feat(core): add section edit tool (#13313)

Close [AI-396](https://linear.app/affine-design/issue/AI-396)

<img width="798" height="294" alt="截屏2025-07-25 11 30 32"
src="https://github.com/user-attachments/assets/6366dab2-688b-470b-8b24-29a2d50a38c9"
/>



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

## Summary by CodeRabbit

* **New Features**
* Introduced a "Section Edit" AI tool for expert editing of specific
markdown sections based on user instructions, preserving formatting and
style.
* Added a new interface and UI component for section editing, allowing
users to view, copy, insert, or save edited content directly from chat
interactions.

* **Improvements**
* Enhanced AI chat and tool rendering to support and display section
editing results.
* Updated chat input handling for improved draft management and message
sending order.

* **Other Changes**
* Registered the new section editing tool in the system for seamless
integration.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/copilot-provider.spec.ts

@@ -531,6 +531,7 @@ The term **“CRDT”** was first introduced by Marc Shapiro, Nuno Preguiça, Ca
       'Make it longer',
       'Make it shorter',
       'Continue writing',
+      'Section Edit',
       'Chat With AFFiNE AI',
       'Search With AFFiNE AI',
     ],

packages/backend/server/src/plugins/copilot/prompt/prompts.ts

@@ -1468,6 +1468,29 @@ When sent new notes, respond ONLY with the contents of the html file.`,
       },
     ],
   },
+  {
+    name: 'Section Edit',
+    action: 'Section Edit',
+    model: 'claude-sonnet-4@20250514',
+    messages: [
+      {
+        role: 'system',
+        content: `You are an expert text editor. Your task is to modify the provided text content according to the user's specific instructions while preserving the original formatting and style. 
+Key requirements:
+- Follow the user's instructions precisely
+- Maintain the original markdown formatting
+- Preserve the tone and style unless specifically asked to change it
+- Only make the requested changes
+- Return only the modified text without any explanations or comments`,
+      },
+      {
+        role: 'user',
+        content: `Please modify the following text according to these instructions: "{{instructions}}"
+Original text:
+{{content}}`,
+      },
+    ],
+  },
 ];
 
 const imageActions: Prompt[] = [
@@ -1924,7 +1947,7 @@ Below is the user's query. Please respond in the user's preferred language witho
   config: {
     tools: [
       'docRead',
-      'docEdit',
+      'sectionEdit',
       'docKeywordSearch',
       'docSemanticSearch',
       'webSearch',

packages/backend/server/src/plugins/copilot/providers/provider.ts

@@ -29,6 +29,7 @@ import {
   createDocSemanticSearchTool,
   createExaCrawlTool,
   createExaSearchTool,
+  createSectionEditTool,
 } from '../tools';
 import { CopilotProviderFactory } from './factory';
 import {
@@ -224,6 +225,10 @@ export abstract class CopilotProvider<C = any> {
             tools.doc_compose = createDocComposeTool(prompt, this.factory);
             break;
           }
+          case 'sectionEdit': {
+            tools.section_edit = createSectionEditTool(prompt, this.factory);
+            break;
+          }
         }
       }
       return tools;

packages/backend/server/src/plugins/copilot/providers/types.ts

@@ -73,6 +73,8 @@ export const PromptConfigStrictSchema = z.object({
       'webSearch',
       // artifact tools
       'docCompose',
+      // section editing
+      'sectionEdit',
     ])
     .array()
     .nullable()

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

@@ -9,6 +9,7 @@ import { createDocReadTool } from './doc-read';
 import { createDocSemanticSearchTool } from './doc-semantic-search';
 import { createExaCrawlTool } from './exa-crawl';
 import { createExaSearchTool } from './exa-search';
+import { createSectionEditTool } from './section-edit';
 
 export interface CustomAITools extends ToolSet {
   code_artifact: ReturnType<typeof createCodeArtifactTool>;
@@ -18,6 +19,7 @@ export interface CustomAITools extends ToolSet {
   doc_keyword_search: ReturnType<typeof createDocKeywordSearchTool>;
   doc_read: ReturnType<typeof createDocReadTool>;
   doc_compose: ReturnType<typeof createDocComposeTool>;
+  section_edit: ReturnType<typeof createSectionEditTool>;
   web_search_exa: ReturnType<typeof createExaSearchTool>;
   web_crawl_exa: ReturnType<typeof createExaCrawlTool>;
 }
@@ -32,3 +34,4 @@ export * from './doc-semantic-search';
 export * from './error';
 export * from './exa-crawl';
 export * from './exa-search';
+export * from './section-edit';

packages/backend/server/src/plugins/copilot/tools/section-edit.ts

@@ -0,0 +1,60 @@
+import { Logger } from '@nestjs/common';
+import { tool } from 'ai';
+import { z } from 'zod';
+
+import type { PromptService } from '../prompt';
+import type { CopilotProviderFactory } from '../providers';
+import { toolError } from './error';
+
+const logger = new Logger('SectionEditTool');
+
+export const createSectionEditTool = (
+  promptService: PromptService,
+  factory: CopilotProviderFactory
+) => {
+  return tool({
+    description:
+      'Intelligently edit and modify a specific section of a document based on user instructions. This tool can refine, rewrite, translate, restructure, or enhance any part of markdown content while preserving formatting and maintaining contextual coherence. Perfect for targeted improvements without affecting the entire document.',
+    parameters: z.object({
+      section: z
+        .string()
+        .describe(
+          'The section of the document to be modified (in markdown format)'
+        ),
+      instructions: z
+        .string()
+        .describe(
+          'Clear instructions from the user describing the desired changes (e.g., "make this more formal", "translate to Chinese", "add more details", "fix grammar errors")'
+        ),
+    }),
+    execute: async ({ section, instructions }) => {
+      try {
+        const prompt = await promptService.get('Section Edit');
+        if (!prompt) {
+          throw new Error('Prompt not found');
+        }
+        const provider = await factory.getProviderByModel(prompt.model);
+        if (!provider) {
+          throw new Error('Provider not found');
+        }
+
+        const content = await provider.text(
+          {
+            modelId: prompt.model,
+          },
+          prompt.finish({
+            content: section,
+            instructions,
+          })
+        );
+
+        return {
+          content: content.trim(),
+        };
+      } catch (err: any) {
+        logger.error(`Failed to edit section`, err);
+        return toolError('Section Edit Failed', err.message);
+      }
+    },
+  });
+};