feat(server): attachment embedding (#13348)

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

* **New Features**
* Added support for managing "blobs" in Copilot context, including
adding and removing blobs via new GraphQL mutations and UI fields.
* Introduced tracking and querying of blob embeddings within workspaces,
enabling search and similarity matching for blob content.
* Extended Copilot context and workspace APIs, schema, and UI to display
and manage blobs alongside existing documents and files.

* **Bug Fixes**
* Updated context and embedding status logic to handle blobs, ensuring
accurate status reporting and embedding management.

* **Tests**
* Added and updated test cases and snapshots to cover blob embedding
insertion, matching, and removal scenarios.

* **Documentation**
* Updated GraphQL schema and TypeScript types to reflect new
blob-related fields and mutations.

* **Chores**
* Refactored and cleaned up code to support new blob entity and
embedding logic, including renaming and updating internal methods and
types.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -1,13 +1,13 @@
 import { nanoid } from 'nanoid';
 
 import {
+  ContextBlob,
   ContextCategories,
   ContextCategory,
   ContextConfig,
   ContextDoc,
   ContextEmbedStatus,
   ContextFile,
-  ContextList,
   FileChunkSimilarity,
   Models,
 } from '../../../models';
@@ -47,6 +47,10 @@ export class ContextSession implements AsyncDisposable {
     return categories.filter(c => c.type === ContextCategories.Collection);
   }
 
+  get blobs(): ContextBlob[] {
+    return this.config.blobs.map(d => ({ ...d }));
+  }
+
   get docs(): ContextDoc[] {
     return this.config.docs.map(d => ({ ...d }));
   }
@@ -65,13 +69,6 @@ export class ContextSession implements AsyncDisposable {
     );
   }
 
-  get sortedList(): ContextList {
-    const { docs, files } = this.config;
-    return [...docs, ...files].toSorted(
-      (a, b) => a.createdAt - b.createdAt
-    ) as ContextList;
-  }
-
   async addCategoryRecord(type: ContextCategories, id: string, docs: string[]) {
     const category = this.config.categories.find(
       c => c.type === type && c.id === id
@@ -120,6 +117,33 @@ export class ContextSession implements AsyncDisposable {
     return true;
   }
 
+  async addBlobRecord(blobId: string): Promise<ContextBlob | null> {
+    const existsBlob = this.config.blobs.find(b => b.id === blobId);
+    if (existsBlob) {
+      return existsBlob;
+    }
+    const blob = await this.models.blob.get(this.config.workspaceId, blobId);
+    if (!blob) return null;
+
+    const record: ContextBlob = {
+      id: blobId,
+      createdAt: Date.now(),
+      status: ContextEmbedStatus.processing,
+    };
+    this.config.blobs.push(record);
+    await this.save();
+    return record;
+  }
+
+  async removeBlobRecord(blobId: string): Promise<boolean> {
+    const index = this.config.blobs.findIndex(b => b.id === blobId);
+    if (index >= 0) {
+      this.config.blobs.splice(index, 1);
+      await this.save();
+    }
+    return true;
+  }
+
   async addDocRecord(docId: string): Promise<ContextDoc> {
     const doc = this.config.docs.find(f => f.id === docId);
     if (doc) {