phase 17: html export commands + extended template vars

HtmlRenderer (nuwiki-core):
- `with_var(k, v)` / `with_vars(map)` add arbitrary `{{key}}`
  substitution alongside the existing `{{title}}` / `{{content}}`.
  Substitution order: content → title → user vars, so a rendered body
  that happens to contain a literal `{{title}}` isn't double-processed.

WikiConfig (nuwiki-lsp/config):
- New `html: HtmlConfig` field with per-wiki export options matching
  vimwiki's `g:vimwiki_*` keys: `html_path`, `template_path`,
  `template_default`, `template_ext`, `template_date_format`,
  `css_name`, `auto_export`, `html_filename_parameterization`,
  `exclude_files`. Defaults: `<root>/_html` and `<root>/_templates`.
- `RawWiki` accepts all of the above through `initializationOptions`
  (and `workspace/didChangeConfiguration` reload).

New `export` module (pure helpers):
- `output_path_for` — page name → on-disk HTML path. Slugifies only
  the final segment when `html_filename_parameterization = true` so
  the `diary/` subdir survives.
- `template_for` — primary/fallback path lookup tuple.
- `fallback_template` — minimal in-memory page used when neither
  template file exists.
- `format_date` — strftime subset (`%Y`/`%m`/`%d`/`%%`) so we don't
  depend on `chrono`/`time`.
- `build_toc_html` — nested `<ul class="toc">` from the doc's
  headings, with HTML escaping.
- `compute_root_path` — `../` prefix per directory depth for
  stylesheet hrefs in nested pages.
- `is_excluded` — glob matcher supporting `*`, `**`, `?`. Used by
  the `allToHtml*` walker against `exclude_files`.
- `render_page_html` — wires the above into HtmlRenderer with
  `{{date}}`, `{{root_path}}`, `{{toc}}`, `{{css}}` populated.
- `DEFAULT_CSS` — minimal stylesheet bundled for first-time exports.

New commands:
- `nuwiki.export.currentToHtml` — render the current buffer; honours
  `%nohtml` and `%template`; ensures CSS exists.
- `nuwiki.export.allToHtml` — walk the wiki root, skip pages matched
  by `exclude_files` and `%nohtml`, and only re-export pages whose
  source is newer than the existing HTML (incremental behaviour
  matching `:VimwikiAll2HTML`).
- `nuwiki.export.allToHtmlForce` — same but unconditional re-export.
- `nuwiki.export.browse` — alias of currentToHtml that returns the
  `file://` URL of the rendered page in the response so the client
  can open it.
- `nuwiki.export.rss` — write `<html_path>/rss.xml` listing the
  wiki's diary entries newest-first.
- `did_save` handler — runs the auto-export equivalent when the
  resolved wiki has `auto_export = true`.

LSP capability:
- `text_document_sync` switched from `Kind(FULL)` to `Options(...)`
  so the server can register a `save` notification (otherwise
  clients never push `did_save` events).

Tests: 33 new in `phase17_html_export.rs` covering HtmlConfig
defaults + JSON-shape config, the `format_date` subset (including
the `%%` escape and pass-through for unsupported specifiers),
root-path computation, output-path slugification rules, the glob
matcher (single-star, globstar, question-mark, non-match),
template_for primary/fallback selection, render_page_html for the
title/content/date/root_path triad and the override-by-extras flow,
and side-effecting disk paths (write_page creates parents, picks up
on-disk template, RSS is newest-first, ensure_css is idempotent).
Total 357 tests pass; fmt + clippy clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/nuwiki-lsp/src/lib.rs

