diff --git a/apps/cards/apps/web/src/lib/api/cards-api.ts b/apps/cards/apps/web/src/lib/api/cards-api.ts
index e871e5021..3bcb9d28e 100644
--- a/apps/cards/apps/web/src/lib/api/cards-api.ts
+++ b/apps/cards/apps/web/src/lib/api/cards-api.ts
@@ -209,6 +209,49 @@ export const cardsApi = {
 				{ auth: 'optional' }
 			),
 	},
+	pullRequests: {
+		create: (
+			deckSlug: string,
+			input: {
+				title: string;
+				body?: string;
+				diff: PullRequestDiffInput;
+			}
+		) =>
+			request<PullRequest>(`/v1/decks/${encodeURIComponent(deckSlug)}/pull-requests`, {
+				method: 'POST',
+				body: input,
+			}),
+		list: (deckSlug: string, status?: 'open' | 'merged' | 'closed' | 'rejected') => {
+			const qs = status ? `?status=${status}` : '';
+			return request<PullRequest[]>(
+				`/v1/decks/${encodeURIComponent(deckSlug)}/pull-requests${qs}`,
+				{ auth: 'optional' }
+			);
+		},
+		get: (id: string) => request<PullRequest>(`/v1/pull-requests/${id}`, { auth: 'optional' }),
+		merge: (id: string, opts: { newSemver?: string; mergeNote?: string } = {}) =>
+			request<{ pullRequest: PullRequest; version: PublicDeckVersion }>(
+				`/v1/pull-requests/${id}/merge`,
+				{ method: 'POST', body: opts }
+			),
+		close: (id: string) =>
+			request<{ ok: true }>(`/v1/pull-requests/${id}/close`, { method: 'POST' }),
+		reject: (id: string) =>
+			request<{ ok: true }>(`/v1/pull-requests/${id}/reject`, { method: 'POST' }),
+	},
+	discussions: {
+		listForCard: (contentHash: string) =>
+			request<CardDiscussion[]>(`/v1/cards/${encodeURIComponent(contentHash)}/discussions`, {
+				auth: 'optional',
+			}),
+		post: (contentHash: string, input: { deckSlug: string; body: string; parentId?: string }) =>
+			request<CardDiscussion>(`/v1/cards/${encodeURIComponent(contentHash)}/discussions`, {
+				method: 'POST',
+				body: input,
+			}),
+		hide: (id: string) => request<{ ok: true }>(`/v1/discussions/${id}/hide`, { method: 'POST' }),
+	},
 };
 
