fix: stabilize mermaid title width and video autolinks

src/markdown/mermaid/flowchart/layout/mod.rs

@@ -23,6 +23,11 @@ use config::FlowLayoutConfig;
 use graph::FlowGraph;
 use sugiyama::SugiyamaLayout;
 
+fn stable_min_width_for_title(title: &str, font_size: f32, text_measurer: &impl TextMeasurer) -> f32 {
+    let title_text_size = text_measurer.measure(title, font_size);
+    (title_text_size.width + 24.0).ceil()
+}
+
 /// Compute layout for a flowchart using a Sugiyama-style layered graph algorithm.
 ///
 /// The `text_measurer` parameter enables accurate text sizing. Use `EguiTextMeasurer`
@@ -118,8 +123,8 @@ fn compute_subgraph_layouts(
 
             // Ensure subgraph width accommodates the title text
             if let Some(title) = &subgraph.title {
-                let title_text_size = text_measurer.measure(title, font_size);
-                let min_width_for_title = title_text_size.width + 24.0;
+                let min_width_for_title =
+                    stable_min_width_for_title(title, font_size, text_measurer);
                 if existing.size.x < min_width_for_title {
                     existing.size.x = min_width_for_title;
                 }
@@ -183,8 +188,8 @@ fn compute_subgraph_layouts(
 
             // Ensure subgraph width accommodates the title text
             if let Some(title) = &subgraph.title {
-                let title_text_size = text_measurer.measure(title, font_size);
-                let min_width_for_title = title_text_size.width + 24.0;
+                let min_width_for_title =
+                    stable_min_width_for_title(title, font_size, text_measurer);
                 let current_width = padded_max.x - padded_min.x;
                 if current_width < min_width_for_title {
                     padded_max.x = padded_min.x + min_width_for_title;

src/markdown/video_embed.rs

@@ -144,18 +144,17 @@ pub fn try_parse_video_paragraph(node: &MarkdownNode) -> Option<VideoEmbedInfo>
 }
 
 fn extract_bare_youtube_url(node: &MarkdownNode) -> Option<String> {
-    let significant: Vec<_> = node
+    let meaningful_children: Vec<&MarkdownNode> = node
         .children
         .iter()
-        .filter(|child| match &child.node_type {
-            MarkdownNodeType::Text(text) => !text.is_empty(),
-            _ => true,
+        .filter(|child| {
+            !matches!(&child.node_type, MarkdownNodeType::Text(text) if text.trim().is_empty())
         })
         .collect();
 
-    match significant.len() {
+    match meaningful_children.len() {
         0 => None,
-        1 => match &significant[0].node_type {
+        1 => match &meaningful_children[0].node_type {
             MarkdownNodeType::Text(text) => {
                 let trimmed = text.trim();
                 if trimmed.is_empty() || trimmed.contains('\n') {
@@ -168,10 +167,9 @@ fn extract_bare_youtube_url(node: &MarkdownNode) -> Option<String> {
             _ => None,
         },
         _ => {
-            if node
-                .children
+            if meaningful_children
                 .iter()
-                .any(|child| !matches!(child.node_type, MarkdownNodeType::Text(_)))
+                .any(|child| !matches!(&child.node_type, MarkdownNodeType::Text(_)))
             {
                 return None;
             }