fix(text-splitters): prevent JSFrameworkTextSplitter from mutating self._separators on each split_text() call (#35316)

libs/text-splitters/langchain_text_splitters/jsx.py

@@ -92,11 +92,15 @@ class JSFrameworkTextSplitter(RecursiveCharacterTextSplitter):
             "\ndefault ",
             " default ",
         ]
+        # Build the effective separator list for this call only.
+        # Do NOT assign back to self._separators: doing so would permanently
+        # append js_separators + component_separators on every invocation,
+        # causing the list to grow unboundedly when split_text() is called
+        # multiple times on the same instance.
         separators = (
             self._separators
             + js_separators
             + component_separators
             + ["<>", "\n\n", "&&\n", "||\n"]
         )
-        self._separators = separators
-        return super().split_text(text)
+        return self._split_text(text, separators)

libs/text-splitters/tests/unit_tests/test_text_splitters.py

@@ -624,6 +624,34 @@ def test_svelte_text_splitter() -> None:
     assert [s.strip() for s in splits] == [s.strip() for s in expected_splits]
 
 
+def test_jsx_splitter_separator_not_mutated_across_calls() -> None:
+    """Regression test: repeated split_text() calls must not mutate separators.
+
+    Calling split_text() multiple times on the same JSFrameworkTextSplitter
+    instance must not grow the internal separator list between calls.
+
+    Before the fix, self._separators was overwritten with the full expanded list
+    on every invocation, so a second call would start with the already-expanded
+    list and append even more separators.
+    """
+    splitter = JSFrameworkTextSplitter(chunk_size=30, chunk_overlap=0)
+
+    # Record separator count after constructing (should be 0 - no custom separators)
+    initial_sep_count = len(splitter._separators)
+
+    # Call split_text twice; the results should be identical for identical input
+    splits_first = splitter.split_text(FAKE_JSX_TEXT)
+    splits_second = splitter.split_text(FAKE_JSX_TEXT)
+
+    assert splits_first == splits_second, (
+        "split_text() must return identical results on repeated calls with the "
+        "same input"
+    )
+    assert len(splitter._separators) == initial_sep_count, (
+        "split_text() must not mutate self._separators between calls"
+    )
+
+
 CHUNK_SIZE = 16