diff --git a/src/idz/world/_facet.ts b/src/idz/file/_facet.ts
similarity index 91%
rename from src/idz/world/_facet.ts
rename to src/idz/file/_facet.ts
index e8960b4..e0373b8 100644
--- a/src/idz/world/_facet.ts
+++ b/src/idz/file/_facet.ts
@@ -1,5 +1,5 @@
 import { loadJson, saveJson } from "./_util";
-import { FacetRepository } from "./defs";
+import { FacetRepository } from "../repo";
 import { Id } from "../model/base";
 import { Profile } from "../model/profile";
 
diff --git a/src/idz/world/_flag.ts b/src/idz/file/_flag.ts
similarity index 92%
rename from src/idz/world/_flag.ts
rename to src/idz/file/_flag.ts
index ff30554..428b3d0 100644
--- a/src/idz/world/_flag.ts
+++ b/src/idz/file/_flag.ts
@@ -1,5 +1,5 @@
 import { loadNumberList, saveNumberList } from "./_util";
-import { FlagRepository } from "./defs";
+import { FlagRepository } from "../repo";
 import { Id } from "../model/base";
 import { Profile } from "../model/profile";
 
diff --git a/src/idz/world/_util.ts b/src/idz/file/_util.ts
similarity index 100%
rename from src/idz/world/_util.ts
rename to src/idz/file/_util.ts
diff --git a/src/idz/world/car.ts b/src/idz/file/car.ts
similarity index 97%
rename from src/idz/world/car.ts
rename to src/idz/file/car.ts
index be730f0..ebc36a6 100644
--- a/src/idz/world/car.ts
+++ b/src/idz/file/car.ts
@@ -1,7 +1,7 @@
 import { existsSync } from "fs";
 
 import { loadJson, saveJson } from "./_util";
-import { CarRepository } from "./defs";
+import { CarRepository } from "../repo";
 import { Id } from "../model/base";
 import { Car, CarSelector } from "../model/car";
 import { Profile } from "../model/profile";
diff --git a/src/idz/world/coursePlays.ts b/src/idz/file/coursePlays.ts
similarity index 95%
rename from src/idz/world/coursePlays.ts
rename to src/idz/file/coursePlays.ts
index c0e8f98..bb3471d 100644
--- a/src/idz/world/coursePlays.ts
+++ b/src/idz/file/coursePlays.ts
@@ -1,5 +1,5 @@
 import { loadNumberList, saveNumberList } from "./_util";
-import { CoursePlaysRepository } from "./defs";
+import { CoursePlaysRepository } from "../repo";
 import { Id } from "../model/base";
 import { Profile } from "../model/profile";
 
diff --git a/src/idz/world/index.ts b/src/idz/file/index.ts
similarity index 88%
rename from src/idz/world/index.ts
rename to src/idz/file/index.ts
index fb79fc1..7822316 100644
--- a/src/idz/world/index.ts
+++ b/src/idz/file/index.ts
@@ -4,15 +4,15 @@ import { FacetRepositoryImpl } from "./_facet";
 import { FlagRepositoryImpl } from "./_flag";
 import { CarRepositoryImpl } from "./car";
 import { CoursePlaysRepositoryImpl } from "./coursePlays";
-import { World } from "./defs";
+import { Repositories } from "../repo";
 import { ProfileRepositoryImpl } from "./profile";
 import { TicketsRepositoryImpl } from "./tickets";
 import { TimeAttackRepositoryImpl } from "./timeAttack";
 import * as Model from "../model";
 
-export { World };
+export { Repositories as World };
 
-class WorldImpl implements World {
+class WorldImpl implements Repositories {
   constructor(private readonly _root: string) {}
 
   backgrounds() {
@@ -67,7 +67,9 @@ class WorldImpl implements World {
   }
 }
 
-export async function createWorld(root: string): Promise<World> {
+export async function beginFilesystemSession(
+  root: string
+): Promise<Repositories> {
   if (!fs.existsSync(root)) {
     fs.mkdirSync(root);
   }
diff --git a/src/idz/world/profile.ts b/src/idz/file/profile.ts
similarity index 94%
rename from src/idz/world/profile.ts
rename to src/idz/file/profile.ts
index 595ea12..fe64ed9 100644
--- a/src/idz/world/profile.ts
+++ b/src/idz/file/profile.ts
@@ -2,7 +2,7 @@ import * as fs from "fs";
 import { promisify } from "util";
 
