diff --git a/packages/tourmaline/src/lib/analysis/aggregator.ts b/packages/tourmaline/src/lib/analysis/aggregator.ts
index 1729781..a14e6bf 100644
--- a/packages/tourmaline/src/lib/analysis/aggregator.ts
+++ b/packages/tourmaline/src/lib/analysis/aggregator.ts
@@ -34,6 +34,8 @@ export interface AggregatedData {
   trackTimestamps: Map<string, number[]>;
   /** artist → count of distinct ISO weeks played in. */
   artistWeeksActive: Map<string, number>;
+  /** artist → count of distinct tracks played. */
+  artistTrackCounts: Map<string, number>;
   // ── Derived stats computed in snapshot() ──────────────────────────────
   eddingtonNumber: number;
   /** How many more days at eddingtonNumber+1 scrobbles are needed to advance. */
@@ -439,6 +441,9 @@ export class Aggregator {
       artistWeeksActive: new Map(
         [...this.artistWeeks.entries()].map(([name, weeks]) => [name, weeks.size]),
       ),
+      artistTrackCounts: new Map(
+        [...this.artistTracks.entries()].map(([name, tracks]) => [name, tracks.size]),
+      ),
       eddingtonNumber,
       daysToNextEddington: daysToNextEddingtonNumber,
       artistCutoverPoint,
diff --git a/packages/tourmaline/src/lib/client/load-profile.ts b/packages/tourmaline/src/lib/client/load-profile.ts
index 31b3d0c..9c57fb8 100644
--- a/packages/tourmaline/src/lib/client/load-profile.ts
+++ b/packages/tourmaline/src/lib/client/load-profile.ts
@@ -137,6 +137,15 @@ export function computeProfile(
     return { name, artist, gapDays: g.gapDays, count: g.count };
   });
 
+  const topArtistsByTrackCount = [...data.artistTrackCounts.entries()]
+    .map(([name, trackCount]) => ({
+      name,
+      trackCount,
+      count: data.artistPlayCounts.get(name) ?? 0,
+    }))
+    .sort((a, b) => b.trackCount - a.trackCount)
+    .slice(0, 10);
+
   const profile: ListenerProfile = {
     did,
     handle,
@@ -183,6 +192,7 @@ export function computeProfile(
     topArtistsByWeeksActive,
     topArtistGaps,
     topTrackGaps,
+    topArtistsByTrackCount,
     scrobbleMilestones: data.scrobbleMilestones,
     artistMilestones: data.artistMilestones,
     trackMilestones: data.trackMilestones,
diff --git a/packages/tourmaline/src/lib/types.ts b/packages/tourmaline/src/lib/types.ts
index 0786576..33675ab 100644
--- a/packages/tourmaline/src/lib/types.ts
+++ b/packages/tourmaline/src/lib/types.ts
@@ -136,6 +136,8 @@ export interface ListenerProfile {
   /** Top 10 artists/tracks by longest gap between two consecutive listens (min 5 plays). */
   topArtistGaps: Array<{ name: string; gapDays: number; count: number }>;
   topTrackGaps: Array<{ name: string; artist: string; gapDays: number; count: number }>;
+  /** Top 10 artists by distinct tracks played — breadth within one artist's catalogue. */
+  topArtistsByTrackCount: Array<{ name: string; trackCount: number; count: number }>;
   /** Per-month most statistically unusual artist (highest z-score). */
   unusualMonths: UnusualMonth[];
   // ── Ported from lastfm-stats-web ─────────────────────────────────────
diff --git a/packages/tourmaline/src/routes/profile/[did]/+page.svelte b/packages/tourmaline/src/routes/profile/[did]/+page.svelte
index f227c49..1231543 100644
--- a/packages/tourmaline/src/routes/profile/[did]/+page.svelte
+++ b/packages/tourmaline/src/routes/profile/[did]/+page.svelte
@@ -35,6 +35,7 @@
 	import WeeksActive from './WeeksActive.svelte';
 	import ListeningCadence from './ListeningCadence.svelte';
 	import BiggestGaps from './BiggestGaps.svelte';
+	import CatalogueDepth from './CatalogueDepth.svelte';
 	import DateRangePicker from './DateRangePicker.svelte';
 	import ListeningPhases from './ListeningPhases.svelte';
 	import StoryRecap from './StoryRecap.svelte';
@@ -535,6 +536,7 @@
 			<WeeksActive artists={profile.topArtistsByWeeksActive} />
 			<ListeningCadence artists={profile.topArtistAvgDeltas} />
 			<BiggestGaps artistGaps={profile.topArtistGaps} trackGaps={profile.topTrackGaps} />
+			<CatalogueDepth artists={profile.topArtistsByTrackCount} />
 
