Task: Split a Fat Interface to Satisfy ISP

The following interface forces multiple client types to depend on methods they never use. Split it to satisfy the Interface Segregation Principle.

Interface Under Review

// src/IDataStore.ts
export interface IDataStore {
  // Used by read-only reporting services
  findById(id: string): Promise<Record<string, unknown> | null>
  findAll(): Promise<Record<string, unknown>[]>
  findByFilter(filter: Record<string, unknown>): Promise<Record<string, unknown>[]>

  // Used only by write-capable services
  save(id: string, data: Record<string, unknown>): Promise<void>
  delete(id: string): Promise<void>

  // Used only by admin tools
  truncate(): Promise<void>
  exportDump(): Promise<string>
  importDump(data: string): Promise<void>
}

Client Context

• ReportingService calls only findById, findAll, and findByFilter.
• CrudService calls findById, findAll, save, and delete.
• AdminMigrationTool calls truncate, exportDump, and importDump.

Output Specification

Produce:

1. Split interface files — one interface per client role. Name them after the role they serve (e.g., IReadableStore.ts, IWritableStore.ts, IAdminStore.ts).
2. isp-analysis.md — explain which client was forced to depend on methods it never uses, and how splitting resolves this.

Rules:

• Each interface must contain only methods actually used by its target client.
• Do NOT create one-method interfaces for methods that are always used together by the same client.
• IReadableStore must be referenced by ReportingService if you produce a refactored version.