 import { loadJson, saveJson } from "./_util";
-import { ProfileRepository } from "./defs";
+import { ProfileRepository } from "../repo";
 import { AimeId, Id } from "../model/base";
 import { Profile } from "../model/profile";
 
diff --git a/src/idz/world/tickets.ts b/src/idz/file/tickets.ts
similarity index 96%
rename from src/idz/world/tickets.ts
rename to src/idz/file/tickets.ts
index c9930b3..5605c3d 100644
--- a/src/idz/world/tickets.ts
+++ b/src/idz/file/tickets.ts
@@ -1,5 +1,5 @@
 import { loadJson, saveJson } from "./_util";
-import { FacetRepository } from "./defs";
+import { FacetRepository } from "../repo";
 import { Tickets } from "../model/tickets";
 import { Id, Profile } from "../model";
 
diff --git a/src/idz/world/timeAttack.ts b/src/idz/file/timeAttack.ts
similarity index 96%
rename from src/idz/world/timeAttack.ts
rename to src/idz/file/timeAttack.ts
index e943532..add1707 100644
--- a/src/idz/world/timeAttack.ts
+++ b/src/idz/file/timeAttack.ts
@@ -1,7 +1,7 @@
 import * as fs from "fs";
 
 import { loadJson, saveJson } from "./_util";
-import { TimeAttackRepository } from "./defs";
+import { TimeAttackRepository } from "../repo";
 import { Id } from "../model/base";
 import { Profile } from "../model/profile";
 import { TimeAttackScore } from "../model/timeAttack";
diff --git a/src/idz/handler/_team.ts b/src/idz/handler/_team.ts
index 7667e3b..5411802 100644
--- a/src/idz/handler/_team.ts
+++ b/src/idz/handler/_team.ts
@@ -4,10 +4,10 @@ import { JoinAutoTeamRequest } from "../request/joinAutoTeam";
 import { LoadTeamRequest } from "../request/loadTeam";
 import { JoinAutoTeamResponse } from "../response/joinAutoTeam";
 import { LoadTeamResponse } from "../response/loadTeam";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function _team(
-  w: World,
+  w: Repositories,
   req: JoinAutoTeamRequest | LoadTeamRequest
 ): JoinAutoTeamResponse | LoadTeamResponse {
   const bits = {
diff --git a/src/idz/handler/checkTeamName.ts b/src/idz/handler/checkTeamName.ts
index 934d766..3627f76 100644
--- a/src/idz/handler/checkTeamName.ts
+++ b/src/idz/handler/checkTeamName.ts
@@ -1,9 +1,9 @@
 import { CheckTeamNameRequest } from "../request/checkTeamName";
 import { CheckTeamNameResponse } from "../response/checkTeamName";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function checkTeamName(
-  w: World,
+  w: Repositories,
   req: CheckTeamNameRequest
 ): CheckTeamNameResponse {
   return {
diff --git a/src/idz/handler/createProfile.ts b/src/idz/handler/createProfile.ts
index 5c8d596..b994543 100644
--- a/src/idz/handler/createProfile.ts
+++ b/src/idz/handler/createProfile.ts
@@ -7,10 +7,10 @@ import { Team } from "../model/team";
 import { Unlocks } from "../model/unlocks";
 import { CreateProfileRequest } from "../request/createProfile";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function createProfile(
-  w: World,
+  w: Repositories,
   req: CreateProfileRequest
 ): Promise<GenericResponse> {
   const profileId = await w.profile().generateId();
diff --git a/src/idz/handler/createTeam.ts b/src/idz/handler/createTeam.ts
index 14f7315..8f6cb5c 100644
--- a/src/idz/handler/createTeam.ts
+++ b/src/idz/handler/createTeam.ts
@@ -2,10 +2,10 @@ import { Id } from "../model/base";
 import { Team } from "../model/team";
 import { CreateTeamRequest } from "../request/createTeam";
 import { CreateTeamResponse } from "../response/createTeam";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function createTeam(
-  w: World,
+  w: Repositories,
   req: CreateTeamRequest
 ): CreateTeamResponse {
   return {
diff --git a/src/idz/handler/discoverProfile.ts b/src/idz/handler/discoverProfile.ts
index f2df986..7aa5597 100644
--- a/src/idz/handler/discoverProfile.ts
+++ b/src/idz/handler/discoverProfile.ts
@@ -1,9 +1,9 @@
 import { DiscoverProfileRequest } from "../request/discoverProfile";
 import { DiscoverProfileResponse } from "../response/discoverProfile";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function discoverProfile(
-  w: World,
+  w: Repositories,
   req: DiscoverProfileRequest
 ): Promise<DiscoverProfileResponse> {
   return {
diff --git a/src/idz/handler/index.ts b/src/idz/handler/index.ts
index c985688..39ac1a0 100644
--- a/src/idz/handler/index.ts
+++ b/src/idz/handler/index.ts
@@ -35,9 +35,12 @@ import { updateUiReport } from "./updateUiReport";
 import { updateUserLog } from "./updateUserLog";
 import { Request } from "../request";
 import { Response } from "../response";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export async function dispatch(w: World, req: Request): Promise<Response> {
+export async function dispatch(
+  w: Repositories,
+  req: Request
+): Promise<Response> {
   switch (req.type) {
     case "check_team_name_req":
       return checkTeamName(w, req);
