diff --git a/grammar/errors.json b/grammar/errors.json
index b25d411..a9d4739 100644
--- a/grammar/errors.json
+++ b/grammar/errors.json
@@ -2,7 +2,7 @@
   "format": 1,
   "generated_by": "grammar_gen.py",
   "note": "Every construction of _ParseError, _SemanticError, _RuntimeError, BuildError, LexError, ValueError, RuntimeError, or TypeError found by walking the AST of every .py file directly under src/liminate/. Liminate's errors carry no tag field -- unlike Planes' errors.json, there is no tags index here grouping entries by a shared identifier, because there is no shared identifier to group by. An id is assigned per entry (file.class.function[-N]) purely so a reader has something stable to point at; it is not a tag the source declares.",
-  "count": 360,
+  "count": 361,
   "literal_message_count": 91,
   "entries": [
     {
@@ -677,17 +677,29 @@
     {
       "id": "analyzer._SemanticError._check_condition-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1398",
+      "source": "analyzer.py:1399",
       "raised_in": "_check_condition",
       "template": "Unknown comparison operator '{cond.op}'.",
       "slots": [
         "cond.op"
       ]
     },
+    {
+      "id": "analyzer._SemanticError._refuse_membership_over_a_known_scalar",
+      "class": "_SemanticError",
+      "source": "analyzer.py:1423",
+      "raised_in": "_refuse_membership_over_a_known_scalar",
+      "template": "'{word}' tests whether a list holds a value, and '{label}' is {_singular(t)}. Liminate has no text-contains test.",
+      "slots": [
+        "word",
+        "label",
+        "_singular(t)"
+      ]
+    },
     {
       "id": "analyzer._SemanticError._require_comparable",
       "class": "_SemanticError",
-      "source": "analyzer.py:1406",
+      "source": "analyzer.py:1434",
       "raised_in": "_require_comparable",
       "template": "'{op}' requires numbers or dates, but '{label}' is {_singular(t)}.",
       "slots": [
@@ -699,7 +711,7 @@
     {
       "id": "analyzer._SemanticError._resolve_field-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1466",
+      "source": "analyzer.py:1494",
       "raised_in": "_resolve_field",
       "template": null,
       "slots": [],
@@ -708,7 +720,7 @@
     {
       "id": "analyzer._SemanticError._resolve_field-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1474",
+      "source": "analyzer.py:1502",
       "raised_in": "_resolve_field",
       "template": "In a list of {_plural(iterator.scalar_type or 'items')}, use 'each' to refer to the current item.",
       "slots": [
@@ -718,7 +730,7 @@
     {
       "id": "analyzer._SemanticError._resolve_field-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:1478",
+      "source": "analyzer.py:1506",
       "raised_in": "_resolve_field",
       "template": "Unexpected field reference.",
       "slots": []
@@ -726,7 +738,7 @@
     {
       "id": "analyzer._SemanticError._resolve_value",
       "class": "_SemanticError",
-      "source": "analyzer.py:1527",
+      "source": "analyzer.py:1555",
       "raised_in": "_resolve_value",
       "template": "Unexpected value in condition.",
       "slots": []
@@ -734,7 +746,7 @@
     {
       "id": "analyzer._SemanticError._check_sum-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1542",
+      "source": "analyzer.py:1570",
       "raised_in": "_check_sum",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -744,7 +756,7 @@
     {
       "id": "analyzer._SemanticError._check_sum-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1549",
+      "source": "analyzer.py:1577",
       "raised_in": "_check_sum",
       "template": "I can only sum numbers. '{name}' contains text.",
       "slots": [
@@ -754,7 +766,7 @@
     {
       "id": "analyzer._SemanticError._check_sum-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:1551",
+      "source": "analyzer.py:1579",
       "raised_in": "_check_sum",
       "template": "I can only sum numbers. '{name}' contains records.",
       "slots": [
@@ -764,7 +776,7 @@
     {
       "id": "analyzer._SemanticError._check_sum-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:1552",
+      "source": "analyzer.py:1580",
       "raised_in": "_check_sum",
       "template": "I can only sum numbers. '{name}' is {_singular(entry.type)}.",
       "slots": [
@@ -775,7 +787,7 @@
     {
       "id": "analyzer._SemanticError._check_extrema-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1572",
+      "source": "analyzer.py:1600",
       "raised_in": "_check_extrema",
       "template": "'{node.word}' on a list of records needs a field \u2014 try: {node.word} <field> of {node.target.name}.",
       "slots": [
@@ -787,7 +799,7 @@
     {
       "id": "analyzer._SemanticError._check_extrema-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1578",
+      "source": "analyzer.py:1606",
       "raised_in": "_check_extrema",
       "template": "'{node.word} {node.field}' needs a list of records. '{node.target.name}' is {_singular(entry.type)} \u2014 try: {node.word} of {node.target.name}.",
