diff --git a/actions/setup/js/add_reaction_and_edit_comment.cjs b/actions/setup/js/add_reaction_and_edit_comment.cjs
index 2afd53e5f58..4773b8aa7b4 100644
--- a/actions/setup/js/add_reaction_and_edit_comment.cjs
+++ b/actions/setup/js/add_reaction_and_edit_comment.cjs
@@ -7,7 +7,7 @@ const { generateWorkflowIdMarker } = require("./generate_footer.cjs");
 const { sanitizeContent } = require("./sanitize_content.cjs");
 const { ERR_API, ERR_NOT_FOUND, ERR_VALIDATION } = require("./error_codes.cjs");
 const { buildWorkflowRunUrl, EVENT_TYPE_DESCRIPTIONS } = require("./workflow_metadata_helpers.cjs");
-const { createDiscussionComment, resolveTopLevelDiscussionCommentId } = require("./github_api_helpers.cjs");
+const { createDiscussionComment, isRestEndpoint, resolveTopLevelDiscussionCommentId } = require("./github_api_helpers.cjs");
 const { resolveInvocationContext } = require("./invocation_context_helpers.cjs");
 const { addReaction, addDiscussionReaction, getDiscussionNodeId, REACTION_MAP } = require("./add_reaction.cjs");
 
@@ -18,14 +18,6 @@ const VALID_REACTIONS = Object.freeze(Object.keys(REACTION_MAP));
  * @typedef {{ route: string, params: Record<string, unknown> }} RestEndpoint
  */
 
-/**
- * @param {unknown} endpoint
- * @returns {endpoint is RestEndpoint}
- */
-function isRestEndpoint(endpoint) {
-  return typeof endpoint === "object" && endpoint !== null && "route" in endpoint && "params" in endpoint;
-}
-
 /**
  * @param {unknown} endpoint
  * @param {string} endpointName
diff --git a/actions/setup/js/add_workflow_run_comment.cjs b/actions/setup/js/add_workflow_run_comment.cjs
index 192e8fb556e..e37e5c9e3d7 100644
--- a/actions/setup/js/add_workflow_run_comment.cjs
+++ b/actions/setup/js/add_workflow_run_comment.cjs
@@ -9,17 +9,9 @@ const { ERR_NOT_FOUND, ERR_VALIDATION } = require("./error_codes.cjs");
 const { getMessages } = require("./messages_core.cjs");
 const { parseBoolTemplatable } = require("./templatable.cjs");
 const { buildWorkflowRunUrl, EVENT_TYPE_DESCRIPTIONS } = require("./workflow_metadata_helpers.cjs");
-const { resolveTopLevelDiscussionCommentId } = require("./github_api_helpers.cjs");
+const { isRestEndpoint, resolveTopLevelDiscussionCommentId } = require("./github_api_helpers.cjs");
 const { resolveInvocationContext } = require("./invocation_context_helpers.cjs");
 
-/**
- * @param {unknown} endpoint
- * @returns {endpoint is { route: string, params: Record<string, unknown> }}
- */
-function isRestEndpoint(endpoint) {
-  return typeof endpoint === "object" && endpoint !== null && "route" in endpoint && "params" in endpoint;
-}
-
 /**
  * @typedef {{ owner: string, repo: string }} RepoRef
  * @typedef {{ id: string, url: string, repo: RepoRef }} CommentMetadata
diff --git a/actions/setup/js/github_api_helpers.cjs b/actions/setup/js/github_api_helpers.cjs
index 7f4020ef363..413e6341716 100644
--- a/actions/setup/js/github_api_helpers.cjs
+++ b/actions/setup/js/github_api_helpers.cjs
@@ -177,6 +177,16 @@ async function resolveTopLevelDiscussionCommentId(github, commentNodeId) {
   }
 }
 
+/**
+ * Type guard for a resolved REST endpoint descriptor, shared by handlers that
+ * choose between a REST call ({route, params}) and a GraphQL/discussion path.
+ * @param {unknown} endpoint
+ * @returns {endpoint is { route: string, params: Record<string, unknown> }}
+ */
+function isRestEndpoint(endpoint) {
+  return typeof endpoint === "object" && endpoint !== null && "route" in endpoint && "params" in endpoint;
+}
+
 /**
  * Create a discussion comment with optional threaded reply target.
  * @param {Object} github - GitHub API client (must support graphql)
@@ -217,6 +227,7 @@ module.exports = {
   createDiscussionComment,
   fetchAllRepoLabels,
   getFileContent,
+  isRestEndpoint,
   logGraphQLError,
   resolveTopLevelDiscussionCommentId,
 };