diff --git a/src/idz/handler/load2on2.ts b/src/idz/handler/load2on2.ts
index cef5a6d..3005afa 100644
--- a/src/idz/handler/load2on2.ts
+++ b/src/idz/handler/load2on2.ts
@@ -1,8 +1,11 @@
 import { Load2on2Request } from "../request/load2on2";
 import { Load2on2Response } from "../response/load2on2";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export function load2on2(w: World, req: Load2on2Request): Load2on2Response {
+export function load2on2(
+  w: Repositories,
+  req: Load2on2Request
+): Load2on2Response {
   return {
     type: "load_2on2_res",
   };
diff --git a/src/idz/handler/loadConfig.ts b/src/idz/handler/loadConfig.ts
index f6370ff..d6efb66 100644
--- a/src/idz/handler/loadConfig.ts
+++ b/src/idz/handler/loadConfig.ts
@@ -1,9 +1,9 @@
 import { LoadConfigRequest } from "../request/loadConfig";
 import { LoadConfigResponse } from "../response/loadConfig";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadConfig(
-  w: World,
+  w: Repositories,
   req: LoadConfigRequest
 ): LoadConfigResponse {
   return {
diff --git a/src/idz/handler/loadConfig2.ts b/src/idz/handler/loadConfig2.ts
index ccb46dd..ae3f6f0 100644
--- a/src/idz/handler/loadConfig2.ts
+++ b/src/idz/handler/loadConfig2.ts
@@ -1,9 +1,9 @@
 import { LoadConfigRequest2 } from "../request/loadConfig2";
 import { LoadConfigResponse2 } from "../response/loadConfig2";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadConfig2(
-  w: World,
+  w: Repositories,
   req: LoadConfigRequest2
 ): LoadConfigResponse2 {
   return {
diff --git a/src/idz/handler/loadGarage.ts b/src/idz/handler/loadGarage.ts
index f30ef31..c3bbd23 100644
--- a/src/idz/handler/loadGarage.ts
+++ b/src/idz/handler/loadGarage.ts
@@ -1,9 +1,9 @@
 import { LoadGarageRequest } from "../request/loadGarage";
 import { LoadGarageResponse } from "../response/loadGarage";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function loadGarage(
-  w: World,
+  w: Repositories,
   req: LoadGarageRequest
 ): Promise<LoadGarageResponse> {
   return {
diff --git a/src/idz/handler/loadGeneralReward.ts b/src/idz/handler/loadGeneralReward.ts
index 8318dc1..03bf1b6 100644
--- a/src/idz/handler/loadGeneralReward.ts
+++ b/src/idz/handler/loadGeneralReward.ts
@@ -1,10 +1,10 @@
 import { LoadGeneralRewardRequest } from "../request/loadGeneralReward";
 import { GenericResponse } from "../response/generic";
 import { LoadGeneralRewardResponse } from "../response/loadGeneralReward";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadGeneralReward(
-  w: World,
+  w: Repositories,
   req: LoadGeneralRewardRequest
 ): LoadGeneralRewardResponse | GenericResponse {
   // A non-generic response is also accepted, but why bother
diff --git a/src/idz/handler/loadGhost.ts b/src/idz/handler/loadGhost.ts
index bca3982..55b29a9 100644
--- a/src/idz/handler/loadGhost.ts
+++ b/src/idz/handler/loadGhost.ts
@@ -1,7 +1,10 @@
 import { LoadGhostRequest } from "../request/loadGhost";
 import { LoadGhostResponse } from "../response/loadGhost";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export function loadGhost(w: World, req: LoadGhostRequest): LoadGhostResponse {
+export function loadGhost(
+  w: Repositories,
+  req: LoadGhostRequest
+): LoadGhostResponse {
   return { type: "load_ghost_res" };
 }
diff --git a/src/idz/handler/loadProfile.ts b/src/idz/handler/loadProfile.ts
index 5f1ab8c..acce479 100644
--- a/src/idz/handler/loadProfile.ts
+++ b/src/idz/handler/loadProfile.ts
@@ -1,9 +1,9 @@
 import { LoadProfileRequest } from "../request/loadProfile";
 import { LoadProfileResponse2 } from "../response/loadProfile2";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function loadProfile(
-  w: World,
+  w: Repositories,
   req: LoadProfileRequest
 ): Promise<LoadProfileResponse2> {
   // Promise.all would be messy here, who cares anyway this isn't supposed to
diff --git a/src/idz/handler/loadRewardTable.ts b/src/idz/handler/loadRewardTable.ts
index 3c49852..23370c6 100644
--- a/src/idz/handler/loadRewardTable.ts
+++ b/src/idz/handler/loadRewardTable.ts
@@ -1,9 +1,9 @@
 import { LoadRewardTableRequest } from "../request/loadRewardTable";
 import { LoadRewardTableResponse } from "../response/loadRewardTable";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadReward(
-  w: World,
+  w: Repositories,
   req: LoadRewardTableRequest
 ): LoadRewardTableResponse {
   return {
diff --git a/src/idz/handler/loadServerList.ts b/src/idz/handler/loadServerList.ts
index 72f2232..aa315b6 100644
--- a/src/idz/handler/loadServerList.ts
+++ b/src/idz/handler/loadServerList.ts
@@ -1,10 +1,10 @@
 import { LoadServerListRequest } from "../request/loadServerList";
 import { LoadServerListResponse } from "../response/loadServerList";
-import { World } from "../world";
+import { Repositories } from "../repo";
 import { hostname } from "../../hostname";
 