       "slots": [
@@ -802,7 +814,7 @@
     {
       "id": "analyzer._SemanticError._check_extrema-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:1588",
+      "source": "analyzer.py:1616",
       "raised_in": "_check_extrema",
       "template": null,
       "slots": [],
@@ -811,7 +823,7 @@
     {
       "id": "analyzer._SemanticError._check_gather",
       "class": "_SemanticError",
-      "source": "analyzer.py:1603",
+      "source": "analyzer.py:1631",
       "raised_in": "_check_gather",
       "template": "That range is too large. The maximum is {GATHER_RANGE_CAP} items.",
       "slots": [
@@ -821,7 +833,7 @@
     {
       "id": "analyzer._SemanticError._check_require_each",
       "class": "_SemanticError",
-      "source": "analyzer.py:1645",
+      "source": "analyzer.py:1673",
       "raised_in": "_check_require_each",
       "template": "The binding name can't be the same as the list name. Try: require each <item> in {name} <condition>.",
       "slots": [
@@ -831,7 +843,7 @@
     {
       "id": "analyzer._SemanticError._check_composition_call_shape-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1715",
+      "source": "analyzer.py:1743",
       "raised_in": "_check_composition_call_shape",
       "template": "I can't find a composition called '{node.name}'.",
       "slots": [
@@ -841,7 +853,7 @@
     {
       "id": "analyzer._SemanticError._check_composition_call_shape-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1720",
+      "source": "analyzer.py:1748",
       "raised_in": "_check_composition_call_shape",
       "template": "'{node.name}' expects an input (from <{param}>). Try: {node.name} from <your-list> or {node.name} from 50.",
       "slots": [
@@ -854,7 +866,7 @@
     {
       "id": "analyzer._SemanticError._check_composition_call_shape-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:1725",
+      "source": "analyzer.py:1753",
       "raised_in": "_check_composition_call_shape",
       "template": "'{node.name}' doesn't take an input. Call it on its own: {node.name}.",
       "slots": [
@@ -865,7 +877,7 @@
     {
       "id": "analyzer._SemanticError._check_composition_call_shape-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:1732",
+      "source": "analyzer.py:1760",
       "raised_in": "_check_composition_call_shape",
       "template": "I can't find '{node.arg}'. You might need to 'remember' it first.",
       "slots": [
@@ -875,7 +887,7 @@
     {
       "id": "analyzer._SemanticError._check_choose_condition-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1831",
+      "source": "analyzer.py:1859",
       "raised_in": "_check_choose_condition",
       "template": "Unexpected condition shape.",
       "slots": []
@@ -883,7 +895,7 @@
     {
       "id": "analyzer._SemanticError._check_choose_condition-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1855",
+      "source": "analyzer.py:1883",
       "raised_in": "_check_choose_condition",
       "template": "Unknown comparison operator '{cond.op}'.",
       "slots": [
@@ -893,7 +905,7 @@
     {
       "id": "analyzer._SemanticError._check_predicate_application",
       "class": "_SemanticError",
-      "source": "analyzer.py:1881",
+      "source": "analyzer.py:1909",
       "raised_in": "_check_predicate_application",
       "template": "I don't know a definition for '{cond.predicate_name}'. Use 'define {cond.predicate_name}: ...' to create one.",
       "slots": [
@@ -904,7 +916,7 @@
     {
       "id": "analyzer._SemanticError._check_self_referential_define-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1936",
+      "source": "analyzer.py:1964",
       "raised_in": "_check_self_referential_define",
       "template": "Definition '{name}' can't refer to itself.",
       "slots": [
@@ -914,7 +926,7 @@
     {
       "id": "analyzer._SemanticError._check_self_referential_define-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1938",
+      "source": "analyzer.py:1966",
       "raised_in": "_check_self_referential_define",
       "template": "Definition '{name}' can't refer to itself.",
       "slots": [
@@ -924,7 +936,7 @@
     {
       "id": "analyzer._SemanticError._check_define_condition-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1955",
+      "source": "analyzer.py:1983",
       "raised_in": "_check_define_condition",
       "template": "Unexpected condition shape.",
       "slots": []
@@ -932,7 +944,7 @@
     {
       "id": "analyzer._SemanticError._check_define_condition-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1957",
+      "source": "analyzer.py:1985",
       "raised_in": "_check_define_condition",
       "template": "Unknown comparison operator '{cond.op}'.",
       "slots": [
@@ -942,7 +954,7 @@
     {
       "id": "analyzer._SemanticError._check_predicate_definition_cycle-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:1974",
+      "source": "analyzer.py:2002",
