diff --git a/src/agents/tools/memory-tool.citations.test.ts b/src/agents/tools/memory-tool.citations.test.ts
index 3a1b4c590..8e4d5c1b7 100644
--- a/src/agents/tools/memory-tool.citations.test.ts
+++ b/src/agents/tools/memory-tool.citations.test.ts
@@ -84,4 +84,40 @@ describe("memory search citations", () => {
     const details = result.details as { results: Array<{ snippet: string; citation?: string }> };
     expect(details.results[0]?.snippet.length).toBeLessThanOrEqual(20);
   });
+
+  it("honors auto mode for direct chats", async () => {
+    backend = "builtin";
+    const cfg = {
+      memory: { citations: "auto" },
+      agents: { list: [{ id: "main", default: true }] },
+    };
+    const tool = createMemorySearchTool({
+      config: cfg,
+      agentSessionKey: "agent:main:discord:dm:u123",
+    });
+    if (!tool) {
+      throw new Error("tool missing");
+    }
+    const result = await tool.execute("auto_mode_direct", { query: "notes" });
+    const details = result.details as { results: Array<{ snippet: string }> };
+    expect(details.results[0]?.snippet).toMatch(/Source:/);
+  });
+
+  it("suppresses citations for auto mode in group chats", async () => {
+    backend = "builtin";
+    const cfg = {
+      memory: { citations: "auto" },
+      agents: { list: [{ id: "main", default: true }] },
+    };
+    const tool = createMemorySearchTool({
+      config: cfg,
+      agentSessionKey: "agent:main:discord:group:c123",
+    });
+    if (!tool) {
+      throw new Error("tool missing");
+    }
+    const result = await tool.execute("auto_mode_group", { query: "notes" });
+    const details = result.details as { results: Array<{ snippet: string }> };
+    expect(details.results[0]?.snippet).not.toMatch(/Source:/);
+  });
 });
diff --git a/src/agents/tools/memory-tool.ts b/src/agents/tools/memory-tool.ts
index e9499e5f8..139e5da90 100644
--- a/src/agents/tools/memory-tool.ts
+++ b/src/agents/tools/memory-tool.ts
@@ -5,6 +5,7 @@ import type { MemoryCitationsMode } from "../../config/types.memory.js";
 import { resolveMemoryBackendConfig } from "../../memory/backend-config.js";
 import { getMemorySearchManager } from "../../memory/index.js";
 import type { MemorySearchResult } from "../../memory/types.js";
+import { parseAgentSessionKey } from "../../routing/session-key.js";
 import { resolveSessionAgentId } from "../agent-scope.js";
 import { resolveMemorySearchConfig } from "../memory-search.js";
 import type { AnyAgentTool } from "./common.js";
@@ -195,14 +196,19 @@ function shouldIncludeCitations(params: {
 }
 
 function deriveChatTypeFromSessionKey(sessionKey?: string): "direct" | "group" | "channel" {
-  if (!sessionKey) {
+  const parsed = parseAgentSessionKey(sessionKey);
+  if (!parsed?.rest) {
     return "direct";
   }
-  if (sessionKey.includes(":group:")) {
-    return "group";
-  }
-  if (sessionKey.includes(":channel:")) {
+  const tokens = parsed.rest
+    .toLowerCase()
+    .split(":")
+    .filter(Boolean);
+  if (tokens.includes("channel")) {
     return "channel";
   }
+  if (tokens.includes("group")) {
+    return "group";
+  }
   return "direct";
 }