diff --git a/publish/src/core/validation.ts b/publish/src/core/validation.ts
new file mode 100644
index 0000000..d51a299
--- /dev/null
+++ b/publish/src/core/validation.ts
@@ -0,0 +1,22 @@
+import type { Frontmatter } from './frontmatter.ts'
+
+const SLUG_RE = /^[a-z0-9][a-z0-9-]*$/
+
+export function validateSlug(slug: string): void {
+  if (!SLUG_RE.test(slug)) {
+    throw new Error(`invalid slug: "${slug}" (must match ${SLUG_RE})`)
+  }
+}
+
+export function validatePost(fm: Frontmatter): void {
+  if (!fm.title || typeof fm.title !== 'string') {
+    throw new Error('missing/invalid title')
+  }
+  if (!fm.slug || typeof fm.slug !== 'string') {
+    throw new Error('missing/invalid slug')
+  }
+  validateSlug(fm.slug)
+  if (!(fm.date instanceof Date) || isNaN(fm.date.getTime())) {
+    throw new Error('missing/invalid date (expected YAML date)')
+  }
+}
diff --git a/publish/tests/validation_test.ts b/publish/tests/validation_test.ts
new file mode 100644
index 0000000..34c46d1
--- /dev/null
+++ b/publish/tests/validation_test.ts
@@ -0,0 +1,41 @@
+import { assertThrows } from '@std/assert'
+import { validatePost, validateSlug } from '../src/core/validation.ts'
+import type { Frontmatter } from '../src/core/frontmatter.ts'
+
+Deno.test('validateSlug: akzeptiert lowercase/digits/hyphen', () => {
+  validateSlug('abc-123')
+  validateSlug('a')
+  validateSlug('dezentrale-oep-oer')
+})
+
+Deno.test('validateSlug: lehnt Großbuchstaben ab', () => {
+  assertThrows(() => validateSlug('Abc'), Error, 'slug')
+})
+
+Deno.test('validateSlug: lehnt Unterstriche/Leerzeichen ab', () => {
+  assertThrows(() => validateSlug('a_b'), Error, 'slug')
+  assertThrows(() => validateSlug('a b'), Error, 'slug')
+})
+
+Deno.test('validateSlug: lehnt führenden Bindestrich ab', () => {
+  assertThrows(() => validateSlug('-abc'), Error, 'slug')
+})
+
+Deno.test('validatePost: ok bei vollständigem Frontmatter', () => {
+  const fm: Frontmatter = {
+    title: 'T',
+    slug: 'ok-slug',
+    date: new Date('2024-01-01'),
+  }
+  validatePost(fm)
+})
+
+Deno.test('validatePost: fehlt title', () => {
+  const fm = { slug: 'ok', date: new Date() } as unknown as Frontmatter
+  assertThrows(() => validatePost(fm), Error, 'title')
+})
+
+Deno.test('validatePost: date muss Date sein', () => {
+  const fm = { title: 'T', slug: 'ok', date: 'not-a-date' } as unknown as Frontmatter
+  assertThrows(() => validatePost(fm), Error, 'date')
+})