 			<!-- Top tracks + albums side by side -->
 			<div class="mb-6 grid gap-4 sm:mb-8 sm:gap-8 lg:grid-cols-2">
diff --git a/packages/tourmaline/src/routes/profile/[did]/CatalogueDepth.svelte b/packages/tourmaline/src/routes/profile/[did]/CatalogueDepth.svelte
new file mode 100644
index 0000000..102c7c6
--- /dev/null
+++ b/packages/tourmaline/src/routes/profile/[did]/CatalogueDepth.svelte
@@ -0,0 +1,28 @@
+<script lang="ts">
+	import { Library } from '@lucide/svelte';
+
+	let { artists }: { artists: Array<{ name: string; trackCount: number; count: number }> } = $props();
+</script>
+
+{#if artists.length > 0}
+	<div class="mb-6 overflow-hidden rounded border border-[var(--border)] bg-[var(--surface)] p-3 sm:mb-8 sm:p-4">
+		<div class="mb-3 flex items-start justify-between gap-4 sm:mb-4">
+			<div>
+				<h2 class="text-base font-semibold sm:text-lg">Deepest Catalogues</h2>
+				<p class="text-xs text-[var(--text-dim)]">Artists you've explored the most distinct tracks from</p>
+			</div>
+			<div class="shrink-0 text-[var(--accent)]">
+				<Library size={18} />
+			</div>
+		</div>
+		<ol class="space-y-2">
+			{#each artists as artist, i (artist.name)}
+				<li class="flex items-center gap-2 overflow-hidden sm:gap-3">
+					<span class="w-5 shrink-0 text-right text-xs text-[var(--text-muted)] sm:w-6 sm:text-sm">{i + 1}</span>
+					<span class="min-w-0 shrink truncate">{artist.name}</span>
+					<span class="shrink-0 font-mono text-xs text-[var(--text-muted)] sm:text-sm">{artist.trackCount} tracks</span>
+				</li>
+			{/each}
+		</ol>
+	</div>
+{/if}
diff --git a/packages/tourmaline/src/routes/profile/[did]/CatalogueTab.svelte b/packages/tourmaline/src/routes/profile/[did]/CatalogueTab.svelte
index 94bbe9c..4d4d9e1 100644
--- a/packages/tourmaline/src/routes/profile/[did]/CatalogueTab.svelte
+++ b/packages/tourmaline/src/routes/profile/[did]/CatalogueTab.svelte
@@ -6,6 +6,7 @@
     import WeeksActive from './WeeksActive.svelte';
     import ListeningCadence from './ListeningCadence.svelte';
     import BiggestGaps from './BiggestGaps.svelte';
+    import CatalogueDepth from './CatalogueDepth.svelte';
     import type { ListenerProfile } from '$lib/types';
     import type { OnThisDayEntry } from '$lib/analysis/on-this-day';
 
@@ -84,6 +85,7 @@
 <WeeksActive artists={profile.topArtistsByWeeksActive} />
 <ListeningCadence artists={profile.topArtistAvgDeltas} />
 <BiggestGaps artistGaps={profile.topArtistGaps} trackGaps={profile.topTrackGaps} />
+<CatalogueDepth artists={profile.topArtistsByTrackCount} />
 
 {#if profile.discoveredArtists.length > 0 || profile.discoveredTracks.length > 0 || profile.discoveredAlbums.length > 0}
     <div class="mb-6 sm:mb-8">