.svelte
+++ b/web/src/lib/components/schema/SchemaSourceTile.svelte
@@ -2,33 +2,45 @@
 	import { toDataUrl } from "$lib/core/io";
 	import type { PixelImage } from "$lib/core/types";
 	import { t } from "$lib/i18n/t";
-	import type { InputMode } from "$lib/registry";
+	import type { InputMode, ToolImageFile } from "$lib/registry";
 	import Dropzone from "./Dropzone.svelte";
+	import PartsGrid from "./PartsGrid.svelte";
 	import PreviewTile from "./PreviewTile.svelte";
 	import SchemaTextSource from "./SchemaTextSource.svelte";
 
 	interface Props {
 		mode: InputMode;
 		source: PixelImage | null;
+		sources?: ToolImageFile[];
 		textSource?: string;
 		running?: boolean;
+		fileCount?: number;
 		ontextinput?: (text: string) => void;
 		onrendertext?: () => void;
 		onupload?: (file: File) => void;
+		onuploadmany?: (files: File[]) => void;
 	}
 	let {
 		mode,
 		source,
+		sources = [],
 		textSource = "",
 		running = false,
+		fileCount = 0,
 		ontextinput,
 		onrendertext,
 		onupload,
+		onuploadmany,
 	}: Props = $props();
 
 	const sourceUrl = $derived(source ? toDataUrl(source) : null);
 	const sourceDims = $derived(
-		source ? `${source.width} × ${source.height}` : undefined,
+		source
+			? `${source.width} × ${source.height}` +
+					(fileCount > 1
+						? ` · ${t("sourceCard.countFiles", { count: fileCount })}`
+						: "")
+			: undefined,
 	);
 
 	let dragging = $state(false);
@@ -57,8 +69,13 @@
 	function onDrop(e: DragEvent) {
 		e.preventDefault();
 		dragging = false;
-		const file = e.dataTransfer?.files?.[0];
-		if (file) onupload?.(file);
+		pickFiles(Array.from(e.dataTransfer?.files ?? []));
+	}
+
+	function pickFiles(files: File[]) {
+		if (files.length === 0) return;
+		if (files.length > 1 && onuploadmany) onuploadmany(files);
+		else if (files[0]) onupload?.(files[0]);
 	}
 
 	function open() {
@@ -106,17 +123,21 @@
 				bind:this={input}
 				type="file"
 				accept="image/*"
+				multiple
 				hidden
 				onchange={(e) => {
-					const file = (e.target as HTMLInputElement).files?.[0];
-					if (file) onupload?.(file);
+					pickFiles(Array.from((e.target as HTMLInputElement).files ?? []));
 				}}
 			/>
-			<img
-				data-testid="source-image"
-				src={sourceUrl}
-				alt={t("sourceCard.alt")}
-			/>
+			{#if sources.length > 1}
+				<PartsGrid files={sources} />
+			{:else}
+				<img
+					data-testid="source-image"
+					src={sourceUrl}
+					alt={t("sourceCard.alt")}
+				/>
+			{/if}
 			{#if dragging}
 				<span class="drop-hint">{t("dropZone.overlayDefault")}</span>
 			{:else}
@@ -124,7 +145,7 @@
 			{/if}
 		</div>
 	{:else if mode === "image"}
-		<Dropzone onfile={onupload} />
+		<Dropzone onfile={onupload} onfiles={onuploadmany} />
 	{:else}
 		<span class="empty">{t("sourceCard.noSource")}</span>
 	{/if}
diff --git a/web/src/lib/components/schema/SchemaToolView.svelte b/web/src/lib/components/schema/SchemaToolView.svelte
index 7a95332..a7dbfef 100644
--- a/web/src/lib/components/schema/SchemaToolView.svelte
+++ b/web/src/lib/components/schema/SchemaToolView.svelte
@@ -22,6 +22,13 @@
 	} from "$lib/core/io";
 	import type { PixelImage } from "$lib/core/types";
 	import { execute } from "$lib/executor";
+	import {
+		baseName,
+		ChainStepError,
+		runChain,
+		uniqueName,
+		type ChainWarning,
+	} from "$lib/run-chain";
 	import {
 		pageDescription,
 		pageTitle,
@@ -51,6 +58,7 @@
 		type FileResult,
 		type Page,
 		type Tool,
+		type ToolImageFile,
 		type ToolResult,
 	} from "$lib/registry";
 	import {
@@ -66,6 +74,7 @@
 	import { SvelteMap, SvelteSet } from "svelte/reactivity";
 	import AddStepButton from "./AddStepButton.svelte";
 	import PreviewTile from "./PreviewTile.svelte";
+	import PartsGrid from "./PartsGrid.svelte";
 	import SchemaActions from "./SchemaActions.svelte";
 	import SchemaFields from "./SchemaFields.svelte";
 	import SchemaPreview from "./SchemaPreview.svelte";
@@ -98,8 +107,13 @@
 	const lastAxis: Record<string, "width" | "height"> = {};
 	let stepDims = $state<(Dimension | undefined)[]>([]);
 	let stepResults = $state<(PixelImage | null)[]>([]);
+	// Full named set per step (batch/fan-out); intermediate tiles show a grid.