       "raised_in": "_check_predicate_definition_cycle",
       "template": "Definition '{name}' can't depend on itself.",
       "slots": [
@@ -952,7 +964,7 @@
     {
       "id": "analyzer._SemanticError._check_predicate_definition_cycle-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:1976",
+      "source": "analyzer.py:2004",
       "raised_in": "_check_predicate_definition_cycle",
       "template": "Definition '{name}' refers back to itself through {chain}. A definition can't depend on itself.",
       "slots": [
@@ -963,7 +975,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_verb-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2070",
+      "source": "analyzer.py:2098",
       "raised_in": "_check_pack_verb",
       "template": "'{slot_label}' expects a name.",
       "slots": [
@@ -973,7 +985,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_verb-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2075",
+      "source": "analyzer.py:2103",
       "raised_in": "_check_pack_verb",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -983,7 +995,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_verb-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2094",
+      "source": "analyzer.py:2122",
       "raised_in": "_check_pack_verb",
       "template": "'{name}' is {shown}, not a {constraint}. '{slot_label}' expects a {constraint}.",
       "slots": [
@@ -997,7 +1009,7 @@
     {
       "id": "analyzer._SemanticError._resolve_slot_target_name",
       "class": "_SemanticError",
-      "source": "analyzer.py:2141",
+      "source": "analyzer.py:2169",
       "raised_in": "_resolve_slot_target_name",
       "template": "Pack verb '{node.word}' needs a name for its target.",
       "slots": [
@@ -1007,7 +1019,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_substring-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2155",
+      "source": "analyzer.py:2183",
       "raised_in": "_check_pack_substring",
       "template": "'{node.word}' expects a name for the source text.",
       "slots": [
@@ -1017,7 +1029,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_substring-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2160",
+      "source": "analyzer.py:2188",
       "raised_in": "_check_pack_substring",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1027,7 +1039,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_substring-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2166",
+      "source": "analyzer.py:2194",
       "raised_in": "_check_pack_substring",
       "template": "'{node.word} from' expects text, but '{name}' is {_singular(entry.type)}.",
       "slots": [
@@ -1039,7 +1051,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_substring-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:2174",
+      "source": "analyzer.py:2202",
       "raised_in": "_check_pack_substring",
       "template": "I can't find '{check_node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1049,7 +1061,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_append",
       "class": "_SemanticError",
-      "source": "analyzer.py:2195",
+      "source": "analyzer.py:2223",
       "raised_in": "_check_pack_append",
       "template": "Pack verb '{node.word}' missing source value.",
       "slots": [
@@ -1059,7 +1071,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_set_field-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2216",
+      "source": "analyzer.py:2244",
       "raised_in": "_check_pack_set_field",
       "template": "I can't find '{target_name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1069,7 +1081,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_set_field-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2222",
+      "source": "analyzer.py:2250",
       "raised_in": "_check_pack_set_field",
       "template": "'{node.word}' expects a record, but '{target_name}' is {_singular(entry.type)}.",
       "slots": [
@@ -1081,7 +1093,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_set_field-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2229",
+      "source": "analyzer.py:2257",
       "raised_in": "_check_pack_set_field",
       "template": "I can't find '{src.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1091,7 +1103,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_compare-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2246",
+      "source": "analyzer.py:2274",
       "raised_in": "_check_pack_compare",
       "template": "'{node.word}' expects a name for '{slot_name}'.",
       "slots": [
@@ -1102,7 +1114,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_compare-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2250",
+      "source": "analyzer.py:2278",
       "raised_in": "_check_pack_compare",
       "template": "I can't find '{value_node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1112,7 +1124,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_numeric_extract-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2264",
