fix(ingestion): preserve type and domain metadata as frontmatter in written notes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ingestion/internal/api/handler_test.go

@@ -79,6 +79,27 @@ func TestQuery_RequiresQuery(t *testing.T) {
 	assert.Equal(t, http.StatusBadRequest, rec.Code)
 }
 
+func TestWrite_IncludesFrontmatterWhenTypeProvided(t *testing.T) {
+	dir, h := setup(t)
+	body, _ := json.Marshal(map[string]any{
+		"content":  "Some learning.",
+		"filename": "typed-note.md",
+		"type":     "concept",
+		"domain":   "software",
+	})
+	req := httptest.NewRequest(http.MethodPost, "/write", bytes.NewReader(body))
+	rec := httptest.NewRecorder()
+
+	h.Write(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code)
+	content, err := os.ReadFile(filepath.Join(dir, "raw", "typed-note.md"))
+	require.NoError(t, err)
+	assert.Contains(t, string(content), "type: concept")
+	assert.Contains(t, string(content), "domain: software")
+	assert.Contains(t, string(content), "Some learning.")
+}
+
 func TestWrite_GeneratesFilenameIfAbsent(t *testing.T) {
 	dir, h := setup(t)
 	body, _ := json.Marshal(map[string]any{"content": "auto name"})