1 files changed, 7 insertions, 1 deletions
diff --git a/tests/test_frontmatter.py b/tests/test_frontmatter.py
index 2257a8a..6cd4b44 100644
--- a/tests/test_frontmatter.py
+++ b/tests/test_frontmatter.py
@@ -1,6 +1,5 @@
 import pytest
 from pathlib import Path
-import tempfile
 from core.frontmatter import parse_frontmatter, write_frontmatter
 
 SAMPLE_MD = """\
@@ -42,6 +41,13 @@ def test_write_preserves_format(tmp_path):
     assert fm2["title"] == "Updated Title"
     assert fm2["type"] == "Tech"
 
+def test_write_is_idempotent(tmp_path):
+    f = tmp_path / "index.md"
+    f.write_text(SAMPLE_MD)
+    fm, body = parse_frontmatter(f)
+    write_frontmatter(f, fm, body)
+    assert f.read_text() == SAMPLE_MD
+
 def test_parse_raises_on_missing_delimiters(tmp_path):
     f = tmp_path / "index.md"
     f.write_text("# No frontmatter\n\nJust body.")