 export function loadServerList(
-  w: World,
+  w: Repositories,
   req: LoadServerListRequest
 ): LoadServerListResponse {
   const myHost = hostname();
diff --git a/src/idz/handler/loadStocker.ts b/src/idz/handler/loadStocker.ts
index 80e6164..93dc353 100644
--- a/src/idz/handler/loadStocker.ts
+++ b/src/idz/handler/loadStocker.ts
@@ -1,9 +1,9 @@
 import { LoadStockerRequest } from "../request/loadStocker";
 import { LoadStockerResponse } from "../response/loadStocker";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function loadStocker(
-  w: World,
+  w: Repositories,
   req: LoadStockerRequest
 ): Promise<LoadStockerResponse> {
   const backgrounds = await w.backgrounds().loadAll(req.profileId);
diff --git a/src/idz/handler/loadTeamRanking.ts b/src/idz/handler/loadTeamRanking.ts
index cc450e5..f68c25b 100644
--- a/src/idz/handler/loadTeamRanking.ts
+++ b/src/idz/handler/loadTeamRanking.ts
@@ -1,9 +1,9 @@
 import { LoadTeamRankingRequest } from "../request/loadTeamRanking";
 import { LoadTeamRankingResponse } from "../response/loadTeamRanking";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadTeamRanking(
-  w: World,
+  w: Repositories,
   req: LoadTeamRankingRequest
 ): LoadTeamRankingResponse {
   return {
diff --git a/src/idz/handler/loadTopTen.ts b/src/idz/handler/loadTopTen.ts
index 6c8112f..264bc13 100644
--- a/src/idz/handler/loadTopTen.ts
+++ b/src/idz/handler/loadTopTen.ts
@@ -1,9 +1,9 @@
 import { LoadTopTenRequest } from "../request/loadTopTen";
 import { LoadTopTenResponse } from "../response/loadTopTen";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function loadTopTen(
-  w: World,
+  w: Repositories,
   req: LoadTopTenRequest
 ): LoadTopTenResponse {
   return {
diff --git a/src/idz/handler/lockGarage.ts b/src/idz/handler/lockGarage.ts
index efcc76e..33c4428 100644
--- a/src/idz/handler/lockGarage.ts
+++ b/src/idz/handler/lockGarage.ts
@@ -1,7 +1,10 @@
 import { LockGarageRequest } from "../request/lockGarage";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export function lockGarage(w: World, req: LockGarageRequest): GenericResponse {
+export function lockGarage(
+  w: Repositories,
+  req: LockGarageRequest
+): GenericResponse {
   return { type: "generic_res" };
 }
diff --git a/src/idz/handler/lockProfile.ts b/src/idz/handler/lockProfile.ts
index 1b6b185..c8b8398 100644
--- a/src/idz/handler/lockProfile.ts
+++ b/src/idz/handler/lockProfile.ts
@@ -1,9 +1,9 @@
 import { LockAccountRequest } from "../request/lockProfile";
 import { LockProfileResponse } from "../response/lockProfile";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function lockProfile(
-  w: World,
+  w: Repositories,
   req: LockAccountRequest
 ): LockProfileResponse {
   return {
diff --git a/src/idz/handler/msg00AD.ts b/src/idz/handler/msg00AD.ts
index be7d754..ea70515 100644
--- a/src/idz/handler/msg00AD.ts
+++ b/src/idz/handler/msg00AD.ts
@@ -1,7 +1,7 @@
 import { Message00AD } from "../request/msg00AD";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export function msg00AD(w: World, req: Message00AD): GenericResponse {
+export function msg00AD(w: Repositories, req: Message00AD): GenericResponse {
   return { type: "generic_res" };
 }
diff --git a/src/idz/handler/saveExpedition.ts b/src/idz/handler/saveExpedition.ts
index 4ecca5a..e136b34 100644
--- a/src/idz/handler/saveExpedition.ts
+++ b/src/idz/handler/saveExpedition.ts
@@ -1,10 +1,10 @@
 import { SaveExpeditionRequest } from "../request/saveExpedition";