+	let stepFileSets = $state<ToolImageFile[][]>([]);
 	let aligned = $state(false);
 	let source = $state<PixelImage | null>(null);
+	// The full named input set (multi-upload); `source` above is the first
+	// image for preview/defaults. Single upload = one element.
+	let sourceFiles = $state<ToolImageFile[]>([]);
 	let result = $state<PixelImage | null>(null);
 	let fileResult = $state<FileResult | null>(null);
 	let textSource = $state("");
@@ -109,6 +123,9 @@
 	);
 	let running = $state(false);
 	let displayError = $state<DisplayError | null>(null);
+	let sourceWarnings = $state<ChainWarning[]>([]);
+	let runWarnings = $state<ChainWarning[]>([]);
+	const allWarnings = $derived([...sourceWarnings, ...runWarnings]);
 	let initedFor = $state("");
 	let format = $state<OutputMime>("image/png");
 	// Lossy-format quality for tools without a quality param in the schema.
@@ -126,8 +143,13 @@
 			tool,
 	);
 	const resultKind = $derived(lastTool.result ?? "image");
-	// Chain can be extended only if the last step outputs an image.
-	const canExtend = $derived((lastTool.result ?? "image") === "image");
+	// Display kind follows the actual output: a batch run of an image tool
+	// produces a file set, not a single image.
+	const displayResultKind = $derived(fileResult ? "files" : resultKind);
+	// Chain can be extended while the last step outputs images (one or many).
+	const canExtend = $derived(
+		["image", "files"].includes(lastTool.result ?? "image"),
+	);
 	const alignedMode = $derived(
 		aligned && resultKind === "image" && steps.length > 1,
 	);
@@ -202,6 +224,11 @@
 			const handoff = takeHandoff(chainId);
 			steps = getChain(chainId)?.steps ?? createChain(page);
 			source = handoff?.source ?? null;
+			sourceFiles =
+				handoff?.sourceFiles ??
+				(handoff?.source
+					? [{ name: `${baseName(page.slug)}.png`, image: handoff.source }]
+					: []);
 			textSource = handoff?.textSource ?? "";
 			if (handoff?.format) format = handoff.format;
 			else format = lastTool.output?.mime ?? "image/png";
@@ -211,8 +238,12 @@
 			format = lastTool.output?.mime ?? "image/png";
 			limitKb = undefined;
 			source = null;
+			sourceFiles = [];
 			textSource = "";
 		}
+		sourceWarnings = [];
+		runWarnings = [];
+		stepFileSets = [];
 		result = null;
 		fileResult = null;
 		textResult = null;
@@ -321,42 +352,65 @@
 		dragFrom = null;
 	}
 
-	async function handleFile(file: File) {
+	async function handleFiles(files: File[]) {
 		displayError = null;
-		try {
-			const decoded = await decodeFile(file);
-			source = decoded;
-			const first = steps[0];
-			const firstSchema = first ? toolSchemaOf(first) : undefined;
-			if (first && firstSchema) {
-				steps = steps.with(0, {
-					...first,
-					params: clampSourceAwareMaxes(
-						firstSchema,
-						applySourceDefaults(
-							firstSchema,
-							first.params,
-							{ source: decoded },
-							touchedFor(first.key),
-						),
-						decoded,
-					),
-				});
+		sourceWarnings = [];
+		const decoded: ToolImageFile[] = [];
+		const usedNames = new SvelteSet<string>();
+		let skipped = 0;
+		for (const file of files) {
+			try {
+				const name = uniqueName(`${baseName(file.name)}.png`, usedNames);
+				usedNames.add(name);
+				decoded.push({ name, image: await decodeFile(file) });
+			} catch {
+				skipped++;
 			}
-		} catch (e) {
-			displayError = toDisplayError(e);
+		}
+		if (decoded.length === 0) {
+			displayError = toDisplayError(new ToolError("errors.imageDecode"));
+			return;
+		}
+		if (skipped > 0) {
+			sourceWarnings = [{ kind: "sourceSkip", skipped, total: files.length }];
+		}
+		const firstImage = decoded[0].image;
