diff --git a/src/agent/identity.ts b/src/agent/identity.ts
index ace8f4f..a557af0 100644
--- a/src/agent/identity.ts
+++ b/src/agent/identity.ts
@@ -108,6 +108,25 @@ ${role}
 - Be concise in your responses -- they are displayed in Discord (2000 char limit per message)
 - If a task is outside your area of expertise, say so clearly
 
+## Sending Files to Discord
+
+To send a file from your workspace back to the user in Discord, include this marker anywhere in your response:
+
+\`\`\`
+[ATTACH: path/to/file.jpg]
+\`\`\`
+
+- The path can be relative to your workspace root or absolute
+- Only files within your workspace directory are allowed
+- Maximum file size: 8 MB
+- Multiple files are supported — one marker per file
+- The marker is removed from the text before display; only the file is sent
+
+Example: If a user asks "send me the image", respond with:
+\`[ATTACH: images/result.png]\`
+
+Do **not** use this for files outside your workspace or for sensitive files.
+
 ## Workspace Contents
 
 Add project-specific context below. Describe the files, conventions,
diff --git a/src/discord/attachment-inbox.ts b/src/discord/attachment-inbox.ts
new file mode 100644
index 0000000..4c423e3
--- /dev/null
+++ b/src/discord/attachment-inbox.ts
@@ -0,0 +1,90 @@
+import { Message } from "discord.js";
+import * as fs from "node:fs";
+import * as path from "node:path";
+import { childLogger } from "../runtime/logger.js";
+
+const log = childLogger("attachment-inbox");
+
+const INBOX_DIR = ".disclaw-inbox";
+const MAX_AGE_MS = 24 * 60 * 60 * 1000; // 24 hours
+
+/**
+ * Saves attachments from a Discord message into <workspacePath>/.disclaw-inbox/
+ * Returns a list of saved file hints to inject into the prompt context.
+ */
+export async function processAttachments(
+  message: Message,
+  workspacePath: string
+): Promise<string[]> {
+  if (message.attachments.size === 0) {
+    return [];
+  }
+
+  const inboxPath = path.join(workspacePath, INBOX_DIR);
+  if (!fs.existsSync(inboxPath)) {
+    fs.mkdirSync(inboxPath, { recursive: true });
+    log.debug({ inboxPath }, "Created inbox directory");
+  }
+
+  const hints: string[] = [];
+  const timestamp = Date.now();
+
+  for (const attachment of message.attachments.values()) {
+    const safeName = path.basename(attachment.name ?? "file");
+    const fileName = `${timestamp}-${safeName}`;
+    const filePath = path.join(inboxPath, fileName);
+
+    try {
+      const response = await fetch(attachment.url);
+      if (!response.ok) {
+        log.warn(
+          { url: attachment.url, status: response.status },
+          "Failed to download attachment"
+        );
+        continue;
+      }
+      const buffer = Buffer.from(await response.arrayBuffer());
+      fs.writeFileSync(filePath, buffer);
+      log.debug({ fileName }, "Saved attachment");
+      hints.push(`[Datei verfügbar: ${INBOX_DIR}/${fileName}]`);
+    } catch (err) {
+      log.warn({ err, fileName }, "Error saving attachment");
+    }
+  }
+
+  return hints;
+}
+
+/**
+ * Deletes files in <workspacePath>/.disclaw-inbox/ older than 24 hours.