 // Override author lookup to send token opportunistically — public reads.
@@ -312,3 +355,39 @@ export interface DiffPayload {
 	unchanged: { contentHash: string; ord: number }[];
 	removed: { contentHash: string }[];
 }
+
+export interface PullRequestDiffInput {
+	add: { type: string; fields: Record<string, string> }[];
+	modify: { previousContentHash: string; type: string; fields: Record<string, string> }[];
+	remove: { contentHash: string }[];
+}
+
+export type PullRequestStatus = 'open' | 'merged' | 'closed' | 'rejected';
+
+export interface PullRequest {
+	id: string;
+	deckId: string;
+	authorUserId: string;
+	status: PullRequestStatus;
+	title: string;
+	body: string | null;
+	diff: {
+		add: { type: string; fields: Record<string, string> }[];
+		modify: { contentHash: string; fields: Record<string, string> }[];
+		remove: { contentHash: string }[];
+	};
+	mergedIntoVersionId: string | null;
+	createdAt: string;
+	resolvedAt: string | null;
+}
+
+export interface CardDiscussion {
+	id: string;
+	cardContentHash: string;
+	deckId: string;
+	authorUserId: string;
+	parentId: string | null;
+	body: string;
+	hidden: boolean;
+	createdAt: string;
+}
diff --git a/apps/cards/apps/web/src/lib/components/PullRequestsSection.svelte b/apps/cards/apps/web/src/lib/components/PullRequestsSection.svelte
new file mode 100644
index 000000000..9da721aad
--- /dev/null
+++ b/apps/cards/apps/web/src/lib/components/PullRequestsSection.svelte
@@ -0,0 +1,233 @@
+<script lang="ts">
+	import { cardsApi, CardsApiError, type PullRequest } from '$lib/api/cards-api';
+	import { authStore } from '$lib/stores/auth.svelte';
+
+	interface Props {
+		deckSlug: string;
+		ownerUserId: string;
+		onMerged?: () => void;
+	}
+
+	let { deckSlug, ownerUserId, onMerged }: Props = $props();
+
+	let prs = $state<PullRequest[]>([]);
+	let loading = $state(false);
+	let error = $state<string | null>(null);
+	let actionBusy = $state<string | null>(null);
+	let expanded = $state<Record<string, boolean>>({});
+
+	const viewerIsOwner = $derived(authStore.user?.id === ownerUserId);
+
+	$effect(() => {
+		void deckSlug;
+		load();
+	});
+
+	async function load() {
+		loading = true;
+		error = null;
+		try {
+			prs = await cardsApi.pullRequests.list(deckSlug);
+		} catch (e) {
+			error = e instanceof CardsApiError ? e.message : (e as Error).message;
+		} finally {
+			loading = false;
+		}
+	}
+
+	async function merge(pr: PullRequest) {
+		if (!confirm(`PR „${pr.title}" mergen? Erstellt eine neue Version.`)) return;
+		actionBusy = pr.id;
+		error = null;
+		try {
+			await cardsApi.pullRequests.merge(pr.id);
+			await load();
+			onMerged?.();
+		} catch (e) {
+			error = e instanceof CardsApiError ? e.message : (e as Error).message;
+		} finally {
+			actionBusy = null;
+		}
+	}
+
+	async function close(pr: PullRequest) {
+		actionBusy = pr.id;
+		error = null;
+		try {
+			await cardsApi.pullRequests.close(pr.id);
+			await load();
+		} catch (e) {
+			error = e instanceof CardsApiError ? e.message : (e as Error).message;
+		} finally {
+			actionBusy = null;
+		}
+	}
+
+	async function reject(pr: PullRequest) {
+		actionBusy = pr.id;
+		error = null;
+		try {
+			await cardsApi.pullRequests.reject(pr.id);
+			await load();
+		} catch (e) {
+			error = e instanceof CardsApiError ? e.message : (e as Error).message;
+		} finally {
+			actionBusy = null;
+		}
+	}
+
+	function statusBadgeClass(s: PullRequest['status']) {
+		if (s === 'open') return 'bg-emerald-500/15 text-emerald-300';
+		if (s === 'merged') return 'bg-violet-500/15 text-violet-300';
+		if (s === 'rejected') return 'bg-red-500/15 text-red-300';
+		return 'bg-neutral-800 text-neutral-400';
+	}
+
+	function diffSummary(pr: PullRequest) {
+		return `+${pr.diff.add.length} · ~${pr.diff.modify.length} · −${pr.diff.remove.length}`;
+	}
+</script>
+
+<section class="mt-10">
+	<header class="mb-3 flex items-center justify-between">
+		<h2 class="text-sm font-semibold uppercase tracking-wide text-neutral-400">
+			Pull Requests {prs.length > 0 ? `(${prs.length})` : ''}
+		</h2>
+		<button
+			class="text-xs text-neutral-500 hover:text-neutral-300"
+			onclick={load}
+			disabled={loading}
+		>
+			{loading ? 'Lädt…' : 'Aktualisieren'}
+		</button>
+	</header>
+
+	{#if error}
+		<p class="mb-3 rounded-lg border border-red-500/30 bg-red-500/10 p-3 text-sm text-red-400">
+			{error}
+		</p>
+	{/if}
+
+	{#if loading && prs.length === 0}
+		<p class="rounded-xl border border-neutral-800 bg-neutral-900 p-4 text-sm text-neutral-500">
+			Lädt…
+		</p>
+	{:else if prs.length === 0}
+		<p class="rounded-xl border border-neutral-800 bg-neutral-900 p-4 text-sm text-neutral-500">
+			Noch keine Pull Requests. Abonnenten können Verbesserungen vorschlagen.
+		</p>
+	{:else}
+		<ul class="space-y-2">
+			{#each prs as pr (pr.id)}
+				<li class="rounded-xl border border-neutral-800 bg-neutral-900 p-4">
+					<div class="flex items-start justify-between gap-3">
+						<div class="min-w-0">
+							<div class="flex items-center gap-2">
+								<span class="rounded-full px-2 py-0.5 text-xs {statusBadgeClass(pr.status)}">
+									{pr.status}
+								</span>
+								<h3 class="truncate font-medium text-neutral-100">{pr.title}</h3>
+							</div>
+							<p class="mt-1 text-xs text-neutral-500">
+								{diffSummary(pr)} · {new Date(pr.createdAt).toLocaleDateString('de-DE')}
+							</p>
+						</div>
+						<button
+							class="shrink-0 text-xs text-neutral-500 hover:text-neutral-300"
+							onclick={() => (expanded[pr.id] = !expanded[pr.id])}
+						>
+							{expanded[pr.id] ? 'Einklappen' : 'Details'}
+						</button>
+					</div>
+
+					{#if expanded[pr.id]}
+						{#if pr.body}
+							<p class="mt-3 whitespace-pre-line text-sm text-neutral-300">{pr.body}</p>
+						{/if}
+
+						{#if pr.diff.modify.length > 0}
+							<div class="mt-3">
+								<div class="mb-1 text-xs uppercase text-neutral-500">Geändert</div>
+								<ul class="space-y-2">
+									{#each pr.diff.modify as m (m.contentHash)}
+										<li class="rounded-lg border border-neutral-800 bg-neutral-950 p-2 text-xs">
+											<div class="text-neutral-500">
+												← {m.contentHash.slice(0, 12)}…
+											</div>
+											{#each Object.entries(m.fields) as [k, v]}
+												<div class="mt-1">
+													<span class="text-neutral-500">{k}:</span>
+													<span class="text-neutral-200">{v}</span>
+												</div>
+											{/each}
+										</li>
+									{/each}
+								</ul>
+							</div>
+						{/if}
+
+						{#if pr.diff.add.length > 0}
+							<div class="mt-3">
+								<div class="mb-1 text-xs uppercase text-neutral-500">
+									Neu (+{pr.diff.add.length})
+								</div>
+								<ul class="space-y-2">
+									{#each pr.diff.add as a, i (i)}
+										<li class="rounded-lg border border-neutral-800 bg-neutral-950 p-2 text-xs">
+											<div class="text-neutral-500">{a.type}</div>
+											{#each Object.entries(a.fields) as [k, v]}
+												<div class="mt-1">
+													<span class="text-neutral-500">{k}:</span>
+													<span class="text-neutral-200">{v}</span>
+												</div>
+											{/each}
+										</li>
+									{/each}
+								</ul>
+							</div>
+						{/if}
+
+						{#if pr.diff.remove.length > 0}
+							<div class="mt-3">
+								<div class="mb-1 text-xs uppercase text-neutral-500">