+		source = firstImage;
+		sourceFiles = decoded;
+		const first = steps[0];
+		const firstSchema = first ? toolSchemaOf(first) : undefined;
+		if (first && firstSchema) {
+			steps = steps.with(0, {
+				...first,
+				params: clampSourceAwareMaxes(
+					firstSchema,
+					applySourceDefaults(
+						firstSchema,
+						first.params,
+						{ source: firstImage },
+						touchedFor(first.key),
+					),
+					firstImage,
+				),
+			});
 		}
 	}
 
+	async function handleFile(file: File) {
+		await handleFiles([file]);
+	}
+
 	function assignResult(out: ToolResult) {
-		if (resultKind === "image") {
-			result = out as PixelImage;
-			textResult = null;
-			fileResult = null;
-		} else if (resultKind === "files") {
-			fileResult = out as FileResult;
+		if (typeof out === "object" && out !== null && "files" in out) {
+			fileResult = out;
 			result = null;
 			textResult = null;
+			verdictVars = undefined;
+		} else if (typeof out === "object" && out !== null && "data" in out) {
+			result = out as PixelImage;
+			fileResult = null;
+			textResult = null;
+			verdictVars = undefined;
 		} else {
 			if (typeof out === "string") {
 				textResult = out;
@@ -378,46 +432,33 @@
 		displayError = null;
 		running = true;
 		try {
-			let current: PixelImage | undefined = source ?? undefined;
-			const dims: (Dimension | undefined)[] = [];
-			const results: (PixelImage | null)[] = [];
-			let out: ToolResult = "";
-			for (let i = 0; i < steps.length; i++) {
-				const stepTool = getTool(steps[i].id);
-				if (!stepTool) continue;
-				try {
-					out = await execute(stepTool, {
-						params: steps[i].params,
-						source: stepTool.input === "image" ? current : undefined,
-						text:
-							stepTool.input === "text" ? textSource || undefined : undefined,
-					});
-				} catch (e) {
-					const base = toDisplayError(e);
-					const msg = base.kind === "i18n" ? t(base.key, base.vars) : base.text;
-					throw new Error(
-						t("toolPage.stepError", {
-							n: i + 1,
-							title: stepTitle(stepTool.id),
-							msg,
-						}),
-						{ cause: e },
-					);
-				}
-				if (out && typeof out === "object" && "data" in out) {
-					current = out as PixelImage;
-					dims[i] = { width: current.width, height: current.height };
-					results[i] = current;
-				} else {
-					current = undefined;
-					results[i] = null;
-				}
-			}
-			stepDims = dims;
-			stepResults = results;
-			assignResult(out);
+			const input =
+				sourceFiles.length > 0
+					? sourceFiles
+					: source
+						? [{ name: `${baseName(page.slug)}.png`, image: source }]
+						: [];
+			const r = await runChain(steps, input, textSource || undefined, execute);
+			stepDims = r.stepDims;
+			stepResults = r.stepResults;
+			stepFileSets = r.stepFileSets;
+			runWarnings = r.warnings;
+			assignResult(r.out);
 		} catch (e) {
-			displayError = toDisplayError(e);
+			if (e instanceof ChainStepError) {
+				const base = toDisplayError(e.cause);
+				const msg = base.kind === "i18n" ? t(base.key, base.vars) : base.text;
+				displayError = {
+					kind: "plain",
+					text: t("toolPage.stepError", {
+						n: e.stepIndex + 1,
+						title: stepTitle(e.toolId),
+						msg,
+					}),
+				};
+			} else {
+				displayError = toDisplayError(e);
+			}
 		} finally {
 			running = false;
 		}
@@ -428,8 +469,7 @@
 		running = true;
 		displayError = null;
 		try {
-			if (resultKind === "files") {
-				if (!fileResult) return;
+			if (fileResult) {
 				await downloadZip(fileResult.files, `${page.slug}.zip`);
 				return;
 			}
@@ -491,7 +531,13 @@
 		void steps;
 		if (isStructuralDefault(page, steps)) return;
