feat: normalize system properties to _archived, _trashed, _trashed_at

Write operations now use underscore-prefixed canonical keys (_archived,
_trashed, _trashed_at). Read operations accept both old keys (Archived,
archived, Trashed, trashed, Trashed at, trashed_at) and new keys via
serde aliases, ensuring backward compatibility without migration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/commands/vault.rs

@@ -207,7 +207,7 @@ pub fn batch_archive_notes(paths: Vec<String>) -> Result<usize, String> {
     let mut count = 0;
     for path in &paths {
         let path = expand_tilde(path);
-        frontmatter::update_frontmatter(&path, "Archived", FrontmatterValue::Bool(true))?;
+        frontmatter::update_frontmatter(&path, "_archived", FrontmatterValue::Bool(true))?;
         count += 1;
     }
     Ok(count)
@@ -219,10 +219,10 @@ pub fn batch_trash_notes(paths: Vec<String>) -> Result<usize, String> {
     let mut count = 0;
     for path in &paths {
         let path = expand_tilde(path);
-        frontmatter::update_frontmatter(&path, "Trashed", FrontmatterValue::Bool(true))?;
+        frontmatter::update_frontmatter(&path, "_trashed", FrontmatterValue::Bool(true))?;
         frontmatter::update_frontmatter(
             &path,
-            "Trashed at",
+            "_trashed_at",
             FrontmatterValue::String(now.clone()),
         )?;
         count += 1;
@@ -276,7 +276,7 @@ mod tests {
             1
         );
         let content = std::fs::read_to_string(&note).unwrap();
-        assert!(content.contains("Archived: true"));
+        assert!(content.contains("_archived: true"));
         assert!(content.contains("Status: Active"));
     }
 
@@ -288,8 +288,8 @@ mod tests {
             1
         );
         let content = std::fs::read_to_string(&note).unwrap();
-        assert!(content.contains("Trashed: true"));
-        assert!(content.contains("Trashed at"));
+        assert!(content.contains("_trashed: true"));
+        assert!(content.contains("_trashed_at"));
     }
 
     #[test]

src-tauri/src/vault/frontmatter.rs

@@ -12,14 +12,16 @@ pub(crate) struct Frontmatter {
     #[serde(default)]
     pub aliases: Option<StringOrList>,
     #[serde(
-        rename = "Archived",
+        rename = "_archived",
+        alias = "Archived",
         alias = "archived",
         default,
         deserialize_with = "deserialize_bool_or_string"
     )]
     pub archived: Option<bool>,
     #[serde(
-        rename = "Trashed",
+        rename = "_trashed",
+        alias = "Trashed",
         alias = "trashed",
         default,
         deserialize_with = "deserialize_bool_or_string"
@@ -27,7 +29,11 @@ pub(crate) struct Frontmatter {
     pub trashed: Option<bool>,
     #[serde(rename = "Status", alias = "status", default)]
     pub status: Option<StringOrList>,
-    #[serde(rename = "Trashed at", alias = "trashed_at")]
+    #[serde(
+        rename = "_trashed_at",
+        alias = "Trashed at",
+        alias = "trashed_at"
+    )]
     pub trashed_at: Option<StringOrList>,
     #[serde(default)]
     pub icon: Option<StringOrList>,
@@ -145,10 +151,13 @@ fn parse_frontmatter(data: &HashMap<String, serde_json::Value>) -> Frontmatter {
         "Is A",
         "is_a",
         "aliases",
+        "_archived",
         "Archived",
         "archived",
+        "_trashed",
         "Trashed",
         "trashed",
+        "_trashed_at",
         "Trashed at",
         "trashed_at",
         "icon",
@@ -182,9 +191,13 @@ const SKIP_KEYS: &[&str] = &[
     "is a",
     "type",
     "aliases",
+    "_archived",
     "archived",
+    "_trashed",
     "trashed",
+    "_trashed_at",
     "trashed at",
+    "trashed_at",
     "icon",
     "color",
     "order",

src-tauri/src/vault/mod_tests.rs

@@ -1092,6 +1092,31 @@ fn test_parse_trashed_no() {
     assert!(!entry.trashed, "'Trashed: No' must be parsed as false");
 }
 
+// --- new canonical underscore-prefixed keys ---
+
+#[test]
+fn test_parse_underscore_trashed_canonical() {
+    let dir = TempDir::new().unwrap();
+    let content = "---\n_trashed: true\n_trashed_at: \"2026-03-15\"\n---\n# Gone\n";
+    let entry = parse_test_entry(&dir, "gone-new.md", content);
+    assert!(entry.trashed, "'_trashed: true' must be parsed as trashed");
+    assert!(
+        entry.trashed_at.is_some(),
+        "'_trashed_at' must be parsed as trashed_at"
+    );
+}
+
+#[test]
+fn test_parse_underscore_archived_canonical() {
+    let dir = TempDir::new().unwrap();
+    let content = "---\n_archived: true\n---\n# Old\n";
+    let entry = parse_test_entry(&dir, "old-new.md", content);
+    assert!(
+        entry.archived,
+        "'_archived: true' must be parsed as archived"
+    );
+}
+
 // --- visible field tests ---
 
 #[test]

src-tauri/src/vault/trash.rs

@@ -14,7 +14,10 @@ fn extract_trashed_at_string(data: &Option<gray_matter::Pod>) -> Option<String>
     let gray_matter::Pod::Hash(ref map) = data.as_ref()? else {
         return None;
     };
-    let pod = map.get("Trashed at").or_else(|| map.get("trashed_at"))?;
+    let pod = map
+        .get("_trashed_at")
+        .or_else(|| map.get("Trashed at"))
+        .or_else(|| map.get("trashed_at"))?;
     match pod {
         gray_matter::Pod::String(s) => Some(s.clone()),
         _ => None,
@@ -74,7 +77,11 @@ pub fn is_file_trashed(path: &Path) -> bool {
 
     // Check for "Trashed: true"
     if let Some(gray_matter::Pod::Hash(ref map)) = parsed.data {
-        if let Some(pod) = map.get("Trashed").or_else(|| map.get("trashed")) {
+        if let Some(pod) = map
+            .get("_trashed")
+            .or_else(|| map.get("Trashed"))
+            .or_else(|| map.get("trashed"))
+        {
             return match pod {
                 gray_matter::Pod::Boolean(b) => *b,
                 gray_matter::Pod::String(s) => {
@@ -373,6 +380,28 @@ mod tests {
         assert!(!is_file_trashed(Path::new("/nonexistent/path.md")));
     }
 
+    #[test]
+    fn test_is_file_trashed_with_underscore_trashed() {
+        let dir = TempDir::new().unwrap();
+        create_test_file(
+            dir.path(),
+            "trashed.md",
+            "---\n_trashed: true\n---\n# Gone\n",
+        );
+        assert!(is_file_trashed(&dir.path().join("trashed.md")));
+    }
+
+    #[test]
+    fn test_is_file_trashed_with_underscore_trashed_at() {
+        let dir = TempDir::new().unwrap();
+        create_test_file(
+            dir.path(),
+            "trashed.md",
+            "---\n_trashed_at: \"2026-03-15\"\n---\n# Gone\n",
+        );
+        assert!(is_file_trashed(&dir.path().join("trashed.md")));
+    }
+
     #[test]
     fn test_is_file_trashed_with_trashed_false() {
         let dir = TempDir::new().unwrap();