feat: add syntect code highlighting with catppuccin themes

- Add syntect dependency (server feature, fancy-regex backend)
- Create highlight module with LazyLock globals for SyntaxSet + themes
- Intercept CodeBlock events in markdown rendering for syntax highlighting
- Update ammonia whitelist to allow span/pre/code class/style attributes
- Add generate_highlight_css binary for CSS generation
- Add highlight-css Makefile target (runs before tailwindcss)
- Import generated highlight.css in input.css
- Remove hardcoded code block colors, let catppuccin CSS take over

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "adler2"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
+
 [[package]]
 name = "aho-corasick"
 version = "1.1.4"
@@ -233,6 +239,30 @@ version = "1.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
 
+[[package]]
+name = "bincode"
+version = "1.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1f45e9417d87227c7a56d22e471c6206462cba514c7590c09aff4cf6d1ddcad"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "bit-set"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08807e080ed7f9d5433fa9b275196cfc35414f66a0c79d864dc51a0d825231a3"
+dependencies = [
+ "bit-vec",
+]
+
+[[package]]
+name = "bit-vec"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e764a1d40d510daf35e07be9eb06e75770908c27d411ee6c92109c9840eaaf7"
+
 [[package]]
 name = "bitflags"
 version = "2.11.1"
@@ -572,6 +602,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crc32fast"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9481c1c90cbf2ac953f07c8d4a58aa3945c425b7185c9154d67a65e4230da511"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.21"
@@ -1482,12 +1521,33 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4443176a9f2c162692bd3d352d745ef9413eec5782a80d8fd6f8a1ac692a07f7"
 
+[[package]]
+name = "fancy-regex"
+version = "0.16.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "998b056554fbe42e03ae0e152895cd1a7e1002aec800fdc6635d20270260c46f"
+dependencies = [
+ "bit-set",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5baebc0774151f905a1a2cc41989300b1e6fbb29aff0ceffa1064fdd3088d582"
 
+[[package]]
+name = "flate2"
+version = "1.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "843fba2746e448b37e26a819579957415c8cef339bf08564fe8b7ddbd959573c"
+dependencies = [
+ "crc32fast",
+ "miniz_oxide",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -2276,6 +2336,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "linked-hash-map"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0717cef1bc8b636c6e1c1bbdefc09e6322da8a9321966e8928ef80d20f7f770f"
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.12.1"
@@ -2484,6 +2550,16 @@ dependencies = [
  "unicase",
 ]
 
+[[package]]
+name = "miniz_oxide"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fa76a2c86f704bdb222d66965fb3d63269ce38518b83cb0575fca855ebb6316"
+dependencies = [
+ "adler2",
+ "simd-adler32",
+]
+
 [[package]]
 name = "mio"
 version = "1.2.0"
@@ -2780,6 +2856,19 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
 
+[[package]]
+name = "plist"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "092791278e026273c1b65bbdcfbba3a300f2994c896bd01ab01da613c29c46f1"
+dependencies = [
+ "base64",
+ "indexmap",
+ "quick-xml",
+ "serde",
+ "time",
+]
+
 [[package]]
 name = "postgres-protocol"
 version = "0.6.11"
@@ -2915,6 +3004,15 @@ version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "007d8adb5ddab6f8e3f491ac63566a7d5002cc7ed73901f72057943fa71ae1ae"
 
+[[package]]
+name = "quick-xml"
+version = "0.39.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdcc8dd4e2f670d309a5f0e83fe36dfdc05af317008fea29144da1a2ac858e5e"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "quinn"
 version = "0.11.9"
@@ -3437,6 +3535,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "simd-adler32"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "703d5c7ef118737c72f1af64ad2f6f8c5e1921f818cdcb97b8fe6fc69bf66214"
+
 [[package]]
 name = "siphasher"
 version = "1.0.3"
@@ -3617,6 +3721,27 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "syntect"
+version = "5.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "656b45c05d95a5704399aeef6bd0ddec7b2b3531b7c9e900abbf7c4d2190c925"
+dependencies = [
+ "bincode",
+ "fancy-regex",
+ "flate2",
+ "fnv",
+ "once_cell",
+ "plist",
+ "regex-syntax",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "thiserror 2.0.18",
+ "walkdir",
+ "yaml-rust",
+]
+
 [[package]]
 name = "system-configuration"
 version = "0.7.0"
@@ -4868,6 +4993,15 @@ version = "0.8.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fdd20c5420375476fbd4394763288da7eb0cc0b8c11deed431a91562af7335d3"
 