+      "source": "analyzer.py:2292",
       "raised_in": "_check_pack_numeric_extract",
       "template": "'{node.word}' expects a name for the source text.",
       "slots": [
@@ -1122,7 +1134,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_numeric_extract-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2269",
+      "source": "analyzer.py:2297",
       "raised_in": "_check_pack_numeric_extract",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1132,7 +1144,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_numeric_extract-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2275",
+      "source": "analyzer.py:2303",
       "raised_in": "_check_pack_numeric_extract",
       "template": "'{node.word} from' expects text, but '{name}' is {_singular(entry.type)}.",
       "slots": [
@@ -1144,7 +1156,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_range_check-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2292",
+      "source": "analyzer.py:2320",
       "raised_in": "_check_pack_range_check",
       "template": "'{node.word}' expects a name for the reference window.",
       "slots": [
@@ -1154,7 +1166,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_range_check-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2297",
+      "source": "analyzer.py:2325",
       "raised_in": "_check_pack_range_check",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1164,7 +1176,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_range_check-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2303",
+      "source": "analyzer.py:2331",
       "raised_in": "_check_pack_range_check",
       "template": "'{node.word} from' expects text, but '{name}' is {_singular(entry.type)}.",
       "slots": [
@@ -1176,7 +1188,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_range_check-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:2310",
+      "source": "analyzer.py:2338",
       "raised_in": "_check_pack_range_check",
       "template": "I can't find '{check_node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1186,7 +1198,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2329",
+      "source": "analyzer.py:2357",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word}' expects a name for the shape.",
       "slots": [
@@ -1196,7 +1208,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2333",
+      "source": "analyzer.py:2361",
       "raised_in": "_check_pack_conformance",
       "template": "I can't find '{shape_node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1206,7 +1218,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2339",
+      "source": "analyzer.py:2367",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word} to' expects a record shape, but '{shape_node.name}' is {_singular(shape_entry.type)}.",
       "slots": [
@@ -1218,7 +1230,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:2349",
+      "source": "analyzer.py:2377",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word} each' can only be used inside an 'each' loop.",
       "slots": [
@@ -1228,7 +1240,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-5",
       "class": "_SemanticError",
-      "source": "analyzer.py:2353",
+      "source": "analyzer.py:2381",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word} each' expects a list of records to check against the shape.",
       "slots": [
@@ -1238,7 +1250,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-6",
       "class": "_SemanticError",
-      "source": "analyzer.py:2359",
+      "source": "analyzer.py:2387",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word}' expects a name for the record.",
       "slots": [
@@ -1248,7 +1260,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-7",
       "class": "_SemanticError",
-      "source": "analyzer.py:2363",
+      "source": "analyzer.py:2391",
       "raised_in": "_check_pack_conformance",
       "template": "I can't find '{record_node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1258,7 +1270,7 @@
     {
       "id": "analyzer._SemanticError._check_pack_conformance-8",
       "class": "_SemanticError",
-      "source": "analyzer.py:2369",
+      "source": "analyzer.py:2397",
       "raised_in": "_check_pack_conformance",
       "template": "'{node.word}' expects a record, but '{record_node.name}' is {_singular(record_entry.type)}.",
       "slots": [
@@ -1270,7 +1282,7 @@
     {
       "id": "analyzer._SemanticError._check_finish",
       "class": "_SemanticError",
-      "source": "analyzer.py:2386",
+      "source": "analyzer.py:2414",
       "raised_in": "_check_finish",
       "template": "'finish' can only be used inside an event handler.",
       "slots": []
@@ -1278,7 +1290,7 @@
     {
       "id": "analyzer._SemanticError._check_list_append-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2461",
+      "source": "analyzer.py:2489",
       "raised_in": "_check_list_append",
