diff --git a/src/agents/tools/gateway-tool.test.ts b/src/agents/tools/gateway-tool.test.ts
index 6e0c9e14e51..2e3cab0f520 100644
--- a/src/agents/tools/gateway-tool.test.ts
+++ b/src/agents/tools/gateway-tool.test.ts
@@ -170,6 +170,33 @@ describe("createGatewayTool – live delivery context guard", () => {
     expect(sentinelPayload?.deliveryContext?.to).toBe("123456789");
   });
 
+  it("does not forward live RPC delivery context when gateway.mode=remote is configured (no URL override)", async () => {
+    // When gateway.mode=remote is set in config, callGatewayTool() routes to
+    // gateway.remote.url without an explicit gatewayUrl param.  resolveGatewayTarget
+    // must return "remote" in this case so deliveryContext is suppressed, preventing
+    // the remote sentinel from being stamped with the local chat route.
+    mocks.callGatewayTool.mockClear();
+    // No gatewayUrl override — config-based remote mode
+    mocks.readGatewayCallOptions.mockReturnValueOnce({});
+    mocks.resolveGatewayTarget.mockReturnValueOnce("remote");
+    const tool = createGatewayTool({
+      agentSessionKey: "agent:main:main",
+      agentChannel: "discord",
+      agentTo: "123456789",
+    });
+
+    await execTool(tool, {
+      action: "config.patch",
+      raw: '{"key":"value"}',
+      baseHash: "abc123",
+      sessionKey: "agent:main:main",
+      note: "config-remote patch (no URL override)",
+    });
+
+    const forwardedParams = getCallArg<Record<string, unknown>>(mocks.callGatewayTool, 0, 2);
+    expect(forwardedParams?.deliveryContext).toBeUndefined();
+  });
+
   it("does not forward live RPC delivery context when gatewayUrl targets a remote gateway", async () => {
     // A remote gateway has its own extractDeliveryInfo(sessionKey) — forwarding
     // the local agent's deliveryContext would write a sentinel with the wrong
diff --git a/src/agents/tools/gateway.ts b/src/agents/tools/gateway.ts
index 1c372403f2a..3f663dc0508 100644
--- a/src/agents/tools/gateway.ts
+++ b/src/agents/tools/gateway.ts
@@ -115,15 +115,21 @@ function resolveGatewayOverrideToken(params: {
 
 /**
  * Resolves whether a GatewayCallOptions points to a local or remote gateway.
- * Returns undefined when no gatewayUrl override is present (default local gateway).
- * Local loopback overrides (127.0.0.1, localhost, [::1]) return "local";
- * all other URL overrides return "remote".
+ * Returns "remote" when a remote gatewayUrl override is present, OR when
+ * gateway.mode=remote is configured and no override is provided (config-based remote).
+ * Returns "local" for explicit loopback URL overrides (127.0.0.1, localhost, [::1]).
+ * Returns undefined only when no override is present and gateway.mode is not "remote"
+ * (i.e. the default local gateway).
  */
 export function resolveGatewayTarget(opts?: GatewayCallOptions): GatewayOverrideTarget | undefined {
-  if (trimToUndefined(opts?.gatewayUrl) === undefined) {
-    return undefined;
-  }
   const cfg = loadConfig();
+  if (trimToUndefined(opts?.gatewayUrl) === undefined) {
+    // No explicit URL override — fall back to config-based mode.
+    // When gateway.mode=remote, callGatewayTool() routes to the configured
+    // gateway.remote.url, so this is effectively a remote target even without
+    // an explicit gatewayUrl param.
+    return cfg.gateway?.mode === "remote" ? "remote" : undefined;
+  }
   return validateGatewayUrlOverrideForAgentTools({
     cfg,
     urlOverride: String(opts?.gatewayUrl),