 		const chain = createNamedChain(autoChainName(), steps);
-		stashHandoff(chain.id, { source, textSource, format, limitKb });
+		stashHandoff(chain.id, {
+			source,
+			sourceFiles,
+			textSource,
+			format,
+			limitKb,
+		});
 		goto(resolve(`/pipeline?id=${chain.id}`), {
 			replaceState: true,
 			keepFocus: true,
@@ -571,11 +617,31 @@
 		return { kind: "plain", text: String(e) };
 	}
 
+	function warningText(w: ChainWarning): string {
+		switch (w.kind) {
+			case "partial":
+				return t("chain.warnPartial", { n: w.step, ok: w.ok, total: w.total });
+			case "firstOnly":
+				return t("chain.warnFirstOnly", { n: w.step, total: w.total });
+			case "sourceSkip":
+				return t("chain.warnSourceSkip", {
+					skipped: w.skipped,
+					total: w.total,
+				});
+		}
+	}
+
 	// Explicit save for a structurally default chain (single tuned step): the
 	// auto-create effect only fires on structural change.
 	function saveAsChain() {
 		const chain = createNamedChain(autoChainName(), steps);
-		stashHandoff(chain.id, { source, textSource, format, limitKb });
+		stashHandoff(chain.id, {
+			source,
+			sourceFiles,
+			textSource,
+			format,
+			limitKb,
+		});
 		goto(resolve(`/pipeline?id=${chain.id}`), {
 			replaceState: true,
 			keepFocus: true,
@@ -688,6 +754,8 @@
 					<SchemaPreview
 						toolId={lastTool.id}
 						{source}
+						sources={sourceFiles}
+						fileCount={sourceFiles.length}
 						{result}
 						{resultNote}
 						{fileResult}
@@ -695,7 +763,7 @@
 						{textResult}
 						textVars={verdictVars}
 						{inputMode}
-						{resultKind}
+						resultKind={displayResultKind}
 						{running}
 						error={errorText}
 						{format}
@@ -703,6 +771,7 @@
 						{limitKb}
 						{alphaLoss}
 						{stepResults}
+						{stepFileSets}
 						{aligned}
 						{stepMaskable}
 						{stepMaskOn}
@@ -718,6 +787,7 @@
 						onquality={setFormatQuality}
 						onlimit={(v) => (limitKb = v)}
 						onupload={handleFile}
+						onuploadmany={handleFiles}
 						ontextsource={(textValue) => {
 							textSource = textValue;
 						}}
@@ -728,6 +798,9 @@
 					/>
 				</section>
 			</div>
+			{#each allWarnings as w (warningText(w))}
+				<p class="warn" role="status">{warningText(w)}</p>
+			{/each}
 		{:else}
 			<div class="aligned">
 				<div class="aligned-row">
@@ -740,7 +813,7 @@
 						</label>
 						<SchemaActions
 							{inputMode}
-							{resultKind}
+							resultKind={displayResultKind}
 							canDownload={result !== null}
 							{running}
 							{format}
@@ -758,6 +831,9 @@
 				{#if errorText}
 					<p class="error" role="alert">{errorText}</p>
 				{/if}
+				{#each allWarnings as w (warningText(w))}
+					<p class="warn" role="status">{warningText(w)}</p>
+				{/each}
 				{#if canExtend}
 					<div class="aligned-row">
 						<AddStepButton onadd={(id) => addStepAt(0, id)} />
@@ -782,19 +858,26 @@
 								<SchemaSourceTile
 									mode={inputMode}
 									{source}
+									sources={sourceFiles}
 									{textSource}
 									{running}
+									fileCount={sourceFiles.length}
 									ontextinput={(v) => (textSource = v)}
 									onrendertext={run}
 									onupload={handleFile}
+									onuploadmany={handleFiles}
 								/>
 							{:else}
+								{@const inSet = stepFileSets[i - 1] ?? []}
 								<PreviewTile
 									label={t("chain.inputLegend")}
 									viewMode="image"
 									dims={input ? `${input.width} × ${input.height}` : undefined}
+									parts={inSet.length > 1 ? inSet.length : undefined}
 								>
-									{#if input}
+									{#if inSet.length > 1}
+										<PartsGrid files={inSet} />
+									{:else if input}