 import { GenericResponse } from "../response/generic";
 import { SaveExpeditionResponse } from "../response/saveExpedition";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function saveExpedition(
-  w: World,
+  w: Repositories,
   req: SaveExpeditionRequest
 ): GenericResponse | SaveExpeditionResponse {
   if (req.field_0004 === 0) {
diff --git a/src/idz/handler/saveGarage.ts b/src/idz/handler/saveGarage.ts
index cde8a58..9417624 100644
--- a/src/idz/handler/saveGarage.ts
+++ b/src/idz/handler/saveGarage.ts
@@ -1,9 +1,9 @@
 import { SaveGarageRequest } from "../request/saveGarage";
 import { SaveGarageResponse } from "../response/saveGarage";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function saveGarage(
-  w: World,
+  w: Repositories,
   req: SaveGarageRequest
 ): SaveGarageResponse {
   return {
diff --git a/src/idz/handler/saveNewCar.ts b/src/idz/handler/saveNewCar.ts
index 5d3cfc1..8654acf 100644
--- a/src/idz/handler/saveNewCar.ts
+++ b/src/idz/handler/saveNewCar.ts
@@ -1,9 +1,9 @@
 import { SaveNewCarRequest } from "../request/saveNewCar";
 import { SaveNewCarResponse } from "../response/saveNewCar";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function saveNewCar(
-  w: World,
+  w: Repositories,
   req: SaveNewCarRequest
 ): Promise<SaveNewCarResponse> {
   await w.car().saveCar(req.profileId, req.car);
diff --git a/src/idz/handler/saveProfile.ts b/src/idz/handler/saveProfile.ts
index f3f3836..da9db4c 100644
--- a/src/idz/handler/saveProfile.ts
+++ b/src/idz/handler/saveProfile.ts
@@ -1,9 +1,9 @@
 import { SaveProfileRequest } from "../request/saveProfile";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function saveProfile(
-  w: World,
+  w: Repositories,
   req: SaveProfileRequest
 ): Promise<GenericResponse> {
   const profile = await w.profile().load(req.profileId);
diff --git a/src/idz/handler/saveSettings.ts b/src/idz/handler/saveSettings.ts
index 6899224..b3c5b77 100644
--- a/src/idz/handler/saveSettings.ts
+++ b/src/idz/handler/saveSettings.ts
@@ -1,9 +1,9 @@
 import { SaveSettingsRequest } from "../request/saveSettings";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function saveSettings(
-  w: World,
+  w: Repositories,
   req: SaveSettingsRequest
 ): Promise<GenericResponse> {
   await w.settings().save(req.profileId, req.settings);
diff --git a/src/idz/handler/saveStocker.ts b/src/idz/handler/saveStocker.ts
index 5e09f6a..e6fdba1 100644
--- a/src/idz/handler/saveStocker.ts
+++ b/src/idz/handler/saveStocker.ts
@@ -1,9 +1,9 @@
 import { SaveStockerRequest } from "../request/saveStocker";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function saveStocker(
-  w: World,
+  w: Repositories,
   req: SaveStockerRequest
 ): Promise<GenericResponse> {
   await Promise.all([
diff --git a/src/idz/handler/saveTimeAttack.ts b/src/idz/handler/saveTimeAttack.ts
index d47a288..62e3d8f 100644
--- a/src/idz/handler/saveTimeAttack.ts
+++ b/src/idz/handler/saveTimeAttack.ts
@@ -1,9 +1,9 @@
 import { SaveTimeAttackRequest } from "../request/saveTimeAttack";
 import { SaveTimeAttackResponse } from "../response/saveTimeAttack";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export async function saveTimeAttack(
-  w: World,
+  w: Repositories,
   req: SaveTimeAttackRequest
 ): Promise<SaveTimeAttackResponse> {
   if (req.payload.totalMsec > 0) {
diff --git a/src/idz/handler/saveTopic.ts b/src/idz/handler/saveTopic.ts
index 56ce121..85a096c 100644
--- a/src/idz/handler/saveTopic.ts
+++ b/src/idz/handler/saveTopic.ts
@@ -1,8 +1,11 @@
