fix(moonshot): stop stamping a synthetic type on if/then/else nodes

_repair_schema didn't recurse into if/then/else, so a bare conditional
wrapper (e.g. an allOf branch expressing "when goal is set, mode must be
one of ...") fell through _fill_missing_type's default and was stamped
with type: "string". That corrupts the schema: the wrapper's actual
instance is an object, so Moonshot (and any strict validator) now
rejects every real argument against it.

if/then/else are added to the recursed node keys, and _fill_missing_type
leaves a bare conditional node untyped instead of defaulting to "string"
since it constrains the parent instance rather than describing its own
shape.

agent/moonshot_schema.py

@@ -19,7 +19,9 @@ _SCHEMA_MAP_KEYS = frozenset({"properties", "patternProperties", "$defs", "defin
 # Values are lists of schemas.
 _SCHEMA_LIST_KEYS = frozenset({"anyOf", "oneOf", "allOf", "prefixItems"})
 # Values are a single nested schema (additionalProperties may also be a bool).
-_SCHEMA_NODE_KEYS = frozenset({"items", "contains", "not", "additionalProperties", "propertyNames"})
+_SCHEMA_NODE_KEYS = frozenset(
+    {"items", "contains", "not", "additionalProperties", "propertyNames", "if", "then", "else"}
+)
 
 _SCALAR_TYPES = frozenset({"string", "integer", "number", "boolean"})
 # bool before int: bool is an int subclass.
@@ -103,7 +105,9 @@ def _fill_missing_type(node: Dict[str, Any]) -> Dict[str, Any]:
     A type list collapses to its first concrete member; otherwise
     ``properties``/``required``/``additionalProperties`` → object,
     ``items``/``prefixItems`` → array, ``enum`` → type of its first value,
-    else ``string`` (safest scalar).
+    else ``string`` (safest scalar). A bare ``if``/``then``/``else`` node
+    constrains whatever instance it is attached to rather than describing
+    its own type, so it is left untyped instead of defaulting to ``string``.
     """
     node_type = node.get("type")
     if isinstance(node_type, list):
@@ -119,6 +123,8 @@ def _fill_missing_type(node: Dict[str, Any]) -> Dict[str, Any]:
     elif isinstance(node.get("enum"), list) and node["enum"]:
         sample = node["enum"][0]
         inferred = next((t for cls, t in _ENUM_SAMPLE_TYPES if isinstance(sample, cls)), "string")
+    elif "if" in node or "then" in node or "else" in node:
+        return node
     else:
         inferred = "string"
     return {**node, "type": inferred}

tests/agent/test_moonshot_schema.py

@@ -92,6 +92,30 @@ class TestMissingTypeFilled:
         assert out["properties"]["payload"]["$ref"] == "#/$defs/Payload"
 
 
+class TestConditionalSchemaNotGivenSyntheticType:
+    """A bare if/then/else conditional constrains the enclosing instance; it
+    does not describe its own type, so it must not be defaulted to "string"."""
+
+    def test_if_then_node_is_not_given_synthetic_type(self):
+        params = {
+            "oneOf": [
+                {"required": ["prompt"], "not": {"required": ["goal"]}},
+                {"required": ["goal"], "not": {"required": ["prompt"]}},
+            ],
+            "allOf": [
+                {
+                    "if": {"required": ["goal"]},
+                    "then": {"properties": {"mode": {"enum": ["build", "edit"]}}},
+                }
+            ],
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        conditional = out["allOf"][0]
+        assert "type" not in conditional
+        # Nested schemas under then/if still get repaired.
+        assert conditional["then"]["properties"]["mode"]["type"] == "string"
+
+
 class TestAnyOfParentType:
     """Rule 2: type must not appear at the anyOf parent level.