+[[package]]
+name = "yaml-rust"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56c1936c4cc7a1c9ab21a1ebb602eb942ba868cbd44a99cb7cdc5892335e1c85"
+dependencies = [
+ "linked-hash-map",
+]
+
 [[package]]
 name = "yggdrasil"
 version = "0.1.0"
@@ -4885,6 +5019,7 @@ dependencies = [
  "rand 0.8.6",
  "regex",
  "serde",
+ "syntect",
  "tokio",
  "tokio-postgres",
  "tower-http",

Cargo.toml

@@ -22,6 +22,7 @@ rand = { version = "0.8", features = ["getrandom"] }
 getrandom = { version = "0.2", features = ["js"] }
 http = "1"
 ammonia = { version = "4", optional = true }
+syntect = { version = "5", default-features = false, features = ["default-syntaxes", "default-themes", "default-fancy", "html", "parsing", "dump-load"], optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 web-sys = { version = "0.3", features = ["Document", "Window", "HtmlDocument", "Storage", "Element", "DomTokenList", "MediaQueryList", "HtmlScriptElement"] }
@@ -50,4 +51,5 @@ server = [
     "dep:tracing-subscriber",
     "dep:tower-http",
     "dep:ammonia",
+    "dep:syntect",
 ]

Makefile

@@ -1,10 +1,14 @@
-.PHONY: dev build css css-watch clean build-editor
+.PHONY: dev build css css-watch clean build-editor highlight-css
 
 build:
 	@$(MAKE) build-editor
+	@$(MAKE) highlight-css
 	@tailwindcss -i input.css -o public/style.css --minify
 	@dx build --release
 
+highlight-css:
+	@cargo run --bin generate_highlight_css
+
 build-editor:
 	@echo "Building Tiptap editor..."
 	@cd libs/tiptap-editor && npm install && npx vite build

input.css

@@ -1,4 +1,5 @@
 @import "tailwindcss";
+@import "./generated/highlight.css";
 
 @custom-variant dark (&:where(.dark, .dark *));
 
@@ -342,7 +343,6 @@
   .md-content pre {
     position: relative;
     margin-bottom: var(--content-gap-paper);
-    background: var(--color-paper-code-block);
     border-radius: var(--radius-paper);
     overflow-x: auto;
   }
@@ -350,7 +350,6 @@
   .md-content pre code {
     display: block;
     padding: 16px;
-    color: rgb(213, 213, 214);
     background: transparent;
     border-radius: 0;
     overflow-x: auto;

src/api/posts.rs

@@ -172,10 +172,13 @@ async fn ensure_unique_slug(
 fn clean_html(input: &str) -> String {
     let mut builder = ammonia::Builder::default();
     builder
-        .add_generic_attributes(&["class", "aria-hidden", "aria-label", "id", "role", "accesskey", "title"])
+        .add_generic_attributes(&["class", "style", "aria-hidden", "aria-label", "id", "role", "accesskey", "title"])
         .add_tags(&["details", "summary"])
         .url_relative(ammonia::UrlRelative::PassThrough)
         .add_tag_attributes("a", &["class", "aria-hidden", "aria-label"])
+        .add_tag_attributes("span", &["class", "style"])
+        .add_tag_attributes("pre", &["class", "style"])
+        .add_tag_attributes("code", &["class", "style"])
         .add_tag_attributes("h1", &["id", "class"])
         .add_tag_attributes("h2", &["id", "class"])
         .add_tag_attributes("h3", &["id", "class"])
@@ -243,12 +246,14 @@ fn render_markdown_enhanced(md: &str) -> RenderedContent {
     let mut html = String::new();
     let mut heading_idx = 0;
     let mut in_heading = false;
+    let mut in_codeblock = false;
+    let mut code_lang: Option<String> = None;
+    let mut code_buffer = String::new();
     let mut non_heading_events: Vec<Event> = Vec::new();
 