+ */
+export function cleanupInbox(workspacePath: string): void {
+  const inboxPath = path.join(workspacePath, INBOX_DIR);
+
+  if (!fs.existsSync(inboxPath)) {
+    return;
+  }
+
+  const now = Date.now();
+  let entries: string[];
+
+  try {
+    entries = fs.readdirSync(inboxPath);
+  } catch (err) {
+    log.warn({ err, inboxPath }, "Failed to read inbox directory for cleanup");
+    return;
+  }
+
+  for (const entry of entries) {
+    const filePath = path.join(inboxPath, entry);
+    try {
+      const stat = fs.statSync(filePath);
+      if (now - stat.mtimeMs > MAX_AGE_MS) {
+        fs.unlinkSync(filePath);
+        log.debug({ filePath }, "Deleted stale inbox file");
+      }
+    } catch (err) {
+      log.warn({ err, filePath }, "Failed to stat/delete inbox file");
+    }
+  }
+}
diff --git a/src/discord/send-response.ts b/src/discord/send-response.ts
new file mode 100644
index 0000000..88cadf3
--- /dev/null
+++ b/src/discord/send-response.ts
@@ -0,0 +1,134 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
+import { TextChannel, Message, AttachmentBuilder } from "discord.js";
+import { splitForDiscord } from "./split.js";
+import { childLogger } from "../runtime/logger.js";
+
+const log = childLogger("send-response");
+
+const FILE_THRESHOLD = 4000;
+const MAX_ATTACH_BYTES = 8 * 1024 * 1024; // 8 MB — Discord limit for regular bots
+
+const ATTACH_PATTERN = /\[ATTACH:\s*([^\]]+)\]/g;
+
+export interface ParsedResponse {
+  text: string;
+  attachPaths: string[];
+}
+
+/**
+ * Extracts [ATTACH: path] markers from agent response text.
+ * Returns cleaned text and a list of resolved absolute paths.
+ * Paths are resolved relative to workspacePath if not absolute.
+ */
+export function parseAttachments(raw: string, workspacePath: string): ParsedResponse {
+  const attachPaths: string[] = [];
+  const text = raw.replace(ATTACH_PATTERN, (_match, rawPath: string) => {
+    const trimmed = rawPath.trim();
+    const resolved = path.isAbsolute(trimmed)
+      ? trimmed
+      : path.resolve(workspacePath, trimmed);
+    attachPaths.push(resolved);
+    return "";
+  }).trim();
+  return { text, attachPaths };
+}
+
+/**
+ * Validates an attach path: must exist, be readable, be within workspacePath,
+ * and be no larger than MAX_ATTACH_BYTES.
+ * Returns an error string if invalid, null if OK.
+ */
+export function validateAttachPath(filePath: string, workspacePath: string): string | null {
+  const workspaceRoot = path.resolve(workspacePath);
+  const resolved = path.resolve(filePath);
+
+  // Path-traversal guard
+  if (!resolved.startsWith(workspaceRoot + path.sep) && resolved !== workspaceRoot) {
+    return `Datei liegt außerhalb des Workspace: \`${path.basename(resolved)}\``;
+  }
+
+  // Existence + read permission
+  try {
+    fs.accessSync(resolved, fs.constants.R_OK);
+  } catch {
+    return `Datei nicht lesbar oder nicht vorhanden: \`${path.basename(resolved)}\``;
+  }
+
+  // Size check
+  const stat = fs.statSync(resolved);
+  if (stat.size > MAX_ATTACH_BYTES) {
+    const mb = (stat.size / (1024 * 1024)).toFixed(1);
+    return `Datei zu groß (${mb} MB, Maximum 8 MB): \`${path.basename(resolved)}\``;
+  }
+
+  return null;
+}
+
+/**
+ * Sends an agent response to a Discord channel.
+ * - If preResolvedAttachPaths is given, those files are sent as attachments (markers
+ *   must already be stripped from `text`). Otherwise [ATTACH: path] markers are parsed
+ *   from `text` on the fly (requires workspacePath).
+ * - Text > 4000 chars is sent as a Markdown file attachment.
+ * - Text <= 4000 chars is split with splitForDiscord and sent as plain messages.
+ */
+export async function sendResponse(
+  channel: TextChannel,
+  text: string,
+  _triggerMessage: Message,
+  workspacePath?: string,
+  preResolvedAttachPaths?: string[]
+): Promise<void> {
+  if (text.length === 0 && (!preResolvedAttachPaths || preResolvedAttachPaths.length === 0)) {
+    return;
+  }
+
+  // Use pre-resolved paths (already extracted before sanitization) when available,
+  // otherwise fall back to parsing markers from the text (requires workspacePath).
