feat: Added margin notes support.

AGENTS.md

@@ -5,10 +5,10 @@ Thor is a static site generator written in [Odin](https://odin-lang.org), replac
 ## Architecture
 
 ```
-thor.json          ← site config (title, base_url, author, params)
+thor.json          ← site config (title, base_url, author, params, sectionate)
 content/           ← markdown and HTML content files
-layouts/           ← Mustache templates + partials
-assets/            ← CSS (Tufte-based) and JS
+layouts/           ← Mustache templates + partials (including icons)
+assets/            ← CSS (Tufte-based, no build step) and JS
 public/            ← build output (generated)
 ```
 
@@ -16,13 +16,16 @@ public/            ← build output (generated)
 
 | File | Responsibility |
 |---|---|
-| `main.odin` | Entry point. Calls `init_site`, `walk_content`, `render_site` |
+| `main.odin` | Entry point. Sets `context.logger`, calls `init_site`, `walk_content`, `render_site` |
 | `site.odin` | `Site` struct (config + arena), `init_site`, `load_site_config`, `site_merge`, `site_allocator`, `destroy_site` |
 | `frontmatter.odin` | JSON frontmatter parser (`{ }` delimited) |
-| `content.odin` | `Page` struct, content walker, page loader, cmark integration, footnote/alert/emoji pipeline |
-| `footnotes.odin` | Footnote definition stripping (pre-cmark) + sidenote injection (post-cmark) |
+| `content.odin` | `Page` struct, content walker, page loader, cmark integration, full markdown pipeline |
+| `footnotes.odin` | Note definition stripping (pre-cmark) + sidenote/marginnote injection (post-cmark) |
 | `alerts.odin` | GitHub alert post-processor (`> [!CAUTION]` → styled blockquote) |
 | `emoji.odin` | Emoji shortcode expander (`:shrug:` → `¯\_(ツ)_/¯`) |
+| `highlight.odin` | Post-cmark Tree-sitter syntax highlighter; loads grammars/queries from Helix, caches loaded grammars, reports syntax errors with file/line |
+| `tree_sitter.odin` | C FFI bindings for Tree-sitter (TSParser, TSQuery, TSQueryCursor, node traversal, dlopen/dlsym) |
+| `sectionate.odin` | `wrap_sections` proc — splits HTML at `<h2` into `<section>` wrappers |
 | `render.odin` | Mustache template rendering, all page types, RSS, sitemap, robots.txt, `load_partials` recursive scan |
 | `feed.odin` | RSS feed + sitemap XML generation |
 | `mustache/` | Vendored [odin-mustache](https://github.com/benjamindblock/odin-mustache) library |
@@ -34,20 +37,21 @@ Icon SVGs live as HTML partials in `layouts/partials/icons/` (home, github, rss,
 ```
 thor.json → init_site → Site (config + Dynamic_Arena)
                             ↓
-content/ → walk_content → []Page (with body_html from cmark pipeline)
+content/ → walk_content → []Page (with body_html from pipeline)
                             ↓
 layouts/*.html → render_site (Mustache render_in_layout) → public/
 ```
 
 ### Config system
 
-`Site` has `params: json.Value` for arbitrary user-defined data from `thor.json`. Social links and other template-only data live under `"params"`:
+`Site` has `params: json.Value` for arbitrary user-defined data from `thor.json`. Social links and other template-only data live under `"params"`. `sectionate: bool` controls automatic `<section>` wrapping at `<h2>` boundaries.
 
 ```json
 {
   "title": "...",
   "base_url": "...",
   "author": "...",
+  "sectionate": true,
   "params": {
     "social": [
       { "name": "github", "url": "...", "icon": "icons/github" }
@@ -69,10 +73,24 @@ raw markdown
   → cmark markdown_to_html (Unsafe mode for HTML passthrough)
   → inject_sidenotes      (post-cmark: [^id] → <label><input><span> markup)
   → inject_alerts         (post-cmark: [!TYPE] blockquotes → styled alerts)
+  → highlight_code        (post-cmark: tree-sitter per code block, with error reporting)
+  → wrap_sections         (post-cmark: if site.sectionate, wraps content in <section> at <h2>)
 ```
 
 `.html` content files skip cmark entirely — body is used as-is.
 