 										<img src={toDataUrl(input)} alt="" />
 									{:else}
 										<span class="empty">{t("resultCard.noResult")}</span>
@@ -803,7 +886,7 @@
 							{/if}
 							{#if i === steps.length - 1}
 								<SchemaResultTile
-									{resultKind}
+									resultKind={displayResultKind}
 									result={out}
 									{resultNote}
 									{fileResult}
@@ -820,15 +903,19 @@
 									ondownloadtxt={downloadText}
 								/>
 							{:else}
+								{@const outSet = stepFileSets[i] ?? []}
 								<PreviewTile
 									label={t("chain.stepResult", { n: i + 1 })}
 									viewMode="image"
 									dims={out ? `${out.width} × ${out.height}` : undefined}
+									parts={outSet.length > 1 ? outSet.length : undefined}
 								>
 									{#snippet actions()}
 										{@render maskChip(i)}
 									{/snippet}
-									{#if out}
+									{#if outSet.length > 1 && !stepMaskOn[i]}
+										<PartsGrid files={outSet} />
+									{:else if out}
 										<img
 											src={toDataUrl(
 												stepMaskOn[i] && stepMasks[i] ? stepMasks[i]! : out,
@@ -1003,6 +1090,11 @@
 		color: var(--color-danger);
 		font: var(--font-size-s) var(--font-mono);
 	}
+	.warn {
+		margin: 0;
+		color: var(--color-warning);
+		font: var(--font-size-s) var(--font-mono);
+	}
 	.empty {
 		font: var(--font-size-s) var(--font-mono);
 	}
diff --git a/web/src/lib/i18n/en.ts b/web/src/lib/i18n/en.ts
index 1e5f499..ce64d22 100644
--- a/web/src/lib/i18n/en.ts
+++ b/web/src/lib/i18n/en.ts
@@ -63,6 +63,10 @@ export const en: Dict = {
 		busyTitle: "Processing…",
 		busyHint: "Running chain step",
 		removeStepAria: "Remove step",
+		warnPartial: "Step {n}: {ok} of {total} files processed, the rest failed",
+		warnFirstOnly:
+			"Step {n}: analyze works on one image — showing the first of {total}",
+		warnSourceSkip: "{skipped} of {total} files could not be read",
 	},
 	savedChains: {
 		pageTitle: "Saved pipelines — easy-png-tools",
@@ -85,6 +89,7 @@ export const en: Dict = {
 		source: "Source",
 		replaceImage: "Replace image",
 		replaceHint: "Click to upload an image",
+		countFiles: "{count} files",
 		chooseImage: "choose an image",
 		noSource: "no source — configure the parameters",
 		alt: "Source image",
diff --git a/web/src/lib/i18n/ru.ts b/web/src/lib/i18n/ru.ts
index 708ef7b..ad4f709 100644
--- a/web/src/lib/i18n/ru.ts
+++ b/web/src/lib/i18n/ru.ts
@@ -64,6 +64,11 @@ export const ru: Dict = {
 		busyTitle: "Обработка…",
 		busyHint: "Выполняется шаг цепочки",
 		removeStepAria: "Убрать шаг",
+		warnPartial:
+			"Шаг {n}: обработано {ok} из {total} файлов, остальные с ошибкой",
+		warnFirstOnly:
+			"Шаг {n}: анализ работает с одним изображением — показан первый из {total}",
+		warnSourceSkip: "{skipped} из {total} файлов не удалось прочитать",
 	},
 	savedChains: {
 		pageTitle: "Сохранённые пайплайны — easy-png-tools",
@@ -86,6 +91,7 @@ export const ru: Dict = {
 		source: "Источник",
 		replaceImage: "Заменить изображение",
 		replaceHint: "Кликните, чтобы загрузить изображение",
+		countFiles: "{count} шт.",
 		chooseImage: "выберите изображение",
 		noSource: "нет источника — настройте параметры",
 		alt: "Исходное изображение",
diff --git a/web/src/lib/pipeline.svelte.ts b/web/src/lib/pipeline.svelte.ts
index c1e36f4..c557ce8 100644
--- a/web/src/lib/pipeline.svelte.ts
+++ b/web/src/lib/pipeline.svelte.ts
@@ -14,14 +14,12 @@ function uid(): string {
 	return crypto.randomUUID();
 }
 
-/** Tool can be inserted mid-chain: it accepts and returns an image. */
+/** Tool can be inserted mid-chain: image in, one or many images out. */
 export function isChainable(toolId: string): boolean {
