diff --git a/src/lib/api/adapters/collection.adapter.ts b/src/lib/api/adapters/collection.adapter.ts
new file mode 100644
index 00000000..11adebe7
--- /dev/null
+++ b/src/lib/api/adapters/collection.adapter.ts
@@ -0,0 +1,366 @@
+/**
+ * Collection Adapter
+ *
+ * Handles all collection-related API operations including CRUD for
+ * characters, weapons, summons, and job accessories in a user's collection.
+ *
+ * @module adapters/collection
+ */
+
+import { BaseAdapter } from './base.adapter'
+import type { AdapterOptions, PaginatedResponse } from './types'
+import { DEFAULT_ADAPTER_CONFIG } from './config'
+import type {
+	CollectionCharacter,
+	CollectionWeapon,
+	CollectionSummon,
+	CollectionJobAccessory,
+	CollectionCharacterInput,
+	CollectionWeaponInput,
+	CollectionSummonInput,
+	CollectionJobAccessoryInput,
+	CollectionFilters,
+	CollectionResponse
+} from '$lib/types/api/collection'
+
+/**
+ * Parameters for listing collection items with pagination
+ */
+export interface CollectionListParams extends CollectionFilters {
+	page?: number
+	limit?: number
+}
+
+/**
+ * Response structure for paginated collection list
+ */
+export interface CollectionCharacterListResponse {
+	characters: CollectionCharacter[]
+	meta: {
+		count: number
+		totalPages: number
+		perPage: number
+		currentPage: number
+	}
+}
+
+/**
+ * Collection adapter for managing user collections
+ */
+export class CollectionAdapter extends BaseAdapter {
+	constructor(options?: AdapterOptions) {
+		super(options)
+	}
+
+	// ============================================
+	// Collection Characters
+	// ============================================
+
+	/**
+	 * Lists the current user's collection characters with optional filters
+	 */
+	async listCharacters(
+		params: CollectionListParams = {}
+	): Promise<PaginatedResponse<CollectionCharacter>> {
+		const response = await this.request<CollectionCharacterListResponse>('/collection/characters', {
+			method: 'GET',
+			query: params
+		})
+
+		return {
+			results: response.characters,
+			page: response.meta.currentPage,
+			total: response.meta.count,
+			totalPages: response.meta.totalPages,
+			perPage: response.meta.perPage
+		}
+	}
+
+	/**
+	 * Gets a single collection character by ID
+	 */
+	async getCharacter(id: string): Promise<CollectionCharacter> {
+		return this.request<CollectionCharacter>(`/collection/characters/${id}`, {
+			method: 'GET'
+		})
+	}
+
+	/**
+	 * Adds a character to the collection
+	 */
+	async addCharacter(input: CollectionCharacterInput): Promise<CollectionCharacter> {
+		return this.request<CollectionCharacter>('/collection/characters', {
+			method: 'POST',
+			body: {
+				collectionCharacter: input
+			}
+		})
+	}
+
+	/**
+	 * Adds multiple characters to the collection
+	 * Makes parallel requests for each character
+	 */
+	async addCharacters(inputs: CollectionCharacterInput[]): Promise<CollectionCharacter[]> {
+		const results = await Promise.all(inputs.map((input) => this.addCharacter(input)))
+		return results
+	}
+
+	/**
+	 * Updates a collection character
+	 */
+	async updateCharacter(
+		id: string,
+		input: Partial<CollectionCharacterInput>
+	): Promise<CollectionCharacter> {
+		return this.request<CollectionCharacter>(`/collection/characters/${id}`, {
+			method: 'PATCH',
+			body: {
+				collectionCharacter: input
+			}
+		})
+	}
+
+	/**
+	 * Removes a character from the collection
+	 */
+	async removeCharacter(id: string): Promise<void> {
+		return this.request<void>(`/collection/characters/${id}`, {
+			method: 'DELETE'
+		})
+	}
+
+	/**
+	 * Gets the IDs of all characters in the current user's collection
+	 * Useful for filtering out already-owned characters in the add modal
+	 */
+	async getCollectedCharacterIds(): Promise<string[]> {
+		// Fetch all pages to get complete list
+		const allIds: string[] = []
+		let page = 1
+		let hasMore = true
+
+		while (hasMore) {
+			const response = await this.listCharacters({ page, limit: 100 })
+			allIds.push(...response.results.map((c) => c.character.id))
+			hasMore = page < response.totalPages
+			page++
+		}
+
+		return allIds
+	}
+
