Determine branch a & b are different in clone time

packages/dds/tree/src/core/index.ts

@@ -202,6 +202,7 @@ export {
 	replaceChange,
 	type RebaseStats,
 	type RebaseStatsWithDuration,
+	isAncestor,
 } from "./rebase/index.js";
 
 export {

packages/dds/tree/src/core/rebase/index.ts

@@ -49,4 +49,5 @@ export {
 	type RebaseStats,
 	type RebaseStatsWithDuration,
 	replaceChange,
+	isAncestor,
 } from "./utils.js";

packages/dds/tree/src/core/rebase/utils.ts

@@ -651,3 +651,30 @@ namespace Rollback {
 		}
 	}
 }
+
+/**
+ * Checks if one node is an ancestor of another in a parent-linked tree structure.
+ * @param ancestor - The potential ancestor node
+ * @param descendant - The potential descendant node
+ * @param allowEqual - If true, returns true when ancestor === descendant
+ * @returns true if ancestor is an ancestor of descendant (or equal if allowEqual is true)
+ */
+export function isAncestor<TNode extends { readonly parent?: TNode }>(
+	ancestor: TNode,
+	descendant: TNode,
+	allowEqual: boolean,
+): boolean {
+	if (allowEqual && ancestor === descendant) {
+		return true;
+	}
+
+	let current = descendant.parent;
+	while (current !== undefined) {
+		if (current === ancestor) {
+			return true;
+		}
+		current = current.parent;
+	}
+
+	return false;
+}

packages/dds/tree/src/shared-tree/treeCheckout.ts

@@ -41,6 +41,7 @@ import {
 	type RevertibleAlphaFactory,
 	type RevertibleAlpha,
 	type GraphCommit,
+	isAncestor,
 } from "../core/index.js";
 import {
 	type FieldBatchCodec,
@@ -605,21 +606,27 @@ export class TreeCheckout implements ITreeCheckoutFork {
 					revertible.dispose();
 				}
 			},
-			clone: (forkedBranch: TreeBranch) => {
-				if (forkedBranch === undefined) {
-					return this.createRevertible(revision, kind, checkout, onRevertibleDisposed);
-				}
-
+			clone: (targetBranch: TreeBranch) => {
 				// TODO:#23442: When a revertible is cloned for a forked branch, optimize to create a fork of a revertible branch once per revision NOT once per revision per checkout.
-				const forkedCheckout = getCheckout(forkedBranch);
+				const targetCheckout = getCheckout(targetBranch);
+
 				const revertibleBranch = this.revertibleCommitBranches.get(revision);
-				assert(
-					revertibleBranch !== undefined,
-					0xa82 /* change to revert does not exist on the given forked branch */,
-				);
-				forkedCheckout.revertibleCommitBranches.set(revision, revertibleBranch.fork());
+				if (revertibleBranch === undefined) {
+					throw new UsageError("Unable to clone a revertible that has been disposed.");
+				}
+
+				const commitToRevert = revertibleBranch.getHead();
+				const activeBranchHead = targetCheckout.#transaction.activeBranch.getHead();
+
+				if (isAncestor(commitToRevert, activeBranchHead, true) === false) {
+					throw new UsageError(
+						"Cannot clone revertible for a commit that is not present on the given branch.",
+					);
+				}
+
+				targetCheckout.revertibleCommitBranches.set(revision, revertibleBranch.fork());
 
-				return this.createRevertible(revision, kind, forkedCheckout, onRevertibleDisposed);
+				return this.createRevertible(revision, kind, targetCheckout, onRevertibleDisposed);
 			},
 			dispose: () => {
 				if (revertible.status === RevertibleStatus.Disposed) {

packages/dds/tree/src/test/shared-tree/undo.spec.ts

@@ -648,7 +648,10 @@ describe("Undo and redo", () => {
 
 		const undoOriginalPropertyOne = undoStack.pop();
 
-		assert.throws(() => undoOriginalPropertyOne?.clone(viewB).revert(), "Error: 0x576");
+		assert.throws(
+			() => undoOriginalPropertyOne?.clone(viewB),
+			/Cannot clone revertible for a commit that is not present on the given branch./,
+		);
 	});
 
 	// TODO:#24414: Enable forkable revertibles tests to run on attached/detached mode.

packages/runtime/test-runtime-utils/src/assertionShortCodesMap.ts

@@ -1632,7 +1632,6 @@ export const shortCodeMap = {
 	"0xa7e": "Expected at least two types",
 	"0xa7f": "Delta manager does not have inbound/outbound queues.",
 	"0xa80": "Invalid delta manager",
-	"0xa82": "change to revert does not exist on the given forked branch",
 	"0xa83": "Expected commit(s) for a non no-op rebase",
 	"0xa84": "Commit must be in the branch's ancestry",
 	"0xa86": "Expected source commits in non no-op merge",