グローバルストアは共有依存性 — スコープ付き状態所有が勝る理由

Redux popularized the idea of a single global store — one tree of state, one set of reducers, one source of truth. It works well with one team and ten slices. It breaks down with five teams and fifty. The global store isn't just where your state lives — it's a shared dependency that every feature, every team, and every pull request must coordinate around. SDuX Vault™ eliminates that coordination cost by scoping state to independent FeatureCells™. The Single Store Assumption Redux centralizes state through a global store and reducer tree. Every feature adds slices to the same root object. Every selector projects from the same tree. Every action broadcasts to every reducer. At small scale, this is manageable. One developer understands the full tree. Renames are safe because the blast radius is visible. Selectors compose predictably because nobody else is changing the shape under you. At team scale, the single store becomes a shared mutable dependency — not in the Redux sense of mutable state, but in the organizational sense. Every team's code touches the same tree. Every refactor requires cross-team awareness. Every selector is one shape change away from a silent regression. Why Global State Becomes a Liability The problems are structural, not conceptual. Redux's ideas about immutability, pure functions, and predictable state transitions are sound. What breaks is the organizational model. Shape coupling: Selectors depend on the global tree structure. When Team A renames a property in their slice, Team B's selector that composes across slices breaks silently. Action namespace collisions: Two teams define RESET action types. Both reducers respond. Neither team realizes the collision until production. Middleware interference: Team A adds logging middleware. Team B adds analytics middleware. Both intercept the same actions. Registration order determines behavior — and nobody documents what the correct order is. Merge conflict magnets: The root reducer file, the root state interface, and the barrel export index are touched by every feature branch. They become the most contested files in the repository. None of these problems are bugs in Redux. They are consequences of putting every feature's state in one shared structure. The global store doesn't scale with teams — it scales with discipline. And discipline doesn't survive deadline pressure. Scoped Ownership with FeatureCells In SDuX Vault, state is owned by independent FeatureCells. Each cell encapsulates its own typed state, its own pipeline, and its own lifecycle boundary. No other cell can read or write another cell's state directly. import { Vault , FeatureCell } from ' @sdux-vault/core ' ; Vault ({ devMode : true , logLevel : ' off ' }); // Team A owns cart state export const cartCell = FeatureCell ({ key : ' cart ' , initialState : { items : [], total : 0 } }); // Team B owns user profile state export const userProfileCell = FeatureCell ({ key : ' user-profile ' , initialState : { name : '' , preferences : {} } }); // Team C owns notifications state export const notificationsCell = FeatureCell ({ key : ' notifications ' , initialState : { items : [], unreadCount : 0 } }); Three teams. Three cells. Zero shared state. Team A can rename every property in the cart state shape without Team B or Team C knowing or caring. There is no root reducer file. There is no global state interface. There is no barrel export that every branch touches. Key takeaway: Each FeatureCell is identified by a unique key and may be registered exactly once. No other cell can access its state directly — isolation is enforced by architecture, not by team agreement. What Changes for Your Team The organizational impact is immediate. When state ownership is scoped to cells, team boundaries align with state boundaries. Global Store FeatureCell Ownership Every team touches the root state interface Each team owns only its cell's type Selector changes require cross-team review State access is scoped to the owning cell Action namespace collisions are possible No actions — updates target the owner directly Root reducer file is a merge conflict magnet No root reducer — cells are registered independently Middleware affects all state Pipeline behaviors are scoped per cell Feature removal requires tree surgery Remove the cell registration — done This isn't just a technical improvement — it's an organizational one. Teams stop coordinating around shared files. Pull requests shrink because they only touch the code their feature owns. Refactors become safe because the blast radius is bounded by the cell boundary. Key takeaway: Redux scopes state by convention (slice naming, selector discipline, action prefixing). SDuX Vault scopes state by architecture — the cell boundary is enforced, not agreed upon. Try It Yourself Read the full Redux Concepts in SDuX Vault page for a section-by-section mapping of State, Actions, Dispatch, Reducers, Effects, Selectors, and Testing. Explore the FeatureCell