refactor: consolidate escape functions and extract weight constants

- Create escape.rs with shared html_escape, html_escape_into, xml_escape
- Remove duplicate implementations from render.rs, highlight.rs, feed.rs, sitemap.rs
- Add DEFAULT_WEIGHT (50) and DEFAULT_WEIGHT_HIGH (99) constants to content.rs
- Replace all magic number weight defaults with named constants

No functional changes; all 67 tests pass.

src/content.rs

@@ -6,6 +6,12 @@ use serde::Serialize;
 use std::fs;
 use std::path::{Path, PathBuf};
 
+/// Default weight for content items in navigation and listings.
+pub const DEFAULT_WEIGHT: i64 = 50;
+
+/// High default weight for content that should appear last (e.g., projects).
+pub const DEFAULT_WEIGHT_HIGH: i64 = 99;
+
 /// The type of content being processed.
 #[derive(Debug, Clone, PartialEq)]
 pub enum ContentKind {
@@ -212,7 +218,7 @@ pub fn discover_nav(content_dir: &Path) -> Result<Vec<NavItem>> {
                             .nav_label
                             .unwrap_or(content.frontmatter.title),
                         path: format!("/{}.html", slug),
-                        weight: content.frontmatter.weight.unwrap_or(50),
+                        weight: content.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT),
                         children: Vec::new(),
                     });
                 }
@@ -245,7 +251,7 @@ pub fn discover_nav(content_dir: &Path) -> Result<Vec<NavItem>> {
                     .map(|item| NavItem {
                         label: item.frontmatter.nav_label.unwrap_or(item.frontmatter.title),
                         path: format!("/{}/{}.html", dir_name, item.slug),
-                        weight: item.frontmatter.weight.unwrap_or(50),
+                        weight: item.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT),
                         children: Vec::new(),
                     })
                     .collect();
@@ -260,7 +266,7 @@ pub fn discover_nav(content_dir: &Path) -> Result<Vec<NavItem>> {
                         .nav_label
                         .unwrap_or(content.frontmatter.title),
                     path: format!("/{}/index.html", dir_name),
-                    weight: content.frontmatter.weight.unwrap_or(50),
+                    weight: content.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT),
                     children,
                 });
             }
@@ -358,8 +364,8 @@ pub fn discover_sections(content_dir: &Path) -> Result<Vec<Section>> {
 
     // Sort by weight
     sections.sort_by(|a, b| {
-        let wa = a.index.frontmatter.weight.unwrap_or(50);
+        let wa = a.index.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT);
-        let wb = b.index.frontmatter.weight.unwrap_or(50);
+        let wb = b.index.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT);
         wa.cmp(&wb)
     });
 

src/escape.rs

@@ -0,0 +1,63 @@
+//! Text escaping utilities for HTML and XML output.
+
+/// Escape HTML special characters for safe embedding in HTML content.
+///
+/// Escapes: `&`, `<`, `>`, `"`
+pub fn html_escape(s: &str) -> String {
+    let mut result = String::with_capacity(s.len());
+    html_escape_into(&mut result, s);
+    result
+}
+
+/// Escape HTML characters into an existing string.
+///
+/// This is more efficient when building output incrementally.
+pub fn html_escape_into(out: &mut String, s: &str) {
+    for c in s.chars() {
+        match c {
+            '&' => out.push_str("&amp;"),
+            '<' => out.push_str("&lt;"),
+            '>' => out.push_str("&gt;"),
+            '"' => out.push_str("&quot;"),
+            _ => out.push(c),
+        }
+    }
+}
+
+/// Escape XML special characters for safe embedding in XML documents.
+///
+/// Escapes: `&`, `<`, `>`, `"`, `'`
+pub fn xml_escape(s: &str) -> String {
+    s.replace('&', "&amp;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
+        .replace('"', "&quot;")
+        .replace('\'', "&apos;")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_html_escape() {
+        assert_eq!(html_escape("Hello & World"), "Hello &amp; World");
+        assert_eq!(html_escape("<tag>"), "&lt;tag&gt;");
+        assert_eq!(html_escape("\"quoted\""), "&quot;quoted&quot;");
+    }
+
+    #[test]
+    fn test_html_escape_into() {
+        let mut buf = String::new();
+        html_escape_into(&mut buf, "a < b");
+        assert_eq!(buf, "a &lt; b");
+    }
+
+    #[test]
+    fn test_xml_escape() {
+        assert_eq!(xml_escape("Hello & World"), "Hello &amp; World");
+        assert_eq!(xml_escape("<tag>"), "&lt;tag&gt;");
+        assert_eq!(xml_escape("\"quoted\""), "&quot;quoted&quot;");
+        assert_eq!(xml_escape("it's"), "it&apos;s");
+    }
+}

src/feed.rs

@@ -2,6 +2,7 @@
 
 use crate::config::SiteConfig;
 use crate::content::SiteManifest;
+use crate::escape::xml_escape;
 use std::path::Path;
 