+	// ============================================
+	// Collection Weapons
+	// ============================================
+
+	/**
+	 * Lists the current user's collection weapons with optional filters
+	 */
+	async listWeapons(params: CollectionListParams = {}): Promise<PaginatedResponse<CollectionWeapon>> {
+		const response = await this.request<{
+			weapons: CollectionWeapon[]
+			meta: { count: number; totalPages: number; perPage: number; currentPage: number }
+		}>('/collection/weapons', {
+			method: 'GET',
+			query: params
+		})
+
+		return {
+			results: response.weapons,
+			page: response.meta.currentPage,
+			total: response.meta.count,
+			totalPages: response.meta.totalPages,
+			perPage: response.meta.perPage
+		}
+	}
+
+	/**
+	 * Adds a weapon to the collection
+	 */
+	async addWeapon(input: CollectionWeaponInput): Promise<CollectionWeapon> {
+		return this.request<CollectionWeapon>('/collection/weapons', {
+			method: 'POST',
+			body: {
+				collectionWeapon: input
+			}
+		})
+	}
+
+	/**
+	 * Updates a collection weapon
+	 */
+	async updateWeapon(id: string, input: Partial<CollectionWeaponInput>): Promise<CollectionWeapon> {
+		return this.request<CollectionWeapon>(`/collection/weapons/${id}`, {
+			method: 'PATCH',
+			body: {
+				collectionWeapon: input
+			}
+		})
+	}
+
+	/**
+	 * Removes a weapon from the collection
+	 */
+	async removeWeapon(id: string): Promise<void> {
+		return this.request<void>(`/collection/weapons/${id}`, {
+			method: 'DELETE'
+		})
+	}
+
+	// ============================================
+	// Collection Summons
+	// ============================================
+
+	/**
+	 * Lists the current user's collection summons with optional filters
+	 */
+	async listSummons(params: CollectionListParams = {}): Promise<PaginatedResponse<CollectionSummon>> {
+		const response = await this.request<{
+			summons: CollectionSummon[]
+			meta: { count: number; totalPages: number; perPage: number; currentPage: number }
+		}>('/collection/summons', {
+			method: 'GET',
+			query: params
+		})
+
+		return {
+			results: response.summons,
+			page: response.meta.currentPage,
+			total: response.meta.count,
+			totalPages: response.meta.totalPages,
+			perPage: response.meta.perPage
+		}
+	}
+
+	/**
+	 * Adds a summon to the collection
+	 */
+	async addSummon(input: CollectionSummonInput): Promise<CollectionSummon> {
+		return this.request<CollectionSummon>('/collection/summons', {
+			method: 'POST',
+			body: {
+				collectionSummon: input
+			}
+		})
+	}
+
+	/**
+	 * Updates a collection summon
+	 */
+	async updateSummon(id: string, input: Partial<CollectionSummonInput>): Promise<CollectionSummon> {
+		return this.request<CollectionSummon>(`/collection/summons/${id}`, {
+			method: 'PATCH',
+			body: {
+				collectionSummon: input
+			}
+		})
+	}
+
+	/**
+	 * Removes a summon from the collection
+	 */
+	async removeSummon(id: string): Promise<void> {
+		return this.request<void>(`/collection/summons/${id}`, {
+			method: 'DELETE'
+		})
+	}
+
+	// ============================================
+	// Collection Job Accessories
+	// ============================================
+
+	/**
+	 * Lists the current user's collection job accessories
+	 */
+	async listJobAccessories(): Promise<CollectionJobAccessory[]> {
+		const response = await this.request<{ jobAccessories: CollectionJobAccessory[] }>(
+			'/collection/job_accessories',
+			{
+				method: 'GET'
+			}
+		)
+		return response.jobAccessories
+	}
+
+	/**
+	 * Adds a job accessory to the collection
+	 */
+	async addJobAccessory(input: CollectionJobAccessoryInput): Promise<CollectionJobAccessory> {
+		return this.request<CollectionJobAccessory>('/collection/job_accessories', {
+			method: 'POST',
+			body: {
+				collectionJobAccessory: input
+			}
+		})
+	}
+
+	/**
+	 * Removes a job accessory from the collection
+	 */
+	async removeJobAccessory(id: string): Promise<void> {
+		return this.request<void>(`/collection/job_accessories/${id}`, {
+			method: 'DELETE'
+		})
+	}
+
+	// ============================================
+	// Public Collection (viewing other users)