API documentation to see the full registration surface, or jump into a live StackBlitz demo to create your own isolated cells with typed state and scoped ownership. StateManagement #Redux #alternative Redux popularized the idea of a single global store — one tree of state, one set of reducers, one source of truth. It works well with one team and ten slices. It breaks down with five teams and fifty. The global store isn't just where your state lives — it's a shared dependency that every feature, every team, and every pull request must coordinate around. SDuX Vault™ eliminates that coordination cost by scoping state to independent FeatureCells™. The Single Store Assumption Redux centralizes state through a global store and reducer tree. Every feature adds slices to the same root object. Every selector projects from the same tree. Every action broadcasts to every reducer. At small scale, this is manageable. One developer understands the full tree. Renames are safe because the blast radius is visible. Selectors compose predictably because nobody else is changing the shape under you. At team scale, the single store becomes a shared mutable dependency — not in the Redux sense of mutable state, but in the organizational sense. Every team's code touches the same tree. Every refactor requires cross-team awareness. Every selector is one shape change away from a silent regression. Why Global State Becomes a Liability The problems are structural, not conceptual. Redux's ideas about immutability, pure functions, and predictable state transitions are sound. What breaks is the organizational model. Shape coupling: Selectors depend on the global tree structure. When Team A renames a property in their slice, Team B's selector that composes across slices breaks silently. Action namespace collisions: Two teams define RESET action types. Both reducers respond. Neither team realizes the collision until production. Middleware interference: Team A adds logging middleware. Team B adds analytics middleware. Both intercept the same actions. Registration order determines behavior — and nobody documents what the correct order is. Merge conflict magnets: The root reducer file, the root state interface, and the barrel export index are touched by every feature branch. They become the most contested files in the repository. None of these problems are bugs in Redux. They are consequences of putting every feature's state in one shared structure. The global store doesn't scale with teams — it scales with discipline. And discipline doesn't survive deadline pressure. Scoped Ownership with FeatureCells In SDuX Vault, state is owned by independent FeatureCells. Each cell encapsulates its own typed state, its own pipeline, and its own lifecycle boundary. No other cell can read or write another cell's state directly. import { Vault , FeatureCell } from ' @sdux-vault/core ' ; Vault ({ devMode : true , logLevel : ' off ' }); // Team A owns cart state export const cartCell = FeatureCell ({ key : ' cart ' , initialState : { items : [], total : 0 } }); // Team B owns user profile state export const userProfileCell = FeatureCell ({ key : ' user-profile ' , initialState : { name : '' , preferences : {} } }); // Team C owns notifications state export const notificationsCell = FeatureCell ({ key : ' notifications ' , initialState : { items : [], unreadCount : 0 } }); Three teams. Three cells. Zero shared state. Team A can rename every property in the cart state shape without Team B or Team C knowing or caring. There is no root reducer file. There is no global state interface. There is no barrel export that every branch touches. Key takeaway: Each FeatureCell is identified by a unique key and may be registered exactly once. No other cell can access its state directly — isolation is enforced by architecture, not by team agreement. What Changes for Your Team The organizational impact is immediate. When state ownership is scoped to cells, team boundaries align with state boundaries. Global Store FeatureCell Ownership Every team touches the root state interface Each team owns only its cell's type Selector changes require cross-team review State access is scoped to the owning cell Action namespace collisions are possible No actions — updates target the owner directly Root reducer file is a merge conflict magnet No root reducer — cells are registered independently Middleware affects all state Pipeline behaviors are scoped per cell Feature removal requires tree surgery Remove the cell registration — done This isn't just a technical improvement — it's an organizational one. Teams stop coordinating around shared files. Pull requests shrink because they only touch the code their feature owns. Refactors become safe because the blast radius is bounded by the cell boundary. Key takeaway: Redux scopes state by convention (slice naming, selector discipline, action prefixing). SDuX Vault scopes state by architecture — the cell boundary is enforced, not agreed upon. Try It Yourself Read t