+  let cleanText = text;
+  let attachPaths: string[] = [];
+  if (preResolvedAttachPaths) {
+    attachPaths = preResolvedAttachPaths;
+  } else if (workspacePath) {
+    const parsed = parseAttachments(text, workspacePath);
+    cleanText = parsed.text;
+    attachPaths = parsed.attachPaths;
+  }
+
+  // Send file attachments
+  for (const filePath of attachPaths) {
+    const err = validateAttachPath(filePath, workspacePath!);
+    if (err) {
+      log.warn({ filePath }, "Attachment rejected: " + err);
+      await channel.send(`⚠️ ${err}`).catch(() => {});
+      continue;
+    }
+    log.debug({ filePath }, "Sending file attachment");
+    await channel.send({
+      files: [new AttachmentBuilder(filePath, { name: path.basename(filePath) })],
+    });
+  }
+
+  // Send text portion
+  if (cleanText.length === 0) {
+    return;
+  }
+
+  if (cleanText.length > FILE_THRESHOLD) {
+    log.debug({ length: cleanText.length }, "Response exceeds threshold — sending as file");
+    await channel.send({
+      files: [
+        new AttachmentBuilder(Buffer.from(cleanText, "utf-8"), {
+          name: "response.md",
+        }),
+      ],
+    });
+    return;
+  }
+
+  const chunks = splitForDiscord(cleanText);
+  for (const chunk of chunks) {
+    await channel.send(chunk);
+  }
+}
diff --git a/src/router.ts b/src/router.ts
index 475a7f9..a3d7ea2 100644
--- a/src/router.ts
+++ b/src/router.ts
@@ -3,11 +3,14 @@ import { Message, TextChannel } from "discord.js";
 import { DisclawDatabase } from "./db/database";
 import { DisclawConfig } from "./config/loader";
 import { runAgent } from "./agent/runner";
-import { splitForDiscord } from "./discord/split";
 import { sanitizeForDiscord } from "./runtime/sanitize";
 import { ChannelQueue } from "./runtime/channel-queue";
+import { sendResponse, parseAttachments } from "./discord/send-response";
+import { processAttachments } from "./discord/attachment-inbox";
 import type { RunResult } from "./agent/types";
 
+const INPUT_LIMIT = 4000;
+
 const channelQueue = new ChannelQueue();
 
 /**
@@ -33,6 +36,21 @@ export async function routeMessage(
   }
 
   const channel = message.channel as TextChannel;
+
+  // Input-length guard — refuse oversized messages before queuing
+  if (message.content.length > INPUT_LIMIT) {
+    message.react?.("⚠️").catch(() => {});
+    await channel
+      .send(
+        `Nachricht zu lang (${message.content.length} Zeichen). Maximum ist ${INPUT_LIMIT} Zeichen.`
+      )
+      .catch(() => {});
+    return true;
+  }
+
+  // Acknowledge receipt immediately
+  message.react?.("👀").catch(() => {});
+
   const sanitizeOpts = {
     repoRoot: workspace.workspace_path,
     home: os.homedir(),
@@ -41,16 +59,25 @@ export async function routeMessage(
   await channelQueue.enqueue(channelId, async () => {
     const typingInterval = setInterval(() => {
       channel.sendTyping().catch(() => {});
-    }, 5000);
+    }, 8000);
     await channel.sendTyping().catch(() => {});
 
     try {
       const history = db.getConversationHistory(workspace.id, 30);
 
+      // Process any file attachments and build hint lines for the prompt
+      const attachmentHints = message.attachments
+        ? await processAttachments(message, workspace.workspace_path)
+        : [];
+      let userMessage = message.content;
+      if (attachmentHints.length > 0) {
+        userMessage = userMessage + "\n\n" + attachmentHints.join("\n");
+      }
+
       const result: RunResult = await runAgent({
         workspacePath: workspace.workspace_path,
         channelName: channel.name,
-        userMessage: message.content,
+        userMessage,
         conversationHistory: history,
       });
 
@@ -63,15 +90,38 @@ export async function routeMessage(
           message.author.username
         );
 
-        const sanitizedResponse = sanitizeForDiscord(result.text, sanitizeOpts);
-        const chunks = splitForDiscord(sanitizedResponse);
+        // Extract [ATTACH: ...] markers BEFORE sanitization so that workspace
+        // paths inside the markers are still resolvable.
