fix: make nested struct fields optional to match voluptuous defaults

src/taskgraph/transforms/task.py

@@ -232,22 +232,22 @@ def verify_index(config, index):
 
 class DockerWorkerCacheEntry(Schema):
     # only one type is supported by any of the workers right now
-    type: Literal["persistent"]
+    type: Literal["persistent"] = "persistent"
     # name of the cache, allowing reuse by subsequent tasks naming the same cache
-    name: str
+    name: Optional[str] = None
     # location in the task image where the cache will be mounted
-    mount_point: str
+    mount_point: Optional[str] = None
     # Whether the cache is not used in untrusted environments (like the Try repo).
     skip_untrusted: Optional[bool] = None
 
 
 class DockerWorkerArtifact(Schema):
     # type of artifact -- simple file, or recursive directory, or a volume mounted directory.
-    type: Literal["file", "directory", "volume"]
+    type: Optional[Literal["file", "directory", "volume"]] = None
     # task image path from which to read artifact
-    path: str
+    path: Optional[str] = None
     # name of the produced artifact (root of the names for type=directory)
-    name: str
+    name: Optional[str] = None
 
 
 class DockerWorkerPayloadSchema(Schema, forbid_unknown_fields=False, kw_only=True):
@@ -675,12 +675,12 @@ def build_generic_worker_payload(config, task, task_def):
 
 
 class ReleaseProperties(Schema):
-    app_name: str
-    app_version: str
-    branch: str
-    build_id: str
-    hash_type: str
-    platform: str
+    app_name: Optional[str] = None
+    app_version: Optional[str] = None
+    branch: Optional[str] = None
+    build_id: Optional[str] = None
+    hash_type: Optional[str] = None
+    platform: Optional[str] = None
 
 
 class UpstreamArtifact(Schema, rename="camel"):

src/taskgraph/util/schema.py

@@ -316,9 +316,9 @@ def validate(cls, data):
 
 class IndexSchema(Schema):
     # the name of the product this build produces
-    product: str
+    product: Optional[str] = None
     # the names to use for this task in the TaskCluster index
-    job_name: str
+    job_name: Optional[str] = None
     # Type of gecko v2 index to use
     type: str = "generic"
     # The rank that the task will receive in the TaskCluster

test/test_util_schema.py

@@ -9,6 +9,7 @@
 
 import taskgraph
 from taskgraph.util.schema import (
+    IndexSchema,
     Schema,
     optionally_keyed_by,
     resolve_keyed_by,
@@ -241,6 +242,35 @@ def test_no_key(self):
         )
 
 
+class TestNestedStructFieldsOptional(unittest.TestCase):
+    """Regression test: bare keys in nested voluptuous dict schemas were optional
+    by default. The msgspec migration must preserve this — nested struct fields
+    without defaults should not be required."""
+
+    def test_index_schema_accepts_partial_fields(self):
+        """IndexSchema should accept data with only 'type', omitting product/job-name."""
+
+        validate_schema(
+            IndexSchema,
+            {"type": "custom-index"},
+            "index schema",
+        )
+
+    def test_index_schema_accepts_all_fields(self):
+        """IndexSchema should still accept full data."""
+
+        validate_schema(
+            IndexSchema,
+            {
+                "type": "generic",
+                "product": "firefox",
+                "job-name": "build",
+                "rank": "by-tier",
+            },
+            "index schema",
+        )
+
+
 def test_optionally_keyed_by():
     typ = optionally_keyed_by("foo", str, use_msgspec=True)
     assert msgspec.convert("baz", typ) == "baz"