       "template": "'{target_name}' is a live value provided by the domain pack. '{verb}' modifies the list and can't be used on it \u2014 the domain pack controls this value.",
       "slots": [
@@ -1289,7 +1301,7 @@
     {
       "id": "analyzer._SemanticError._check_list_append-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2467",
+      "source": "analyzer.py:2495",
       "raised_in": "_check_list_append",
       "template": "I can't find '{target_name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1299,7 +1311,7 @@
     {
       "id": "analyzer._SemanticError._check_list_append-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2473",
+      "source": "analyzer.py:2501",
       "raised_in": "_check_list_append",
       "template": "I can only {verb} {prep} a list. '{target_name}' is {_singular(entry.type)}.",
       "slots": [
@@ -1312,7 +1324,7 @@
     {
       "id": "analyzer._SemanticError._check_list_append-4",
       "class": "_SemanticError",
-      "source": "analyzer.py:2479",
+      "source": "analyzer.py:2507",
       "raised_in": "_check_list_append",
       "template": "'{target_name}' is the list being iterated \u2014 you can't {verb} {prep} it while iterating. Try {verb}ing {prep} a different list.",
       "slots": [
@@ -1326,7 +1338,7 @@
     {
       "id": "analyzer._SemanticError._check_list_append-5",
       "class": "_SemanticError",
-      "source": "analyzer.py:2497",
+      "source": "analyzer.py:2525",
       "raised_in": "_check_list_append",
       "template": "'{target_name}' is {_singular(entry.type)}. '{item_label}' is {_singular(item_type)} and can't be {action} it.",
       "slots": [
@@ -1340,7 +1352,7 @@
     {
       "id": "analyzer._SemanticError._infer_add_item_type-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2535",
+      "source": "analyzer.py:2563",
       "raised_in": "_infer_add_item_type",
       "template": "I can't find '{item.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1350,7 +1362,7 @@
     {
       "id": "analyzer._SemanticError._infer_add_item_type-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2545",
+      "source": "analyzer.py:2573",
       "raised_in": "_infer_add_item_type",
       "template": "Unexpected item for 'add': {type(item).__name__}.",
       "slots": [
@@ -1360,7 +1372,7 @@
     {
       "id": "analyzer._SemanticError._resolve_choose_operand-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2567",
+      "source": "analyzer.py:2595",
       "raised_in": "_resolve_choose_operand",
       "template": "I can't find '{node.name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1370,7 +1382,7 @@
     {
       "id": "analyzer._SemanticError._resolve_choose_operand-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2592",
+      "source": "analyzer.py:2620",
       "raised_in": "_resolve_choose_operand",
       "template": "'each' only refers to the current item inside an 'each' or 'where' clause. In 'choose', name the value directly.",
       "slots": []
@@ -1378,7 +1390,7 @@
     {
       "id": "analyzer._SemanticError._resolve_choose_operand-3",
       "class": "_SemanticError",
-      "source": "analyzer.py:2604",
+      "source": "analyzer.py:2632",
       "raised_in": "_resolve_choose_operand",
       "template": "Unexpected operand in 'choose' condition.",
       "slots": []
@@ -1386,7 +1398,7 @@
     {
       "id": "analyzer._SemanticError._require_list-1",
       "class": "_SemanticError",
-      "source": "analyzer.py:2619",
+      "source": "analyzer.py:2647",
       "raised_in": "_require_list",
       "template": "I can't find '{name}'. You might need to 'remember' it first.",
       "slots": [
@@ -1396,7 +1408,7 @@
     {
       "id": "analyzer._SemanticError._require_list-2",
       "class": "_SemanticError",
-      "source": "analyzer.py:2637",
+      "source": "analyzer.py:2665",
       "raised_in": "_require_list",
       "template": null,
       "slots": [],
@@ -1405,7 +1417,7 @@
     {
       "id": "analyzer._SemanticError._make_iterator",
       "class": "_SemanticError",
-      "source": "analyzer.py:2653",
+      "source": "analyzer.py:2681",
       "raised_in": "_make_iterator",
       "template": "'{name}' isn't a list I can iterate.",
       "slots": [
diff --git a/src/liminate/analyzer.py b/src/liminate/analyzer.py
index c3079bb..ea0fde1 100644
--- a/src/liminate/analyzer.py
+++ b/src/liminate/analyzer.py
@@ -1388,7 +1388,8 @@ def _check_condition(
     if cond.op == "equal_to":
         return  # any same-type comparison; analyzer doesn't enforce
     if cond.op in ("includes", "not_includes"):
-        return  # list-membership — analyzer accepts any operand types
+        _refuse_membership_over_a_known_scalar(field_type, field_label, cond.op)
+        return
     if cond.op.startswith("not_"):
         inner = cond.op[len("not_"):]
         if inner in ("above", "below"):
@@ -1398,6 +1399,33 @@ def _check_condition(
     raise _SemanticError(f"Unknown comparison operator '{cond.op}'.")