+	// ============================================
+
+	/**
+	 * Gets a user's public collection (respects privacy settings)
+	 * @param userId - The user's ID
+	 * @param type - Optional type filter: 'characters', 'weapons', 'summons', 'job_accessories'
+	 */
+	async getPublicCollection(
+		userId: string,
+		type?: 'characters' | 'weapons' | 'summons' | 'job_accessories'
+	): Promise<CollectionResponse> {
+		return this.request<CollectionResponse>(`/users/${userId}/collection`, {
+			method: 'GET',
+			query: type ? { type } : undefined
+		})
+	}
+
+	/**
+	 * Gets a user's public character collection
+	 */
+	async getPublicCharacters(userId: string): Promise<CollectionCharacter[]> {
+		const response = await this.getPublicCollection(userId, 'characters')
+		return response.characters || []
+	}
+
+	/**
+	 * Gets a user's public weapon collection
+	 */
+	async getPublicWeapons(userId: string): Promise<CollectionWeapon[]> {
+		const response = await this.getPublicCollection(userId, 'weapons')
+		return response.weapons || []
+	}
+
+	/**
+	 * Gets a user's public summon collection
+	 */
+	async getPublicSummons(userId: string): Promise<CollectionSummon[]> {
+		const response = await this.getPublicCollection(userId, 'summons')
+		return response.summons || []
+	}
+
+	// ============================================
+	// Cache Management
+	// ============================================
+
+	/**
+	 * Clears collection-related cache
+	 */
+	clearCollectionCache() {
+		this.clearCache('/collection')
+		this.clearCache('/users')
+	}
+}
+
+/**
+ * Default collection adapter instance
+ */
+export const collectionAdapter = new CollectionAdapter(DEFAULT_ADAPTER_CONFIG)
diff --git a/src/lib/api/mutations/collection.mutations.ts b/src/lib/api/mutations/collection.mutations.ts
new file mode 100644
index 00000000..e40fa070
--- /dev/null
+++ b/src/lib/api/mutations/collection.mutations.ts
@@ -0,0 +1,256 @@
+/**
+ * Collection Mutation Configurations
+ *
+ * Provides mutation configurations for collection operations
+ * with cache invalidation using TanStack Query v6.
+ *
+ * @module api/mutations/collection
+ */
+
+import { useQueryClient, createMutation } from '@tanstack/svelte-query'
+import { collectionAdapter } from '$lib/api/adapters/collection.adapter'
+import { collectionKeys } from '$lib/api/queries/collection.queries'
+import type {
+	CollectionCharacter,
+	CollectionCharacterInput,
+	CollectionWeaponInput,
+	CollectionSummonInput,
+	CollectionJobAccessoryInput
+} from '$lib/types/api/collection'
+
+// ============================================================================
+// Character Mutations
+// ============================================================================
+
+/**
+ * Add characters to collection mutation
+ *
+ * Adds one or more characters to the user's collection.
+ *
+ * @example
+ * ```svelte
+ * <script lang="ts">
+ *   import { useAddToCollection } from '$lib/api/mutations/collection.mutations'
+ *
+ *   const addToCollection = useAddToCollection()
+ *
+ *   function handleAdd(characterIds: string[]) {
+ *     addToCollection.mutate(
+ *       characterIds.map(id => ({ characterId: id }))
+ *     )
+ *   }
+ * </script>
+ * ```
+ */
+export function useAddCharactersToCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (inputs: CollectionCharacterInput[]) => collectionAdapter.addCharacters(inputs),
+		onSuccess: () => {
+			// Invalidate all character-related collection queries
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characters() })
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characterIds() })
+		}
+	}))
+}
+
+/**
+ * Add single character to collection mutation
+ */
+export function useAddCharacterToCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (input: CollectionCharacterInput) => collectionAdapter.addCharacter(input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characters() })
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characterIds() })
+		}
+	}))
+}
+
+/**
+ * Update collection character mutation
+ *
+ * Updates a character's customizations (uncap, rings, etc.) in the collection.
