fix: align exec default reporting with runtime

src/agents/exec-defaults.test.ts

@@ -1,8 +1,17 @@
-import { describe, expect, it } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
 import type { SessionEntry } from "../config/sessions.js";
+import * as execApprovals from "../infra/exec-approvals.js";
 import { resolveExecDefaults } from "./exec-defaults.js";
 
 describe("resolveExecDefaults", () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+    vi.spyOn(execApprovals, "loadExecApprovals").mockReturnValue({
+      version: 1,
+      agents: {},
+    });
+  });
+
   it("does not advertise node routing when exec host is pinned to gateway", () => {
     expect(
       resolveExecDefaults({
@@ -55,4 +64,44 @@ describe("resolveExecDefaults", () => {
       }).canRequestNode,
     ).toBe(true);
   });
+
+  it("uses host approval defaults for gateway when exec policy is unset", () => {
+    expect(
+      resolveExecDefaults({
+        cfg: {
+          tools: {
+            exec: {
+              host: "auto",
+            },
+          },
+        },
+        sandboxAvailable: false,
+      }),
+    ).toMatchObject({
+      host: "auto",
+      effectiveHost: "gateway",
+      security: "full",
+      ask: "off",
+    });
+  });
+
+  it("keeps sandbox deny by default when auto resolves to sandbox", () => {
+    expect(
+      resolveExecDefaults({
+        cfg: {
+          tools: {
+            exec: {
+              host: "auto",
+            },
+          },
+        },
+        sandboxAvailable: true,
+      }),
+    ).toMatchObject({
+      host: "auto",
+      effectiveHost: "sandbox",
+      security: "deny",
+      ask: "off",
+    });
+  });
 });