 /// Generate an Atom 1.0 feed from blog posts in the manifest.
@@ -80,15 +81,6 @@ pub fn generate_atom_feed(
     )
 }
 
-/// Escape XML special characters.
-fn xml_escape(s: &str) -> String {
-    s.replace('&', "&")
-        .replace('<', "&lt;")
-        .replace('>', "&gt;")
-        .replace('"', "&quot;")
-        .replace('\'', "&apos;")
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/highlight.rs

@@ -8,6 +8,7 @@ use std::collections::HashMap;
 use std::sync::LazyLock;
 use std::time::Duration;
 
+use crate::escape::{html_escape, html_escape_into};
 use ropey::RopeSlice;
 use tree_house::highlighter::{Highlight, HighlightEvent, Highlighter};
 use tree_house::{
@@ -624,26 +625,6 @@ fn render_html<'a>(source: &str, mut highlighter: Highlighter<'a, 'a, SukrLoader
     html
 }
 
-/// Simple HTML escape for fallback.
-fn html_escape(s: &str) -> String {
-    let mut result = String::with_capacity(s.len());
-    html_escape_into(&mut result, s);
-    result
-}
-
-/// Escape HTML characters into an existing string.
-fn html_escape_into(out: &mut String, s: &str) {
-    for c in s.chars() {
-        match c {
-            '&' => out.push_str("&amp;"),
-            '<' => out.push_str("&lt;"),
-            '>' => out.push_str("&gt;"),
-            '"' => out.push_str("&quot;"),
-            _ => out.push(c),
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/main.rs

@@ -6,6 +6,7 @@ mod config;
 mod content;
 mod css;
 mod error;
+mod escape;
 mod feed;
 mod highlight;
 mod math;
@@ -14,7 +15,7 @@ mod render;
 mod sitemap;
 mod template_engine;
 
-use crate::content::{Content, ContentKind, NavItem};
+use crate::content::{Content, ContentKind, DEFAULT_WEIGHT, DEFAULT_WEIGHT_HIGH, NavItem};
 use crate::error::{Error, Result};
 use crate::template_engine::{ContentContext, TemplateEngine};
 use std::fs;
@@ -123,8 +124,8 @@ fn run(config_path: &Path) -> Result<()> {
                 items.sort_by(|a, b| {
                     a.frontmatter
                         .weight
-                        .unwrap_or(99)
+                        .unwrap_or(DEFAULT_WEIGHT_HIGH)
-                        .cmp(&b.frontmatter.weight.unwrap_or(99))
+                        .cmp(&b.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT_HIGH))
                 });
             }
             _ => {
@@ -132,8 +133,8 @@ fn run(config_path: &Path) -> Result<()> {
                 items.sort_by(|a, b| {
                     a.frontmatter
                         .weight
-                        .unwrap_or(50)
+                        .unwrap_or(DEFAULT_WEIGHT)
-                        .cmp(&b.frontmatter.weight.unwrap_or(50))
+                        .cmp(&b.frontmatter.weight.unwrap_or(DEFAULT_WEIGHT))
                         .then_with(|| a.frontmatter.title.cmp(&b.frontmatter.title))
                 });
             }

src/render.rs

@@ -1,5 +1,6 @@
 //! Markdown to HTML rendering via pulldown-cmark with syntax highlighting.
 
+use crate::escape::html_escape;
 use crate::highlight::{highlight_code, Language};
 use pulldown_cmark::{CodeBlockKind, Event, HeadingLevel, Options, Parser, Tag, TagEnd};
 use serde::Serialize;
@@ -247,13 +248,6 @@ pub fn markdown_to_html(markdown: &str) -> (String, Vec<Anchor>) {
     (html_output, anchors)
 }
 
-fn html_escape(s: &str) -> String {
-    s.replace('&', "&amp;")
-        .replace('<', "&lt;")
-        .replace('>', "&gt;")
-        .replace('"', "&quot;")
-}
-
 /// Convert heading text to a URL-friendly slug ID.
 fn slugify(text: &str) -> String {
     text.to_lowercase()

src/sitemap.rs

@@ -2,6 +2,7 @@
 
 use crate::config::SiteConfig;
 use crate::content::SiteManifest;
+use crate::escape::xml_escape;
 use std::path::Path;
 
 /// A URL entry for the sitemap.
@@ -88,15 +89,6 @@ fn build_sitemap_xml(entries: &[SitemapEntry]) -> String {
     )
 }
 
-/// Escape XML special characters.
-fn xml_escape(s: &str) -> String {
-    s.replace('&', "&")
-        .replace('<', "&lt;")
-        .replace('>', "&gt;")
-        .replace('"', "&quot;")
-        .replace('\'', "&apos;")
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;