 	const tool = getTool(toolId);
-	return (
-		tool !== undefined &&
-		tool.input === "image" &&
-		(tool.result ?? "image") === "image"
-	);
+	if (!tool || tool.input !== "image") return false;
+	const kind = tool.result ?? "image";
+	return kind === "image" || kind === "files";
 }
 
 /** Pages whose tools can be added as steps (for the picker). */
diff --git a/web/src/lib/pipeline.test.ts b/web/src/lib/pipeline.test.ts
index 743a1bd..ba1830d 100644
--- a/web/src/lib/pipeline.test.ts
+++ b/web/src/lib/pipeline.test.ts
@@ -21,10 +21,10 @@ describe("pipeline: step chain", () => {
 		expect(chain[0].params).toMatchObject({ x: 0, y: 0 });
 	});
 
-	it("isChainable: image->image allowed, terminal and text-input not", () => {
+	it("isChainable: image->image and image->files allowed, terminal and text-input not", () => {
 		expect(isChainable("resize")).toBe(true);
+		expect(isChainable("split-into-parts")).toBe(true); // result: files, fan-out
 		expect(isChainable("to-base64")).toBe(false); // result: text
-		expect(isChainable("split-into-parts")).toBe(false); // result: files
 		expect(isChainable("from-svg")).toBe(false); // input: text
 		expect(isChainable("unknown-tool")).toBe(false);
 	});
diff --git a/web/src/lib/run-chain.test.ts b/web/src/lib/run-chain.test.ts
new file mode 100644
index 0000000..b874119
--- /dev/null
+++ b/web/src/lib/run-chain.test.ts
@@ -0,0 +1,127 @@
+import { describe, expect, it } from "vitest";
+import { makeImage } from "./core/test-helpers";
+import type { PixelImage } from "./core/types";
+import type { ExecuteContext } from "./executor";
+import { getTool, type Tool, type ToolImageFile } from "./registry";
+import { ChainStepError, glueName, runChain, uniqueName } from "./run-chain";
+
+const realExecute = (tool: Tool, ctx: ExecuteContext) =>
+	Promise.resolve(tool.run(ctx as never));
+
+function named(name: string, image: PixelImage): ToolImageFile {
+	return { name, image };
+}
+
+const img4x2 = makeImage(4, 2, new Array(8).fill([100, 100, 100, 255]));
+const img2x2 = makeImage(2, 2, new Array(4).fill([200, 50, 0, 255]));
+
+describe("runChain", () => {
+	it("single image through an image step returns a plain image", async () => {
+		const r = await runChain(
+			[{ id: "grayscale", params: {} }],
+			[named("photo.png", img2x2)],
+			undefined,
+			realExecute,
+		);
+		expect("data" in (r.out as PixelImage)).toBe(true);
+		expect(r.stepResults[0]?.width).toBe(2);
+		expect(r.warnings).toEqual([]);
+	});
+
+	it("split mid-chain fans out: next step applies to every part", async () => {
+		const r = await runChain(
+			[
+				{
+					id: "split-into-parts",
+					params: { mode: "grid", columns: 2, rows: 1 },
+				},
+				{ id: "grayscale", params: {} },
+			],
+			[named("img.png", img4x2)],
+			undefined,
+			realExecute,
+		);
+		const files = (r.out as { files: ToolImageFile[] }).files;
+		expect(files).toHaveLength(2);
+		expect(files.map((f) => f.name)).toEqual([
+			"img-part-1-1.png",
+			"img-part-1-2.png",
+		]);
+		// full per-step sets: split -> 2 parts, grayscale -> 2 images
+		expect(r.stepFileSets.map((s) => s.length)).toEqual([2, 2]);
+		// grayscale is deterministic: part pixels are gray both in R and B
+		const px = files[0].image.data;
+		expect(px[0]).toBe(px[2]);
+	});
+
+	it("batch input: one image step over many files yields a named set", async () => {
+		const r = await runChain(
+			[{ id: "grayscale", params: {} }],
+			[named("a.png", img2x2), named("b.png", img2x2)],
+			undefined,
+			realExecute,
+		);
+		const files = (r.out as { files: ToolImageFile[] }).files;
+		expect(files.map((f) => f.name)).toEqual(["a.png", "b.png"]);