+									Entfernt (−{pr.diff.remove.length})
+								</div>
+								<ul class="space-y-1 text-xs text-neutral-400">
+									{#each pr.diff.remove as r (r.contentHash)}
+										<li>· {r.contentHash.slice(0, 12)}…</li>
+									{/each}
+								</ul>
+							</div>
+						{/if}
+
+						{#if pr.status === 'open' && viewerIsOwner}
+							<div class="mt-4 flex gap-2">
+								<button
+									class="rounded-lg bg-violet-500 px-3 py-1.5 text-xs text-white hover:bg-violet-400 disabled:opacity-50"
+									onclick={() => merge(pr)}
+									disabled={actionBusy === pr.id}
+								>
+									{actionBusy === pr.id ? 'Mergt…' : 'Mergen'}
+								</button>
+								<button
+									class="rounded-lg border border-red-500/40 px-3 py-1.5 text-xs text-red-300 hover:bg-red-500/10 disabled:opacity-50"
+									onclick={() => reject(pr)}
+									disabled={actionBusy === pr.id}
+								>
+									Ablehnen
+								</button>
+								<button
+									class="rounded-lg border border-neutral-700 px-3 py-1.5 text-xs hover:bg-neutral-800 disabled:opacity-50"
+									onclick={() => close(pr)}
+									disabled={actionBusy === pr.id}
+								>
+									Schließen
+								</button>
+							</div>
+						{/if}
+					{/if}
+				</li>
+			{/each}
+		</ul>
+	{/if}
+</section>
diff --git a/apps/cards/apps/web/src/lib/components/SuggestEditModal.svelte b/apps/cards/apps/web/src/lib/components/SuggestEditModal.svelte
new file mode 100644
index 000000000..1b994a1c5
--- /dev/null
+++ b/apps/cards/apps/web/src/lib/components/SuggestEditModal.svelte
@@ -0,0 +1,190 @@
+<script lang="ts">
+	import { cardsApi, CardsApiError } from '$lib/api/cards-api';
+	import type { Card } from '@mana/cards-core';
+
+	type Mode = 'modify' | 'remove';
+
+	interface Props {
+		card: Card;
+		deckSlug: string;
+		open: boolean;
+		onClose: () => void;
+		onSubmitted?: () => void;
+	}
+
+	let { card, deckSlug, open, onClose, onSubmitted }: Props = $props();
+
+	let mode = $state<Mode>('modify');
+	let title = $state('');
+	let body = $state('');
+	let editedFields = $state<Record<string, string>>({});
+	let busy = $state(false);
+	let error = $state<string | null>(null);
+	let success = $state(false);
+
+	$effect(() => {
+		if (open) {
+			editedFields = { ...card.fields };
+			title = `Verbesserung: Karte ${card.order + 1}`;
+			body = '';
+			mode = 'modify';
+			error = null;
+			success = false;
+		}
+	});
+
+	const fieldKeys = $derived(Object.keys(editedFields));
+
+	const hasChanges = $derived.by(() => {
+		if (mode === 'remove') return true;
+		return fieldKeys.some((k) => editedFields[k] !== card.fields[k]);
+	});
+
+	async function submit() {
+		if (!card.serverContentHash) {
+			error = 'Diese Karte stammt nicht aus einem abonnierten Deck.';
+			return;
+		}
+		if (!hasChanges) {
+			error = 'Keine Änderungen zu vorschlagen.';
+			return;
+		}
+		if (!title.trim()) {
+			error = 'Titel fehlt.';
+			return;
+		}
+		busy = true;
+		error = null;
+		try {
+			const diff =
+				mode === 'remove'
+					? {
+							add: [],
+							modify: [],
+							remove: [{ contentHash: card.serverContentHash }],
+						}
+					: {
+							add: [],
+							modify: [
+								{
+									previousContentHash: card.serverContentHash,
+									type: card.type,
+									fields: editedFields,
+								},
+							],
+							remove: [],
+						};
+			await cardsApi.pullRequests.create(deckSlug, {
+				title: title.trim(),
+				body: body.trim() || undefined,
+				diff,
+			});
+			success = true;
+			onSubmitted?.();
+			setTimeout(() => onClose(), 1200);
+		} catch (e) {
+			error = e instanceof CardsApiError ? e.message : (e as Error).message;
+		} finally {
+			busy = false;
+		}
+	}
+</script>
+
+{#if open}
+	<div
+		class="fixed inset-0 z-50 flex items-center justify-center bg-black/70 px-4"
+		role="dialog"
+		aria-modal="true"
+	>
+		<div class="w-full max-w-xl rounded-xl border border-neutral-800 bg-neutral-950 p-6">
+			<header class="mb-4 flex items-center justify-between">
+				<h2 class="text-lg font-semibold">Verbesserung vorschlagen</h2>
+				<button
+					class="text-neutral-400 hover:text-neutral-100"
+					onclick={onClose}
+					aria-label="Schließen">✕</button
+				>
+			</header>
+
+			{#if success}
+				<p
+					class="rounded-lg border border-emerald-500/30 bg-emerald-500/10 p-3 text-sm text-emerald-300"
+				>
+					Pull Request gesendet — der Author wird benachrichtigt.
+				</p>
+			{:else}
+				<div class="mb-4 inline-flex rounded-lg border border-neutral-800 p-1">
+					<button
+						class="rounded px-3 py-1 text-xs"
+						class:bg-neutral-800={mode === 'modify'}
+						onclick={() => (mode = 'modify')}>Inhalt ändern</button
+					>
+					<button
+						class="rounded px-3 py-1 text-xs"
+						class:bg-neutral-800={mode === 'remove'}
+						onclick={() => (mode = 'remove')}>Karte entfernen</button
+					>
+				</div>
+
+				<label class="mb-3 block">
+					<span class="mb-1 block text-xs text-neutral-400">Titel</span>
+					<input
+						class="w-full rounded-lg border border-neutral-800 bg-neutral-900 px-3 py-2 text-sm"
+						bind:value={title}
+						placeholder="Kurzbeschreibung der Verbesserung"
+					/>
+				</label>
+
+				{#if mode === 'modify'}
+					<div class="mb-3 space-y-2">
+						{#each fieldKeys as key (key)}
+							<label class="block">
+								<span class="mb-1 block text-xs text-neutral-400">{key}</span>
+								<textarea
+									class="w-full rounded-lg border border-neutral-800 bg-neutral-900 px-3 py-2 text-sm"
+									rows="2"
+									bind:value={editedFields[key]}
+								></textarea>
+							</label>
+						{/each}
+					</div>
+				{:else}
+					<p
+						class="mb-3 rounded-lg border border-amber-500/30 bg-amber-500/10 p-3 text-sm text-amber-200"
+					>
+						Diese Karte wird beim Merge aus dem Deck entfernt.
+					</p>
+				{/if}
+
+				<label class="mb-4 block">
+					<span class="mb-1 block text-xs text-neutral-400">Begründung (optional)</span>
+					<textarea
+						class="w-full rounded-lg border border-neutral-800 bg-neutral-900 px-3 py-2 text-sm"
+						rows="3"
+						bind:value={body}
+						placeholder="Warum ist diese Änderung sinnvoll?"
+					></textarea>
+				</label>
+
+				{#if error}
+					<p class="mb-3 text-sm text-red-400">{error}</p>
+				{/if}
+
+				<div class="flex items-center justify-end gap-2">
+					<button
+						class="rounded-lg border border-neutral-800 px-4 py-2 text-sm hover:border-neutral-700"
+						onclick={onClose}
+						disabled={busy}>Abbrechen</button
+					>
+					<button
+						class="rounded-lg bg-indigo-500 px-4 py-2 text-sm text-white hover:bg-indigo-400 disabled:opacity-50"
+						onclick={submit}
+						disabled={busy || !hasChanges}
+					>
+						{busy ? 'Sende…' : 'PR senden'}
+					</button>
+				</div>
+			{/if}
+		</div>
+	</div>
+{/if}
diff --git a/apps/cards/apps/web/src/lib/queries.ts b/apps/cards/apps/web/src/lib/queries.ts
index acf2f4462..869f7ae45 100644
--- a/apps/cards/apps/web/src/lib/queries.ts
+++ b/apps/cards/apps/web/src/lib/queries.ts
@@ -39,6 +39,8 @@ export function toDeck(local: LocalDeck): Deck {
 		cardCount: local.cardCount,
 		createdAt: local.createdAt ?? new Date().toISOString(),
 		updatedAt: local.updatedAt ?? local.createdAt ?? new Date().toISOString(),
+		subscribedFromSlug: local.subscribedFromSlug,
+		subscribedAtVersion: local.subscribedAtVersion,
 	};
 }
 
