diff --git a/apps/web/messages/en.json b/apps/web/messages/en.json
index a01d1ce..f9f11fb 100644
--- a/apps/web/messages/en.json
+++ b/apps/web/messages/en.json
@@ -180,6 +180,9 @@
 	"sync_conflicts_back": "Back to settings",
 	"settings_about": "About",
 	"settings_about_version": "v{version} · {commit} · {date}",
+	"settings_about_view_changelog": "View changelog",
+	"changelog_modal_title": "Changelog",
+	"changelog_modal_close": "Close",
 	"sync_offline": "You're offline — changes will sync when you reconnect",
 	"sync_syncing": "Syncing…",
 	"undo": "Undo",
diff --git a/apps/web/messages/es.json b/apps/web/messages/es.json
index 625bfb9..d279f27 100644
--- a/apps/web/messages/es.json
+++ b/apps/web/messages/es.json
@@ -180,6 +180,9 @@
 	"sync_conflicts_back": "Volver a ajustes",
 	"settings_about": "Acerca de",
 	"settings_about_version": "v{version} · {commit} · {date}",
+	"settings_about_view_changelog": "Ver historial",
+	"changelog_modal_title": "Historial de cambios",
+	"changelog_modal_close": "Cerrar",
 	"sync_offline": "Sin conexión — los cambios se sincronizarán al reconectar",
 	"sync_syncing": "Sincronizando…",
 	"undo": "Deshacer",
diff --git a/apps/web/src/lib/components/ChangelogModal.svelte b/apps/web/src/lib/components/ChangelogModal.svelte
new file mode 100644
index 0000000..59608e2
--- /dev/null
+++ b/apps/web/src/lib/components/ChangelogModal.svelte
@@ -0,0 +1,174 @@
+<!--
+  Fase 17.2 — About-modal that renders the repo-root CHANGELOG.md.
+
+  Architecture notes:
+    * CHANGELOG is imported via Vite's `?raw` query so the file is
+      bundled at build time — no fetch at runtime, no SSR + adapter-node
+      filesystem read, no service-worker miss. Bundle size is ~6 KB
+      today; revisit (dynamic import, marked, etc.) when it grows past
+      ~30 KB or starts using non-trivial markdown features (tables,
+      links, code blocks).
+    * The path is 5 levels up from this file:
+      components → lib → src → web → apps → repo-root. The plan
+      estimated 3; documenting the off-by-two so anyone moving the
+      component up/down the tree adjusts the import accordingly.
+    * Markdown is parsed inline (`renderMarkdown` below). Input is
+      static repo content, never user-supplied, so we're not exposed to
+      the usual sanitisation concerns — we still HTML-escape every
+      input line before adding our own tags to keep the surface clean
+      and to defend against accidentally putting `<` in a future entry.
+    * Esc + overlay-click both call `onClose`. We attach the keydown
+      listener to `window` only while the modal is open; otherwise
+      typing Escape outside the modal would still call back.
+-->
+<script lang="ts">
+	import { onDestroy } from 'svelte';
+	import * as m from '$lib/paraglide/messages';
+	import changelogRaw from '../../../../../CHANGELOG.md?raw';
+
+	interface Props {
+		open: boolean;
+		onClose: () => void;
+	}
+	let { open, onClose }: Props = $props();
+
+	function escapeHtml(s: string): string {
+		return s
+			.replace(/&/g, '&amp;')
+			.replace(/</g, '&lt;')
+			.replace(/>/g, '&gt;')
+			.replace(/"/g, '&quot;')
+			.replace(/'/g, '&#39;');
+	}
+
+	// Tailwind class strings for each rendered element. Living here so
+	// JIT scans them at build time — putting them inside a template
+	// string in renderMarkdown also works, but keeping them as named
+	// constants makes them grep-able and theme-able.
