diff --git a/MAIN_PLAN.md b/MAIN_PLAN.md
index 7df377c..2d1733e 100644
--- a/MAIN_PLAN.md
+++ b/MAIN_PLAN.md
@@ -272,6 +272,14 @@
   - manifest JSON 파싱 검증 로직 추가
 - 브랜치/PR: `feat/manifest-robots-auto` → CI 트리거 및 자동 머지 대상(automerge 라벨 조건)
 
+### SEO/Perf 개선(TDD): theme-color, hero width/height
+- 테스트: `lib/exporter/seoPerf.themeColor.heroDims.test.ts`
+  - `<meta name="theme-color" content="#0ea5e9" />` 헤드 포함 검증(page.theme.primaryColor 사용)
+  - hero 이미지에 `width`/`height` 속성 존재 검증(CLS 저감)
+- 구현: `lib/exporter/html.ts`
+  - `buildHead`에 theme-color 메타 추가
+  - `renderHero` 이미지 태그에 width/height 기본값 추가(1200x675)
+- 브랜치/PR: `feat/seo-perf-themecolor-hero-dims` → CI 트리거 및 자동 머지 대상
 ### ZIP 검증 TDD Phase5(extras 내용 검증)
 - 테스트: `lib/exporter/zip.validation.phase5.test.ts`
   - `robots.txt` 텍스트 베이스라인 확인(`User-agent: *`)
diff --git a/lib/exporter/extras.overrides.test.ts b/lib/exporter/extras.overrides.test.ts
new file mode 100644
index 0000000..e1c6bbd
--- /dev/null
+++ b/lib/exporter/extras.overrides.test.ts
@@ -0,0 +1,47 @@
+import { describe, it, expect } from 'vitest'
+import { pageSchema, type Page } from '@/lib/schema/page'
+import { buildExtrasForPage } from '@/lib/exporter/extras'
+
+function makePage(): Page {
+  return pageSchema.parse({
+    title: 'Overrides Demo',
+    locale: 'en',
+    theme: { primaryColor: '#123456', fontFamily: 'Inter' },
+    sections: [
+      { type: 'hero', props: { heading: 'Hello', subheading: 'World', imageUrl: 'https://img.example/hero.png' } },
+    ],
+    form: { actionUrl: '', fields: [], spamProtection: { honeypotFieldName: '_hp', minSubmitSeconds: 2 } },
+    seo: { title: 'Overrides', description: 'Desc' },
+  })
+}
+
+describe('extras overrides', () => {
+  it('allows overriding robots.txt content', () => {
+    const page = makePage()
+    const extras = buildExtrasForPage(page, {
+      robotsText: 'User-agent: *\nDisallow: /private',
+    })
+    const robots = new TextDecoder().decode(extras['robots.txt'])
+    expect(robots).toContain('Disallow: /private')
+  })
+
+  it('allows overriding manifest fields (name, short_name, start_url, display, theme_color)', () => {
+    const page = makePage()
+    const extras = buildExtrasForPage(page, {
+      manifest: {
+        name: 'Custom Name',
+        short_name: 'Custom',
+        start_url: '/home',
+        display: 'minimal-ui',
+        theme_color: '#abcdef',
+      },
+    })
+    const manifestRaw = new TextDecoder().decode(extras['site.webmanifest'])
+    const manifest = JSON.parse(manifestRaw)
+    expect(manifest.name).toBe('Custom Name')
+    expect(manifest.short_name).toBe('Custom')
+    expect(manifest.start_url).toBe('/home')
+    expect(manifest.display).toBe('minimal-ui')
+    expect(manifest.theme_color).toBe('#abcdef')
+  })
+})
diff --git a/lib/exporter/extras.ts b/lib/exporter/extras.ts
index e112772..8b9fa4d 100644
--- a/lib/exporter/extras.ts
+++ b/lib/exporter/extras.ts
@@ -1,13 +1,25 @@
 import type { Page } from '@/lib/schema/page'
 
+type ExtrasOverrides = {
+  robotsText?: string
+  manifest?: Partial<{
+    name: string
+    short_name: string
+    start_url: string
+    display: string
+    theme_color: string
+  }>
+}
+
 // Sheets 템플릿 등 ZIP 루트/서브 경로에 포함할 추가 파일(extras)을 구성한다.
 // - actionUrl이 비어있을 때만 Google Apps Script 템플릿을 포함한다.
-export function buildExtrasForPage(page: Page): Record<string, Uint8Array> {
+export function buildExtrasForPage(page: Page, overrides?: ExtrasOverrides): Record<string, Uint8Array> {
   const extras: Record<string, Uint8Array> = {}
   const te = new TextEncoder()
 
   // Always provide a baseline robots.txt
-  const robots = `User-agent: *\nDisallow:`
+  const robotsDefault = `User-agent: *\nDisallow:`
+  const robots = overrides?.robotsText ?? robotsDefault
   extras['robots.txt'] = te.encode(robots)
 
   // Provide a minimal site.webmanifest derived from Page
@@ -20,6 +32,13 @@ export function buildExtrasForPage(page: Page): Record<string, Uint8Array> {
       start_url: '/',
       display: 'standalone',
       theme_color: page.theme?.primaryColor ?? '#000000',
+      ...((overrides?.manifest as object) || {}),
+    } as {
+      name: string
+      short_name: string
+      start_url: string
+      display: string
+      theme_color: string
     }
     extras['site.webmanifest'] = te.encode(JSON.stringify(manifest))
   } catch {}