+        const { text: textWithoutMarkers, attachPaths } = parseAttachments(
+          result.text,
+          workspace.workspace_path
+        );
+        const sanitizedResponse = sanitizeForDiscord(textWithoutMarkers, sanitizeOpts);
+
         let firstMsgId: string | null = null;
 
-        for (const chunk of chunks) {
-          const sent = await channel.send(chunk);
-          if (!firstMsgId) {
-            firstMsgId = sent.id;
-          }
+        // Use sendResponse which handles the file-vs-chunks decision
+        // We need to capture the first message id for DB storage.
+        // sendResponse sends all chunks; we wrap with a one-shot intercept.
+        const originalSend = channel.send.bind(channel);
+        const sentIds: string[] = [];
+        const patchedSend = async (...args: Parameters<typeof originalSend>) => {
+          const sent = await originalSend(...(args as [Parameters<typeof originalSend>[0]]));
+          sentIds.push(sent.id);
+          return sent;
+        };
+
+        // Temporarily patch channel.send for sendResponse
+        (channel as unknown as { send: typeof patchedSend }).send = patchedSend;
+        try {
+          // Pass pre-parsed attachPaths; sendResponse skips re-parsing when provided
+          await sendResponse(channel, sanitizedResponse, message, workspace.workspace_path, attachPaths);
+        } finally {
+          (channel as unknown as { send: typeof originalSend }).send = originalSend;
+        }
+
+        if (sentIds.length > 0) {
+          firstMsgId = sentIds[0];
         }
 
         if (firstMsgId) {
@@ -83,20 +133,26 @@ export async function routeMessage(
             null
           );
         }
+
+        message.react?.("✅").catch(() => {});
       } else if (result.status === "timeout") {
+        message.react?.("❌").catch(() => {});
         await channel
           .send(`⏱️ Agent-Timeout nach ${result.timeoutMs / 1000}s`)
           .catch(() => {});
       } else if (result.status === "cli-error") {
+        message.react?.("❌").catch(() => {});
         await channel
           .send(sanitizeForDiscord(`❌ CLI-Fehler: ${result.message}`, sanitizeOpts))
           .catch(() => {});
       } else if (result.status === "parse-error") {
+        message.react?.("❌").catch(() => {});
         await channel
           .send(`⚠️ Antwort konnte nicht gelesen werden`)
           .catch(() => {});
       }
     } catch (error) {
+      message.react?.("❌").catch(() => {});
       const msg = error instanceof Error ? error.message : "Unbekannter Fehler";
       await channel
         .send(sanitizeForDiscord(`Fehler bei der Verarbeitung: ${msg}`, sanitizeOpts))
diff --git a/tasks/DIS-154.md b/tasks/DIS-154.md
index dcbb515..71f4355 100644
--- a/tasks/DIS-154.md
+++ b/tasks/DIS-154.md
@@ -1,12 +1,12 @@
 ---
 id: DIS-154
-status: ready
+status: in-progress
 phase: 1.5
 priority: p1
 labels: [phase:1.5, type:feat, priority:p1]
 branch: refinement/discord-rich-features
-assignee: null
-started: null
+assignee: developer-agent
+started: 2026-04-13
 pr: null
 merged: null
 ---
@@ -70,6 +70,30 @@ Aktuell senden Agents nur Plaintext. Discord bietet viel mehr:
 ## Abhängigkeiten
 Phase 1 abgeschlossen (splitForDiscord, RunResult).
