feat(server): add doc keyword search tool (#12837)

close AI-185

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

- **New Features**
- Introduced a keyword-based document search tool, allowing users to
search for relevant documents within their workspace using keywords.
- Search results include document titles, summaries, and direct links,
enhancing document discovery and navigation.
- **Bug Fixes**
  - None.
- **Tests**
- Added new tests to verify document search by IDs and by keywords,
ensuring accurate and reliable search functionality.
- **Documentation**
  - None.
- **Chores**
- Updated configuration file organization for improved clarity; no
changes to functionality.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->








#### PR Dependency Tree


* **PR #12867**
  * **PR #12863**
    * **PR #12837** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

packages/backend/server/src/plugins/copilot/tools/doc-keyword-search.ts

@@ -0,0 +1,64 @@
+import { tool } from 'ai';
+import { z } from 'zod';
+
+import type { AccessController } from '../../../core/permission';
+import type { IndexerService, SearchDoc } from '../../indexer';
+import type { CopilotChatOptions } from '../providers';
+
+export const buildDocKeywordSearchGetter = (
+  ac: AccessController,
+  indexerService: IndexerService
+) => {
+  const searchDocs = async (options: CopilotChatOptions, query?: string) => {
+    if (!options || !query?.trim() || !options.user || !options.workspace) {
+      return undefined;
+    }
+    const canAccess = await ac
+      .user(options.user)
+      .workspace(options.workspace)
+      .can('Workspace.Read');
+    if (!canAccess) return undefined;
+    const docs = await indexerService.searchDocsByKeyword(
+      options.workspace,
+      query
+    );
+
+    // filter current user readable docs
+    const readableDocs = await ac
+      .user(options.user)
+      .workspace(options.workspace)
+      .docs(docs, 'Doc.Read');
+    return readableDocs;
+  };
+  return searchDocs;
+};
+
+export const createDocKeywordSearchTool = (
+  searchDocs: (query: string) => Promise<SearchDoc[] | undefined>
+) => {
+  return tool({
+    description:
+      'Full-text search for relevant documents in the current workspace',
+    parameters: z.object({
+      query: z.string().describe('The query to search for'),
+    }),
+    execute: async ({ query }) => {
+      try {
+        const docs = await searchDocs(query);
+        if (!docs) {
+          return;
+        }
+        return docs.map(doc => ({
+          docId: doc.docId,
+          title: doc.title,
+          createdAt: doc.createdAt,
+          updatedAt: doc.updatedAt,
+          createdByUser: doc.createdByUser,
+          updatedByUser: doc.updatedByUser,
+        }));
+      } catch {
+        return 'Failed to search documents.';
+      }
+    },
+  });
+};

packages/backend/server/src/plugins/copilot/tools/index.ts

@@ -1,2 +1,3 @@
+export * from './doc-keyword-search';
 export * from './doc-semantic-search';
 export * from './web-search';