     for event in parser {
         match event {
             Event::Start(Tag::Heading { level, .. }) => {
-                // Flush non-heading events first
                 if !non_heading_events.is_empty() {
                     pulldown_cmark::html::push_html(&mut html, non_heading_events.into_iter());
                     non_heading_events = Vec::new();
@@ -286,9 +291,39 @@ fn render_markdown_enhanced(md: &str) -> RenderedContent {
                 }
                 in_heading = false;
             }
+            Event::Start(Tag::CodeBlock(kind)) => {
+                if !non_heading_events.is_empty() {
+                    pulldown_cmark::html::push_html(&mut html, non_heading_events.into_iter());
+                    non_heading_events = Vec::new();
+                }
+                in_codeblock = true;
+                code_lang = match kind {
+                    pulldown_cmark::CodeBlockKind::Fenced(lang) => {
+                        if lang.is_empty() {
+                            None
+                        } else {
+                            Some(lang.to_string())
+                        }
+                    }
+                    _ => None,
+                };
+                code_buffer.clear();
+            }
+            Event::Text(text) if in_codeblock => {
+                code_buffer.push_str(&text);
+            }
+            Event::End(TagEnd::CodeBlock) => {
+                let highlighted =
+                    crate::highlight::server::highlight_code(&code_buffer, code_lang.as_deref());
+                html.push_str("<pre><code>");
+                html.push_str(&highlighted);
+                html.push_str("</code></pre>");
+                in_codeblock = false;
+                code_lang = None;
+                code_buffer.clear();
+            }
             _ => {
                 if in_heading {
-                    // Manually render heading content
                     match event {
                         Event::Text(text) => html.push_str(&clean_html(&text)),
                         Event::Code(code) => {
@@ -298,7 +333,7 @@ fn render_markdown_enhanced(md: &str) -> RenderedContent {
                         }
                         _ => {}
                     }
-                } else {
+                } else if !in_codeblock {
                     non_heading_events.push(event);
                 }
             }

src/bin/generate_highlight_css.rs

@@ -0,0 +1,104 @@
+use syntect::highlighting::ThemeSet;
+use syntect::html::{css_for_theme_with_class_style, ClassStyle};
+
+fn main() {
+    let latte = ThemeSet::get_theme("themes/Catppuccin Latte.tmTheme")
+        .expect("Failed to load Catppuccin Latte theme");
+    let mocha = ThemeSet::get_theme("themes/Catppuccin Mocha.tmTheme")
+        .expect("Failed to load Catppuccin Mocha theme");
+
+    let latte_css = css_for_theme_with_class_style(&latte, ClassStyle::Spaced)
+        .expect("Failed to generate Latte CSS");
+    let mocha_css = css_for_theme_with_class_style(&mocha, ClassStyle::Spaced)
+        .expect("Failed to generate Mocha CSS");
+
+    let latte_clean = strip_comments(&latte_css);
+    let mocha_clean = strip_comments(&mocha_css);
+
+    let latte_rewritten = rewrite_rules(&latte_clean, ".md-content pre code", "");
+    let mocha_rewritten = rewrite_rules(&mocha_clean, ".md-content pre code", ".dark ");
+
+    let mut output = String::new();
+    output.push_str("/* Auto-generated by generate_highlight_css — DO NOT EDIT */\n\n");
+    output.push_str("/* Catppuccin Latte (light) */\n");
+    output.push_str(&latte_rewritten);
+    output.push_str("\n/* Catppuccin Mocha (dark) */\n");
+    output.push_str(&mocha_rewritten);
+
+    std::fs::create_dir_all("generated").expect("Failed to create generated/");
+    std::fs::write("generated/highlight.css", output)
+        .expect("Failed to write generated/highlight.css");
+
+    println!("Generated generated/highlight.css");
+}
+
+fn strip_comments(css: &str) -> String {
+    let mut result = String::with_capacity(css.len());
+    let chars: Vec<char> = css.chars().collect();
+    let mut i = 0;
+    while i < chars.len() {
+        if i + 1 < chars.len() && chars[i] == '/' && chars[i + 1] == '*' {
+            while i + 1 < chars.len() && !(chars[i] == '*' && chars[i + 1] == '/') {
+                i += 1;
+            }
+            i += 2;
+        } else {
+            result.push(chars[i]);
+            i += 1;
+        }
+    }
+    result
+}
+
+fn rewrite_rules(css: &str, base: &str, prefix: &str) -> String {
+    let mut out = String::new();
+    let mut pos = 0;
+    let bytes = css.as_bytes();
+
+    while pos < bytes.len() {
+        let rest = &css[pos..];
+
+        let open = match rest.find('{') {
+            Some(i) => i,
+            None => break,
+        };
+
+        let selector = rest[..open].trim();
+        if selector.is_empty() {
+            pos += open + 1;
+            continue;
+        }
+
+        let after_open = pos + open + 1;
+        let mut depth = 1usize;
+        let mut close = after_open;
+        while close < bytes.len() && depth > 0 {
+            if bytes[close] == b'{' {
+                depth += 1;
+            } else if bytes[close] == b'}' {
+                depth -= 1;
+            }
+            close += 1;
+        }
+
+        let body = css[after_open..close - 1].trim();
+        pos = close;
+
+        if body.is_empty() {
+            continue;
+        }
+
+        if selector == ".code" {
+            out.push_str(&format!("{}{} {{\n{}\n}}\n\n", prefix, base, body));
+        } else {
+            let rewritten = selector
+                .split(',')
+                .map(|s| format!("{}{} {}", prefix, base, s.trim()))
+                .collect::<Vec<_>>()
+                .join(",\n");
+            out.push_str(&format!("{} {{\n{}\n}}\n\n", rewritten, body));
+        }
+    }
+
+    out
+}

