feat: H1-as-title — title resolution, TitleField hiding, breadcrumb filename

- Rust: extract_title now prioritizes H1 > frontmatter > filename
- Rust: add has_h1 field to VaultEntry for frontend TitleField control
- Frontend: hide TitleField + icon picker when note has H1 in body
- Frontend: breadcrumb shows filename stem instead of display title
- Frontend: new notes use untitled-{type}-{timestamp}.md, no title in frontmatter
- CSS: only hide first H1 in BlockNote when TitleField is visible
- Updated all tests for new title resolution and note creation behavior

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

src-tauri/src/vault/entry.rs

@@ -78,6 +78,10 @@ pub struct VaultEntry {
     /// Configured via `_list_properties_display` in the type file's frontmatter.
     #[serde(rename = "listPropertiesDisplay", default)]
     pub list_properties_display: Vec<String>,
+    /// Whether the note body has an H1 heading on the first non-empty line.
+    /// Used by the frontend to decide whether to show the TitleField.
+    #[serde(rename = "hasH1")]
+    pub has_h1: bool,
     /// File kind: "markdown", "text", or "binary".
     /// Determines how the frontend renders and opens the file.
     #[serde(rename = "fileKind", default = "default_file_kind")]

src-tauri/src/vault/mod.rs

@@ -57,6 +57,7 @@ pub fn parse_md_file(path: &Path, git_dates: Option<(u64, u64)>) -> Result<Vault
     let (frontmatter, mut relationships, properties) = extract_fm_and_rels(parsed.data, &content);
 
     let title = extract_title(frontmatter.title.as_deref(), &content, &filename);
+    let has_h1 = parsing::extract_h1_title(&content).is_some();
     let snippet = extract_snippet(&content);
     let word_count = count_body_words(&content);
     let outgoing_links = extract_outgoing_links(&parsed.content);
@@ -116,6 +117,7 @@ pub fn parse_md_file(path: &Path, git_dates: Option<(u64, u64)>) -> Result<Vault
         word_count,
         outgoing_links,
         properties,
+        has_h1,
         file_kind: "markdown".to_string(),
     })
 }

src-tauri/src/vault/parsing.rs

@@ -21,15 +21,40 @@ pub(super) fn slug_to_title(stem: &str) -> String {
         .join(" ")
 }
 
+/// Extract the H1 title from the first non-empty line of the body (after frontmatter).
+/// Returns `None` if no H1 is found on the first non-empty line.
+pub(super) fn extract_h1_title(content: &str) -> Option<String> {
+    let body = strip_frontmatter(content);
+    for line in body.lines() {
+        let trimmed = line.trim();
+        if trimmed.is_empty() {
+            continue;
+        }
+        if let Some(title) = trimmed.strip_prefix("# ") {
+            let title = strip_markdown_chars(title).trim().to_string();
+            if !title.is_empty() {
+                return Some(title);
+            }
+        }
+        break; // first non-empty line is not H1
+    }
+    None
+}
+
 /// Extract the display title for a note.
-/// Priority: frontmatter `title:` → filename-derived title.
-/// H1 headings are treated as body content, not title source.
-pub(super) fn extract_title(fm_title: Option<&str>, _content: &str, filename: &str) -> String {
+/// Priority: H1 on first non-empty line → frontmatter `title:` → filename-derived title.
+pub(super) fn extract_title(fm_title: Option<&str>, content: &str, filename: &str) -> String {
+    // 1. H1 on first non-empty line of body
+    if let Some(h1) = extract_h1_title(content) {
+        return h1;
+    }
+    // 2. frontmatter title (legacy, backward compat)
     if let Some(title) = fm_title {
         if !title.is_empty() {
             return title.to_string();
         }
     }
+    // 3. filename slug
     let stem = filename.strip_suffix(".md").unwrap_or(filename);
     slug_to_title(stem)
 }