diff --git a/packages/doc-core/src/index.ts b/packages/doc-core/src/index.ts
index 84dde8d5..b90c071b 100644
--- a/packages/doc-core/src/index.ts
+++ b/packages/doc-core/src/index.ts
@@ -1,4 +1,36 @@
 export * from '../../../src/formats/marks.js';
-export * from '../../../src/formats/provenance-sidecar.js';
+// Explicit re-export of provenance-sidecar to avoid name collisions with marks.js:
+// marks.js owns the bare createComment, getUnresolvedComments, and CommentReply
+// names in the new marks-based API. The provenance-sidecar versions are still
+// re-exported here under Sidecar-prefixed aliases so legacy sidecar consumers
+// keep a working path.
+export type {
+  AttestationLevel,
+  TextOrigin,
+  ProvenanceSpan,
+  AttentionData,
+  AttentionEventType,
+  AttentionEvent,
+  ProvenanceMetadata,
+  CommentSelector,
+  Comment,
+  ProvenanceData,
+  CommentReply as SidecarCommentReply,
+} from '../../../src/formats/provenance-sidecar.js';
+export {
+  migrateLegacyProvenance,
+  isLegacyFormat,
+  extractEmbeddedProvenance,
+  generateCommentId,
+  generateReplyId,
+  createReply,
+  addComment,
+  addReplyToComment,
+  setCommentResolved,
+  deleteComment,
+  ensureCommentsArray,
+  createComment as createSidecarComment,
+  getUnresolvedComments as getUnresolvedSidecarComments,
+} from '../../../src/formats/provenance-sidecar.js';
 export * from '../../../src/formats/remark-proof-marks.js';
 export * from '../../../src/shared/agent-identity.js';