diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 11bfd88..9173a19 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -1,20 +1,20 @@
 version: 2
 updates:
-  - package-ecosystem: "npm"
-    directory: "/"
+  - package-ecosystem: 'npm'
+    directory: '/'
     schedule:
-      interval: "weekly"
+      interval: 'weekly'
     open-pull-requests-limit: 10
     groups:
       dependencies:
         patterns:
-          - "*"
+          - '*'
         update-types:
-          - "minor"
-          - "patch"
+          - 'minor'
+          - 'patch'
     ignore:
-      - dependency-name: "*"
-        update-types: ["version-update:semver-major"]
+      - dependency-name: '*'
+        update-types: ['version-update:semver-major']
     labels:
-      - "dependencies"
-      - "security"
+      - 'dependencies'
+      - 'security'
diff --git a/src/app/c/[slug]/page.tsx b/src/app/c/[slug]/page.tsx
index 0ab3b0f..f4a2de3 100644
--- a/src/app/c/[slug]/page.tsx
+++ b/src/app/c/[slug]/page.tsx
@@ -2,12 +2,20 @@
  * Category page - Shows topics for a specific category.
  * URL: /c/{slug}
  * Server-side rendered with SEO metadata and JSON-LD.
+ * Maturity-aware: Adult categories are noindex'd, Mature get rating meta.
  * @see specs/prd-web.md Section 3.1
  */
 
 import type { Metadata } from 'next'
 import { notFound } from 'next/navigation'
-import { getCategoryBySlug, getCategories, getTopics, ApiError } from '@/lib/api/client'
+import {
+  getCategoryBySlug,
+  getCategories,
+  getTopics,
+  getPublicSettings,
+  ApiError,
+} from '@/lib/api/client'
+import { getEffectiveMaturity, getMaturityMeta, shouldIncludeOgTags } from '@/lib/seo'
 