 
 
+def _refuse_membership_over_a_known_scalar(t: str, label: str, op: str) -> None:
+    """Refuse `includes` where the schema already says the operand is a scalar.
+
+    A non-list operand evaluates to false at runtime, deliberately — see
+    `test_includes_with_scalar_left_operand_is_false`. That is right where the
+    type is whatever the value turned out to be, and wrong here, where the
+    record schema has already said the field holds text: `filter the orders
+    where title includes "roof"` would validate clean, empty the list, and
+    report success.
+
+    So: answer where the type is known, defer where it is not. A list-valued
+    field is `unknown` statically, so it still reaches runtime, and nothing
+    that worked before this stops working.
+
+    Reachable only since the reorderer admitted `includes` after `where`. The
+    refusal that change replaced was safe and described the wrong problem; what
+    replaced it described nothing and was wrong.
+    """
+    if t not in ("string", "number", "date"):
+        return
+    word = op.replace("not_", "not ")
+    raise _SemanticError(
+        f"'{word}' tests whether a list holds a value, and '{label}' is "
+        f"{_singular(t)}. Liminate has no text-contains test."
+    )
+
+
 def _require_comparable(t: str, label: str, op: str) -> None:
     """Accept numbers or dates for ordered comparison; reject everything
     else. Mixed number/date is caught at runtime by _apply_op."""
diff --git a/tests/fixtures/conformance-0.18.1.json b/tests/fixtures/conformance-0.18.1.json
index 60f064b..c0816f0 100644
--- a/tests/fixtures/conformance-0.18.1.json
+++ b/tests/fixtures/conformance-0.18.1.json
@@ -68,6 +68,26 @@
       ],
       "source": "remember an event called e1 with title as launch and starts-at as 2026-03-15\nremember a list called events with e1\nfilter the events where starts-at is not below 2026-01-01\nfilter the events where starts-at is not above 2026-12-31"
     },
+    {
+      "id": "membership over a text field is refused, because includes is not contains",
+      "results": [
+        {
+          "canonical": "remember an order called o1 with title as roofing and total as 75",
+          "status": "success"
+        },
+        {
+          "canonical": "remember a list called orders with o1",
+          "status": "success"
+        },
+        {
+          "canonical": "filter the orders where title includes roof",
+          "errorKind": "semantic",
+          "errorMessage": "'includes' tests whether a list holds a value, and 'title' is text. Liminate has no text-contains test.",
+          "status": "error"
+        }
+      ],
+      "source": "remember an order called o1 with title as roofing and total as 75\nremember a list called orders with o1\nfilter the orders where title includes \"roof\""
+    },
     {
       "id": "a range comparison over text is refused",
       "results": [
diff --git a/tests/fixtures/conformance_corpus.txt b/tests/fixtures/conformance_corpus.txt
index fe91a67..c357409 100644
--- a/tests/fixtures/conformance_corpus.txt
+++ b/tests/fixtures/conformance_corpus.txt
@@ -17,6 +17,11 @@ remember a list called events with e1
 filter the events where starts-at is not below 2026-01-01
 filter the events where starts-at is not above 2026-12-31
 
+# membership over a text field is refused, because includes is not contains
+remember an order called o1 with title as roofing and total as 75
+remember a list called orders with o1
+filter the orders where title includes "roof"
+
 # a range comparison over text is refused
 remember a string called title with "roof"
 require title is above 50
diff --git a/tests/test_integration_includes_remove.py b/tests/test_integration_includes_remove.py
index 75761f0..118ac0e 100644
--- a/tests/test_integration_includes_remove.py
+++ b/tests/test_integration_includes_remove.py
@@ -268,3 +268,45 @@ def test_when_not_includes_fires_on_initial_evaluation():
     fires = [r for r in results if r.status is ResultStatus.HANDLER_FIRE]
     assert len(fires) == 1
     assert fires[0].output == ["flask not active"]
+
+
+# `includes` over a field the schema says is a scalar — refused, not answered.
