chore(server): improve semantic search (#12838)

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

## Summary by CodeRabbit

- **New Features**
- Updated document-related tools in chat prompts, including new options
for document keyword and semantic search.

- **Refactor**
- Renamed and reorganized document search tools for improved clarity in
tool selection and results display.

- **Bug Fixes**
- Ensured tool identifiers and results are consistent across chat and
search features.

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

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

@@ -0,0 +1,54 @@
+import { tool } from 'ai';
+import { z } from 'zod';
+
+import type { AccessController } from '../../../core/permission';
+import type { ChunkSimilarity } from '../../../models';
+import type { CopilotContextService } from '../context';
+import type { CopilotChatOptions } from '../providers';
+
+export const buildDocSearchGetter = (
+  ac: AccessController,
+  context: CopilotContextService
+) => {
+  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 chunks = await context.matchWorkspaceAll(options.workspace, query);
+    const docChunks = await ac
+      .user(options.user)
+      .workspace(options.workspace)
+      .docs(
+        chunks.filter(c => 'docId' in c),
+        'Doc.Read'
+      );
+    const fileChunks = chunks.filter(c => 'fileId' in c);
+    if (!docChunks.length && !fileChunks.length) return undefined;
+    return [...fileChunks, ...docChunks];
+  };
+  return searchDocs;
+};
+
+export const createDocSemanticSearchTool = (
+  searchDocs: (query: string) => Promise<ChunkSimilarity[] | undefined>
+) => {
+  return tool({
+    description:
+      'Semantic search for relevant documents in the current workspace',
+    parameters: z.object({
+      query: z.string().describe('The query to search for.'),
+    }),
+    execute: async ({ query }) => {
+      try {
+        return await searchDocs(query);
+      } catch {
+        return 'Failed to search documents.';
+      }
+    },
+  });
+};