fix(tui): stop /shell dropping quotes from the command it runs

src/tui.mjs

@@ -105,6 +105,15 @@ export function splitCommandLine(line) {
   return parts;
 }
 
+// Everything after the first word of a command line, exactly as typed. `/shell`
+// hands this straight to `$SHELL -c`, the same way `!cmd` does: the shell does
+// its own parsing, so re-joining the tokenized parts would strip the user's
+// quotes and escapes and silently split `-m "two words"` into two arguments.
+function commandRemainder(line) {
+  const firstWord = /^\s*\S+\s*/.exec(String(line));
+  return firstWord ? String(line).slice(firstWord[0].length).trim() : "";
+}
+
 function printEngines() {
   console.log(bone("  engines") + ash("  — autonomous ") + acid("/agents <name>") + ash(" · raw ") + acid("/start <name>"));
   for (const e of engineStatus()) {
@@ -361,8 +370,9 @@ export async function tui() {
       continue;
     }
     if (cmd === "shell" || cmd === "sh") {
+      const rawCmd = commandRemainder(line);
       rl.close();
-      await openShell(rest.length ? rest.join(" ") : null);
+      await openShell(rawCmd || null);
       rl = mkrl();
       continue;
     }

test/tui.test.mjs

@@ -80,3 +80,28 @@ test("TUI /run passes positional args through to moshscript argv", () => {
   assert.match(result.stdout, /alpha/);
   assert.match(result.stdout, /two words/);
 });
+
+// `/shell <cmd>` and `!<cmd>` are the same feature — both hand the command to
+// `$SHELL -c`, which does its own parsing. Re-joining the tokenized parts drops
+// the user's quotes, so `-m "two words"` reaches the shell as two arguments.
+const posixShell = process.platform === "win32" ? { skip: "needs a POSIX shell" } : {};
+
+test("TUI /shell hands the raw command line to the shell, quoting intact", posixShell, async () => {
+  const result = await runTui('/shell printf "[%s]\\n" "two words"\n/quit\n');
+
+  assert.equal(result.status, 0);
+  assert.match(result.stdout, /\[two words\]/);
+  assert.doesNotMatch(result.stdout, /\[two\]/);
+});
+
+test("TUI /shell and !cmd run an identical command identically", posixShell, async () => {
+  const command = 'printf "[%s]\\n" "two words"';
+  const bracketed = (out) => out.match(/\[[^\]\n]*\]/g) || [];
+
+  const viaSlash = await runTui(`/shell ${command}\n/quit\n`);
+  const viaBang = await runTui(`!${command}\n/quit\n`);
+
+  assert.equal(viaSlash.status, 0);
+  assert.equal(viaBang.status, 0);
+  assert.deepEqual(bracketed(viaSlash.stdout), bracketed(viaBang.stdout));
+});