+		expect(r.stepResults[0]).toBe(files[0].image);
+	});
+
+	it("partial failure: the step continues, warning reports the count", async () => {
+		const flaky = (tool: Tool, ctx: ExecuteContext) => {
+			if (ctx.source?.data[0] === 200) return Promise.reject(new Error("bad"));
+			return realExecute(tool, ctx);
+		};
+		const r = await runChain(
+			[{ id: "grayscale", params: {} }],
+			[named("ok.png", img4x2), named("bad.png", img2x2)],
+			undefined,
+			flaky,
+		);
+		// a single survivor degrades to a plain image result
+		expect("data" in (r.out as PixelImage)).toBe(true);
+		expect(r.warnings).toEqual([{ kind: "partial", step: 1, ok: 1, total: 2 }]);
+	});
+
+	it("total failure: ChainStepError with the step index", async () => {
+		const failing = () => Promise.reject(new Error("nope"));
+		await expect(
+			runChain(
+				[{ id: "grayscale", params: {} }],
+				[named("a.png", img2x2)],
+				undefined,
+				failing,
+			),
+		).rejects.toSatisfy(
+			(e) => e instanceof ChainStepError && e.stepIndex === 0,
+		);
+	});
+
+	it("analyze step over a batch sees only the first file", async () => {
+		const r = await runChain(
+			[{ id: "is-transparent", params: {} }],
+			[named("a.png", img2x2), named("b.png", img2x2)],
+			undefined,
+			realExecute,
+		);
+		expect(r.warnings).toEqual([{ kind: "firstOnly", step: 1, total: 2 }]);
+		expect(r.out).toBe("transparentNo");
+	});
+});
+
+describe("glueName", () => {
+	it("strips the parent extension, keeps the part name", () => {
+		expect(glueName("photo.jpeg", "part-1-1.png")).toBe("photo-part-1-1.png");
+	});
+});
+
+describe("uniqueName", () => {
+	it("keeps the first, suffixes duplicates", () => {
+		const used = new Set<string>();
+		const a = uniqueName("image.png", used);
+		used.add(a);
+		const b = uniqueName("image.png", used);
+		used.add(b);
+		const c = uniqueName("image.png", used);
+		expect([a, b, c]).toEqual(["image.png", "image-2.png", "image-3.png"]);
+	});
+});
diff --git a/web/src/lib/run-chain.ts b/web/src/lib/run-chain.ts
new file mode 100644
index 0000000..3413f19
--- /dev/null
+++ b/web/src/lib/run-chain.ts
@@ -0,0 +1,165 @@
+import type { PixelImage } from "./core/types";
+import type { ExecuteContext } from "./executor";
+import {
+	getTool,
+	type FileResult,
+	type Tool,
+	type ToolImageFile,
+	type ToolResult,
+} from "./registry";
+import type { Dimension } from "./registry-schema";
+
+export type ChainExecutor = (
+	tool: Tool,
+	ctx: ExecuteContext,
+) => Promise<ToolResult>;
+
+export type ChainWarning =
+	| { kind: "partial"; step: number; ok: number; total: number }
+	| { kind: "firstOnly"; step: number; total: number }
+	| { kind: "sourceSkip"; skipped: number; total: number };
+
+export class ChainStepError extends Error {
+	constructor(
+		readonly stepIndex: number,
+		readonly toolId: string,
+		readonly cause: unknown,
+	) {
+		super(`step ${stepIndex + 1} (${toolId}) failed`);
+	}
+}
+
+export interface ChainRunOutput {
+	stepResults: (PixelImage | null)[];
+	/** Full named set per step; empty for text/verdict/none steps. */
+	stepFileSets: ToolImageFile[][];
+	stepDims: (Dimension | undefined)[];
+	out: ToolResult;
+	warnings: ChainWarning[];
+}
+
+/** Zip entries are encoded as PNG (see zip.ts), so names stay .png. */
+export function baseName(name: string): string {
+	return name.replace(/\.[^./\\]+$/, "");
+}
+
+export function glueName(parent: string, part: string): string {
+	return `${baseName(parent)}-${part}`;
+}
+
+/**
+ * Zip entries and keyed lists address files by name, so duplicates must not
+ * occur: "image.png" repeated -> "image-2.png", "image-3.png".