@@ -70,6 +72,7 @@ export function toCard(local: LocalCard): Card {
 		order: local.order,
 		createdAt: local.createdAt ?? new Date().toISOString(),
 		updatedAt: local.updatedAt ?? local.createdAt ?? new Date().toISOString(),
+		serverContentHash: local.serverContentHash,
 	};
 }
 
diff --git a/apps/cards/apps/web/src/routes/d/[slug]/+page.svelte b/apps/cards/apps/web/src/routes/d/[slug]/+page.svelte
index 2de50f830..995d7a6a9 100644
--- a/apps/cards/apps/web/src/routes/d/[slug]/+page.svelte
+++ b/apps/cards/apps/web/src/routes/d/[slug]/+page.svelte
@@ -10,6 +10,7 @@
 	} from '$lib/api/cards-api';
 	import { isSubscribedLocally, subscribeAndPull, unsubscribe } from '$lib/services/subscribe';
 	import { cardDeckTable } from '$lib/data/database';
+	import PullRequestsSection from '$lib/components/PullRequestsSection.svelte';
 
 	const slug = $derived(page.params.slug as string);
 
@@ -202,6 +203,8 @@
 			<p class="mt-10 text-xs text-neutral-500">
 				Veröffentlicht: {new Date(deck.createdAt).toLocaleDateString('de-DE')}
 			</p>
+
+			<PullRequestsSection deckSlug={deck.slug} ownerUserId={deck.ownerUserId} onMerged={load} />
 		</article>
 	{/if}
 
diff --git a/apps/cards/apps/web/src/routes/learn/[deckId]/+page.svelte b/apps/cards/apps/web/src/routes/learn/[deckId]/+page.svelte
index 3d730a667..505b7af75 100644
--- a/apps/cards/apps/web/src/routes/learn/[deckId]/+page.svelte
+++ b/apps/cards/apps/web/src/routes/learn/[deckId]/+page.svelte
@@ -6,6 +6,7 @@
 	import { reviewStore } from '$lib/stores/reviews.svelte';
 	import { studyBlockStore } from '$lib/stores/study-blocks.svelte';
 	import CardFace from '$lib/components/CardFace.svelte';
+	import SuggestEditModal from '$lib/components/SuggestEditModal.svelte';
 	import type { Card, CardReview, ReviewGrade } from '@mana/cards-core';
 
 	const deckId = $derived(page.params.deckId as string);
@@ -22,6 +23,9 @@
 
 	const current = $derived(queue[currentIndex]);
 	const deckTitle = $derived($deckQuery?.title ?? 'Deck');
+	const subscribedSlug = $derived($deckQuery?.subscribedFromSlug);
+	const canSuggest = $derived(!!subscribedSlug && !!current?.card.serverContentHash);
+	let suggestOpen = $state(false);
 
