fix(toc): honour toc_header/level in single-wiki config + div.toc on export

Two TOC bugs:

1. :NuwikiTOC ignored toc_header / toc_header_level (always "= Contents ="
   at level 1). In the single-wiki shorthand the server only carried
   file_extension/syntax from the top-level options into the synthesized
   wiki; every other per-wiki key (toc_header, toc_header_level,
   links_header, html_path, auto_export, …) was dropped. Add
   single_wiki_from_value(), which re-parses the top-level object as a full
   RawWiki (injecting root from wiki_root), so all per-wiki keys set at the
   top level flow through. Wired into from_init_params + apply_change.

2. HTML export put class="toc" on the <hN> element, but upstream vimwiki
   (and its stylesheet) wraps the TOC heading in <div class="toc">…</div>.
   render_heading now emits the div wrapper, matching upstream so .toc CSS
   applies. With (1) fixed, detection also works for a custom toc_header.

Tests: single_wiki_shorthand_honours_top_level_per_wiki_keys (config),
toc_header_heading_wrapped_in_div_toc + non_toc_heading_not_wrapped
(renderer). Full suite 572 passed; clippy clean; config-parity goldens
match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/nuwiki-lsp/src/config.rs

@@ -639,14 +639,11 @@ impl Config {
 
         let wikis = if let Some(list) = raw.wikis {
             list.into_iter().map(WikiConfig::from).collect()
-        } else if let Some(root) = raw.wiki_root.as_deref().and_then(expand_path) {
-            let mut wc = WikiConfig::from_root(root);
-            if let Some(ext) = raw.file_extension {
-                wc.file_extension = ext;
-            }
-            if let Some(s) = raw.syntax {
-                wc.syntax = s;
-            }
+        } else if let Some(wc) = params
+            .initialization_options
+            .as_ref()
+            .and_then(single_wiki_from_value)
+        {
             vec![wc]
         } else if let Some(folder) = first_workspace_folder(params) {
             vec![WikiConfig::from_root(folder)]
@@ -687,14 +684,7 @@ impl Config {
         };
         if let Some(list) = raw.wikis {
             self.wikis = list.into_iter().map(WikiConfig::from).collect();
-        } else if let Some(root) = raw.wiki_root.as_deref().and_then(expand_path) {
-            let mut wc = WikiConfig::from_root(root);
-            if let Some(ext) = raw.file_extension {
-                wc.file_extension = ext;
-            }
-            if let Some(s) = raw.syntax {
-                wc.syntax = s;
-            }
+        } else if let Some(wc) = single_wiki_from_value(inner) {
             self.wikis = vec![wc];
         }
         // Only touch diagnostic settings when the payload carries them, so a
@@ -1042,6 +1032,32 @@ impl From<RawWiki> for WikiConfig {
     }
 }
 
+/// Build the single-wiki [`WikiConfig`] from the flat top-level options object
+/// (single-wiki shorthand: a `wiki_root` plus any per-wiki keys set alongside
+/// it). Returns `None` when there's no expandable `wiki_root` (so callers fall
+/// through to the workspace-folder default) or a `wikis` list is present.
+///
+/// Re-uses the full [`RawWiki`] schema so **every** per-wiki key set at the top
+/// level — `toc_header`/`toc_header_level`, `links_header`, `html_path`,
+/// `auto_export`, … — is honoured, not just `file_extension`/`syntax`. The
+/// shorthand keys on `wiki_root`; `RawWiki` keys on `root`, so we inject it.
+fn single_wiki_from_value(value: &serde_json::Value) -> Option<WikiConfig> {
+    let obj = value.as_object()?;
+    if obj.contains_key("wikis") {
+        return None;
+    }
+    let wiki_root = obj.get("wiki_root").and_then(|v| v.as_str())?;
+    // Bail (→ workspace-folder fallback) when the root can't be expanded.
+    expand_path(wiki_root)?;
+    let mut wiki_obj = obj.clone();
+    wiki_obj.insert(
+        "root".to_string(),
+        serde_json::Value::String(wiki_root.to_string()),
+    );
+    let raw: RawWiki = serde_json::from_value(serde_json::Value::Object(wiki_obj)).ok()?;
+    Some(WikiConfig::from(raw))
+}
+
 fn expand_path(s: &str) -> Option<PathBuf> {
     let trimmed = s.trim();
     if trimmed.is_empty() {

crates/nuwiki-lsp/tests/index_and_config.rs

@@ -152,6 +152,28 @@ fn v1_0_single_wiki_desugars_to_one_entry() {
     assert_eq!(cfg.wikis[0].syntax, "vimwiki");
 }
 
+#[test]
+fn single_wiki_shorthand_honours_top_level_per_wiki_keys() {
+    // Regression: a single-wiki user sets per-wiki keys at the top level
+    // (alongside wiki_root); they must reach the synthesized wiki, not just
+    // file_extension/syntax. Previously toc_header_level etc. were dropped.
+    let cfg = config_from_json(json!({
+        "wiki_root": "/tmp/vimwiki",
+        "toc_header": "Table of Contents",
+        "toc_header_level": 2,
+        "links_header_level": 3,
+        "auto_export": true,
+        "html_path": "/tmp/out",
+    }));
+    assert_eq!(cfg.wikis.len(), 1);
+    let w = &cfg.wikis[0];
+    assert_eq!(w.toc_header, "Table of Contents");
+    assert_eq!(w.toc_header_level, 2);
+    assert_eq!(w.links_header_level, 3);
+    assert!(w.html.auto_export);
+    assert_eq!(w.html.html_path, PathBuf::from("/tmp/out"));
+}
+
 #[test]
 fn explicit_wikis_list_overrides_legacy_shape() {
     let cfg = config_from_json(json!({