Implement first knowledge engine runtime slice

tests/test_artifacts.py

@@ -0,0 +1,75 @@
+from kontextual_engine import (
+    Artifact,
+    ArtifactMetadata,
+    ArtifactReference,
+    ArtifactType,
+    Collection,
+    Relationship,
+    RelationshipGraph,
+    RelationshipType,
+    content_digest,
+)
+
+
+def test_artifact_create_updates_digest_and_roundtrips() -> None:
+    artifact = Artifact.create(
+        "collection-1",
+        "brief",
+        "first version",
+        artifact_type=ArtifactType.DOCUMENT,
+        metadata=ArtifactMetadata(tags=["example"], media_type="text/plain"),
+    )
+
+    assert artifact.content_digest == content_digest("first version")
+    assert artifact.content_size == len("first version".encode("utf-8"))
+
+    artifact.update_content("second version")
+    assert artifact.content_digest == content_digest("second version")
+
+    restored = Artifact.from_dict(artifact.to_dict())
+    assert restored.id == artifact.id
+    assert restored.metadata.tags == ["example"]
+    assert restored.artifact_type == ArtifactType.DOCUMENT
+
+
+def test_artifact_reference_parse_formats() -> None:
+    assert ArtifactReference.parse("name") == ArtifactReference(name="name")
+    assert ArtifactReference.parse("space:name") == ArtifactReference(
+        name="name",
+        collection_id="space",
+    )
+    assert str(ArtifactReference.parse("space:name@v1")) == "space:name@v1"
+
+
+def test_collection_and_relationship_roundtrip() -> None:
+    collection = Collection.create("project", domain="markitect")
+    restored_collection = Collection.from_dict(collection.to_dict())
+    assert restored_collection.name == "project"
+    assert restored_collection.domain == "markitect"
+
+    relationship = Relationship.create(
+        "a",
+        "b",
+        "depends on",
+        relationship_type=RelationshipType.DEPENDS_ON,
+        evidence="test evidence",
+    )
+    assert relationship.edge() == ("a", "b", "depends on")
+    restored_relationship = Relationship.from_dict(relationship.to_dict())
+    assert restored_relationship.relationship_type == RelationshipType.DEPENDS_ON
+    assert restored_relationship.evidence == "test evidence"
+
+
+def test_relationship_graph_detects_cycles_and_orders_dependencies() -> None:
+    edge_ab = Relationship.create("A", "B", "depends on")
+    edge_bc = Relationship.create("B", "C", "depends on")
+    graph = RelationshipGraph.from_relationships([edge_ab, edge_bc])
+
+    assert graph.successors("A") == {"B"}
+    assert graph.predecessors("C") == {"B"}
+    assert graph.detect_cycles() == []
+    assert graph.topological_sort().index("C") < graph.topological_sort().index("A")
+
+    graph.add(Relationship.create("C", "A", "depends on"))
+    assert graph.detect_cycles()
+