 	$effect(() => {
 		const snap = $dueQuery;
@@ -135,6 +139,18 @@
 			onTypedAnswer={(v) => (typedAnswer = v)}
 		/>
 
+		{#if canSuggest}
+			<div class="mt-3 text-right">
+				<button
+					class="text-xs text-neutral-500 hover:text-indigo-300"
+					onclick={() => (suggestOpen = true)}
+					title="Verbesserung dieser Karte vorschlagen"
+				>
+					✏️ Verbessern
+				</button>
+			</div>
+		{/if}
+
 		{#if !showBack}
 			<button
 				class="mt-6 w-full rounded-lg bg-indigo-500 py-3 text-base text-white hover:bg-indigo-400"
@@ -178,3 +194,12 @@
 		<div class="text-center text-sm text-neutral-400">Lade…</div>
 	{/if}
 </div>
+
+{#if subscribedSlug && current}
+	<SuggestEditModal
+		card={current.card}
+		deckSlug={subscribedSlug}
+		open={suggestOpen}
+		onClose={() => (suggestOpen = false)}
+	/>
+{/if}
diff --git a/packages/cards-core/src/types.ts b/packages/cards-core/src/types.ts
index 6d29118f5..f686d8a46 100644
--- a/packages/cards-core/src/types.ts
+++ b/packages/cards-core/src/types.ts
@@ -128,6 +128,10 @@ export interface Deck {
 	cardCount: number;
 	createdAt: string;
 	updatedAt: string;
+	/** Marketplace slug if this deck was pulled from a subscription. */
+	subscribedFromSlug?: string;
+	/** Semver of the subscribed-from version that's currently local. */
+	subscribedAtVersion?: string;
 }
 
 export interface Card {
@@ -148,6 +152,13 @@ export interface Card {
 	nextReview?: string;
 	/** @deprecated legacy DTO field — read from cardReviews going forward. */
 	reviewCount?: number;
+
+	/**
+	 * For cards from a subscribed deck: the server's content-hash for
+	 * the card as it was published. The PR-creation flow uses this as
+	 * `previousContentHash` when proposing a "modify" diff.
+	 */
+	serverContentHash?: string;
 }
 
 export interface CardReview {
diff --git a/services/cards-server/src/index.ts b/services/cards-server/src/index.ts
index 72bd9f908..c76544372 100644
--- a/services/cards-server/src/index.ts
+++ b/services/cards-server/src/index.ts
@@ -21,11 +21,15 @@ import { DeckService } from './services/decks';
 import { ExploreService } from './services/explore';
 import { EngagementService } from './services/engagement';
 import { SubscriptionService } from './services/subscriptions';
+import { PullRequestService } from './services/pull-requests';
+import { DiscussionService } from './services/discussions';
 import { createAuthorRoutes } from './routes/authors';
 import { createDeckRoutes } from './routes/decks';
 import { createExploreRoutes } from './routes/explore';
 import { createEngagementRoutes } from './routes/engagement';
 import { createSubscriptionRoutes } from './routes/subscriptions';
+import { createPullRequestRoutes } from './routes/pull-requests';
+import { createDiscussionRoutes } from './routes/discussions';
 
 // ─── Bootstrap ──────────────────────────────────────────────
 
@@ -37,6 +41,8 @@ const deckService = new DeckService(db, config.manaLlmUrl);
 const exploreService = new ExploreService(db);
 const engagementService = new EngagementService(db);
 const subscriptionService = new SubscriptionService(db);
+const pullRequestService = new PullRequestService(db);
+const discussionService = new DiscussionService(db);
 
 // ─── App ────────────────────────────────────────────────────
 
@@ -77,6 +83,8 @@ v1.use('/*', optionalAuth(config.manaAuthUrl));
 v1.route('/', createExploreRoutes(exploreService));
 v1.route('/', createEngagementRoutes(engagementService));
 v1.route('/', createSubscriptionRoutes(subscriptionService));
+v1.route('/', createPullRequestRoutes(pullRequestService));
+v1.route('/', createDiscussionRoutes(discussionService));
 v1.route('/authors', createAuthorRoutes(authorService));
 v1.route('/decks', createDeckRoutes(authorService, deckService));
 
