Add canonical chunk plan source model

internal/core/source/source_test.go

@@ -1,6 +1,7 @@
 package source
 
 import (
+	"encoding/json"
 	"strings"
 	"testing"
 )
@@ -258,6 +259,28 @@ func TestDigestChunkIsDeterministicAndIncludesReference(t *testing.T) {
 	}
 }
 
+func TestDigestChunkIncludesAnnotationScopes(t *testing.T) {
+	doc := validDocument()
+	chunk := Chunk{
+		ID: "chunk-1", SourceID: doc.ID, Ref: SourceRef{SourceID: doc.ID, StartUnitID: 1, EndUnitID: 2},
+		Content: []byte("content"), MediaType: "text/plain", Units: doc.Units,
+		Annotations:     ChunkAnnotations{"scope": json.RawMessage(`{"value":1}`)},
+		PlanAnnotations: ChunkAnnotations{"scope": json.RawMessage(`{"value":2}`)},
+	}
+	base, err := DigestChunk(chunk)
+	if err != nil {
+		t.Fatalf("DigestChunk() error = %v", err)
+	}
+	chunk.Annotations["scope"] = json.RawMessage(`{"value":3}`)
+	rangeChanged, _ := DigestChunk(chunk)
+	chunk.Annotations["scope"] = json.RawMessage(`{"value":1}`)
+	chunk.PlanAnnotations["scope"] = json.RawMessage(`{"value":3}`)
+	planChanged, _ := DigestChunk(chunk)
+	if base == rangeChanged || base == planChanged || rangeChanged == planChanged {
+		t.Fatalf("annotation scope digests did not change distinctly: %q %q %q", base, rangeChanged, planChanged)
+	}
+}
+
 func TestValidateRefValid(t *testing.T) {
 	doc := validDocument()
 	ref := SourceRef{