feat: add Discord image receiving for Claude Code and Codex agents

Download Discord image attachments to DATA_DIR/attachments/ and pass
them as multimodal content blocks to both agent types:
- Claude Code: base64 ImageBlockParam via Agent SDK MessageParam
- Codex: localImage input block via app-server turn/start

container/agent-runner/src/index.ts

@@ -48,9 +48,13 @@ interface SessionsIndex {
   entries: SessionEntry[];
 }
 
+type ContentBlock =
+  | { type: 'text'; text: string }
+  | { type: 'image'; source: { type: 'base64'; media_type: string; data: string } };
+
 interface SDKUserMessage {
   type: 'user';
-  message: { role: 'user'; content: string };
+  message: { role: 'user'; content: string | ContentBlock[] };
   parent_tool_use_id: null;
   session_id: string;
 }
@@ -68,6 +72,51 @@ const MAX_TURNS = 100;
 const IPC_INPUT_CLOSE_SENTINEL = path.join(IPC_INPUT_DIR, '_close');
 const IPC_POLL_MS = 500;
 
+const IMAGE_TAG_RE = /\[Image:\s*(\/[^\]]+)\]/g;
+const MIME_TYPES: Record<string, string> = {
+  '.jpg': 'image/jpeg', '.jpeg': 'image/jpeg',
+  '.png': 'image/png', '.gif': 'image/gif', '.webp': 'image/webp',
+};
+
+/**
+ * Parse [Image: /absolute/path] tags from text and build multimodal content.
+ * Returns a plain string if no images found, or ContentBlock[] with text + image blocks.
+ */
+function buildMultimodalContent(text: string): string | ContentBlock[] {
+  const imagePaths: string[] = [];
+  let match;
+  while ((match = IMAGE_TAG_RE.exec(text)) !== null) {
+    imagePaths.push(match[1].trim());
+  }
+  IMAGE_TAG_RE.lastIndex = 0; // reset regex state
+
+  if (imagePaths.length === 0) return text;
+
+  const blocks: ContentBlock[] = [];
+  const cleanText = text.replace(IMAGE_TAG_RE, '').trim();
+  if (cleanText) {
+    blocks.push({ type: 'text', text: cleanText });
+  }
+
+  for (const imgPath of imagePaths) {
+    try {
+      if (!fs.existsSync(imgPath)) {
+        log(`Image not found, skipping: ${imgPath}`);
+        continue;
+      }
+      const data = fs.readFileSync(imgPath).toString('base64');
+      const ext = path.extname(imgPath).toLowerCase();
+      const mediaType = MIME_TYPES[ext] || 'image/png';
+      blocks.push({ type: 'image', source: { type: 'base64', media_type: mediaType, data } });
+      log(`Added image block: ${imgPath} (${mediaType})`);
+    } catch (err) {
+      log(`Failed to read image ${imgPath}: ${err instanceof Error ? err.message : String(err)}`);
+    }
+  }
+
+  return blocks.length > 0 ? blocks : text;
+}
+
 /**
  * Push-based async iterable for streaming user messages to the SDK.
  * Keeps the iterable alive until end() is called, preventing isSingleUserTurn.
@@ -78,9 +127,10 @@ class MessageStream {
   private done = false;
 
   push(text: string): void {
+    const content = buildMultimodalContent(text);
     this.queue.push({
       type: 'user',
-      message: { role: 'user', content: text },
+      message: { role: 'user', content },
       parent_tool_use_id: null,
       session_id: '',
     });

container/codex-runner/src/index.ts

@@ -325,9 +325,35 @@ class CodexAppServer {
   }
 
   async startTurn(threadId: string, text: string): Promise<string> {
+    // Parse [Image: /absolute/path] patterns and convert to multimodal input
+    const imagePattern = /\[Image:\s*(\/[^\]]+)\]/g;
+    const input: Array<Record<string, unknown>> = [];
+    const imagePaths: string[] = [];
+    let match;
+    while ((match = imagePattern.exec(text)) !== null) {
+      imagePaths.push(match[1].trim());
+    }
+    // Add text (with image tags stripped) as first input block
+    const cleanText = text.replace(imagePattern, '').trim();
+    if (cleanText) {
+      input.push({ type: 'text', text: cleanText, text_elements: [] });
+    }
+    // Add image input blocks
+    for (const imgPath of imagePaths) {
+      if (fs.existsSync(imgPath)) {
+        input.push({ type: 'localImage', path: imgPath });
+        log(`Adding image input: ${imgPath}`);
+      } else {
+        log(`Image not found, skipping: ${imgPath}`);
+      }
+    }
+    if (input.length === 0) {
+      input.push({ type: 'text', text, text_elements: [] });
+    }
+
     const params: Record<string, unknown> = {
       threadId,
-      input: [{ type: 'text', text, text_elements: [] }],
+      input,
     };
     if (CODEX_EFFORT) params.effort = CODEX_EFFORT;
 

src/channels/discord.ts

@@ -1,3 +1,6 @@
+import fs from 'fs';
+import path from 'path';
+
 import {
   Attachment,
   Client,
@@ -7,10 +10,30 @@ import {
   TextChannel,
 } from 'discord.js';
 
-import { ASSISTANT_NAME, TRIGGER_PATTERN } from '../config.js';
+import { ASSISTANT_NAME, DATA_DIR, TRIGGER_PATTERN } from '../config.js';
 import { readEnvFile } from '../env.js';
 import { logger } from '../logger.js';
 
+const ATTACHMENTS_DIR = path.join(DATA_DIR, 'attachments');
+
+/**
+ * Download a Discord image attachment to local disk.
+ * Returns the absolute path to the saved file.
+ */
+async function downloadImage(att: Attachment): Promise<string> {
+  const res = await fetch(att.url);
+  if (!res.ok) throw new Error(`Download failed: ${res.status}`);
+  const buffer = Buffer.from(await res.arrayBuffer());
+
+  fs.mkdirSync(ATTACHMENTS_DIR, { recursive: true });
+  const ext = path.extname(att.name || 'image.png') || '.png';
+  const filename = `${Date.now()}-${att.id}${ext}`;
+  const filePath = path.join(ATTACHMENTS_DIR, filename);
+  fs.writeFileSync(filePath, buffer);
+  logger.info({ file: filename, size: buffer.length }, 'Image downloaded');
+  return filePath;
+}
+
 /**
  * Transcribe an audio attachment via OpenAI Whisper API.
  * Returns the transcribed text, or a fallback placeholder on failure.
@@ -158,7 +181,13 @@ export class DiscordChannel implements Channel {
             if (contentType.startsWith('audio/') && openaiKey) {
               return transcribeAudio(att, openaiKey);
             } else if (contentType.startsWith('image/')) {
-              return `[Image: ${att.name || 'image'}]`;
+              try {
+                const imgPath = await downloadImage(att);
+                return `[Image: ${imgPath}]`;
+              } catch (err) {
+                logger.error({ err, file: att.name }, 'Image download failed');
+                return `[Image: ${att.name || 'image'} (download failed)]`;
+              }
             } else if (contentType.startsWith('video/')) {
               return `[Video: ${att.name || 'video'}]`;
             } else if (contentType.startsWith('audio/')) {