Add prompt input materials and session IDs

internal/framework/contracts/contracts_test.go

@@ -251,6 +251,53 @@ func TestReferenceItemJSONOmitsContent(t *testing.T) {
 	}
 }
 
+func TestLLMInputMaterialCopiesContentAndOmitsContentFromJSON(t *testing.T) {
+	content := []byte("raw source bytes")
+	material := NewLLMInputMaterial("transcript", "application/json", content, "sha256:source", "file:///tmp/source.json")
+	content[0] = 'R'
+	if got := string(material.Content); got != "raw source bytes" {
+		t.Fatalf("material content = %q, want defensive copy", got)
+	}
+	if material.SizeBytes != int64(len("raw source bytes")) {
+		t.Fatalf("SizeBytes = %d, want content length", material.SizeBytes)
+	}
+
+	clone := material.Clone()
+	clone.Content[0] = 'X'
+	if got := string(material.Content); got != "raw source bytes" {
+		t.Fatalf("cloned material content aliased original: %q", got)
+	}
+
+	encoded, err := json.Marshal(material)
+	if err != nil {
+		t.Fatalf("json.Marshal() error = %v, want nil", err)
+	}
+	var got map[string]any
+	if err := json.Unmarshal(encoded, &got); err != nil {
+		t.Fatalf("json.Unmarshal() error = %v, want nil", err)
+	}
+	if _, ok := got["content"]; ok {
+		t.Fatalf("encoded material leaked content: %s", encoded)
+	}
+	if _, ok := got["Content"]; ok {
+		t.Fatalf("encoded material leaked Content: %s", encoded)
+	}
+	if got["digest"] != "sha256:source" || got["origin_uri"] != "file:///tmp/source.json" {
+		t.Fatalf("encoded material = %#v, want non-secret provenance", got)
+	}
+}
+
+func TestLLMInputSetCloneCopiesContent(t *testing.T) {
+	set := LLMInputSet{
+		"transcript": NewLLMInputMaterial("transcript", "application/json", []byte("source"), "sha256:source", "file:///tmp/source.json"),
+	}
+	clone := set.Clone()
+	clone["transcript"].Content[0] = 'S'
+	if got := string(set["transcript"].Content); got != "source" {
+		t.Fatalf("input set clone aliased content: %q", got)
+	}
+}
+
 func TestFakeMergeNormalizeAndOutputContracts(t *testing.T) {
 	candidate := artifacts.ArtifactCandidate{
 		Index:         0,