refactor: make providers use dedicated session handling classes

server/shared/interfaces.ts

@@ -19,9 +19,7 @@ export interface IProvider {
   readonly id: LLMProvider;
   readonly mcp: IProviderMcp;
   readonly auth: IProviderAuth;
-
-  normalizeMessage(raw: unknown, sessionId: string | null): NormalizedMessage[];
-  fetchHistory(sessionId: string, options?: FetchHistoryOptions): Promise<FetchHistoryResult>;
+  readonly sessions: IProviderSessions;
 }
 
 
@@ -46,3 +44,11 @@ export interface IProviderMcp {
     input: { name: string; scope?: McpScope; workspacePath?: string },
   ): Promise<{ removed: boolean; provider: LLMProvider; name: string; scope: McpScope }>;
 }
+
+/**
+ * Session/history contract for one provider.
+ */
+export interface IProviderSessions {
+  normalizeMessage(raw: unknown, sessionId: string | null): NormalizedMessage[];
+  fetchHistory(sessionId: string, options?: FetchHistoryOptions): Promise<FetchHistoryResult>;
+}

server/shared/types.ts

@@ -5,6 +5,8 @@ export type ApiSuccessShape<TData = unknown> = {
   data: TData;
 };
 
+export type AnyRecord = Record<string, any>;
+
 // ---------------------------------------------------------------------------------------------
 
 export type LLMProvider = 'claude' | 'codex' | 'gemini' | 'cursor';

server/shared/utils.ts

@@ -6,6 +6,7 @@ import path from 'node:path';
 import type { NextFunction, Request, RequestHandler, Response } from 'express';
 
 import type {
+  AnyRecord,
   ApiSuccessShape,
   AppErrorOptions,
   NormalizedMessage,
@@ -89,12 +90,12 @@ export function createNormalizedMessage(fields: NormalizedMessageInput): Normali
  * treat the returned value as a JSON-style object map without repeating the same
  * defensive shape checks at every config read site.
  */
-export const readObjectRecord = (value: unknown): Record<string, unknown> | null => {
+export const readObjectRecord = (value: any): AnyRecord | null => {
   if (!value || typeof value !== 'object' || Array.isArray(value)) {
     return null;
   }
 
-  return value as Record<string, unknown>;
+  return value as AnyRecord;
 };
 
 /**