 
+### 6. Agent sendet Dateien zurück (`src/discord/send-response.ts`)
+- Agent schreibt `[ATTACH: pfad/zur/datei.ext]` in seine Antwort
+- Bot parst alle `[ATTACH: ...]`-Marker heraus, entfernt sie aus dem Text
+- Sicherheitscheck vor dem Senden:
+  - Datei muss existieren und lesbar sein (`fs.accessSync(path, fs.constants.R_OK)`)
+  - Pfad darf nicht außerhalb des Workspace liegen (Path-Traversal-Schutz via `path.resolve`)
+  - Max. Dateigröße: **8 MB** (Discord-Limit für reguläre Bots)
+- Erlaubte Pfade: relativ zum Workspace-Root oder absolut innerhalb des Workspace
+- Dateien werden als Discord-Attachments gesendet, verbleibender Text normal
+- CLAUDE.md-Template informiert den Agent über die `[ATTACH: ...]`-Konvention
+
+## Definition of Done
+- [ ] Reactions `👀` / `✅` / `❌` werden korrekt gesetzt
+- [ ] Typing-Intervall 8s, endet mit Agent-Antwort
+- [ ] Antworten > 4000 Zeichen kommen als `.md`-Attachment
+- [ ] Eingehende Dateien landen im `.disclaw-inbox/`-Verzeichnis
+- [ ] Input > 4000 Zeichen → `⚠️` + Hinweis, kein Agent-Aufruf
+- [ ] Agent kann mit `[ATTACH: pfad]` Dateien zurücksenden
+- [ ] Path-Traversal-Schutz: nur Dateien im Workspace erlaubt
+- [ ] Dateien > 8 MB → Fehlermeldung an Channel statt Absturz
+- [ ] CLAUDE.md-Template enthält Hinweis auf `[ATTACH: ...]`
+- [ ] Unit-Tests: `send-response`, `attachment-inbox`
+- [ ] `npm run build && npm test` grün
+
 ## Hinweis
 Reactions, Embeds, Threads und Polls (voller SF-004-Scope) können in Folge-Issues
 ausgebaut werden. Dieses Issue implementiert den Kern-QoL-Teil.
diff --git a/tests/unit/attachment-inbox.test.ts b/tests/unit/attachment-inbox.test.ts
new file mode 100644
index 0000000..6d4bed2
--- /dev/null
+++ b/tests/unit/attachment-inbox.test.ts
@@ -0,0 +1,144 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import * as fs from "node:fs";
+import * as path from "node:path";
+import * as os from "node:os";
+import type { Message, Collection, Attachment } from "discord.js";
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function makeMessage(attachments: Attachment[] = []): Message {
+  const col = new Map(attachments.map((a) => [a.id, a]));
+  return {
+    attachments: {
+      size: attachments.length,
+      values: () => col.values(),
+    },
+  } as unknown as Message;
+}
+
+function makeAttachment(id: string, name: string, url: string): Attachment {
+  return { id, name, url } as unknown as Attachment;
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+describe("processAttachments", () => {
+  let tmpDir: string;
+
+  beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-inbox-test-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+    vi.restoreAllMocks();
+  });
+
+  it("returns an empty array when message has no attachments", async () => {
+    const { processAttachments } = await import("../../src/discord/attachment-inbox");
+    const message = makeMessage([]);
+    const hints = await processAttachments(message, tmpDir);
+    expect(hints).toEqual([]);
+    // No inbox directory created
+    expect(fs.existsSync(path.join(tmpDir, ".disclaw-inbox"))).toBe(false);
+  });
+
+  it("saves an attachment to .disclaw-inbox/ and returns a hint", async () => {
+    // Mock global fetch
+    const fileContent = "print('hello')\n";
+    const contentBytes = Buffer.from(fileContent, "utf-8");
+    // Allocate a clean ArrayBuffer (not the Node shared pool) so Buffer.from() round-trips correctly
+    const cleanArrayBuffer = contentBytes.buffer.slice(
+      contentBytes.byteOffset,
+      contentBytes.byteOffset + contentBytes.byteLength
+    );
+    vi.stubGlobal(
+      "fetch",
+      vi.fn().mockResolvedValue({
+        ok: true,
+        arrayBuffer: async () => cleanArrayBuffer,
+      })
+    );
+
+    const { processAttachments } = await import("../../src/discord/attachment-inbox");
+    const attachment = makeAttachment("att-1", "example.py", "https://cdn.discord.com/example.py");
+    const message = makeMessage([attachment]);
+
+    const hints = await processAttachments(message, tmpDir);