 export const dynamic = 'force-dynamic'
 import { ForumLayout } from '@/components/layout/forum-layout'
@@ -24,18 +32,32 @@ interface CategoryPageProps {
 export async function generateMetadata({ params }: CategoryPageProps): Promise<Metadata> {
   const { slug } = await params
   try {
-    const category = await getCategoryBySlug(slug)
+    const [category, publicSettings] = await Promise.all([
+      getCategoryBySlug(slug),
+      getPublicSettings().catch(() => null),
+    ])
+
+    const communityRating = publicSettings?.maturityRating ?? 'safe'
+    const effectiveMaturity = getEffectiveMaturity(communityRating, category.maturityRating)
+    const maturityMeta = getMaturityMeta(effectiveMaturity)
+    const includeOg = shouldIncludeOgTags(effectiveMaturity)
+
     return {
       title: category.name,
       description: category.description ?? `Topics in ${category.name}`,
       alternates: {
         canonical: `/c/${slug}`,
       },
-      openGraph: {
-        title: category.name,
-        description: category.description ?? `Topics in ${category.name}`,
-        type: 'website',
-      },
+      ...(includeOg
+        ? {
+            openGraph: {
+              title: category.name,
+              description: category.description ?? `Topics in ${category.name}`,
+              type: 'website',
+            },
+          }
+        : {}),
+      ...maturityMeta,
     }
   } catch {
     return { title: 'Category Not Found' }
diff --git a/src/app/robots.ts b/src/app/robots.ts
index 47d4ce1..f80a675 100644
--- a/src/app/robots.ts
+++ b/src/app/robots.ts
@@ -18,7 +18,7 @@ export default function robots(): MetadataRoute.Robots {
         disallow: ['/admin/', '/auth/', '/api/', '/search', '/settings', '/notifications'],
       },
       {
-        userAgent: ['SemrushBot', 'AhrefsBot', 'MJ12bot'],
+        userAgent: ['SemrushBot', 'AhrefsBot', 'MJ12bot', 'BLEXBot'],
         disallow: '/',
       },
       {
diff --git a/src/app/sitemap.test.ts b/src/app/sitemap.test.ts
index dbdadc7..63ecbb2 100644
--- a/src/app/sitemap.test.ts
+++ b/src/app/sitemap.test.ts
@@ -67,6 +67,7 @@ beforeEach(() => {
         cid: 'bafyabc',
         replyCount: 5,
         reactionCount: 3,
+        categoryMaturityRating: 'safe' as const,
         lastActivityAt: '2025-06-15T12:00:00Z',
         createdAt: '2025-06-01T00:00:00Z',
         indexedAt: '2025-06-01T00:00:00Z',
@@ -84,6 +85,7 @@ beforeEach(() => {
         cid: 'bafydef',
         replyCount: 0,
         reactionCount: 1,
+        categoryMaturityRating: 'safe' as const,
         lastActivityAt: '2025-06-10T08:00:00Z',
         createdAt: '2025-06-10T00:00:00Z',
         indexedAt: '2025-06-10T00:00:00Z',
@@ -161,4 +163,115 @@ describe('sitemap', () => {
     expect(result.length).toBeGreaterThanOrEqual(1)
     expect(result[0].url).toBe('https://barazo.forum')
   })
+
+  it('excludes adult-rated categories from sitemap', async () => {
+    mockGetCategories.mockResolvedValue({
+      categories: [
+        {
+          id: '1',
+          slug: 'general',
+          name: 'General',
+          description: null,
+          parentId: null,
+          sortOrder: 0,
+          communityDid: 'did:plc:test',
+          maturityRating: 'safe' as const,
+          createdAt: '2025-01-01T00:00:00Z',
+          updatedAt: '2025-06-01T00:00:00Z',
+          children: [],
+        },
+        {
+          id: '3',
+          slug: 'adult-zone',
+          name: 'Adult Zone',
+          description: null,
+          parentId: null,
+          sortOrder: 1,
+          communityDid: 'did:plc:test',
+          maturityRating: 'adult' as const,
+          createdAt: '2025-01-01T00:00:00Z',
+          updatedAt: '2025-06-01T00:00:00Z',
+          children: [],
+        },
+      ],
+    })
+
+    const result = await sitemap()
+    const urls = result.map((entry) => entry.url)
+    expect(urls).toContain('https://barazo.forum/c/general')
+    expect(urls).not.toContain('https://barazo.forum/c/adult-zone')
+  })
+
+  it('excludes topics with adult categoryMaturityRating from sitemap', async () => {
+    mockGetTopics.mockResolvedValue({
+      topics: [
+        {
+          uri: 'at://did:plc:test/forum.barazo.topic/safe1',
+          rkey: 'safe1',
+          authorDid: 'did:plc:author1',
+          title: 'Safe Topic',
+          content: 'Safe content',
+          contentFormat: null,
+          category: 'general',
+          tags: null,
+          communityDid: 'did:plc:test',
+          cid: 'bafysafe',
+          replyCount: 0,
+          reactionCount: 0,
+          categoryMaturityRating: 'safe' as const,
+          lastActivityAt: '2025-06-15T12:00:00Z',
+          createdAt: '2025-06-01T00:00:00Z',
+          indexedAt: '2025-06-01T00:00:00Z',
+        },
+        {
+          uri: 'at://did:plc:test/forum.barazo.topic/adult1',
+          rkey: 'adult1',
+          authorDid: 'did:plc:author2',
+          title: 'Adult Topic',
+          content: 'Adult content',
+          contentFormat: null,
+          category: 'adult-zone',
+          tags: null,
+          communityDid: 'did:plc:test',
+          cid: 'bafyadult',
+          replyCount: 0,
+          reactionCount: 0,
+          categoryMaturityRating: 'adult' as const,
+          lastActivityAt: '2025-06-10T08:00:00Z',
+          createdAt: '2025-06-10T00:00:00Z',
+          indexedAt: '2025-06-10T00:00:00Z',
+        },
+      ],
+      cursor: null,
+    })
+
+    const result = await sitemap()
+    const urls = result.map((entry) => entry.url)
+    expect(urls).toContain('https://barazo.forum/t/safe-topic/safe1')
+    expect(urls).not.toContain('https://barazo.forum/t/adult-topic/adult1')
+  })
+
+  it('includes mature-rated categories in sitemap', async () => {
+    mockGetCategories.mockResolvedValue({
+      categories: [
+        {
+          id: '1',
+          slug: 'mature-zone',
+          name: 'Mature Zone',
+          description: null,
+          parentId: null,
+          sortOrder: 0,
+          communityDid: 'did:plc:test',
+          maturityRating: 'mature' as const,
+          createdAt: '2025-01-01T00:00:00Z',
+          updatedAt: '2025-06-01T00:00:00Z',
+          children: [],
+        },
+      ],
+    })
+
+    const result = await sitemap()
+    const urls = result.map((entry) => entry.url)
+    expect(urls).toContain('https://barazo.forum/c/mature-zone')
+  })
 })
diff --git a/src/app/sitemap.ts b/src/app/sitemap.ts
index 6539edf..05cb431 100644
--- a/src/app/sitemap.ts
+++ b/src/app/sitemap.ts
@@ -1,6 +1,7 @@
 /**
  * Dynamic sitemap generation.
  * Includes homepage, categories (flattened tree), and topics.
+ * Excludes Adult-rated categories and their topics.
  * @see specs/prd-web.md Section 5 (Sitemaps)
  */
 
