fix: escape the union operator in tag filter values

redisvl/mcp/filters.py

@@ -23,8 +23,8 @@
 # Dropping them costs nothing in containment, because containment comes from the
 # delimiters rather than from these. With `(` and `)` escaped, the value cannot
 # close its own `@field:(...)`, so anything it carries -- including a `|`, which
-# no escaper in RedisVL touches -- stays scoped to this one field instead of
-# reaching the surrounding expression.
+# the like path deliberately leaves live so a pattern can express a union --
+# stays scoped to this one field instead of reaching the surrounding expression.
 _LIKE_ESCAPED_CHARS = re.compile(r"[,.<>{}\[\]\\\"\':;!@#$^&()\-+=~\/]")
 _LIKE_ESCAPER = TokenEscaper(escape_chars_re=_LIKE_ESCAPED_CHARS)
 

redisvl/utils/token_escaper.py

@@ -10,9 +10,12 @@ class TokenEscaper:
 
     # Characters that Redis Search requires us to escape during queries.
     # Source: https://redis.io/docs/latest/develop/ai/search-and-query/advanced-concepts/escaping/
-    DEFAULT_ESCAPED_CHARS = r"[,.<>{}\[\]\\\"\':;!@#$%^&*()\-+=~\/ \?]"
+    DEFAULT_ESCAPED_CHARS = r"[,.<>{}\[\]\\\"\':;!@#$%^&*()\-+=~|\/ \?]"
 
-    # Same as above but excludes * and ? to allow wildcard patterns
+    # Same as above but excludes * and ? to allow wildcard patterns, and `|`
+    # because the `%` (LIKE) operator documents it as a union between wildcard
+    # patterns -- see `Tag.__mod__`. On the default path `|` is escaped, since
+    # a value carrying one would otherwise widen its clause into a union.
     ESCAPED_CHARS_NO_WILDCARD = r"[,.<>{}\[\]\\\"\':;!@#$%^&()\-+=~\/ ]"
 
     def __init__(self, escape_chars_re: Pattern | None = None):

tests/unit/test_filter.py

@@ -107,6 +107,19 @@ def test_tag_wildcard_preserves_asterisk():
     assert str(tf_like) == "@tag_field:{tech*}"
 
 
+def test_tag_equality_escapes_pipe_but_list_still_unions():
+    """A `|` inside one tag value is literal; a list of values is still a union."""
+    # Unescaped, this value would widen its clause into a union across tenants.
+    assert str(Tag("tenant_id") == "acme|victim") == "@tenant_id:{acme\\|victim}"
+    assert str(Tag("tenant_id") != "acme|victim") == "(-@tenant_id:{acme\\|victim})"
+
+    # Values are escaped before being joined, so the list form is unaffected.
+    assert str(Tag("tenant_id") == ["acme", "victim"]) == "@tenant_id:{acme|victim}"
+
+    # The % operator documents `|` as a union between wildcard patterns.
+    assert str(Tag("category") % "elec*|*soft") == "@category:{elec*|*soft}"
+
+
 def test_tag_wildcard_combined_with_exact_match():
     """Test combining wildcard and exact match Tag filters in the same query."""
     # Create filters with different operators

tests/unit/test_token_escaper.py

@@ -121,3 +121,24 @@ def test_escape_long_string(escaper):
     # Use pytest's benchmark fixture to check performance
     escaped = escaper.escape(long_str)
     assert escaped == expected
+
+
+@pytest.mark.parametrize(
+    ("test_input,expected"),
+    [
+        ("acme|victim", r"acme\|victim"),
+        ("a|b|c", r"a\|b\|c"),
+        ("|leading", r"\|leading"),
+    ],
+    ids=["pair", "chain", "leading"],
+)
+def test_escape_pipe_on_the_default_path(escaper, test_input, expected):
+    # A `|` is RediSearch's union operator and binds looser than the implicit
+    # intersection, so one reaching the query string raw widens its clause.
+    assert escaper.escape(test_input) == expected
+
+
+def test_pipe_stays_live_when_wildcards_are_preserved(escaper):
+    # The `%` operator documents `|` as a union between wildcard patterns, so
+    # the no-wildcard class must not escape it.
+    assert escaper.escape("elec*|*soft", preserve_wildcards=True) == "elec*|*soft"