diff --git a/services/cards-server/src/routes/discussions.ts b/services/cards-server/src/routes/discussions.ts
new file mode 100644
index 000000000..8a663d548
--- /dev/null
+++ b/services/cards-server/src/routes/discussions.ts
@@ -0,0 +1,47 @@
+import { Hono } from 'hono';
+import { z } from 'zod';
+import type { AuthUser } from '../middleware/jwt-auth';
+import type { DiscussionService } from '../services/discussions';
+import { BadRequestError, UnauthorizedError } from '../lib/errors';
+
+function requireUser(user: AuthUser | undefined): AuthUser {
+	if (!user || !user.userId) throw new UnauthorizedError();
+	return user;
+}
+
+const postSchema = z.object({
+	deckSlug: z.string().min(1),
+	body: z.string().min(1).max(4000),
+	parentId: z.string().uuid().optional(),
+});
+
+export function createDiscussionRoutes(service: DiscussionService) {
+	const router = new Hono<{ Variables: { user?: AuthUser } }>();
+
+	router.get('/cards/:contentHash/discussions', async (c) => {
+		const list = await service.listForCard(c.req.param('contentHash'));
+		return c.json(list);
+	});
+
+	router.post('/cards/:contentHash/discussions', async (c) => {
+		const user = requireUser(c.get('user'));
+		const parsed = postSchema.safeParse(await c.req.json().catch(() => ({})));
+		if (!parsed.success) throw new BadRequestError('Invalid body', parsed.error.format());
+		const row = await service.post(
+			user.userId,
+			parsed.data.deckSlug,
+			c.req.param('contentHash'),
+			parsed.data.body,
+			parsed.data.parentId
+		);
+		return c.json(row, 201);
+	});
+
+	router.post('/discussions/:id/hide', async (c) => {
+		const user = requireUser(c.get('user'));
+		await service.hide(user.userId, c.req.param('id'));
+		return c.json({ ok: true });
+	});
+
+	return router;
+}
diff --git a/services/cards-server/src/routes/pull-requests.ts b/services/cards-server/src/routes/pull-requests.ts
new file mode 100644
index 000000000..943b0da3d
--- /dev/null
+++ b/services/cards-server/src/routes/pull-requests.ts
@@ -0,0 +1,99 @@
+import { Hono } from 'hono';
+import { z } from 'zod';
+import type { AuthUser } from '../middleware/jwt-auth';
+import type { PullRequestService } from '../services/pull-requests';
+import { BadRequestError, UnauthorizedError } from '../lib/errors';
+
+function requireUser(user: AuthUser | undefined): AuthUser {
+	if (!user || !user.userId) throw new UnauthorizedError();
+	return user;
+}
+
+const cardTypes = [
+	'basic',
+	'basic-reverse',
+	'cloze',
+	'type-in',
+	'image-occlusion',
+	'audio',
+	'multiple-choice',
+] as const;
+
+const cardPayloadSchema = z.object({
+	type: z.enum(cardTypes),
+	fields: z.record(z.string(), z.string()),
+});
+
+const createPrSchema = z.object({
+	title: z.string().min(1).max(140),
+	body: z.string().max(4000).optional(),
+	diff: z.object({
+		add: z.array(cardPayloadSchema).default([]),
+		modify: z
+			.array(
+				cardPayloadSchema.extend({
+					previousContentHash: z.string().min(1),
+				})
+			)
+			.default([]),
+		remove: z.array(z.object({ contentHash: z.string().min(1) })).default([]),
+	}),
+});
+
+const mergeSchema = z.object({
+	newSemver: z
+		.string()
+		.regex(/^\d+\.\d+\.\d+$/)
+		.optional(),
+	mergeNote: z.string().max(2000).optional(),
+});
+
+export function createPullRequestRoutes(service: PullRequestService) {
+	const router = new Hono<{ Variables: { user?: AuthUser } }>();
+
+	router.post('/decks/:slug/pull-requests', async (c) => {
+		const user = requireUser(c.get('user'));
+		const parsed = createPrSchema.safeParse(await c.req.json().catch(() => ({})));
+		if (!parsed.success) throw new BadRequestError('Invalid body', parsed.error.format());
+		const pr = await service.create(user.userId, c.req.param('slug'), parsed.data);
+		return c.json(pr, 201);
+	});
+
+	router.get('/decks/:slug/pull-requests', async (c) => {
+		const url = new URL(c.req.url);
+		const status = url.searchParams.get('status');
+		const valid = ['open', 'merged', 'closed', 'rejected'] as const;
+		const statusFilter = (valid as readonly string[]).includes(status ?? '')
+			? (status as (typeof valid)[number])
+			: undefined;
+		const list = await service.list(c.req.param('slug'), statusFilter);
+		return c.json(list);
+	});
+
+	router.get('/pull-requests/:id', async (c) => {
+		const pr = await service.get(c.req.param('id'));
+		return c.json(pr);
+	});
+
+	router.post('/pull-requests/:id/close', async (c) => {
+		const user = requireUser(c.get('user'));
+		await service.close(user.userId, c.req.param('id'));
+		return c.json({ ok: true });
+	});
+
+	router.post('/pull-requests/:id/reject', async (c) => {
+		const user = requireUser(c.get('user'));
+		await service.reject(user.userId, c.req.param('id'));
+		return c.json({ ok: true });
+	});
+
+	router.post('/pull-requests/:id/merge', async (c) => {
+		const user = requireUser(c.get('user'));
+		const parsed = mergeSchema.safeParse(await c.req.json().catch(() => ({})));
+		if (!parsed.success) throw new BadRequestError('Invalid body', parsed.error.format());
+		const result = await service.merge(user.userId, c.req.param('id'), parsed.data);
+		return c.json(result, 201);
+	});
+
+	return router;
+}
diff --git a/services/cards-server/src/services/discussions.ts b/services/cards-server/src/services/discussions.ts
new file mode 100644
index 000000000..2c4ad2a32
--- /dev/null
+++ b/services/cards-server/src/services/discussions.ts
@@ -0,0 +1,84 @@
+/**
+ * Card discussions — lightweight inline threads keyed by
+ * `card_content_hash` (not card-id) so a thread survives across
+ * version bumps as long as the card content stays.
+ *
+ * Threads are flat-with-parent: every reply has `parent_id` →
