diff --git a/audits/agentic/rules.py b/audits/agentic/rules.py
index 3b1bba72..0806077e 100644
--- a/audits/agentic/rules.py
+++ b/audits/agentic/rules.py
@@ -73,6 +73,8 @@ def validate_rules(rules: Any) -> list[RuleError]:
             errors.append(RuleError(index, "", "each rule must be an object"))
         elif rule.get("type") != "check":
             errors.append(RuleError(index, str(rule.get("type", "")), "rules must be custom checks"))
+        elif set(rule) == {"type", "check", "legacy"} and rule["check"] == "unsupported" and isinstance(rule["legacy"], dict):
+            continue  # kept by migration 0004; the engine reports it as INCONCLUSIVE
         else:
             errors.extend(RuleError(index, "check", problem) for problem in validate_check(rule))
     return errors
diff --git a/audits/agentic/tests/test_rule_migration.py b/audits/agentic/tests/test_rule_migration.py
index 5aabda47..d493ab75 100644
--- a/audits/agentic/tests/test_rule_migration.py
+++ b/audits/agentic/tests/test_rule_migration.py
@@ -38,3 +38,22 @@ def test_all_of_groups_are_flattened_into_separate_rules():
 def test_metadata_without_rules_is_unchanged():
     metadata = {"agentic": {"trace": {"required": True}}}
     assert migration.convert_metadata(metadata) == metadata
+
+
+def test_unsupported_rules_kept_by_the_migration_pass_validation_and_are_inconclusive():
+    from audits.agentic.checks.rules import rule_checks
+    from audits.agentic.expectations import validate_agentic_metadata
+    from audits.agentic.trajectory import normalize
+
+    metadata = migration.convert_metadata({"agentic": {"schema_version": 2, "enforcement": {}, "rules": [
+        {"type": "precedes", "first": "a", "then": "b"}]}})
+    converted = metadata["agentic"]["rules"]
+    assert validate_agentic_metadata(metadata).rules == converted
+    trace = normalize([{"span_id": "t1", "name": "execute_tool", "attributes": {
+        "gen_ai.operation.name": "execute_tool", "gen_ai.tool.name": "a"}}])
+    assert [check.status for check in rule_checks(trace, converted)] == ["INCONCLUSIVE"]
+
+
+def test_only_the_migration_shape_of_an_unsupported_rule_skips_validation():
+    junk = {"type": "check", "check": "unsupported", "select": "junk"}
+    assert validate_rules([junk]) != []
diff --git a/infra/tests/test_rules_form.py b/infra/tests/test_rules_form.py
index 9935a237..0962e081 100644
--- a/infra/tests/test_rules_form.py
+++ b/infra/tests/test_rules_form.py
@@ -46,3 +46,10 @@ def test_custom_check_built_in_the_editor_is_saved():
             "check": "count", "expect": {"op": "at_least", "value": 1}}
     merged = _merge_structured_agentic_fields({}, _post(agentic_rules_json=json.dumps([rule])))
     assert merged["agentic"]["rules"] == [rule]
+
+
+def test_unsupported_rule_from_the_migration_is_saved_unchanged_beside_a_new_rule():
+    unsupported = {"type": "check", "check": "unsupported", "legacy": {"type": "precedes", "first": "a", "then": "b"}}
+    rule = {"type": "check", "select": {"kind": "tool", "where": []}, "check": "count", "expect": {"op": "at_least", "value": 1}}
+    merged = _merge_structured_agentic_fields({}, _post(agentic_rules_json=json.dumps([unsupported, rule])))
+    assert merged["agentic"]["rules"] == [unsupported, rule]
diff --git a/templates/partials/agentic_rules_editor.html b/templates/partials/agentic_rules_editor.html
index 4afedb8c..0a233d23 100644
--- a/templates/partials/agentic_rules_editor.html
+++ b/templates/partials/agentic_rules_editor.html
@@ -173,6 +173,15 @@
       card.querySelector('[data-remove]').addEventListener('click', () => { rules.splice(index, 1); render(); sync(); });
     }
 
+    // Mirrors rule_engine.unsupported_text. The rule is shown as stored and kept unchanged on save.
+    function renderUnsupported(card, rule, index) {
+      const legacy = rule.legacy && typeof rule.legacy === 'object' ? rule.legacy : {};
+      const name = legacy.type || rule.check || rule.type || 'rule';
+      card.querySelector('[data-summary]').textContent = `No longer supported (${name}): edit this rule to a count, exists or none check.`;
+      card.querySelector('[data-code]').textContent = JSON.stringify(legacy);
+      card.querySelector('[data-remove]').addEventListener('click', () => { rules.splice(index, 1); render(); sync(); });
+    }
+
     function render() {
       list.innerHTML = '';
       rules.forEach((rule, index) => {
@@ -186,7 +195,8 @@
             <button type="button" data-remove class="text-[11px] text-gray-500 hover:text-red-300 shrink-0">Remove</button>
           </div>
           <div class="grid grid-cols-1 md:grid-cols-2 gap-2" data-fields></div>`;
-        renderCustom(card, card.querySelector('[data-fields]'), rule, index);
+        if (rule.check === 'unsupported') renderUnsupported(card, rule, index);
+        else renderCustom(card, card.querySelector('[data-fields]'), rule, index);
         list.appendChild(card);
       });
       sync();