+	const CLS_H1 = 'mb-3 text-xl font-bold text-slate-900 dark:text-slate-50';
+	const CLS_H2 = 'mt-6 mb-2 text-base font-semibold text-slate-900 dark:text-slate-50';
+	const CLS_H3 = 'mt-4 mb-1 text-sm font-semibold text-slate-800 dark:text-slate-100';
+	const CLS_UL = 'mt-1 mb-3 list-disc pl-5 space-y-0.5';
+	const CLS_LI = 'leading-relaxed';
+	const CLS_P = 'my-2 leading-relaxed';
+	const CLS_STRONG = 'font-semibold text-slate-900 dark:text-slate-50';
+
+	function renderMarkdown(src: string): string {
+		const lines = src.split('\n');
+		const out: string[] = [];
+		let inList = false;
+		const closeList = () => {
+			if (inList) {
+				out.push('</ul>');
+				inList = false;
+			}
+		};
+
+		const inlineStrong = (s: string): string =>
+			s.replace(/\*\*([^*]+)\*\*/g, `<strong class="${CLS_STRONG}">$1</strong>`);
+
+		for (const raw of lines) {
+			const line = raw.trimEnd();
+			if (line.startsWith('### ')) {
+				closeList();
+				out.push(`<h3 class="${CLS_H3}">${inlineStrong(escapeHtml(line.slice(4)))}</h3>`);
+			} else if (line.startsWith('## ')) {
+				closeList();
+				out.push(`<h2 class="${CLS_H2}">${inlineStrong(escapeHtml(line.slice(3)))}</h2>`);
+			} else if (line.startsWith('# ')) {
+				closeList();
+				out.push(`<h1 class="${CLS_H1}">${inlineStrong(escapeHtml(line.slice(2)))}</h1>`);
+			} else if (/^[-*]\s+/.test(line)) {
+				if (!inList) {
+					out.push(`<ul class="${CLS_UL}">`);
+					inList = true;
+				}
+				const body = line.replace(/^[-*]\s+/, '');
+				out.push(`<li class="${CLS_LI}">${inlineStrong(escapeHtml(body))}</li>`);
+			} else if (line === '') {
+				closeList();
+			} else {
+				closeList();
+				out.push(`<p class="${CLS_P}">${inlineStrong(escapeHtml(line))}</p>`);
+			}
+		}
+		closeList();
+		return out.join('\n');
+	}
+
+	// Pre-render once on module evaluation — the source is build-time
+	// static, so there's no point re-running per modal open. Placed
+	// after the const class strings + renderMarkdown declaration so the
+	// TDZ doesn't kick in.
+	const html = renderMarkdown(changelogRaw);
+
+	function handleKey(e: KeyboardEvent) {
+		if (e.key === 'Escape') onClose();
+	}
+
+	// Attach the global keydown listener as soon as `open` flips true.
+	// $effect runs after mount and re-runs on each prop change, so this
+	// gives us subscribe-on-open and unsubscribe-on-close without an
+	// extra `mounted` gate (which delayed subscription past the first
+	// dispatched keydown in jsdom).
+	$effect(() => {
+		if (typeof window === 'undefined') return;
+		if (!open) return;
+		window.addEventListener('keydown', handleKey);
+		return () => window.removeEventListener('keydown', handleKey);
+	});
+
+	onDestroy(() => {
+		if (typeof window !== 'undefined') {
+			window.removeEventListener('keydown', handleKey);
+		}
+	});
+
+	function onOverlayClick(e: MouseEvent) {
+		if (e.target === e.currentTarget) onClose();
+	}
+</script>
+
+{#if open}
+	<div
+		data-testid="changelog-modal-overlay"
+		class="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4"
+		onclick={onOverlayClick}
+		role="presentation"
+	>
+		<div
+			data-testid="changelog-modal"
+			class="flex w-full max-w-2xl flex-col rounded-lg bg-surface shadow-[0px_20px_40px_rgba(15,23,42,0.2)] dark:bg-surface-raised"
+			role="dialog"
+			aria-modal="true"
+			aria-label={m.changelog_modal_title()}
+		>
+			<header
+				class="flex items-center justify-between border-b border-slate-200 px-5 py-3 dark:border-slate-700"
+			>
+				<h2 class="text-base font-semibold text-slate-900 dark:text-slate-50">
+					{m.changelog_modal_title()}
+				</h2>
+				<button
+					type="button"