+ * something else in the same `card_content_hash` group. The UI
+ * renders a one-level-deep tree (Reddit-style with a max depth) —
+ * if we want full nesting later it's already there.
+ */
+
+import { and, asc, eq } from 'drizzle-orm';
+import type { Database } from '../db/connection';
+import { cardDiscussions, publicDecks } from '../db/schema';
+import { ForbiddenError, NotFoundError } from '../lib/errors';
+
+export class DiscussionService {
+	constructor(private readonly db: Database) {}
+
+	async post(
+		userId: string,
+		deckSlug: string,
+		cardContentHash: string,
+		body: string,
+		parentId?: string
+	) {
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.slug, deckSlug),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+
+		if (parentId) {
+			const parent = await this.db.query.cardDiscussions.findFirst({
+				where: eq(cardDiscussions.id, parentId),
+			});
+			if (!parent) throw new NotFoundError('Parent comment not found');
+			if (parent.cardContentHash !== cardContentHash) {
+				throw new ForbiddenError('Parent comment is on a different card');
+			}
+		}
+
+		const [row] = await this.db
+			.insert(cardDiscussions)
+			.values({
+				cardContentHash,
+				deckId: deck.id,
+				authorUserId: userId,
+				parentId: parentId ?? null,
+				body,
+			})
+			.returning();
+		return row;
+	}
+
+	async listForCard(cardContentHash: string) {
+		const rows = await this.db
+			.select()
+			.from(cardDiscussions)
+			.where(
+				and(eq(cardDiscussions.cardContentHash, cardContentHash), eq(cardDiscussions.hidden, false))
+			)
+			.orderBy(asc(cardDiscussions.createdAt));
+		return rows;
+	}
+
+	async hide(actorUserId: string, discussionId: string) {
+		const row = await this.db.query.cardDiscussions.findFirst({
+			where: eq(cardDiscussions.id, discussionId),
+		});
+		if (!row) throw new NotFoundError('Discussion not found');
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.id, row.deckId),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+		// Author of the comment OR deck owner can hide.
+		if (row.authorUserId !== actorUserId && deck.ownerUserId !== actorUserId) {
+			throw new ForbiddenError('Not allowed to hide this comment');
+		}
+		await this.db
+			.update(cardDiscussions)
+			.set({ hidden: true })
+			.where(eq(cardDiscussions.id, discussionId));
+	}
+}
diff --git a/services/cards-server/src/services/pull-requests.ts b/services/cards-server/src/services/pull-requests.ts
new file mode 100644
index 000000000..dcffc7cf4
--- /dev/null
+++ b/services/cards-server/src/services/pull-requests.ts
@@ -0,0 +1,263 @@
+/**
+ * Pull-requests on decks. The differentiator vs. Anki/Quizlet/etc.:
+ * subscribers can submit a card-level patch, the deck author reviews
+ * + merges, and the merge auto-creates a new version that ripples
+ * through every other subscriber's smart-merge.
+ *
+ * The diff payload mirrors GitHub's three-way model in the small:
+ *   - add:    cards to insert (server picks the next ord)
+ *   - modify: replace existing cards by previous-content-hash
+ *   - remove: drop cards by content-hash
+ *
+ * Status lifecycle:
+ *   open ──merge──► merged   (creates a new deck_version)
+ *   open ──close──► closed   (author OR PR-author can close)
+ *   open ──reject─► rejected (author-only — distinct from "closed"
+ *                             so the PR-author sees clear feedback)
+ *
+ * Merging bumps the deck's semver minor by default (1.2.0 → 1.3.0)
+ * unless the request specifies otherwise. Author can override at
+ * merge-time.
+ */
+
+import { and, desc, eq } from 'drizzle-orm';
+import type { Database } from '../db/connection';
+import { deckPullRequests, publicDeckCards, publicDeckVersions, publicDecks } from '../db/schema';
+import { hashCard, hashVersionCards } from '../lib/hash';
+import { BadRequestError, ForbiddenError, NotFoundError } from '../lib/errors';
+
+export interface PullRequestDiffInput {
+	add: { type: string; fields: Record<string, string> }[];
+	modify: { previousContentHash: string; type: string; fields: Record<string, string> }[];
+	remove: { contentHash: string }[];
+}
+
+export interface CreatePullRequestInput {
+	title: string;
+	body?: string;
+	diff: PullRequestDiffInput;
+}
+
+const SEMVER_RE = /^(\d+)\.(\d+)\.(\d+)$/;
+
+function bumpMinor(semver: string): string {
+	const m = semver.match(SEMVER_RE);
+	if (!m) return '1.0.0';
+	return `${m[1]}.${Number(m[2]) + 1}.0`;
+}
+
+export class PullRequestService {
+	constructor(private readonly db: Database) {}
+
+	async create(authorUserId: string, deckSlug: string, input: CreatePullRequestInput) {
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.slug, deckSlug),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+		if (deck.isTakedown) throw new ForbiddenError('Deck under takedown');
+
+		const total = input.diff.add.length + input.diff.modify.length + input.diff.remove.length;
+		if (total === 0) throw new BadRequestError('Diff is empty');
+
+		const [pr] = await this.db
+			.insert(deckPullRequests)
+			.values({
+				deckId: deck.id,
+				authorUserId,
+				title: input.title,
+				body: input.body,
+				status: 'open',
+				diff: {
+					add: input.diff.add,
+					modify: input.diff.modify.map((m) => ({
+						contentHash: m.previousContentHash,
+						fields: m.fields,
+					})),
+					remove: input.diff.remove,
+				},
+			})
+			.returning();
+		return pr;
+	}
+
+	async list(deckSlug: string, status?: 'open' | 'merged' | 'closed' | 'rejected') {
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.slug, deckSlug),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+
+		const where = status