+#
+# `includes` is a list-membership probe and a non-list operand evaluates to
+# false (see `test_includes_with_scalar_left_operand_is_false`). That rule is
+# right at runtime, where the operand's type is whatever the value turned out
+# to be. It is the wrong answer at analysis time when the record schema already
+# says the field holds text: `filter the orders where title includes "roof"`
+# then validates clean, empties the list, and reports success.
+#
+# Reachable only since the reorderer stopped refusing `includes` after `where`.
+# The refusal it replaced was safe and said the wrong thing; what replaced it
+# said nothing and was wrong. So the analyzer answers where it can, and defers
+# where it cannot — a field whose type is `unknown` (which is what a
+# list-valued field is, statically) still goes to runtime.
+
+def test_includes_over_a_text_field_is_refused_rather_than_answered():
+    session, setup = run_lines([
+        "remember an order called o1 with title as roofing and total as 75",
+        "remember an order called o2 with title as plumbing and total as 30",
+        "remember a list called orders with o1 and o2",
+    ])
+    assert all(r.status is ResultStatus.SUCCESS for r in setup), [r.message for r in setup]
+    result = session.run_line('filter the orders where title includes "roof"')
+    assert result.status is ResultStatus.ERROR_SEMANTIC, (
+        f"got {result.status.value}: a text field silently matched nothing"
+    )
+    assert "includes" in (result.message or "")
+    assert len(session.symtab["orders"].value) == 2, "the list must not have been touched"
+
+
+def test_includes_over_a_list_valued_field_still_works():
+    session, setup = run_lines([
+        'remember a list called roof-tags with "urgent" and "roof"',
+        "remember an order called o1 with total as 75 and tags as roof-tags",
+        "remember a list called orders with o1",
+    ])
+    assert all(r.status is ResultStatus.SUCCESS for r in setup), [r.message for r in setup]
+    result = session.run_line('filter the orders where tags includes "urgent"')
+    assert result.status is ResultStatus.SUCCESS, result.message
+    assert len(session.symtab["orders"].value) == 1
diff --git a/tests/test_reorderer.py b/tests/test_reorderer.py
index 81dbf14..d2633e1 100644
--- a/tests/test_reorderer.py
+++ b/tests/test_reorderer.py
@@ -328,14 +328,18 @@ def test_where_includes_filters_a_list_valued_field_correctly():
     ]
 
 
-def test_where_includes_over_scalar_items_keeps_the_documented_answer():
+def test_where_includes_over_scalar_items_is_refused():
     """The boundary, stated rather than discovered later.
 
-    `each` is an item, not a list, and `includes` over a non-list operand is
-    false by decision — see `test_includes_with_scalar_left_operand_is_false`.
-    So `where each includes "x"` empties the list rather than matching text.
-    Widening the gate does not change that and must not be read as making
-    `includes` a substring test; text-contains is not in the language.
+    `each` is an item, not a list, so `where each includes "x"` is a membership
+    test over a scalar. At runtime that is false by decision — see
+    `test_includes_with_scalar_left_operand_is_false` — which would have
+    emptied the list and reported success.
+
+    The analyzer answers first where the type is known, so this is refused and
+    the list is untouched. Widening the gate must not be read as making
+    `includes` a substring test; text-contains is not in the language, and the
+    refusal now says so.
     """
     from liminate.run import run
 
@@ -344,7 +348,10 @@ def test_where_includes_over_scalar_items_keeps_the_documented_answer():
         'add "routine-check" to tags\n'
     )
     result = run(base + 'filter tags where each includes "urgent"\nshow tags')
-    assert result.results[-1].output == [""]
+    refusal = result.results[-2]
+    assert refusal.status.value == "error_semantic", refusal.status.value
+    assert "no text-contains" in (refusal.message or "").lower()
+    assert result.results[-1].output == ["urgent-repair, routine-check"]
 
 
 def test_a_genuinely_scrambled_condition_is_still_rejected():