feat(channels): implement binary uploads for matrix signal mattermost

src/channels/signal/adapter.test.ts

@@ -68,6 +68,33 @@ describe('SignalAdapter', () => {
     expect(sendCall?.[1]).toEqual(['-u', '+15551234567', 'send', '-m', 'Hello group', '-g', 'abcd1234']);
   });
 
+  it('send uploads binary attachments via --attachment', async () => {
+    const adapter = new SignalAdapter({ account: '+15551234567' });
+    mockExecFileOnce((callback) => callback(null, 'signal-cli 0.13.2', ''));
+    mockExecFileOnce((callback) => callback(null, '', ''));
+    mockExecFileOnce((callback) => callback(null, '', ''));
+
+    await adapter.connect();
+    await adapter.send('+15550001111', {
+      text: '',
+      attachments: [{ mimeType: 'image/png', data: 'aGVsbG8=', filename: 'image.png' }],
+    });
+    await adapter.disconnect();
+
+    const attachmentCall = mockExecFile.mock.calls.find((call) => {
+      const args = call[1];
+      return Array.isArray(args) && args.includes('--attachment');
+    });
+    expect(attachmentCall).toBeDefined();
+    const args = attachmentCall?.[1] as string[];
+    expect(args[0]).toBe('-u');
+    expect(args[1]).toBe('+15551234567');
+    expect(args[2]).toBe('send');
+    expect(args[3]).toBe('--attachment');
+    expect(typeof args[4]).toBe('string');
+    expect(args[5]).toBe('+15550001111');
+  });
+
   it('parses DM receive payload and forwards inbound message', async () => {
     const adapter = new SignalAdapter({
       account: '+15551234567',

src/channels/signal/adapter.ts

@@ -1,4 +1,7 @@
 import { execFile } from 'child_process';
+import { mkdtemp, rm, writeFile } from 'fs/promises';
+import { tmpdir } from 'os';
+import { join } from 'path';
 
 import type {
   InboundMessage,
@@ -63,6 +66,7 @@ export class SignalAdapter implements ChannelAdapter {
   private readonly config: SignalAdapterConfig;
   private pollTimer: NodeJS.Timeout | null = null;
   private polling = false;
+  private attachmentTempCounter = 0;
 
   get status(): ChannelStatus {
     return this._status;
@@ -120,8 +124,7 @@ export class SignalAdapter implements ChannelAdapter {
           const line = a.filename ? `${a.filename}: ${a.url}` : a.url;
           await this.sendText(peerId, line);
         } else if (a.data) {
-          // Keep adapter minimal and robust: no temp-file attachment upload in this pass.
-          console.warn(`Signal: skipping attachment data (${a.mimeType}) — upload not implemented`);
+          await this.sendBinaryAttachment(peerId, a.data, a.filename, a.mimeType);
         }
       }
     }
@@ -141,6 +144,31 @@ export class SignalAdapter implements ChannelAdapter {
     await this.execSignal(args);
   }
 
+  private async sendBinaryAttachment(
+    peerId: string,
+    base64Data: string,
+    filename?: string,
+    mimeType?: string,
+  ): Promise<void> {
+    const tempDir = await mkdtemp(join(tmpdir(), 'flynn-signal-'));
+    const ext = extensionFromMimeType(mimeType);
+    const safeName = sanitizeFilename(filename) || `attachment${ext}`;
+    const tempPath = join(tempDir, `${this.attachmentTempCounter++}-${safeName}`);
+    try {
+      await writeFile(tempPath, Buffer.from(base64Data, 'base64'));
+      const args = ['-u', this.config.account, 'send', '--attachment', tempPath];
+      const groupId = this.extractGroupId(peerId);
+      if (groupId) {
+        args.push('-g', groupId);
+      } else {
+        args.push(peerId);
+      }
+      await this.execSignal(args);
+    } finally {
+      await rm(tempDir, { recursive: true, force: true });
+    }
+  }
+
   private async pollOnce(): Promise<void> {
     if (this.polling || !this.messageHandler || this._status !== 'connected') {
       return;
@@ -327,6 +355,36 @@ export class SignalAdapter implements ChannelAdapter {
   }
 }
 
+function extensionFromMimeType(mimeType?: string): string {
+  if (!mimeType) {
+    return '.bin';
+  }
+  if (mimeType.startsWith('image/jpeg')) {
+    return '.jpg';
+  }
+  if (mimeType.startsWith('image/png')) {
+    return '.png';
+  }
+  if (mimeType.startsWith('image/gif')) {
+    return '.gif';
+  }
+  if (mimeType.startsWith('application/pdf')) {
+    return '.pdf';
+  }
+  const [, subtype] = mimeType.split('/');
+  if (!subtype) {
+    return '.bin';
+  }
+  return `.${subtype.split('+')[0]}`;
+}
+
+function sanitizeFilename(filename?: string): string {
+  if (!filename) {
+    return '';
+  }
+  return filename.replace(/[^a-zA-Z0-9._-]/g, '_');
+}
+
 function escapeRegex(value: string): string {
   return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
 }