feat(core): support lazy load for ai session history (#13221)

Close [AI-331](https://linear.app/affine-design/issue/AI-331)

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

## Summary by CodeRabbit

* **New Features**
* Added infinite scroll and incremental loading for AI session history,
allowing users to load more sessions as they scroll.

* **Refactor**
* Improved session history component with better state management and
modular rendering for loading, empty, and history states.

* **Bug Fixes**
* Enhanced handling of absent or uninitialized chat sessions, reducing
potential errors when session data is missing.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/blocksuite/ai/actions/types.ts

@@ -407,7 +407,8 @@ declare global {
       ) => Promise<CopilotChatHistoryFragment[] | undefined>;
       getRecentSessions: (
         workspaceId: string,
-        limit?: number
+        limit?: number,
+        offset?: number
       ) => Promise<AIRecentSession[] | undefined>;
       updateSession: (options: UpdateChatSessionInput) => Promise<string>;
     }

packages/frontend/core/src/blocksuite/ai/chat-panel/ai-title.ts

@@ -106,7 +106,7 @@ export class AIChatPanelTitle extends SignalWatcher(
   accessor notificationService!: NotificationService;
 
   @property({ attribute: false })
-  accessor session!: CopilotChatHistoryFragment;
+  accessor session!: CopilotChatHistoryFragment | null | undefined;
 
   @property({ attribute: false })
   accessor status!: ChatStatus;

packages/frontend/core/src/blocksuite/ai/components/ai-chat-toolbar/ai-session-history.ts

@@ -3,8 +3,8 @@ import { WithDisposable } from '@blocksuite/affine/global/lit';
 import { scrollbarStyle } from '@blocksuite/affine/shared/styles';
 import { unsafeCSSVar, unsafeCSSVarV2 } from '@blocksuite/affine/shared/theme';
 import { ShadowlessElement } from '@blocksuite/affine/std';
-import { css, html, nothing } from 'lit';
-import { property, state } from 'lit/decorators.js';
+import { css, html, nothing, type PropertyValues } from 'lit';
+import { property, query, state } from 'lit/decorators.js';
 
 import { AIProvider } from '../../provider';
 import type { DocDisplayConfig } from '../ai-chat-chips';
@@ -133,11 +133,21 @@ export class AISessionHistory extends WithDisposable(ShadowlessElement) {
   @property({ attribute: false })
   accessor onDocClick!: (docId: string, sessionId: string) => void;
 
-  @state()
-  private accessor sessions: BlockSuitePresets.AIRecentSession[] = [];
+  @query('.ai-session-history')
+  accessor scrollContainer!: HTMLElement;
 
   @state()
-  private accessor loading = true;
+  private accessor sessions: BlockSuitePresets.AIRecentSession[] | undefined;
+
+  @state()
+  private accessor loadingMore = false;
+
+  @state()
+  private accessor hasMore = true;
+
+  private accessor currentOffset = 0;
+
+  private readonly pageSize = 10;
 
   private groupSessionsByTime(
     sessions: BlockSuitePresets.AIRecentSession[]
@@ -188,23 +198,46 @@ export class AISessionHistory extends WithDisposable(ShadowlessElement) {
   }
 
   private async getRecentSessions() {
-    this.loading = true;
-    const limit = 50;
-    const sessions = await AIProvider.session?.getRecentSessions(
-      this.workspaceId,
-      limit
-    );
-    if (sessions) {
-      this.sessions = sessions;
-    }
-    this.loading = false;
+    this.loadingMore = true;
+
+    const moreSessions =
+      (await AIProvider.session?.getRecentSessions(
+        this.workspaceId,
+        this.pageSize,
+        this.currentOffset
+      )) || [];
+    this.sessions = [...(this.sessions || []), ...moreSessions];
+
+    this.currentOffset += moreSessions.length;
+    this.hasMore = moreSessions.length === this.pageSize;
+    this.loadingMore = false;
   }
 