src/highlight.rs

@@ -0,0 +1,68 @@
+#[cfg(feature = "server")]
+pub mod server {
+    use std::sync::{LazyLock, OnceLock};
+
+    use syntect::highlighting::{Theme, ThemeSet};
+    use syntect::html::{ClassedHTMLGenerator, ClassStyle};
+    use syntect::parsing::{SyntaxReference, SyntaxSet};
+    use syntect::util::LinesWithEndings;
+
+    static SYNTAX_SET: LazyLock<SyntaxSet> =
+        LazyLock::new(|| SyntaxSet::load_defaults_newlines());
+
+    static LATTE_THEME: LazyLock<Theme> = LazyLock::new(|| {
+        ThemeSet::get_theme("themes/Catppuccin Latte.tmTheme")
+            .expect("Failed to load Catppuccin Latte theme")
+    });
+
+    static MOCHA_THEME: LazyLock<Theme> = LazyLock::new(|| {
+        ThemeSet::get_theme("themes/Catppuccin Mocha.tmTheme")
+            .expect("Failed to load Catppuccin Mocha theme")
+    });
+
+    static FALLBACK_SYNTAX: OnceLock<SyntaxReference> = OnceLock::new();
+
+    fn find_syntax(lang: Option<&str>) -> &'static SyntaxReference {
+        let ss = &*SYNTAX_SET;
+        if let Some(lang) = lang {
+            if !lang.is_empty() {
+                if let Some(s) = ss.find_syntax_by_extension(lang) {
+                    return s;
+                }
+                if let Some(s) = ss.find_syntax_by_name(lang) {
+                    return s;
+                }
+            }
+        }
+        let plain = ss
+            .find_syntax_by_extension("txt")
+            .or_else(|| ss.find_syntax_by_name("Plain Text"))
+            .expect("no plain text syntax");
+        FALLBACK_SYNTAX.get_or_init(|| plain.clone())
+    }
+
+    pub fn highlight_code(code: &str, lang: Option<&str>) -> String {
+        let syntax = find_syntax(lang);
+        let ss = &*SYNTAX_SET;
+        let mut generator =
+            ClassedHTMLGenerator::new_with_class_style(syntax, ss, ClassStyle::Spaced);
+
+        for line in LinesWithEndings::from(code) {
+            let _ = generator.parse_html_for_line_which_includes_newline(line);
+        }
+
+        generator.finalize()
+    }
+
+    pub fn get_latte_theme() -> &'static Theme {
+        &*LATTE_THEME
+    }
+
+    pub fn get_mocha_theme() -> &'static Theme {
+        &*MOCHA_THEME
+    }
+
+    pub fn get_syntax_set() -> &'static SyntaxSet {
+        &*SYNTAX_SET
+    }
+}

src/main.rs

@@ -3,6 +3,7 @@ mod auth;
 mod components;
 mod context;
 mod db;
+mod highlight;
 mod hooks;
 mod models;
 mod pages;