diff --git a/src/journal_bot/vault_writer.py b/src/journal_bot/vault_writer.py
new file mode 100644
index 0000000..e479d86
--- /dev/null
+++ b/src/journal_bot/vault_writer.py
@@ -0,0 +1,34 @@
+from datetime import date
+from pathlib import Path
+
+
+class VaultWriter:
+    """Appends entries to daily notes; creates files with frontmatter when missing."""
+
+    def __init__(self, vault_path: Path):
+        self.vault_path = vault_path
+
+    def append(
+        self,
+        relative_path: str,
+        entry_markdown: str,
+        clarifications: list[str] | None = None,
+    ) -> None:
+        target = self.vault_path / relative_path
+        target.parent.mkdir(parents=True, exist_ok=True)
+
+        block = entry_markdown.rstrip()
+        if clarifications:
+            lines = "\n".join(f"> - {c}" for c in clarifications)
+            block += f"\n\n> [!warning] Klärung\n{lines}"
+
+        if not target.exists():
+            iso = target.stem
+            frontmatter = f"---\ntags: [daily]\ndate: {iso}\n---\n\n"
+            target.write_text(frontmatter + block + "\n", encoding="utf-8")
+            return
+
+        existing = target.read_text(encoding="utf-8")
+        if not existing.endswith("\n"):
+            existing += "\n"
+        target.write_text(existing + "\n" + block + "\n", encoding="utf-8")
diff --git a/tests/test_vault_writer.py b/tests/test_vault_writer.py
new file mode 100644
index 0000000..2ad0780
--- /dev/null
+++ b/tests/test_vault_writer.py
@@ -0,0 +1,42 @@
+from pathlib import Path
+from journal_bot.vault_writer import VaultWriter
+
+
+def test_creates_file_with_frontmatter(tmp_path):
+    vault = tmp_path
+    (vault / "05 Daily Notes").mkdir()
+    w = VaultWriter(vault)
+    w.append("05 Daily Notes/2026-06-14.md", "## 14:32\nHallo")
+    content = (vault / "05 Daily Notes" / "2026-06-14.md").read_text(encoding="utf-8")
+    assert content.startswith("---\n")
+    assert "tags: [daily]" in content
+    assert "date: 2026-06-14" in content
+    assert "## 14:32\nHallo" in content
+
+
+def test_appends_to_existing_file(tmp_path):
+    vault = tmp_path
+    daily = vault / "05 Daily Notes"
+    daily.mkdir()
+    existing = daily / "2026-06-14.md"
+    existing.write_text("---\ntags: [daily]\ndate: 2026-06-14\n---\n\n## 09:00\nMorgen\n", encoding="utf-8")
+    w = VaultWriter(vault)
+    w.append("05 Daily Notes/2026-06-14.md", "## 14:32\nNachmittag")
+    content = existing.read_text(encoding="utf-8")
+    assert "## 09:00\nMorgen" in content
+    assert "## 14:32\nNachmittag" in content
+    assert content.count("---\ntags: [daily]") == 1  # frontmatter not duplicated
+
+
+def test_appends_clarifications_callout(tmp_path):
+    vault = tmp_path
+    (vault / "05 Daily Notes").mkdir()
+    w = VaultWriter(vault)
+    w.append(
+        "05 Daily Notes/2026-06-14.md",
+        "## 14:32\nTreffen mit Steffen",
+        clarifications=["Welcher Steffen?"],
+    )
+    content = (vault / "05 Daily Notes" / "2026-06-14.md").read_text(encoding="utf-8")
+    assert "> [!warning] Klärung" in content
+    assert "> - Welcher Steffen?" in content