test(config): verify Vim/Neovim config payload parity

Expose the init_options payload builders publicly in both clients
(M.init_options/M.server_settings in Lua, nuwiki#lsp#settings() in Vim) so
they can be inspected. Add editor harnesses that dump each client's
server-bound config as deterministic key=value lines and diff against a
shared golden file: nvim == golden and vim == golden together prove the two
clients send identical config. Add a server-side test asserting the Vim flat
shape and the Neovim {nuwiki:{...}} wrapper desugar to the same WikiConfig.
Wire both harnesses into CI.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/nuwiki-lsp/tests/index_and_config.rs

@@ -319,6 +319,54 @@ fn raw_wiki_parses_every_new_key() {
     assert!(w.auto_toc);
 }
 
+#[test]
+fn vim_flat_and_neovim_wrapped_payloads_desugar_identically() {
+    // Parity guard for the two client shapes:
+    //   * Vim   (`autoload/nuwiki/lsp.vim`)  → flat init_options dict.
+    //   * Neovim (`lua/nuwiki/lsp.lua`)       → `{ nuwiki = { … } }` for
+    //     `workspace/didChangeConfiguration` (server_settings()).
+    // Both must produce the same wikis; otherwise switching editors would
+    // silently change how the server resolves links/diary/HTML paths.
+    let inner = json!({
+        "wiki_root": "/tmp/base",
+        "file_extension": ".md",
+        "syntax": "vimwiki",
+        "log_level": "debug",
+        "wikis": [
+            {
+                "name": "personal",
+                "root": "/tmp/personal",
+                "file_extension": ".wiki",
+                "index": "home",
+                "diary_rel_path": "journal",
+            },
+            { "name": "work", "root": "/tmp/work" },
+        ],
+    });
+
+    let flat = config_from_json(inner.clone());
+    let wrapped = config_from_json(json!({ "nuwiki": inner }));
+
+    assert_eq!(flat.wikis.len(), wrapped.wikis.len());
+    for (a, b) in flat.wikis.iter().zip(wrapped.wikis.iter()) {
+        assert_eq!(a.name, b.name);
+        assert_eq!(a.root, b.root);
+        assert_eq!(a.file_extension, b.file_extension);
+        assert_eq!(a.syntax, b.syntax);
+        assert_eq!(a.index, b.index);
+        assert_eq!(a.diary_rel_path, b.diary_rel_path);
+    }
+
+    // And the desugared list matches the per-wiki values both clients send.
+    assert_eq!(flat.wikis[0].name, "personal");
+    assert_eq!(flat.wikis[0].root, PathBuf::from("/tmp/personal"));
+    assert_eq!(flat.wikis[0].file_extension, ".wiki");
+    assert_eq!(flat.wikis[0].index, "home");
+    assert_eq!(flat.wikis[0].diary_rel_path, "journal");
+    assert_eq!(flat.wikis[1].name, "work");
+    assert_eq!(flat.wikis[1].root, PathBuf::from("/tmp/work"));
+}
+
 #[test]
 fn legacy_single_wiki_shape_picks_up_defaults() {
     let cfg = config_from_json(serde_json::json!({