+ */
+export function useUpdateCollectionCharacter() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: ({ id, input }: { id: string; input: Partial<CollectionCharacterInput> }) =>
+			collectionAdapter.updateCharacter(id, input),
+		onMutate: async ({ id, input }) => {
+			// Cancel any outgoing refetches
+			await queryClient.cancelQueries({ queryKey: collectionKeys.character(id) })
+
+			// Snapshot the previous value
+			const previousCharacter = queryClient.getQueryData<CollectionCharacter>(
+				collectionKeys.character(id)
+			)
+
+			// Optimistically update the cache
+			if (previousCharacter) {
+				queryClient.setQueryData(collectionKeys.character(id), {
+					...previousCharacter,
+					...input
+				})
+			}
+
+			return { previousCharacter }
+		},
+		onError: (_err, { id }, context) => {
+			// Rollback on error
+			if (context?.previousCharacter) {
+				queryClient.setQueryData(collectionKeys.character(id), context.previousCharacter)
+			}
+		},
+		onSettled: (_data, _err, { id }) => {
+			// Always refetch after mutation
+			queryClient.invalidateQueries({ queryKey: collectionKeys.character(id) })
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characters() })
+		}
+	}))
+}
+
+/**
+ * Remove character from collection mutation
+ */
+export function useRemoveCharacterFromCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (id: string) => collectionAdapter.removeCharacter(id),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characters() })
+			queryClient.invalidateQueries({ queryKey: collectionKeys.characterIds() })
+		}
+	}))
+}
+
+// ============================================================================
+// Weapon Mutations
+// ============================================================================
+
+/**
+ * Add weapon to collection mutation
+ */
+export function useAddWeaponToCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (input: CollectionWeaponInput) => collectionAdapter.addWeapon(input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.weapons() })
+		}
+	}))
+}
+
+/**
+ * Update collection weapon mutation
+ */
+export function useUpdateCollectionWeapon() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: ({ id, input }: { id: string; input: Partial<CollectionWeaponInput> }) =>
+			collectionAdapter.updateWeapon(id, input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.weapons() })
+		}
+	}))
+}
+
+/**
+ * Remove weapon from collection mutation
+ */
+export function useRemoveWeaponFromCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (id: string) => collectionAdapter.removeWeapon(id),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.weapons() })
+		}
+	}))
+}
+
+// ============================================================================
+// Summon Mutations
+// ============================================================================
+
+/**
+ * Add summon to collection mutation
+ */
+export function useAddSummonToCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (input: CollectionSummonInput) => collectionAdapter.addSummon(input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.summons() })
+		}
+	}))
+}
+
+/**
+ * Update collection summon mutation
+ */
+export function useUpdateCollectionSummon() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: ({ id, input }: { id: string; input: Partial<CollectionSummonInput> }) =>
+			collectionAdapter.updateSummon(id, input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.summons() })
+		}
+	}))
+}
+
+/**
+ * Remove summon from collection mutation
+ */
+export function useRemoveSummonFromCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (id: string) => collectionAdapter.removeSummon(id),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.summons() })
+		}
+	}))
+}
+
+// ============================================================================
+// Job Accessory Mutations
+// ============================================================================
+
+/**
+ * Add job accessory to collection mutation
+ */
+export function useAddJobAccessoryToCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (input: CollectionJobAccessoryInput) => collectionAdapter.addJobAccessory(input),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.all })
+		}
+	}))
+}
+
+/**
+ * Remove job accessory from collection mutation
+ */
+export function useRemoveJobAccessoryFromCollection() {
+	const queryClient = useQueryClient()
+
+	return createMutation(() => ({
+		mutationFn: (id: string) => collectionAdapter.removeJobAccessory(id),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: collectionKeys.all })
+		}
+	}))
+}
diff --git a/src/lib/api/queries/collection.queries.ts b/src/lib/api/queries/collection.queries.ts
new file mode 100644
index 00000000..5e9fb4d1
--- /dev/null
+++ b/src/lib/api/queries/collection.queries.ts
@@ -0,0 +1,233 @@
+/**
+ * Collection Query Options Factory
+ *
+ * Provides type-safe, reusable query configurations for collection operations
+ * using TanStack Query v6 patterns.