 import { SaveTopicRequest } from "../request/saveTopic";
 import { SaveTopicResponse } from "../response/saveTopic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
-export function saveTopic(w: World, req: SaveTopicRequest): SaveTopicResponse {
+export function saveTopic(
+  w: Repositories,
+  req: SaveTopicRequest
+): SaveTopicResponse {
   return {
     type: "save_topic_res",
   };
diff --git a/src/idz/handler/unlockProfile.ts b/src/idz/handler/unlockProfile.ts
index 8aecc6f..a107f77 100644
--- a/src/idz/handler/unlockProfile.ts
+++ b/src/idz/handler/unlockProfile.ts
@@ -1,9 +1,9 @@
 import { UnlockProfileRequest } from "../request/unlockProfile";
 import { UnlockProfileResponse } from "../response/unlockProfile";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function unlockProfile(
-  w: World,
+  w: Repositories,
   req: UnlockProfileRequest
 ): UnlockProfileResponse {
   return {
diff --git a/src/idz/handler/updateProvisionalStoreRank.ts b/src/idz/handler/updateProvisionalStoreRank.ts
index 6d703f1..f233cb3 100644
--- a/src/idz/handler/updateProvisionalStoreRank.ts
+++ b/src/idz/handler/updateProvisionalStoreRank.ts
@@ -1,9 +1,9 @@
 import { UpdateProvisionalStoreRankRequest } from "../request/updateProvisionalStoreRank";
 import { UpdateProvisionalStoreRankResponse } from "../response/updateProvisionalStoreRank";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function updateProvisionalStoreRank(
-  w: World,
+  w: Repositories,
   req: UpdateProvisionalStoreRankRequest
 ): UpdateProvisionalStoreRankResponse {
   return {
diff --git a/src/idz/handler/updateStoryClearNum.ts b/src/idz/handler/updateStoryClearNum.ts
index 6aa0d2d..2b4970e 100644
--- a/src/idz/handler/updateStoryClearNum.ts
+++ b/src/idz/handler/updateStoryClearNum.ts
@@ -1,9 +1,9 @@
 import { UpdateStoryClearNumRequest } from "../request/updateStoryClearNum";
 import { UpdateStoryClearNumResponse } from "../response/updateStoryClearNum";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function updateStoryClearNum(
-  w: World,
+  w: Repositories,
   req: UpdateStoryClearNumRequest
 ): UpdateStoryClearNumResponse {
   return {
diff --git a/src/idz/handler/updateTeamPoints.ts b/src/idz/handler/updateTeamPoints.ts
index 7206e2b..91d915f 100644
--- a/src/idz/handler/updateTeamPoints.ts
+++ b/src/idz/handler/updateTeamPoints.ts
@@ -1,9 +1,9 @@
 import { UpdateTeamPointsRequest } from "../request/updateTeamPoints";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function updateTeamPoints(
-  w: World,
+  w: Repositories,
   req: UpdateTeamPointsRequest
 ): GenericResponse {
   return { type: "generic_res" };
diff --git a/src/idz/handler/updateUiReport.ts b/src/idz/handler/updateUiReport.ts
index 0f65279..1a4c41a 100644
--- a/src/idz/handler/updateUiReport.ts
+++ b/src/idz/handler/updateUiReport.ts
@@ -1,9 +1,9 @@
 import { UpdateUiReportRequest } from "../request/updateUiReport";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function updateUiReport(
-  w: World,
+  w: Repositories,
   req: UpdateUiReportRequest
 ): GenericResponse {
   return { type: "generic_res" };
diff --git a/src/idz/handler/updateUserLog.ts b/src/idz/handler/updateUserLog.ts
index f962046..61eb14c 100644
--- a/src/idz/handler/updateUserLog.ts
+++ b/src/idz/handler/updateUserLog.ts
@@ -1,9 +1,9 @@
 import { UpdateUserLogRequest } from "../request/updateUserLog";
 import { GenericResponse } from "../response/generic";
-import { World } from "../world";
+import { Repositories } from "../repo";
 
