Add a red test for cross-tenant command audit leakage

Why: GET /api/commands/audit returns every tenant's audit rows; the regression test pins the desired owner-scoped behavior before the fix.
Evidence: go test ./internal/server -run TestCommandAuditOwnerScoping FAIL (owner alice sees bob's row; output recorded on the task card).
Impact: Test only; suite red on this commit by design.
Refs: Task card R1; U0 proposal section 5 C7 security finding.

internal/server/audit_scope_test.go

@@ -0,0 +1,68 @@
+package server
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	agentcommand "agent-command"
+)
+
+// 命令审计按租户作用域（回归：GET /api/commands/audit 曾返回全租户审计行——
+// ListAudits 无 owner 条件、command_audit 无 owner 列；多用户档下任何登录
+// 用户可读他人命令 ID、入口、会话 ID 与参数摘要）。
+// 经真实认证中间件（API key → owner）请求，断言每个租户只见本租户的行。
+func TestCommandAuditOwnerScoping(t *testing.T) {
+	srv, st := newAuthTestServer(t)
+	h := srv.Handler()
+
+	aliceKey, err := st.CreateAPIKey("alice", "e2e")
+	if err != nil {
+		t.Fatal(err)
+	}
+	bobKey, err := st.CreateAPIKey("bob", "e2e")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// 两租户各产生一条命令审计（信封 Actor=发起租户——修复前唯一可用的归属线索）。
+	if err := st.AppendAudit(agentcommand.AuditEnvelope{
+		CommandID: "cmd.alice", Actor: "alice", State: agentcommand.StateCommitted,
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if err := st.AppendAudit(agentcommand.AuditEnvelope{
+		CommandID: "cmd.bob", Actor: "bob", State: agentcommand.StateCommitted,
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	get := func(key string) []map[string]any {
+		t.Helper()
+		req := httptest.NewRequest(http.MethodGet, "/api/commands/audit", nil)
+		req.Header.Set("Authorization", "Bearer "+key)
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code != http.StatusOK {
+			t.Fatalf("audit query: %d %s", rec.Code, rec.Body.String())
+		}
+		var out struct {
+			Audits []map[string]any `json:"audits"`
+		}
+		if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+			t.Fatal(err)
+		}
+		return out.Audits
+	}
+
+	for key, owner := range map[string]string{aliceKey: "alice", bobKey: "bob"} {
+		rows := get(key)
+		if len(rows) != 1 {
+			t.Fatalf("owner %s: audit rows = %d, want 1（跨租户行不得返回；got=%v）", owner, len(rows), rows)
+		}
+		if rows[0]["actor"] != owner || rows[0]["commandId"] != "cmd."+owner {
+			t.Fatalf("owner %s: wrong row %v", owner, rows[0])
+		}
+	}
+}