+
+    expect(hints).toHaveLength(1);
+    expect(hints[0]).toMatch(/^\[Datei verfügbar: \.disclaw-inbox\//);
+    expect(hints[0]).toContain("example.py");
+
+    // File must exist in inbox
+    const inboxDir = path.join(tmpDir, ".disclaw-inbox");
+    const files = fs.readdirSync(inboxDir);
+    expect(files).toHaveLength(1);
+    expect(files[0]).toMatch(/example\.py$/);
+
+    // File content must match
+    const savedContent = fs.readFileSync(path.join(inboxDir, files[0]), "utf-8");
+    expect(savedContent).toBe(fileContent);
+  });
+
+  it("skips an attachment when fetch fails", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn().mockResolvedValue({
+        ok: false,
+        status: 403,
+      })
+    );
+
+    const { processAttachments } = await import("../../src/discord/attachment-inbox");
+    const attachment = makeAttachment("att-1", "secret.txt", "https://cdn.discord.com/secret.txt");
+    const message = makeMessage([attachment]);
+
+    const hints = await processAttachments(message, tmpDir);
+    expect(hints).toEqual([]);
+  });
+});
+
+describe("cleanupInbox", () => {
+  let tmpDir: string;
+
+  beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-cleanup-test-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+    vi.restoreAllMocks();
+  });
+
+  it("does nothing when inbox directory does not exist", async () => {
+    const { cleanupInbox } = await import("../../src/discord/attachment-inbox");
+    expect(() => cleanupInbox(tmpDir)).not.toThrow();
+  });
+
+  it("deletes files older than 24 hours and keeps newer files", async () => {
+    const { cleanupInbox } = await import("../../src/discord/attachment-inbox");
+
+    const inboxDir = path.join(tmpDir, ".disclaw-inbox");
+    fs.mkdirSync(inboxDir);
+
+    const oldFile = path.join(inboxDir, "old-file.txt");
+    const newFile = path.join(inboxDir, "new-file.txt");
+
+    fs.writeFileSync(oldFile, "old");
+    fs.writeFileSync(newFile, "new");
+
+    // Backdate old file by 25 hours
+    const oldTime = new Date(Date.now() - 25 * 60 * 60 * 1000);
+    fs.utimesSync(oldFile, oldTime, oldTime);
+
+    cleanupInbox(tmpDir);
+
+    expect(fs.existsSync(oldFile)).toBe(false);
+    expect(fs.existsSync(newFile)).toBe(true);
+  });
+});
diff --git a/tests/unit/send-response.test.ts b/tests/unit/send-response.test.ts
new file mode 100644
index 0000000..5508016
--- /dev/null
+++ b/tests/unit/send-response.test.ts
@@ -0,0 +1,159 @@
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { sendResponse, parseAttachments, validateAttachPath } from "../../src/discord/send-response";
+import type { TextChannel, Message } from "discord.js";
+
+function makeChannel() {
+  return {
+    send: vi.fn().mockResolvedValue({ id: "msg-1" }),
+  } as unknown as TextChannel;
+}
+
+function makeMessage() {
+  return {} as Message;
+}
+
+describe("parseAttachments", () => {
+  it("returns empty attachPaths and original text when no markers", () => {
+    const result = parseAttachments("Hello world", "/workspace");
+    expect(result.text).toBe("Hello world");
+    expect(result.attachPaths).toHaveLength(0);
+  });
+
+  it("extracts a single relative [ATTACH: ...] marker", () => {
+    const result = parseAttachments("Here is the file [ATTACH: images/cat.jpg]", "/workspace");
+    expect(result.text).toBe("Here is the file");
+    expect(result.attachPaths).toHaveLength(1);
+    expect(result.attachPaths[0]).toBe(path.resolve("/workspace", "images/cat.jpg"));
+  });
+
+  it("extracts an absolute [ATTACH: ...] marker unchanged", () => {
+    const abs = path.resolve("/workspace/file.txt");
+    const result = parseAttachments(`See [ATTACH: ${abs}]`, "/workspace");
+    expect(result.attachPaths[0]).toBe(abs);
+  });
+
+  it("extracts multiple markers", () => {
+    const result = parseAttachments(
+      "Files: [ATTACH: a.txt] and [ATTACH: b.png]",
+      "/workspace"
+    );
+    expect(result.attachPaths).toHaveLength(2);
+    expect(result.text).toBe("Files:  and");
+  });
+});
+
+describe("validateAttachPath", () => {
