fix: parser mishandles escapes in quoted arguments

src/parser.ts

@@ -60,10 +60,20 @@ function tokenizeCommand(input) {
     const ch = input[i];
 
     if (quote) {
+      // In single-quoted strings, everything is literal (no escape processing)
+      if (quote === "'") {
+        if (ch === "'") {
+          quote = null;
+          continue;
+        }
+        current += ch;
+        continue;
+      }
+      // In double-quoted strings, preserve escape sequences (backslash + next char)
       if (ch === '\\') {
         const next = input[i + 1];
         if (next) {
-          current += next;
+          current += ch + next;
           i++;
           continue;
         }

test/parser.test.ts

@@ -18,3 +18,19 @@ test('parsePipeline keeps quoted pipes', () => {
   assert.equal(p.length, 2);
   assert.deepEqual(p[0].args._, ['echo', 'a|b']);
 });
+
+test('single-quoted strings are fully literal (no escape processing)', () => {
+  const p = parsePipeline("exec echo 'hello\\nworld'");
+  assert.deepEqual(p[0].args._, ['echo', 'hello\\nworld']);
+});
+
+test('double-quoted strings preserve escape sequences', () => {
+  const p = parsePipeline('exec echo "line1\\nline2"');
+  assert.deepEqual(p[0].args._, ['echo', 'line1\\nline2']);
+});
+
+test('--args-json with escaped JSON in double quotes', () => {
+  const p = parsePipeline('invoke --args-json "{\\"prompt\\":\\"line1\\\\nline2\\"}"');
+  // Backslashes are preserved in double-quoted strings: \" stays as \"
+  assert.equal(p[0].args['args-json'], '{\\"prompt\\":\\"line1\\\\nline2\\"}');
+});