feat(detection-core): build the strict canonical artifact boundary

tests/detection_core_fixtures.py

@@ -0,0 +1,61 @@
+"""Deterministic content-resolver fixtures shared by detection-core contract tests."""
+
+from __future__ import annotations
+
+from collections.abc import Mapping
+from dataclasses import dataclass
+from types import MappingProxyType
+
+from openultrasast.core import canonical
+
+
+@dataclass(frozen=True)
+class InMemoryContentResolver:
+    """Read-only resolver keyed by opaque artifact identity."""
+
+    artifacts: Mapping[str, canonical.ResolvedContent]
+
+    def __post_init__(self) -> None:
+        object.__setattr__(self, "artifacts", MappingProxyType(dict(self.artifacts)))
+
+    def resolve(self, reference: canonical.ContentRef) -> canonical.ResolvedContent:
+        artifact_id = reference.artifact_id
+        try:
+            return self.artifacts[artifact_id]
+        except KeyError as exc:
+            raise canonical.ArtifactResolutionError(f"artifact not found: {artifact_id}") from exc
+
+
+def stored_artifact(
+    content: bytes,
+    *,
+    artifact_id: str = "artifact-1",
+    store_identity: str = "trusted-store",
+    retention_policy_digest: str | None = None,
+) -> tuple[canonical.ContentRef, InMemoryContentResolver]:
+    """Create a reference and resolver whose receipt identities are reproducible."""
+    retention = retention_policy_digest or canonical.content_digest("retain-30-days")
+    digest = canonical.bytes_digest(content)
+    receipt_digest = canonical.derive_storage_receipt_digest(
+        store_identity=store_identity,
+        content_digest=digest,
+        byte_length=len(content),
+        retention_policy_digest=retention,
+    )
+    receipt = canonical.StorageReceipt(
+        store_identity=store_identity,
+        content_digest=digest,
+        byte_length=len(content),
+        retention_policy_digest=retention,
+        receipt_digest=receipt_digest,
+    )
+    reference = canonical.ContentRef(
+        artifact_id=artifact_id,
+        content_digest=digest,
+        media_type="application/json",
+        byte_length=len(content),
+        retention_policy_digest=retention,
+        storage_receipt_digest=receipt_digest,
+    )
+    resolver = InMemoryContentResolver({artifact_id: canonical.ResolvedContent(content=content, receipt=receipt)})
+    return reference, resolver