diff --git a/actions/setup/js/add_comment.cjs b/actions/setup/js/add_comment.cjs
index 16ce9cd0c1e..7f85c86c74d 100644
--- a/actions/setup/js/add_comment.cjs
+++ b/actions/setup/js/add_comment.cjs
@@ -435,6 +435,8 @@ async function main(config = {}) {
   const requiredLabels = Array.isArray(config.required_labels) ? config.required_labels : [];
   const requiredTitlePrefix = config.required_title_prefix || "";
   const mentionsDisabled = config.mentions === false || config.mentions?.enabled === false;
+  const preResolvedMentionAliases =
+    !mentionsDisabled && Array.isArray(config.allowedMentionAliases) ? config.allowedMentionAliases.map(alias => (typeof alias === "string" ? alias.trim().replace(/^@+/, "") : "")).filter(alias => alias.length > 0) : [];
   const configuredMentionAliases =
     !mentionsDisabled && Array.isArray(config.mentions?.allowed) ? config.mentions.allowed.map(alias => (typeof alias === "string" ? alias.trim().replace(/^@+/, "") : "")).filter(alias => alias.length > 0) : [];
 
@@ -656,7 +658,7 @@ async function main(config = {}) {
         }
       }
     }
-    const allowedMentionAliases = deduplicateCaseInsensitive([...parentAuthors, ...configuredMentionAliases]);
+    const allowedMentionAliases = deduplicateCaseInsensitive([...parentAuthors, ...preResolvedMentionAliases, ...configuredMentionAliases]);
 
     if (allowedMentionAliases.length > 0) {
       core.info(`[MENTIONS] Allowing aliases in comment: ${allowedMentionAliases.join(", ")}`);
diff --git a/actions/setup/js/add_comment.test.cjs b/actions/setup/js/add_comment.test.cjs
index 82a9541e4b3..400fd851dba 100644
--- a/actions/setup/js/add_comment.test.cjs
+++ b/actions/setup/js/add_comment.test.cjs
@@ -2849,6 +2849,42 @@ describe("add_comment", () => {
       expect(capturedBody).not.toContain("`@copilot`");
     });
 
+    it("should preserve pre-resolved allowed mentions from handler manager", async () => {
+      const addCommentScript = fs.readFileSync(path.join(__dirname, "add_comment.cjs"), "utf8");
+
+      mockContext.payload = {
+        pull_request: {
+          number: 8535,
+          user: { login: "PRAuthor", type: "User" },
+        },
+      };
+
+      let capturedBody = null;
+      mockGithub.rest.issues.createComment = async params => {
+        capturedBody = params.body;
+        return {
+          data: {
+            id: 12345,
+            html_url: "https://github.com/owner/repo/issues/8535#issuecomment-12345",
+          },
+        };
+      };
+
+      const handler = await eval(`(async () => { ${addCommentScript}; return await main({ mentions: { allowedTeams: ["myorg/eng"] }, allowedMentionAliases: ["TeamMate"] }); })()`);
+
+      const message = {
+        type: "add_comment",
+        body: "@TeamMate thanks for taking a look",
+      };
+
+      const result = await handler(message, {});
+
+      expect(result.success).toBe(true);
+      expect(capturedBody).toBeDefined();
+      expect(capturedBody).toContain("@TeamMate");
+      expect(capturedBody).not.toContain("`@TeamMate`");
+    });
+
     it("should escape all mentions when mentions.enabled is false", async () => {
       const addCommentScript = fs.readFileSync(path.join(__dirname, "add_comment.cjs"), "utf8");