+ *
+ * @module api/queries/collection
+ */
+
+import { queryOptions, infiniteQueryOptions } from '@tanstack/svelte-query'
+import { collectionAdapter } from '$lib/api/adapters/collection.adapter'
+import type {
+	CollectionCharacter,
+	CollectionWeapon,
+	CollectionSummon,
+	CollectionFilters
+} from '$lib/types/api/collection'
+
+/**
+ * Page result format for collection infinite queries
+ */
+export interface CollectionPageResult<T> {
+	results: T[]
+	page: number
+	totalPages: number
+	total: number
+	perPage: number
+}
+
+/**
+ * Collection query options factory
+ *
+ * @example
+ * ```typescript
+ * import { createQuery, createInfiniteQuery } from '@tanstack/svelte-query'
+ * import { collectionQueries } from '$lib/api/queries/collection.queries'
+ *
+ * // Own collection characters
+ * const characters = createInfiniteQuery(() => collectionQueries.characters())
+ *
+ * // Public collection
+ * const publicChars = createQuery(() => collectionQueries.publicCharacters(userId))
+ *
+ * // Collected character IDs (for filtering add modal)
+ * const ownedIds = createQuery(() => collectionQueries.collectedCharacterIds())
+ * ```
+ */
+export const collectionQueries = {
+	/**
+	 * Current user's collection characters with infinite scroll
+	 */
+	characters: (filters?: CollectionFilters) =>
+		infiniteQueryOptions({
+			queryKey: ['collection', 'characters', filters] as const,
+			queryFn: async ({ pageParam }): Promise<CollectionPageResult<CollectionCharacter>> => {
+				const response = await collectionAdapter.listCharacters({
+					...filters,
+					page: pageParam
+				})
+				return {
+					results: response.results,
+					page: response.page,
+					totalPages: response.totalPages,
+					total: response.total,
+					perPage: response.perPage ?? 50
+				}
+			},
+			initialPageParam: 1,
+			getNextPageParam: (lastPage) => {
+				if (lastPage.page < lastPage.totalPages) {
+					return lastPage.page + 1
+				}
+				return undefined
+			},
+			staleTime: 1000 * 60 * 2, // 2 minutes
+			gcTime: 1000 * 60 * 15 // 15 minutes
+		}),
+
+	/**
+	 * Current user's collection weapons with infinite scroll
+	 */
+	weapons: (filters?: CollectionFilters) =>
+		infiniteQueryOptions({
+			queryKey: ['collection', 'weapons', filters] as const,
+			queryFn: async ({ pageParam }): Promise<CollectionPageResult<CollectionWeapon>> => {
+				const response = await collectionAdapter.listWeapons({
+					...filters,
+					page: pageParam
+				})
+				return {
+					results: response.results,
+					page: response.page,
+					totalPages: response.totalPages,
+					total: response.total,
+					perPage: response.perPage ?? 50
+				}
+			},
+			initialPageParam: 1,
+			getNextPageParam: (lastPage) => {
+				if (lastPage.page < lastPage.totalPages) {
+					return lastPage.page + 1
+				}
+				return undefined
+			},
+			staleTime: 1000 * 60 * 2,
+			gcTime: 1000 * 60 * 15
+		}),
+
+	/**
+	 * Current user's collection summons with infinite scroll
+	 */
+	summons: (filters?: CollectionFilters) =>
+		infiniteQueryOptions({
+			queryKey: ['collection', 'summons', filters] as const,
+			queryFn: async ({ pageParam }): Promise<CollectionPageResult<CollectionSummon>> => {
+				const response = await collectionAdapter.listSummons({
+					...filters,
+					page: pageParam
+				})
+				return {
+					results: response.results,
+					page: response.page,
+					totalPages: response.totalPages,
+					total: response.total,
+					perPage: response.perPage ?? 50
+				}
+			},
+			initialPageParam: 1,
+			getNextPageParam: (lastPage) => {
+				if (lastPage.page < lastPage.totalPages) {
