feat(core): add get session graphql api (#12237)

Close [AI-116](https://linear.app/affine-design/issue/AI-116)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Added the ability to retrieve detailed information for a specific Copilot session by its ID, including model metadata and optional models, via the user interface and API.
  - Session data now includes additional fields such as the model used and a list of optional models.
  - Enhanced GraphQL queries and UI components to support fetching and displaying these new session details.

- **Improvements**
  - Session lists now provide richer information, including model details, for each session.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/copilot/resolver.ts

@@ -41,6 +41,7 @@ import {
   AvailableModels,
   type ChatHistory,
   type ChatMessage,
+  type ChatSessionState,
   type ListHistoriesOptions,
   SubmittedMessage,
 } from './types';
@@ -277,7 +278,7 @@ class CopilotPromptType {
 }
 
 @ObjectType()
-class CopilotSessionType {
+export class CopilotSessionType {
   @Field(() => ID)
   id!: string;
 
@@ -286,6 +287,12 @@ class CopilotSessionType {
 
   @Field(() => String)
   promptName!: string;
+
+  @Field(() => String)
+  model!: string;
+
+  @Field(() => [String])
+  optionalModels!: string[];
 }
 
 // ================== Resolver ==================
@@ -329,6 +336,30 @@ export class CopilotResolver {
     return (await this.sessions(copilot, user, docId, options)).map(s => s.id);
   }
 
+  @ResolveField(() => CopilotSessionType, {
+    description: 'Get the session by id',
+    complexity: 2,
+  })
+  async session(
+    @Parent() copilot: CopilotType,
+    @CurrentUser() user: CurrentUser,
+    @Args('sessionId') sessionId: string
+  ): Promise<CopilotSessionType> {
+    if (!copilot.workspaceId) {
+      throw new NotFoundException('Workspace not found');
+    }
+    await this.ac
+      .user(user.id)
+      .workspace(copilot.workspaceId)
+      .allowLocal()
+      .assert('Workspace.Copilot');
+    const session = await this.chatSession.getSession(sessionId);
+    if (!session) {
+      throw new NotFoundException('Session not found');
+    }
+    return this.transformToSessionType(session);
+  }
+
   @ResolveField(() => [CopilotSessionType], {
     description: 'Get the session list in the workspace',
     complexity: 2,
@@ -339,18 +370,21 @@ export class CopilotResolver {
     @Args('docId', { nullable: true }) docId?: string,
     @Args('options', { nullable: true }) options?: QueryChatSessionsInput
   ): Promise<CopilotSessionType[]> {
-    if (!copilot.workspaceId) return [];
+    if (!copilot.workspaceId) {
+      throw new NotFoundException('Workspace not found');
+    }
     await this.ac
       .user(user.id)
       .workspace(copilot.workspaceId)
       .allowLocal()
       .assert('Workspace.Copilot');
-    return await this.chatSession.listSessions(
+    const sessions = await this.chatSession.listSessions(
       user.id,
       copilot.workspaceId,
       docId,
       options
     );
+    return sessions.map(this.transformToSessionType);
   }
 
   @ResolveField(() => [CopilotHistoriesType], {})
@@ -556,6 +590,18 @@ export class CopilotResolver {
       throw new CopilotFailedToCreateMessage(e.message);
     }
   }
+
+  private transformToSessionType(
+    session: Omit<ChatSessionState, 'messages'>
+  ): CopilotSessionType {
+    return {
+      id: session.sessionId,
+      parentSessionId: session.parentSessionId,
+      promptName: session.prompt.name,
+      model: session.prompt.model,
+      optionalModels: session.prompt.optionalModels,
+    };
+  }
 }
 
 @Throttle()

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

@@ -307,9 +307,7 @@ export class ChatSessionService {
     });
   }
 
-  private async getSession(
-    sessionId: string
-  ): Promise<ChatSessionState | undefined> {
+  async getSession(sessionId: string): Promise<ChatSessionState | undefined> {
     return await this.db.aiSession
       .findUnique({
         where: { id: sessionId, deletedAt: null },
@@ -414,13 +412,7 @@ export class ChatSessionService {
     workspaceId: string,
     docId?: string,
     options?: { action?: boolean }
-  ): Promise<
-    Array<{
-      id: string;
-      parentSessionId: string | null;
-      promptName: string;
-    }>
-  > {
+  ): Promise<Omit<ChatSessionState, 'messages'>[]> {
     return await this.db.aiSession
       .findMany({
         where: {
@@ -434,17 +426,31 @@ export class ChatSessionService {
         },
         select: {
           id: true,
+          userId: true,
+          workspaceId: true,
+          docId: true,
           parentSessionId: true,
           promptName: true,
         },
       })
-      .then(sessions =>
-        sessions.map(({ id, parentSessionId, promptName }) => ({
-          id,
-          parentSessionId: parentSessionId || null,
-          promptName,
-        }))
-      );
+      .then(sessions => {
+        return Promise.all(
+          sessions.map(async session => {
+            const prompt = await this.prompt.get(session.promptName);
+            if (!prompt)
+              throw new CopilotPromptNotFound({ name: session.promptName });
+
+            return {
+              sessionId: session.id,
+              userId: session.userId,
+              workspaceId: session.workspaceId,
+              docId: session.docId,
+              parentSessionId: session.parentSessionId,
+              prompt,
+            };
+          })
+        );
+      });
   }
 
   async listHistories(