 export function updateUserLog(
-  w: World,
+  w: Repositories,
   req: UpdateUserLogRequest
 ): GenericResponse {
   return { type: "generic_res" };
diff --git a/src/idz/index.ts b/src/idz/index.ts
index 77ef67b..a6e2e91 100644
--- a/src/idz/index.ts
+++ b/src/idz/index.ts
@@ -1,11 +1,11 @@
 import { Socket } from "net";
 
+import { beginFilesystemSession } from "./file";
 import { dispatch } from "./handler";
 import { setup } from "./setup";
-import { createWorld } from "./world";
 
 export default async function idz(socket: Socket) {
-  const world = await createWorld("./state");
+  const world = await beginFilesystemSession("./state");
   const { input, output } = setup(socket);
 
   console.log("Idz: Connection opened");
diff --git a/src/idz/world/defs.ts b/src/idz/repo.ts
similarity index 93%
rename from src/idz/world/defs.ts
rename to src/idz/repo.ts
index 68ad0bc..948446f 100644
--- a/src/idz/world/defs.ts
+++ b/src/idz/repo.ts
@@ -1,4 +1,4 @@
-import * as Model from "../model";
+import * as Model from "./model";
 
 export interface CarRepository {
   countCars(profileId: Model.Id<Model.Profile>): Promise<number>;
@@ -65,7 +65,7 @@ export interface TimeAttackRepository {
   ): Promise<void>;
 }
 
-export interface World {
+export interface Repositories {
   backgrounds(): FlagRepository<Model.BackgroundCode>;
 
   car(): CarRepository;
@@ -92,3 +92,9 @@ export interface World {
 
   unlocks(): FacetRepository<Model.Unlocks>;
 }
+
+export interface Transaction extends Repositories {
+  commit(): Promise<void>;
+
+  rollback(): Promise<void>;
+}