diff --git a/apps/web/core/issues/mutations.ts b/apps/web/core/issues/mutations.ts
index 678978f9..85c15166 100644
--- a/apps/web/core/issues/mutations.ts
+++ b/apps/web/core/issues/mutations.ts
@@ -11,6 +11,22 @@ import type {
 } from "@/shared/types";
 import type { TimelineEntry, IssueSubscriber, Reaction } from "@/shared/types";
 
+// ---------------------------------------------------------------------------
+// Shared mutation variable types — used by both mutation hooks and
+// useMutationState consumers to keep the type assertion in sync.
+// ---------------------------------------------------------------------------
+
+export type ToggleCommentReactionVars = {
+  commentId: string;
+  emoji: string;
+  existing: Reaction | undefined;
+};
+
+export type ToggleIssueReactionVars = {
+  emoji: string;
+  existing: IssueReaction | undefined;
+};
+
 // ---------------------------------------------------------------------------
 // Done issue pagination
 // ---------------------------------------------------------------------------
@@ -339,11 +355,7 @@ export function useToggleCommentReaction(issueId: string) {
       commentId,
       emoji,
       existing,
-    }: {
-      commentId: string;
-      emoji: string;
-      existing: Reaction | undefined;
-    }) => {
+    }: ToggleCommentReactionVars) => {
       if (existing) {
         await api.removeReaction(commentId, emoji);
         return null;
@@ -367,10 +379,7 @@ export function useToggleIssueReaction(issueId: string) {
     mutationFn: async ({
       emoji,
       existing,
-    }: {
-      emoji: string;
-      existing: IssueReaction | undefined;
-    }) => {
+    }: ToggleIssueReactionVars) => {
       if (existing) {
         await api.removeIssueReaction(issueId, emoji);
         return null;
diff --git a/apps/web/features/issues/hooks/use-issue-reactions.ts b/apps/web/features/issues/hooks/use-issue-reactions.ts
index 44a5a30f..6435d77a 100644
--- a/apps/web/features/issues/hooks/use-issue-reactions.ts
+++ b/apps/web/features/issues/hooks/use-issue-reactions.ts
@@ -8,7 +8,7 @@ import type {
   IssueReactionRemovedPayload,
 } from "@/shared/types";
 import { issueReactionsOptions, issueKeys } from "@core/issues/queries";
-import { useToggleIssueReaction } from "@core/issues/mutations";
+import { useToggleIssueReaction, type ToggleIssueReactionVars } from "@core/issues/mutations";
 import { useWSEvent, useWSReconnect } from "@/features/realtime";
 
 export function useIssueReactions(issueId: string, userId?: string) {
@@ -80,9 +80,7 @@ export function useIssueReactions(issueId: string, userId?: string) {
       status: "pending",
     },
     select: (m) =>
-      m.state.variables as
-        | { emoji: string; existing: IssueReaction | undefined }
-        | undefined,
+      m.state.variables as ToggleIssueReactionVars | undefined,
   });
 
   const reactions = useMemo(() => {
@@ -111,7 +109,7 @@ export function useIssueReactions(issueId: string, userId?: string) {
               actor_type: "member",
               actor_id: userId ?? "",
               emoji: vars.emoji,
-              created_at: new Date().toISOString(),
+              created_at: "",
             },
           ];
         }
diff --git a/apps/web/features/issues/hooks/use-issue-timeline.ts b/apps/web/features/issues/hooks/use-issue-timeline.ts
index cd37e68d..c21baa58 100644
--- a/apps/web/features/issues/hooks/use-issue-timeline.ts
+++ b/apps/web/features/issues/hooks/use-issue-timeline.ts
@@ -17,6 +17,7 @@ import {
   useUpdateComment,
   useDeleteComment,
   useToggleCommentReaction,
+  type ToggleCommentReactionVars,
 } from "@core/issues/mutations";
 import { useWSEvent, useWSReconnect } from "@/features/realtime";
 import { toast } from "sonner";
@@ -269,9 +270,7 @@ export function useIssueTimeline(issueId: string, userId?: string) {
       status: "pending",
     },
     select: (m) =>
-      m.state.variables as
-        | { commentId: string; emoji: string; existing: Reaction | undefined }
-        | undefined,
+      m.state.variables as ToggleCommentReactionVars | undefined,
   });
 
   const optimisticTimeline = useMemo(() => {
@@ -306,7 +305,7 @@ export function useIssueTimeline(issueId: string, userId?: string) {
                 actor_type: "member",
                 actor_id: userId ?? "",
                 emoji: vars.emoji,
-                created_at: new Date().toISOString(),
+                created_at: "",
               },
             ];
           }