+					return lastPage.page + 1
+				}
+				return undefined
+			},
+			staleTime: 1000 * 60 * 2,
+			gcTime: 1000 * 60 * 15
+		}),
+
+	/**
+	 * Get IDs of characters already in the user's collection
+	 * Used to filter out owned characters in the add modal
+	 */
+	collectedCharacterIds: () =>
+		queryOptions({
+			queryKey: ['collection', 'characters', 'ids'] as const,
+			queryFn: () => collectionAdapter.getCollectedCharacterIds(),
+			staleTime: 1000 * 60 * 5, // 5 minutes
+			gcTime: 1000 * 60 * 30 // 30 minutes
+		}),
+
+	/**
+	 * Single collection character by ID
+	 */
+	character: (id: string) =>
+		queryOptions({
+			queryKey: ['collection', 'character', id] as const,
+			queryFn: () => collectionAdapter.getCharacter(id),
+			enabled: !!id,
+			staleTime: 1000 * 60 * 5,
+			gcTime: 1000 * 60 * 30
+		}),
+
+	/**
+	 * Public collection for a user (respects privacy)
+	 */
+	publicCharacters: (userId: string) =>
+		queryOptions({
+			queryKey: ['collection', 'public', userId, 'characters'] as const,
+			queryFn: () => collectionAdapter.getPublicCharacters(userId),
+			enabled: !!userId,
+			staleTime: 1000 * 60 * 5,
+			gcTime: 1000 * 60 * 30
+		}),
+
+	/**
+	 * Public weapon collection for a user
+	 */
+	publicWeapons: (userId: string) =>
+		queryOptions({
+			queryKey: ['collection', 'public', userId, 'weapons'] as const,
+			queryFn: () => collectionAdapter.getPublicWeapons(userId),
+			enabled: !!userId,
+			staleTime: 1000 * 60 * 5,
+			gcTime: 1000 * 60 * 30
+		}),
+
+	/**
+	 * Public summon collection for a user
+	 */
+	publicSummons: (userId: string) =>
+		queryOptions({
+			queryKey: ['collection', 'public', userId, 'summons'] as const,
+			queryFn: () => collectionAdapter.getPublicSummons(userId),
+			enabled: !!userId,
+			staleTime: 1000 * 60 * 5,
+			gcTime: 1000 * 60 * 30
+		})
+}
+
+/**
+ * Query key helpers for cache invalidation
+ *
+ * @example
+ * ```typescript
+ * import { useQueryClient } from '@tanstack/svelte-query'
+ * import { collectionKeys } from '$lib/api/queries/collection.queries'
+ *
+ * const queryClient = useQueryClient()
+ *
+ * // Invalidate all collection data
+ * queryClient.invalidateQueries({ queryKey: collectionKeys.all })
+ *
+ * // Invalidate only characters
+ * queryClient.invalidateQueries({ queryKey: collectionKeys.characters() })
+ * ```
+ */
+export const collectionKeys = {
+	all: ['collection'] as const,
+	characters: () => [...collectionKeys.all, 'characters'] as const,
+	characterList: (filters?: CollectionFilters) =>
+		[...collectionKeys.characters(), filters] as const,
+	character: (id: string) => [...collectionKeys.all, 'character', id] as const,
+	characterIds: () => [...collectionKeys.characters(), 'ids'] as const,
+	weapons: () => [...collectionKeys.all, 'weapons'] as const,
+	weaponList: (filters?: CollectionFilters) => [...collectionKeys.weapons(), filters] as const,
+	summons: () => [...collectionKeys.all, 'summons'] as const,
+	summonList: (filters?: CollectionFilters) => [...collectionKeys.summons(), filters] as const,
+	public: (userId: string) => [...collectionKeys.all, 'public', userId] as const,
+	publicCharacters: (userId: string) =>
+		[...collectionKeys.public(userId), 'characters'] as const,
+	publicWeapons: (userId: string) => [...collectionKeys.public(userId), 'weapons'] as const,
+	publicSummons: (userId: string) => [...collectionKeys.public(userId), 'summons'] as const
+}
diff --git a/src/lib/types/api/collection.ts b/src/lib/types/api/collection.ts
new file mode 100644
index 00000000..871cf233
--- /dev/null
+++ b/src/lib/types/api/collection.ts
@@ -0,0 +1,164 @@
