feat(server): basic context api (#10056)

fix CLOUD-97
fix CLOUD-98

packages/backend/server/src/plugins/copilot/context/session.ts

@@ -0,0 +1,58 @@
+import { ContextConfig, ContextDoc, ContextList } from './types';
+
+export class ContextSession implements AsyncDisposable {
+  constructor(
+    private readonly contextId: string,
+    private readonly config: ContextConfig,
+    private readonly dispatcher?: (config: ContextConfig) => Promise<void>
+  ) {}
+
+  get id() {
+    return this.contextId;
+  }
+
+  get workspaceId() {
+    return this.config.workspaceId;
+  }
+
+  listDocs(): ContextDoc[] {
+    return [...this.config.docs];
+  }
+
+  listFiles() {
+    return this.config.files.map(f => ({ ...f }));
+  }
+
+  get sortedList(): ContextList {
+    const { docs, files } = this.config;
+    return [...docs, ...files].toSorted(
+      (a, b) => a.createdAt - b.createdAt
+    ) as ContextList;
+  }
+
+  async addDocRecord(docId: string): Promise<ContextList> {
+    if (!this.config.docs.some(f => f.id === docId)) {
+      this.config.docs.push({ id: docId, createdAt: Date.now() });
+      await this.save();
+    }
+    return this.sortedList;
+  }
+
+  async removeDocRecord(docId: string): Promise<boolean> {
+    const index = this.config.docs.findIndex(f => f.id === docId);
+    if (index >= 0) {
+      this.config.docs.splice(index, 1);
+      await this.save();
+      return true;
+    }
+    return false;
+  }
+
+  async save() {
+    await this.dispatcher?.(this.config);
+  }
+
+  async [Symbol.asyncDispose]() {
+    await this.save();
+  }
+}