@@ -26,6 +26,7 @@ pub mod config;
 pub mod diagnostics;
 pub mod diary;
 pub mod edits;
+pub mod export;
 pub mod index;
 pub mod nav;
 pub mod rename;
@@ -44,19 +45,21 @@ use tower_lsp::lsp_types::{
     CompletionItem, CompletionItemKind, CompletionOptions, CompletionParams, CompletionResponse,
     DeleteFilesParams, Diagnostic, DiagnosticSeverity, DidChangeConfigurationParams,
     DidChangeTextDocumentParams, DidCloseTextDocumentParams, DidOpenTextDocumentParams,
-    DocumentSymbol, DocumentSymbolParams, DocumentSymbolResponse, ExecuteCommandOptions,
-    ExecuteCommandParams, FileOperationFilter, FileOperationPattern, FileOperationPatternKind,
-    FileOperationRegistrationOptions, GotoDefinitionParams, GotoDefinitionResponse, Hover,
-    HoverContents, HoverParams, HoverProviderCapability, InitializeParams, InitializeResult,
-    InitializedParams, Location, MarkupContent, MarkupKind, MessageType, OneOf,
-    PositionEncodingKind, ProgressParams, ProgressParamsValue, ProgressToken, Range,
-    ReferenceParams, RenameFilesParams, RenameParams, SemanticTokens, SemanticTokensFullOptions,
-    SemanticTokensOptions, SemanticTokensParams, SemanticTokensRangeParams,
-    SemanticTokensRangeResult, SemanticTokensResult, SemanticTokensServerCapabilities,
-    ServerCapabilities, ServerInfo, SymbolInformation as LspSymbolInformation, SymbolKind,
-    TextDocumentSyncCapability, TextDocumentSyncKind, Url, WorkDoneProgress, WorkDoneProgressBegin,
-    WorkDoneProgressEnd, WorkDoneProgressOptions, WorkspaceEdit,
-    WorkspaceFileOperationsServerCapabilities, WorkspaceServerCapabilities, WorkspaceSymbolParams,
+    DidSaveTextDocumentParams, DocumentSymbol, DocumentSymbolParams, DocumentSymbolResponse,
+    ExecuteCommandOptions, ExecuteCommandParams, FileOperationFilter, FileOperationPattern,
+    FileOperationPatternKind, FileOperationRegistrationOptions, GotoDefinitionParams,
+    GotoDefinitionResponse, Hover, HoverContents, HoverParams, HoverProviderCapability,
+    InitializeParams, InitializeResult, InitializedParams, Location, MarkupContent, MarkupKind,
+    MessageType, OneOf, PositionEncodingKind, ProgressParams, ProgressParamsValue, ProgressToken,
+    Range, ReferenceParams, RenameFilesParams, RenameParams, SaveOptions, SemanticTokens,
+    SemanticTokensFullOptions, SemanticTokensOptions, SemanticTokensParams,
+    SemanticTokensRangeParams, SemanticTokensRangeResult, SemanticTokensResult,
+    SemanticTokensServerCapabilities, ServerCapabilities, ServerInfo,
+    SymbolInformation as LspSymbolInformation, SymbolKind, TextDocumentSyncCapability,
+    TextDocumentSyncKind, TextDocumentSyncOptions, TextDocumentSyncSaveOptions, Url,
+    WorkDoneProgress, WorkDoneProgressBegin, WorkDoneProgressEnd, WorkDoneProgressOptions,
+    WorkspaceEdit, WorkspaceFileOperationsServerCapabilities, WorkspaceServerCapabilities,
+    WorkspaceSymbolParams,
 };
 use tower_lsp::{Client, LanguageServer, LspService, Server};
 
@@ -293,8 +296,19 @@ impl LanguageServer for Backend {
         Ok(InitializeResult {
             capabilities: ServerCapabilities {
                 position_encoding,
-                text_document_sync: Some(TextDocumentSyncCapability::Kind(
-                    TextDocumentSyncKind::FULL,
+                text_document_sync: Some(TextDocumentSyncCapability::Options(
+                    TextDocumentSyncOptions {
+                        open_close: Some(true),
+                        change: Some(TextDocumentSyncKind::FULL),
+                        will_save: None,
+                        will_save_wait_until: None,
+                        // Phase 17 `auto_export` listens on `did_save`. Asking
+                        // for `include_text: false` since the document store
+                        // already mirrors the live buffer.
+                        save: Some(TextDocumentSyncSaveOptions::SaveOptions(SaveOptions {
+                            include_text: Some(false),
+                        })),
+                    },
                 )),
                 document_symbol_provider: Some(OneOf::Left(true)),
                 workspace_symbol_provider: Some(OneOf::Left(true)),
@@ -440,6 +454,54 @@ impl LanguageServer for Backend {
         }
     }
 
+    async fn did_save(&self, params: DidSaveTextDocumentParams) {
+        // Phase 17: when `auto_export` is set on the resolved wiki, run
+        // the equivalent of `nuwiki.export.currentToHtml` after the file
+        // hits disk. Best-effort — failures are logged but do not bubble
+        // to the client. Skips pages with the `%nohtml` directive.
+        let uri = params.text_document.uri.clone();
+        let wiki = match self.wiki_for_uri(&uri) {
+            Some(w) => w,
+            None => return,
+        };
+        if !wiki.config.html.auto_export {
+            return;
+        }
+        let doc = match self.documents.get(&uri) {
+            Some(d) => d,
+            None => return,
+        };
+        if doc.ast.metadata.nohtml {
+            return;
+        }
+        let name = index::page_name_from_uri(&uri, Some(&wiki.config.root));
+        let outcome = commands::export_ops::write_page(&doc.ast, &name, &wiki.config);
+        drop(doc);
+        match outcome {
+            Ok(out) => {
+                let _ = commands::export_ops::ensure_css(&wiki.config);
+                self.client
+                    .log_message(
+                        MessageType::INFO,
+                        format!(
+                            "nuwiki: auto-exported {} → {}",
+                            name,
+                            out.output_path.display()
+                        ),
+                    )
+                    .await;
+            }
+            Err(e) => {
+                self.client
+                    .log_message(
+                        MessageType::ERROR,
+                        format!("nuwiki: auto-export of {name} failed — {e}"),
+                    )
+                    .await;
+            }
+        }
+    }
+
     async fn did_close(&self, params: DidCloseTextDocumentParams) {
         let uri = &params.text_document.uri;
         self.documents.remove(uri);