+// Collection types based on Rails CollectionCharacter/Weapon/Summon blueprints
+// These define user-owned items with customizations
+
+import type { Character, Weapon, Summon, JobAccessory, Awakening } from './entities'
+
+/**
+ * Extended mastery modifier (used for rings and earrings)
+ */
+export interface ExtendedMastery {
+	modifier: number
+	strength: number
+}
+
+/**
+ * Collection character from CollectionCharacterBlueprint
+ * Represents a user's owned character with customizations
+ */
+export interface CollectionCharacter {
+	id: string
+	uncapLevel: number
+	transcendenceStep: number
+	perpetuity: boolean
+	ring1: ExtendedMastery | null
+	ring2: ExtendedMastery | null
+	ring3: ExtendedMastery | null
+	ring4: ExtendedMastery | null
+	earring: ExtendedMastery | null
+	awakening: {
+		type: Awakening
+		level: number
+	} | null
+	character: Character
+	createdAt: string
+	updatedAt: string
+}
+
+/**
+ * Collection weapon from CollectionWeaponBlueprint
+ * Represents a user's owned weapon with customizations
+ */
+export interface CollectionWeapon {
+	id: string
+	uncapLevel: number
+	transcendenceStep: number
+	element?: number // For element-changeable weapons
+	ax?: Array<{ modifier: number; strength: number }>
+	awakening: {
+		type: Awakening
+		level: number
+	} | null
+	weaponKeys?: Array<{
+		id: string
+		name: { en: string; ja: string }
+		slot: number
+	}>
+	weapon: Weapon
+	createdAt: string
+	updatedAt: string
+}
+
+/**
+ * Collection summon from CollectionSummonBlueprint
+ * Represents a user's owned summon with customizations
+ */
+export interface CollectionSummon {
+	id: string
+	uncapLevel: number
+	transcendenceStep: number
+	summon: Summon
+	createdAt: string
+	updatedAt: string
+}
+
+/**
+ * Collection job accessory from CollectionJobAccessoryBlueprint
+ */
+export interface CollectionJobAccessory {
+	id: string
+	jobAccessory: JobAccessory
+	createdAt: string
+	updatedAt: string
+}
+
+/**
+ * Full collection response (when no type filter is applied)
+ */
+export interface CollectionResponse {
+	characters?: CollectionCharacter[]
+	weapons?: CollectionWeapon[]
+	summons?: CollectionSummon[]
+	jobAccessories?: CollectionJobAccessory[]
+}
+
+/**
+ * Input for creating a collection character
+ */
+export interface CollectionCharacterInput {
+	characterId: string
+	uncapLevel?: number
+	transcendenceStep?: number
+	perpetuity?: boolean
+	awakeningId?: string
+	awakeningLevel?: number
+	ring1?: ExtendedMastery
+	ring2?: ExtendedMastery
+	ring3?: ExtendedMastery
+	ring4?: ExtendedMastery
+	earring?: ExtendedMastery
+}
+
+/**
+ * Input for creating a collection weapon
+ */
+export interface CollectionWeaponInput {
+	weaponId: string
+	uncapLevel?: number
+	transcendenceStep?: number
+	element?: number
+	weaponKey1Id?: string
+	weaponKey2Id?: string
+	weaponKey3Id?: string
+	weaponKey4Id?: string
+	awakeningId?: string
+	awakeningLevel?: number
+	axModifier1?: number
+	axStrength1?: number
+	axModifier2?: number
+	axStrength2?: number
+}
+
+/**
+ * Input for creating a collection summon
+ */
+export interface CollectionSummonInput {
+	summonId: string
+	uncapLevel?: number
+	transcendenceStep?: number
+}
+
+/**
+ * Input for creating a collection job accessory
+ */
+export interface CollectionJobAccessoryInput {
+	jobAccessoryId: string
+}
+
+/**
+ * Filters for listing collection items
+ */
+export interface CollectionFilters {
+	element?: number[]
+	rarity?: number[]
+	page?: number
+	limit?: number
+}
+
+/**
+ * Collection privacy levels (matches Rails enum)
+ */
+export enum CollectionPrivacy {
+	Everyone = 0,
+	CrewOnly = 1,
+	Private = 2
+}