+ */
+export function uniqueName(name: string, used: Set<string>): string {
+	if (!used.has(name)) return name;
+	const base = baseName(name);
+	const ext = name.slice(base.length);
+	for (let n = 2; ; n++) {
+		const candidate = `${base}-${n}${ext}`;
+		if (!used.has(candidate)) return candidate;
+	}
+}
+
+function isImage(out: ToolResult): out is PixelImage {
+	return typeof out === "object" && out !== null && "data" in out;
+}
+
+/**
+ * Fan-out chain runner: image steps apply to every file of the set,
+ * files-steps glue part names, analyze steps see only the first file.
+ * A step fails the chain only when every file fails (ChainStepError).
+ */
+export async function runChain(
+	steps: { id: string; params: Record<string, unknown> }[],
+	source: ToolImageFile[],
+	textSource: string | undefined,
+	execute: ChainExecutor,
+): Promise<ChainRunOutput> {
+	const stepResults: (PixelImage | null)[] = [];
+	const stepFileSets: ToolImageFile[][] = [];
+	const stepDims: (Dimension | undefined)[] = [];
+	const warnings: ChainWarning[] = [];
+	let current: ToolImageFile[] = source;
+	let out: ToolResult = "";
+
+	for (let i = 0; i < steps.length; i++) {
+		const tool = getTool(steps[i].id);
+		if (!tool) continue;
+
+		if (tool.input === "text" || tool.input === "none") {
+			out = await execute(tool, {
+				params: steps[i].params,
+				text: tool.input === "text" ? textSource : undefined,
+			});
+			if (isImage(out)) {
+				current = [{ name: tool.id, image: out }];
+				stepResults[i] = out;
+				stepFileSets[i] = current;
+				stepDims[i] = { width: out.width, height: out.height };
+			} else {
+				current = [];
+				stepResults[i] = null;
+				stepFileSets[i] = [];
+			}
+			continue;
+		}
+
+		const analyze = tool.result === "text" || tool.result === "verdict";
+		const inputs =
+			analyze && current.length > 1 ? current.slice(0, 1) : current;
+		if (analyze && current.length > 1) {
+			warnings.push({ kind: "firstOnly", step: i + 1, total: current.length });
+		}
+
+		const produced: ToolImageFile[] = [];
+		let failed = 0;
+		let firstError: unknown;
+		for (const file of inputs) {
+			try {
+				const res = await execute(tool, {
+					params: steps[i].params,
+					source: file.image,
+				});
+				out = res;
+				if (isImage(res)) {
+					produced.push({ name: file.name, image: res });
+				} else if (typeof res === "object" && res !== null && "files" in res) {
+					produced.push(
+						...res.files.map((f) => ({
+							name: glueName(file.name, f.name),
+							image: f.image,
+						})),
+					);
+				}
+			} catch (e) {
+				failed++;
+				firstError ??= e;
+			}
+		}
+		if (inputs.length > 0 && failed === inputs.length) {
+			throw new ChainStepError(i, tool.id, firstError);
+		}
+		if (failed > 0) {
+			warnings.push({
+				kind: "partial",
+				step: i + 1,
+				ok: inputs.length - failed,
+				total: inputs.length,
+			});
+		}
+		current = produced;
+		stepResults[i] = produced[0]?.image ?? null;
+		stepFileSets[i] = produced;
+		stepDims[i] = produced[0]
+			? { width: produced[0].image.width, height: produced[0].image.height }
+			: undefined;
+	}
+
+	if (current.length > 1) {
+		out = { files: current } satisfies FileResult;
+	} else if (current.length === 1) {
+		out = current[0].image;
+	}
+	return { stepResults, stepFileSets, stepDims, out, warnings };
+}