+  let tmpDir: string;
+  let tmpFile: string;
+
+  beforeEach(() => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-test-"));
+    tmpFile = path.join(tmpDir, "file.txt");
+    fs.writeFileSync(tmpFile, "hello");
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  });
+
+  it("returns null for a valid readable file within workspace", () => {
+    expect(validateAttachPath(tmpFile, tmpDir)).toBeNull();
+  });
+
+  it("rejects paths outside workspace (path traversal)", () => {
+    const outsideFile = path.join(os.tmpdir(), "outside.txt");
+    fs.writeFileSync(outsideFile, "secret");
+    const err = validateAttachPath(outsideFile, tmpDir);
+    expect(err).toMatch(/außerhalb/);
+    fs.unlinkSync(outsideFile);
+  });
+
+  it("rejects non-existent files", () => {
+    const missing = path.join(tmpDir, "ghost.txt");
+    const err = validateAttachPath(missing, tmpDir);
+    expect(err).toMatch(/nicht lesbar/);
+  });
+});
+
+describe("sendResponse", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("sends chunks via channel.send() for text <= 4000 chars", async () => {
+    const channel = makeChannel();
+    await sendResponse(channel, "Hello, world!", makeMessage());
+    expect(channel.send).toHaveBeenCalledTimes(1);
+    const call = vi.mocked(channel.send).mock.calls[0][0];
+    expect(typeof call).toBe("string");
+  });
+
+  it("sends an attachment for text > 4000 chars", async () => {
+    const channel = makeChannel();
+    await sendResponse(channel, "x".repeat(4001), makeMessage());
+    expect(channel.send).toHaveBeenCalledTimes(1);
+    const call = vi.mocked(channel.send).mock.calls[0][0];
+    expect(typeof call).toBe("object");
+    expect((call as { files: unknown[] }).files).toHaveLength(1);
+  });
+
+  it("does not call channel.send() for empty text", async () => {
+    const channel = makeChannel();
+    await sendResponse(channel, "", makeMessage());
+    expect(channel.send).not.toHaveBeenCalled();
+  });
+
+  it("sends [ATTACH: ...] file as Discord attachment", async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-attach-"));
+    const filePath = path.join(tmpDir, "result.txt");
+    fs.writeFileSync(filePath, "data");
+
+    try {
+      const channel = makeChannel();
+      await sendResponse(channel, `Here it is [ATTACH: result.txt]`, makeMessage(), tmpDir);
+
+      // One call for the file, one for the text
+      expect(channel.send).toHaveBeenCalledTimes(2);
+      const fileCall = vi.mocked(channel.send).mock.calls[0][0] as { files: unknown[] };
+      expect(fileCall.files).toHaveLength(1);
+      const textCall = vi.mocked(channel.send).mock.calls[1][0];
+      expect(typeof textCall).toBe("string");
+      expect(textCall as string).toContain("Here it is");
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  });
+
+  it("sends warning message for file outside workspace", async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-ws-"));
+    const outsideDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-out-"));
+    const outsideFile = path.join(outsideDir, "secret.txt");
+    fs.writeFileSync(outsideFile, "secret");
+
+    try {
+      const channel = makeChannel();
+      await sendResponse(channel, `[ATTACH: ${outsideFile}]`, makeMessage(), tmpDir);
+      expect(channel.send).toHaveBeenCalledTimes(1);
+      const call = vi.mocked(channel.send).mock.calls[0][0] as string;
+      expect(call).toMatch(/⚠️/);
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+      fs.rmSync(outsideDir, { recursive: true, force: true });
+    }
+  });
+
+  it("only sends text when no [ATTACH: ...] present and workspacePath given", async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "disclaw-plain-"));
+    try {
+      const channel = makeChannel();
+      await sendResponse(channel, "Plain text response", makeMessage(), tmpDir);
+      expect(channel.send).toHaveBeenCalledTimes(1);
+      expect(vi.mocked(channel.send).mock.calls[0][0]).toBe("Plain text response");
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  });
+});