@@ -38,10 +39,11 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     getTopics({ limit: 1000, sort: 'latest' }).catch(() => null),
   ])
 
-  // Add category pages
+  // Add category pages (exclude Adult-rated)
   if (categoriesResult) {
     const allCategories = flattenCategories(categoriesResult.categories)
     for (const category of allCategories) {
+      if (category.maturityRating === 'adult') continue
       entries.push({
         url: `${SITE_URL}/c/${category.slug}`,
         lastModified: new Date(category.updatedAt),
@@ -51,9 +53,10 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     }
   }
 
-  // Add topic pages
+  // Add topic pages (exclude Adult-rated)
   if (topicsResult) {
     for (const topic of topicsResult.topics) {
+      if (topic.categoryMaturityRating === 'adult') continue
       entries.push({
         url: `${SITE_URL}/t/${slugify(topic.title)}/${topic.rkey}`,
         lastModified: new Date(topic.lastActivityAt),
diff --git a/src/app/t/[slug]/[rkey]/page.tsx b/src/app/t/[slug]/[rkey]/page.tsx
index e41da70..201df6f 100644
--- a/src/app/t/[slug]/[rkey]/page.tsx
+++ b/src/app/t/[slug]/[rkey]/page.tsx
@@ -2,13 +2,26 @@
  * Topic detail page - Shows topic post and threaded replies.
  * URL: /t/{slug}/{rkey}
  * Server-side rendered with JSON-LD DiscussionForumPosting.
+ * Maturity-aware: Adult topics are noindex'd, Mature topics get rating meta.
  * @see specs/prd-web.md Section 3.1, Section 5
  */
 
 import type { Metadata } from 'next'
 import { notFound } from 'next/navigation'
-import { getTopicByRkey, getCategories, getReplies, ApiError } from '@/lib/api/client'
+import {
+  getTopicByRkey,
+  getCategories,
+  getReplies,
+  getPublicSettings,
+  ApiError,
+} from '@/lib/api/client'
 import { slugify } from '@/lib/format'
+import {
+  getEffectiveMaturity,
+  getMaturityMeta,
+  shouldIncludeJsonLd,
+  shouldIncludeOgTags,
+} from '@/lib/seo'
 import { ForumLayout } from '@/components/layout/forum-layout'
 import { CategoryNav } from '@/components/category-nav'
 import { Breadcrumbs } from '@/components/breadcrumbs'
@@ -26,21 +39,35 @@ interface TopicPageProps {
 export async function generateMetadata({ params }: TopicPageProps): Promise<Metadata> {
   const { rkey } = await params
   try {
-    const topic = await getTopicByRkey(rkey)
+    const [topic, publicSettings] = await Promise.all([
+      getTopicByRkey(rkey),
+      getPublicSettings().catch(() => null),
+    ])
     const description =
       topic.content.length > 160 ? topic.content.slice(0, 157) + '...' : topic.content
+
+    const communityRating = publicSettings?.maturityRating ?? 'safe'
+    const effectiveMaturity = getEffectiveMaturity(communityRating, topic.categoryMaturityRating)
+    const maturityMeta = getMaturityMeta(effectiveMaturity)
+    const includeOg = shouldIncludeOgTags(effectiveMaturity)
+
     return {
       title: topic.title,
       description,
       alternates: {
         canonical: `/t/${slugify(topic.title)}/${rkey}`,
       },
-      openGraph: {
-        title: topic.title,
-        description,
-        type: 'article',
-        publishedTime: topic.createdAt,
-      },
+      ...(includeOg
+        ? {
+            openGraph: {
+              title: topic.title,
+              description,
+              type: 'article',
+              publishedTime: topic.createdAt,
+            },
+          }
+        : {}),
+      ...maturityMeta,
     }
   } catch {
     return { title: 'Topic Not Found' }
@@ -62,6 +89,11 @@ export default async function TopicPage({ params }: TopicPageProps) {
     throw error
   }
 
+  // Fetch community settings for maturity context
+  const publicSettings = await getPublicSettings().catch(() => null)
+  const communityRating = publicSettings?.maturityRating ?? 'safe'
+  const effectiveMaturity = getEffectiveMaturity(communityRating, topic.categoryMaturityRating)
+
   let categoriesResult: CategoriesResponse = { categories: [] }
   let repliesResult: RepliesResponse = { replies: [], cursor: null }
 