+### Syntax highlighting
+
+Build-time highlighting via Tree-sitter C FFI. No client-side JavaScript.
+
+- Grammars loaded via `dlopen` from Helix's compiled `.so` files
+- Highlight queries (`.scm`) loaded from Helix's runtime directory
+- Paths hardcoded in `tree_sitter.odin` (Nix store paths, Helix-version-dependent)
+- Capture names mapped to CSS classes: `keyword` → `.hl-keyword`, `constant.numeric.integer` → `.hl-constant-numeric-integer`, etc.
+- Atom-one-dark color theme in `main.css`
+- Failed grammar loads are cached (no retries) and logged via `log.warnf`
+- Syntax errors detected via `ts_node_has_error`, reported with file path and line number relative to code block
+
 ### Memory management
 
 - `Site` owns a `mem.Dynamic_Arena`
@@ -80,6 +98,7 @@ raw markdown
 - Config loading (flags + JSON) uses the arena allocator explicitly
 - `site_allocator(site)` returns the arena allocator for callers
 - `destroy_site` frees the arena
+- `main.odin` sets `context.logger = log.create_console_logger()` — without this, all `log.*` calls are silently dropped
 - **Not yet wired:** `context.allocator` is not set to the arena in `main.odin`, so rendering and content processing still use the heap allocator
 
 ## Building
@@ -90,12 +109,12 @@ raw markdown
 nix develop
 # From blog root:
 odin run ./thor -- -drafts
-cp assets/css/tufte.css public/css/tufte.css
+cp assets/css/main.css public/css/main.css
 cp assets/js/main.js public/js/main.js
 caddy run  # serves public/ on blog.localhost
 ```
 
-No CSS build step — `tufte.css` is static CSS, no preprocessor or compiler needed.
+No CSS build step — `main.css` is static Tufte-based CSS, no preprocessor or compiler needed.
 
 ### Production build
 
@@ -119,7 +138,7 @@ Four modifications to `mustache/mustache.odin`:
 
 2. **Layout partials** — `layout_template.partials = tmpl.partials` added so partials (`{{> nav}}`, `{{> footer}}`) work inside the base layout template.
 
-3. **Inline partial rendering** — replaced `template_insert_partial` (which injected tokens into the main token list, breaking section iteration) with `template_render_partial` (which lexes the partial, temporarily swaps `tmpl.lexer`, and recursively processes via `template_process_tokens`). Fixes partials inside sections.
+3. **Inline partial rendering** — replaced `template_insert_partial` (which injected tokens into the main token list, breaking section iteration) with `template_render_partial` (which lexes the partial, temporarily swaps `tmpl.lexer`, and recursively processes via `template_process_tokens`). Fixes partials inside sections. Standalone indentation applied to partial source before lexing.
 
 4. **Dynamic Names** — `{{>*key}}` support. When a partial token value starts with `*`, the remaining key is resolved from the data context stack, and the resolved string is used as the partial name. Enables per-item partial selection inside sections (e.g., `{{>* icon}}` resolves `icon` from each social link).
 
@@ -131,6 +150,14 @@ Extracted `template_process_tokens` from `template_eat_tokens` to separate ROOT
 - CSS/JS cache busting uses manual `?v=N` query params instead of content hashing.
 - The `shrug` emoji has a backslash that may not display correctly.
 - `json.Value` params require 64-byte aligned arena (workaround for `dynamic_arena_allocator_proc` ignoring per-allocation alignment).
+- Tree-sitter grammar/query paths hardcoded in `tree_sitter.odin` (Nix store hashes, Helix-version-dependent).
+- `TSQueryCapture` needs explicit `_padding: u32` field for C ABI compatibility (40-byte sizeof).
+- `{{&content}}` in layout template must have no leading whitespace — `template_insert_content_into_layout` indents all lines by preceding whitespace, which corrupts `<pre>` blocks.
+- highlight.js removed; syntax highlighting is build-time only (no fallback if Tree-sitter fails).
+
+## Design decisions
+
+See `HUGO.md` for analysis of why thor doesn't need Hugo's shortcode context isolation.
 
 ## TODO