diff --git a/src/lib/api/mutations/job.mutations.ts b/src/lib/api/mutations/job.mutations.ts
index 1b6cd7db..8784da54 100644
--- a/src/lib/api/mutations/job.mutations.ts
+++ b/src/lib/api/mutations/job.mutations.ts
@@ -129,9 +129,11 @@ export function useRemovePartyJobSkill() {
 			const previousParty = queryClient.getQueryData<Party>(partyKeys.detail(shortcode))
 
 			// Optimistically remove the skill from the slot
+			// Convert slot number to string key to match jobSkills type (0-3)
 			if (previousParty?.jobSkills) {
 				const updatedSkills = { ...previousParty.jobSkills }
-				delete updatedSkills[slot]
+				const key = String(slot) as unknown as keyof typeof updatedSkills
+				delete updatedSkills[key]
 				queryClient.setQueryData(partyKeys.detail(shortcode), {
 					...previousParty,
 					jobSkills: updatedSkills
diff --git a/src/lib/api/queries/party.queries.ts b/src/lib/api/queries/party.queries.ts
index b8ae67a2..d1460ae1 100644
--- a/src/lib/api/queries/party.queries.ts
+++ b/src/lib/api/queries/party.queries.ts
@@ -21,8 +21,8 @@ export interface PartyPageResult {
 	results: Party[]
 	page: number
 	totalPages: number
-	total: number
-	perPage: number
+	total?: number
+	perPage?: number
 }
 
 /**
diff --git a/src/lib/query/ssr.ts b/src/lib/query/ssr.ts
index 3ef7e822..008177cd 100644
--- a/src/lib/query/ssr.ts
+++ b/src/lib/query/ssr.ts
@@ -15,9 +15,10 @@ import type { QueryClient } from '@tanstack/svelte-query'
  */
 export interface InitialDataOptions<TData> {
 	/**
-	 * The data fetched on the server to use as initial data
+	 * The data fetched on the server to use as initial data.
+	 * TanStack Query accepts TData | undefined but NOT null.
 	 */
-	initialData: TData | undefined | null
+	initialData?: TData
 
 	/**
 	 * Optional timestamp when the data was fetched on the server.
@@ -33,6 +34,9 @@ export interface InitialDataOptions<TData> {
  * Use this helper when you have data fetched in a +page.server.ts load function
  * and want to use it as initial data for a TanStack Query.
  *
+ * Note: This helper strips `null` from the input since TanStack Query's
+ * initialData only accepts `TData | undefined`, not `null`.
+ *
  * @example
  * ```svelte
  * <script lang="ts">
@@ -51,16 +55,16 @@ export interface InitialDataOptions<TData> {
  * </script>
  * ```
  *
- * @param initialData - The data fetched on the server
+ * @param initialData - The data fetched on the server (null is converted to undefined)
  * @param updatedAt - Optional timestamp when data was fetched (defaults to 0)
  * @returns Query options object with initialData and initialDataUpdatedAt
  */
 export function withInitialData<TData>(
 	initialData: TData | undefined | null,
 	updatedAt?: number
-): InitialDataOptions<TData> {
+): InitialDataOptions<NonNullable<TData>> {
 	return {
-		initialData: initialData ?? undefined,
+		initialData: (initialData ?? undefined) as NonNullable<TData> | undefined,
 		initialDataUpdatedAt: updatedAt ?? 0
 	}
 }