@@ -124,11 +156,13 @@ export default async function TopicPage({ params }: TopicPageProps) {
         ) : undefined
       }
     >
-      {/* JSON-LD */}
-      <script
-        type="application/ld+json"
-        dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
-      />
+      {/* JSON-LD: omitted for Adult content */}
+      {shouldIncludeJsonLd(effectiveMaturity) && (
+        <script
+          type="application/ld+json"
+          dangerouslySetInnerHTML={{ __html: JSON.stringify(jsonLd) }}
+        />
+      )}
 
       {/* Breadcrumbs */}
       <Breadcrumbs items={breadcrumbItems} />
diff --git a/src/lib/api/client.ts b/src/lib/api/client.ts
index 52349d5..9c41d89 100644
--- a/src/lib/api/client.ts
+++ b/src/lib/api/client.ts
@@ -12,6 +12,7 @@ import type {
   CommunitySettings,
   CommunityStats,
   CreateTopicInput,
+  PublicSettings,
   Topic,
   TopicsResponse,
   UpdatePreferencesInput,
@@ -234,6 +235,10 @@ export function getCommunitySettings(options?: FetchOptions): Promise<CommunityS
   })
 }
 
+export function getPublicSettings(options?: FetchOptions): Promise<PublicSettings> {
+  return apiFetch<PublicSettings>('/api/settings/public', options)
+}
+
 export function getCommunityStats(
   accessToken: string,
   options?: FetchOptions
diff --git a/src/lib/api/types.ts b/src/lib/api/types.ts
index 29f3bd0..c54dcdd 100644
--- a/src/lib/api/types.ts
+++ b/src/lib/api/types.ts
@@ -46,6 +46,7 @@ export interface Topic {
   cid: string
   replyCount: number
   reactionCount: number
+  categoryMaturityRating: MaturityRating
   lastActivityAt: string
   createdAt: string
   indexedAt: string
@@ -163,6 +164,13 @@ export interface CommunitySettings {
   updatedAt: string
 }
 