+			? and(eq(deckPullRequests.deckId, deck.id), eq(deckPullRequests.status, status))
+			: eq(deckPullRequests.deckId, deck.id);
+		return this.db
+			.select()
+			.from(deckPullRequests)
+			.where(where)
+			.orderBy(desc(deckPullRequests.createdAt));
+	}
+
+	async get(prId: string) {
+		const pr = await this.db.query.deckPullRequests.findFirst({
+			where: eq(deckPullRequests.id, prId),
+		});
+		if (!pr) throw new NotFoundError('Pull request not found');
+		return pr;
+	}
+
+	async close(actorUserId: string, prId: string): Promise<void> {
+		const pr = await this.get(prId);
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.id, pr.deckId),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+		// Either the deck owner or the PR author can close.
+		if (pr.authorUserId !== actorUserId && deck.ownerUserId !== actorUserId) {
+			throw new ForbiddenError('Only PR author or deck owner can close');
+		}
+		if (pr.status !== 'open') throw new BadRequestError(`PR already ${pr.status}`);
+		await this.db
+			.update(deckPullRequests)
+			.set({ status: 'closed', resolvedAt: new Date() })
+			.where(eq(deckPullRequests.id, prId));
+	}
+
+	async reject(actorUserId: string, prId: string): Promise<void> {
+		const pr = await this.get(prId);
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.id, pr.deckId),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+		if (deck.ownerUserId !== actorUserId) {
+			throw new ForbiddenError('Only the deck owner can reject');
+		}
+		if (pr.status !== 'open') throw new BadRequestError(`PR already ${pr.status}`);
+		await this.db
+			.update(deckPullRequests)
+			.set({ status: 'rejected', resolvedAt: new Date() })
+			.where(eq(deckPullRequests.id, prId));
+	}
+
+	/**
+	 * Merge a PR. Builds a brand-new version's card list by applying
+	 * the PR's diff to the deck's latest version, then writes the
+	 * usual version + cards rows and bumps `latest_version_id`.
+	 *
+	 * The merge happens in a single transaction so a partial failure
+	 * doesn't leave the deck pointing at an empty version.
+	 */
+	async merge(
+		actorUserId: string,
+		prId: string,
+		opts: { newSemver?: string; mergeNote?: string } = {}
+	) {
+		const pr = await this.get(prId);
+		if (pr.status !== 'open') throw new BadRequestError(`PR already ${pr.status}`);
+
+		const deck = await this.db.query.publicDecks.findFirst({
+			where: eq(publicDecks.id, pr.deckId),
+		});
+		if (!deck) throw new NotFoundError('Deck not found');
+		if (deck.ownerUserId !== actorUserId) {
+			throw new ForbiddenError('Only the deck owner can merge');
+		}
+		if (!deck.latestVersionId) {
+			throw new BadRequestError('Deck has no published version yet — publish first');
+		}
+		const latest = await this.db.query.publicDeckVersions.findFirst({
+			where: eq(publicDeckVersions.id, deck.latestVersionId),
+		});
+		if (!latest) throw new NotFoundError('Latest version row missing');
+
+		const newSemver = opts.newSemver ?? bumpMinor(latest.semver);
+		if (!SEMVER_RE.test(newSemver)) {
+			throw new BadRequestError(`Invalid semver: ${newSemver}`);
+		}
+
+		// Pull current cards as the base for the merge.
+		const currentCards = await this.db
+			.select()
+			.from(publicDeckCards)
+			.where(eq(publicDeckCards.versionId, latest.id))
+			.orderBy(publicDeckCards.ord);
+
+		const diff = pr.diff as {
+			add: { type: string; fields: Record<string, string> }[];
+			modify: { contentHash: string; fields: Record<string, string> }[];
+			remove: { contentHash: string }[];
+		};
+
+		const removedHashes = new Set(diff.remove.map((r) => r.contentHash));
+		const modifyByHash = new Map(diff.modify.map((m) => [m.contentHash, m.fields]));
+
+		const merged: { type: string; fields: Record<string, string>; ord: number }[] = [];
+		let nextOrd = 0;
+		for (const c of currentCards) {
+			if (removedHashes.has(c.contentHash)) continue;
+			const replaced = modifyByHash.get(c.contentHash);
+			merged.push({
+				type: c.type,
+				fields: replaced ?? (c.fields as Record<string, string>),
+				ord: nextOrd++,
+			});
+		}
+		for (const a of diff.add) {
+			merged.push({ type: a.type, fields: a.fields, ord: nextOrd++ });
+		}
+
+		if (merged.length === 0) {
+			throw new BadRequestError('Merge would result in an empty deck — refusing');
+		}
+
+		const versionContentHash = hashVersionCards(merged);
+
+		const result = await this.db.transaction(async (tx) => {
+			const [version] = await tx
+				.insert(publicDeckVersions)
+				.values({
+					deckId: deck.id,
+					semver: newSemver,
+					changelog:
+						opts.mergeNote ??
+						`Merged PR: ${pr.title} (+${diff.add.length} added, ~${diff.modify.length} modified, −${diff.remove.length} removed)`,
+					contentHash: versionContentHash,
+					cardCount: merged.length,
+				})
+				.returning();
+
+			await tx.insert(publicDeckCards).values(
+				merged.map((c) => ({
+					versionId: version.id,
+					type: c.type as
+						| 'basic'
+						| 'basic-reverse'
+						| 'cloze'
+						| 'type-in'
+						| 'image-occlusion'
+						| 'audio'
+						| 'multiple-choice',
+					fields: c.fields,
+					ord: c.ord,
+					contentHash: hashCard({ type: c.type, fields: c.fields }),
+				}))
+			);
+
+			await tx
+				.update(publicDecks)
+				.set({ latestVersionId: version.id })
+				.where(eq(publicDecks.id, deck.id));
+
+			await tx
+				.update(deckPullRequests)
+				.set({
+					status: 'merged',
+					mergedIntoVersionId: version.id,
+					resolvedAt: new Date(),
+				})
+				.where(eq(deckPullRequests.id, prId));
+
+			return { version };
+		});
+
+		return { pullRequest: { ...pr, status: 'merged' as const }, version: result.version };
+	}
+}