+  private readonly onScroll = () => {
+    if (!this.hasMore || this.loadingMore) {
+      return;
+    }
+    // load more when within 50px of bottom
+    const { scrollTop, scrollHeight, clientHeight } = this.scrollContainer;
+    const threshold = 50;
+    if (scrollTop + clientHeight >= scrollHeight - threshold) {
+      this.getRecentSessions().catch(console.error);
+    }
+  };
+
   override connectedCallback() {
     super.connectedCallback();
     this.getRecentSessions().catch(console.error);
   }
 
+  override firstUpdated(changedProperties: PropertyValues) {
+    super.firstUpdated(changedProperties);
+    this.disposables.add(() => {
+      this.scrollContainer.removeEventListener('scroll', this.onScroll);
+    });
+    this.scrollContainer.addEventListener('scroll', this.onScroll);
+  }
+
   private renderSessionGroup(
     title: string,
     sessions: BlockSuitePresets.AIRecentSession[]
@@ -256,35 +289,43 @@ export class AISessionHistory extends WithDisposable(ShadowlessElement) {
     </div>`;
   }
 
-  override render() {
-    if (this.loading) {
-      return html`
-        <div class="ai-session-history">
-          <div class="loading-container">
-            <div class="loading-title">Loading history...</div>
-          </div>
-        </div>
-      `;
+  private renderLoading() {
+    return html`
+      <div class="loading-container">
+        <div class="loading-title">Loading history...</div>
+      </div>
+    `;
+  }
+
+  private renderEmpty() {
+    return html`
+      <div class="empty-container">
+        <div class="empty-title">Empty history</div>
+      </div>
+    `;
+  }
+
+  private renderHistory() {
+    if (!this.sessions) {
+      return this.renderLoading();
     }
 
     if (this.sessions.length === 0) {
-      return html`
-        <div class="ai-session-history">
-          <div class="empty-container">
-            <div class="empty-title">Empty history</div>
-          </div>
-        </div>
-      `;
+      return this.renderEmpty();
     }
 
     const groupedSessions = this.groupSessionsByTime(this.sessions);
     return html`
-      <div class="ai-session-history">
-        ${this.renderSessionGroup('Today', groupedSessions.today)}
-        ${this.renderSessionGroup('Last 7 days', groupedSessions.last7Days)}
-        ${this.renderSessionGroup('Last 30 days', groupedSessions.last30Days)}
-        ${this.renderSessionGroup('Older', groupedSessions.older)}
-      </div>
+      ${this.renderSessionGroup('Today', groupedSessions.today)}
+      ${this.renderSessionGroup('Last 7 days', groupedSessions.last7Days)}
+      ${this.renderSessionGroup('Last 30 days', groupedSessions.last30Days)}
+      ${this.renderSessionGroup('Older', groupedSessions.older)}
+    `;
+  }
+
+  override render() {
+    return html`
+      <div class="ai-session-history">${this.renderHistory()}</div>
     `;
   }
 }

packages/frontend/core/src/blocksuite/ai/provider/copilot-client.ts

@@ -186,13 +186,18 @@ export class CopilotClient {
     }
   }
 
-  async getRecentSessions(workspaceId: string, limit?: number) {
+  async getRecentSessions(
+    workspaceId: string,
+    limit?: number,
+    offset?: number
+  ) {
     try {
       const res = await this.gql({
         query: getCopilotRecentSessionsQuery,
         variables: {
           workspaceId,
           limit,
+          offset,
         },
       });
       return res.currentUser?.copilot?.chats.edges.map(e => e.node);

packages/frontend/core/src/blocksuite/ai/provider/setup-provider.tsx

@@ -589,8 +589,12 @@ Could you make a new website based on these notes and send back just the html fi
     ) => {
       return client.getSessions(workspaceId, {}, docId, options);
     },
-    getRecentSessions: async (workspaceId: string, limit?: number) => {
-      return client.getRecentSessions(workspaceId, limit);
+    getRecentSessions: async (
+      workspaceId: string,
+      limit?: number,
+      offset?: number
+    ) => {
+      return client.getRecentSessions(workspaceId, limit, offset);
     },
     updateSession: async (options: UpdateChatSessionInput) => {
       return client.updateSession(options);