+					data-testid="changelog-modal-close"
+					onclick={onClose}
+					aria-label={m.changelog_modal_close()}
+					class="rounded-md p-1 text-slate-500 hover:bg-slate-100 hover:text-slate-900 dark:text-slate-400 dark:hover:bg-slate-700 dark:hover:text-slate-50"
+				>
+					<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+						<line x1="18" y1="6" x2="6" y2="18" />
+						<line x1="6" y1="6" x2="18" y2="18" />
+					</svg>
+				</button>
+			</header>
+
+			<div
+				data-testid="changelog-modal-body"
+				class="max-h-[70vh] overflow-y-auto px-5 py-4 text-sm text-slate-700 dark:text-slate-200"
+			>
+				{@html html}
+			</div>
+		</div>
+	</div>
+{/if}
diff --git a/apps/web/src/lib/components/ChangelogModal.test.ts b/apps/web/src/lib/components/ChangelogModal.test.ts
new file mode 100644
index 0000000..225e324
--- /dev/null
+++ b/apps/web/src/lib/components/ChangelogModal.test.ts
@@ -0,0 +1,77 @@
+/**
+ * Fase 17.4.1 — ChangelogModal unit tests.
+ *
+ * Mirrors the Spinner.test.ts pattern (Svelte 5 `mount`/`unmount`, no
+ * @testing-library dependency). The modal imports CHANGELOG.md via Vite's
+ * `?raw` query — vitest runs against the same Vite config (see
+ * apps/web/vitest.config.ts) so the import resolves to the file contents at
+ * test time.
+ *
+ * Specs:
+ *   CHM-U-01 — `open={false}` renders nothing.
+ *   CHM-U-02 — `open={true}` renders the CHANGELOG `<h1>`.
+ *   CHM-U-03 — click on the overlay fires `onClose`.
+ *   CHM-U-04 — pressing Escape fires `onClose`.
+ */
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { flushSync, mount, unmount } from 'svelte';
+import ChangelogModal from './ChangelogModal.svelte';
+
+let host: HTMLElement;
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+let instance: any;
+
+function render(props: Record<string, unknown>) {
+	host = document.createElement('div');
+	document.body.appendChild(host);
+	instance = mount(ChangelogModal, { target: host, props });
+	return host;
+}
+
+beforeEach(() => {
+	host = document.createElement('div');
+});
+
+afterEach(() => {
+	if (instance) unmount(instance);
+	if (host?.parentNode) host.parentNode.removeChild(host);
+	instance = null;
+});
+
+describe('ChangelogModal component', () => {
+	it('CHM-U-01: open=false renders nothing visible', () => {
+		const root = render({ open: false, onClose: () => {} });
+		expect(root.querySelector('[data-testid="changelog-modal"]')).toBeNull();
+	});
+
+	it('CHM-U-02: open=true renders the CHANGELOG h1 heading', () => {
+		const root = render({ open: true, onClose: () => {} });
+		const modal = root.querySelector('[data-testid="changelog-modal"]');
+		expect(modal).not.toBeNull();
+		const h1 = modal?.querySelector('h1');
+		expect(h1).not.toBeNull();
+		expect(h1?.textContent?.trim()).toBe('Changelog');
+	});
+
+	it('CHM-U-03: click on overlay fires onClose', () => {
+		const onClose = vi.fn();
+		const root = render({ open: true, onClose });
+		const overlay = root.querySelector('[data-testid="changelog-modal-overlay"]') as
+			| HTMLElement
+			| null;
+		expect(overlay).not.toBeNull();
+		overlay?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
+		expect(onClose).toHaveBeenCalledTimes(1);
+	});
+
+	it('CHM-U-04: Escape key fires onClose', () => {
+		const onClose = vi.fn();
+		render({ open: true, onClose });
+		// $effect runs in a microtask after mount. flushSync drains pending
+		// reactive effects so the keydown listener is attached before we
+		// dispatch the event.
+		flushSync();
+		window.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+		expect(onClose).toHaveBeenCalledTimes(1);
+	});
+});