fix(vim): only shadow leader keys, not operators a mapping starts with

Since #2355 every rc mapping unmapped the built-in bound to its first key,
so a mapping such as nmap dx or nnoremap yz disabled d / c / y entirely,
and the built-in stayed gone after the mapping was removed. Shadow only the
single-key motions a leader reuses (<Space>, <BS>, <Del>, comma, semicolon
and their variants) and always restore them on the next rc apply.

src/features/vim/__tests__/vim.test.ts

@@ -173,6 +173,21 @@ describe("Vim engine", () => {
     d();
   });
 
+  it.each([
+    ["nmap dx <Action>(GotoFile)", ["d", "w"], "two\nthree"],
+    ["nmap cs <Action>(GotoFile)", ["c", "w"], " two\nthree"],
+    ["nnoremap yz yy", ["y", "y", "p"], "one two\none two\nthree"],
+  ])("keeps built-in operators a mapping starts with (%s)", async (rc, keys, doc) => {
+    const view = makeView();
+    const cm = getCM(view)!;
+    applyRcCommands(parseVimrc(rc).commands);
+    for (const k of keys) Vim.handleKey(cm as never, k, "user");
+    await tick();
+    expect(view.state.doc.toString()).toBe(doc);
+    applyRcCommands([]);
+    view.destroy();
+  });
+
   it("restores the built-in key the leader shadowed once the rc stops using it (#2337)", async () => {
     const view = makeView();
     const cm = getCM(view)!;

src/features/vim/engine.ts

@@ -327,10 +327,10 @@ const LEADER_BUILTIN_DEFAULTS: Record<string, Record<string, unknown>> = {
 };
 
 /** Built-ins unmapped to make room for a user mapping's first key, by key. */
-const shadowedBuiltins = new Map<string, Record<string, unknown> | null>();
+const shadowedBuiltins = new Map<string, Record<string, unknown>>();
 
 function firstKey(lhs: string): string {
-  return /^<[CSMA]-*\w+>|^./i.exec(lhs)?.[0] ?? lhs;
+  return /^<[^<>]+>|^./.exec(lhs)?.[0] ?? lhs;
 }
 
 /** Applies rc commands (replacing earlier rc mappings). Returns problems to report. */
@@ -342,17 +342,19 @@ export function applyRcCommands(commands: readonly RcCommand[]): string[] {
   // one's first keys collide with. Restoring first keeps mapclear's
   // user/default boundary honest — it assumes the default region never shrank.
   for (const [key, entry] of shadowedBuiltins) {
-    if (entry) Vim._mapCommand(entry as never);
+    Vim._mapCommand(entry as never);
     shadowedBuiltins.delete(key);
   }
 
   for (const c of commands) {
     if (c.kind !== "map" && c.kind !== "mapEx") continue;
     const key = firstKey(c.lhs);
+    // Only the single-key motions a leader reuses: unmapping an operator or prefix
+    // (`d`, `c`, `y`, `<C-d>`…) would break every command built on it.
+    const builtin = LEADER_BUILTIN_DEFAULTS[key];
+    if (!builtin || shadowedBuiltins.has(key)) continue;
     // The builtins this shadows are context-less; `undefined` matches them.
-    if (!shadowedBuiltins.has(key) && Vim.unmap(key, undefined as unknown as string)) {
-      shadowedBuiltins.set(key, LEADER_BUILTIN_DEFAULTS[key] ?? null);
-    }
+    if (Vim.unmap(key, undefined as unknown as string)) shadowedBuiltins.set(key, builtin);
   }
   for (const c of commands) {
     try {