fix: preserve image attachments in live and restored conversations

electron/coding-projects/attachment-store.ts

@@ -1,5 +1,5 @@
-import { randomUUID } from 'node:crypto';
-import { mkdir, readFile, rename, writeFile } from 'node:fs/promises';
+import { createHash, randomUUID } from 'node:crypto';
+import { mkdir, readFile, rename, stat, writeFile } from 'node:fs/promises';
 import path from 'node:path';
 
 const ATTACHMENT_ID_PATTERN = /^[A-Za-z0-9-]{1,64}$/;
@@ -22,14 +22,14 @@ export interface CodingAttachmentStoreOptions {
 }
 
 export class CodingAttachmentStore {
-  private readonly createId: () => string;
+  private readonly createId: (() => string) | undefined;
   private readonly maxBytes: number;
 
   constructor(
     private readonly rootDir: string,
     options: CodingAttachmentStoreOptions = {},
   ) {
-    this.createId = options.createId ?? randomUUID;
+    this.createId = options.createId;
     this.maxBytes = options.maxBytes ?? DEFAULT_MAX_ATTACHMENT_BYTES;
   }
 
@@ -39,11 +39,21 @@ export class CodingAttachmentStore {
     if (data.byteLength === 0 || data.byteLength > this.maxBytes) {
       throw new Error('Attachment size is invalid');
     }
-    const attachmentId = this.createId();
+    // Live events and session hydration repeat the same large image. Reuse its
+    // stored bytes, including the original upload, instead of writing a new copy.
+    const attachmentId = this.createId?.() ?? createHash('sha256')
+      .update(normalizedMime).update('\0').update(data).digest('hex');
     if (!ATTACHMENT_ID_PATTERN.test(attachmentId)) throw new Error('Attachment id is invalid');
     await mkdir(this.rootDir, { recursive: true });
     const dataPath = path.join(this.rootDir, `${attachmentId}.bin`);
     const metadataPath = path.join(this.rootDir, `${attachmentId}.json`);
+    if (!this.createId) {
+      const existing = await stat(metadataPath).catch((error: NodeJS.ErrnoException) => {
+        if (error.code === 'ENOENT') return null;
+        throw error;
+      });
+      if (existing) return { attachmentId, mime: normalizedMime, byteLength: data.byteLength };
+    }
     const temporaryDataPath = `${dataPath}.${randomUUID()}.tmp`;
     const temporaryMetadataPath = `${metadataPath}.${randomUUID()}.tmp`;
     const reference: CodingAttachmentRef = {