+export interface PublicSettings {
+  communityName: string
+  maturityRating: MaturityRating
+  communityDescription: string | null
+  communityLogoUrl: string | null
+}
+
 export interface CommunityStats {
   topicCount: number
   replyCount: number
diff --git a/src/lib/seo.test.ts b/src/lib/seo.test.ts
new file mode 100644
index 0000000..2412f25
--- /dev/null
+++ b/src/lib/seo.test.ts
@@ -0,0 +1,86 @@
+/**
+ * Tests for maturity-aware SEO helpers.
+ * @see src/lib/seo.ts
+ */
+
+import { describe, it, expect } from 'vitest'
+import {
+  getEffectiveMaturity,
+  getMaturityMeta,
+  shouldIncludeJsonLd,
+  shouldIncludeOgTags,
+} from './seo'
+
+describe('getEffectiveMaturity', () => {
+  it('returns safe when both ratings are safe', () => {
+    expect(getEffectiveMaturity('safe', 'safe')).toBe('safe')
+  })
+
+  it('returns mature when community is safe and category is mature', () => {
+    expect(getEffectiveMaturity('safe', 'mature')).toBe('mature')
+  })
+
+  it('returns mature when community is mature and category is safe', () => {
+    expect(getEffectiveMaturity('mature', 'safe')).toBe('mature')
+  })
+
+  it('returns adult when community is adult and category is safe', () => {
+    expect(getEffectiveMaturity('adult', 'safe')).toBe('adult')
+  })
+
+  it('returns adult when community is safe and category is adult', () => {
+    expect(getEffectiveMaturity('safe', 'adult')).toBe('adult')
+  })
+
+  it('returns adult when both are adult', () => {
+    expect(getEffectiveMaturity('adult', 'adult')).toBe('adult')
+  })
+
+  it('returns adult when community is mature and category is adult', () => {
+    expect(getEffectiveMaturity('mature', 'adult')).toBe('adult')
+  })
+})
+
+describe('getMaturityMeta', () => {
+  it('returns empty object for safe rating', () => {
+    expect(getMaturityMeta('safe')).toEqual({})
+  })
+
+  it('returns rating meta for mature', () => {
+    const meta = getMaturityMeta('mature')
+    expect(meta).toEqual({ other: { rating: 'mature' } })
+  })
+
+  it('returns noindex/nofollow for adult', () => {
+    const meta = getMaturityMeta('adult')
+    expect(meta).toEqual({ robots: { index: false, follow: false } })
+  })
+})
+
+describe('shouldIncludeJsonLd', () => {
+  it('returns true for safe', () => {
+    expect(shouldIncludeJsonLd('safe')).toBe(true)
+  })
+
+  it('returns true for mature', () => {
+    expect(shouldIncludeJsonLd('mature')).toBe(true)
+  })
+
+  it('returns false for adult', () => {
+    expect(shouldIncludeJsonLd('adult')).toBe(false)
+  })
+})
+
+describe('shouldIncludeOgTags', () => {
+  it('returns true for safe', () => {
+    expect(shouldIncludeOgTags('safe')).toBe(true)
+  })
+
+  it('returns true for mature', () => {
+    expect(shouldIncludeOgTags('mature')).toBe(true)
+  })
+
+  it('returns false for adult', () => {
+    expect(shouldIncludeOgTags('adult')).toBe(false)
+  })
+})
diff --git a/src/lib/seo.ts b/src/lib/seo.ts
new file mode 100644
index 0000000..de8d040
--- /dev/null
+++ b/src/lib/seo.ts
@@ -0,0 +1,60 @@
+/**
+ * Maturity-aware SEO helpers.
+ * Determines meta tags, JSON-LD inclusion, and OG tag inclusion
+ * based on content maturity ratings (safe/mature/adult).
+ * @see decisions/frontend.md Section: Content Maturity + SEO
+ */
+
+import type { Metadata } from 'next'
+import type { MaturityRating } from '@/lib/api/types'
+
+/** Maturity tier ordering for comparison. */
+const MATURITY_ORDER: Record<MaturityRating, number> = {
+  safe: 0,
+  mature: 1,
+  adult: 2,
+}
+
+/**
+ * Returns the higher (more restrictive) of two maturity ratings.
+ * Used to combine community-level and category-level ratings.
+ */
+export function getEffectiveMaturity(
+  communityRating: MaturityRating,
+  categoryRating: MaturityRating
+): MaturityRating {
+  return MATURITY_ORDER[communityRating] >= MATURITY_ORDER[categoryRating]
+    ? communityRating
+    : categoryRating
+}
+
+/**
+ * Returns metadata fields to merge based on the effective maturity rating.
+ * - safe: no special tags
+ * - mature: adds rating meta tag
+ * - adult: sets noindex/nofollow
+ */
+export function getMaturityMeta(rating: MaturityRating): Partial<Metadata> {
+  switch (rating) {
+    case 'safe':
+      return {}
+    case 'mature':
+      return {
+        other: { rating: 'mature' },
+      }
+    case 'adult':
+      return {
+        robots: { index: false, follow: false },
+      }
+  }
+}
+
+/** Whether JSON-LD structured data should be included for this rating. */
+export function shouldIncludeJsonLd(rating: MaturityRating): boolean {
+  return rating !== 'adult'
+}
+
+/** Whether OpenGraph tags should be included for this rating. */
+export function shouldIncludeOgTags(rating: MaturityRating): boolean {
+  return rating !== 'adult'
+}
diff --git a/src/mocks/data.ts b/src/mocks/data.ts
index f0d5fc7..6a4c154 100644
--- a/src/mocks/data.ts
+++ b/src/mocks/data.ts
@@ -144,6 +144,7 @@ export const mockTopics: Topic[] = [
     cid: 'bafyreib1',
     replyCount: 5,
     reactionCount: 12,
+    categoryMaturityRating: 'safe',
     lastActivityAt: NOW,
     createdAt: TWO_DAYS_AGO,
     indexedAt: TWO_DAYS_AGO,
@@ -161,6 +162,7 @@ export const mockTopics: Topic[] = [
     cid: 'bafyreib2',
     replyCount: 8,
     reactionCount: 23,
+    categoryMaturityRating: 'safe',
     lastActivityAt: YESTERDAY,
     createdAt: TWO_DAYS_AGO,
     indexedAt: TWO_DAYS_AGO,
@@ -178,6 +180,7 @@ export const mockTopics: Topic[] = [
     cid: 'bafyreib3',
     replyCount: 3,
     reactionCount: 7,
+    categoryMaturityRating: 'safe',
     lastActivityAt: YESTERDAY,
     createdAt: YESTERDAY,
     indexedAt: YESTERDAY,
@@ -195,6 +198,7 @@ export const mockTopics: Topic[] = [
     cid: 'bafyreib4',
     replyCount: 15,
     reactionCount: 31,
+    categoryMaturityRating: 'safe',
     lastActivityAt: NOW,
     createdAt: YESTERDAY,
     indexedAt: YESTERDAY,
@@ -212,6 +216,7 @@ export const mockTopics: Topic[] = [
     cid: 'bafyreib5',
     replyCount: 2,
     reactionCount: 9,
+    categoryMaturityRating: 'safe',
     lastActivityAt: NOW,
     createdAt: NOW,
     indexedAt: NOW,