agentnetwork: fold in extra unit tests from review

Add coverage raised in review (originally generated in a separate PR):
- gRPC CheckLLMPolicyLimits handler: model forwarding, empty-model passthrough,
  model_blocked deny envelope, selector-error -> Internal, unconfigured ->
  Unimplemented.
- selector: guardrail-lookup error propagates, orphaned guardrail reference is
  unrestricted, model filter narrows candidates before cap scoring.
- proxy guardrail: enabled-but-empty allowlist and all-blank factory entries
  both deny every model for the provider.

management/internals/modules/agentnetwork/policyselect_model_test.go

@@ -2,6 +2,7 @@ package agentnetwork
 
 import (
 	"context"
+	"errors"
 	"testing"
 	"time"
 
@@ -246,3 +247,83 @@ func TestSelectPolicy_UnionAcrossPolicyGuardrails(t *testing.T) {
 	assert.True(t, res.Allow, "a model in any of the policy's allowlist guardrails must be permitted")
 	assert.Equal(t, "pol-A", res.SelectedPolicyID)
 }
+
+// TestSelectPolicy_GuardrailLookupErrorPropagates proves a store failure while
+// resolving the candidate policies' guardrails surfaces as an error, not a
+// silent allow/deny.
+func TestSelectPolicy_GuardrailLookupErrorPropagates(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mgr, mockStore := newSelectorMgr(t, ctrl)
+
+	policy := guardedPolicy("pol-A", "acc-1", []string{"grp-eng"}, "prov-1", "g-1")
+	expectPolicies(mockStore, "acc-1", policy)
+	mockStore.EXPECT().
+		GetAccountAgentNetworkGuardrails(gomock.Any(), gomock.Any(), "acc-1").
+		Return(nil, errors.New("store unavailable"))
+
+	res, err := mgr.SelectPolicyForRequest(context.Background(), PolicySelectionInput{
+		AccountID:  "acc-1",
+		GroupIDs:   []string{"grp-eng"},
+		ProviderID: "prov-1",
+		Model:      "gpt-4o",
+	})
+	require.Error(t, err, "a guardrail-lookup failure must surface as an error")
+	assert.Nil(t, res)
+}
+
+// TestSelectPolicy_MissingGuardrailReferenceTreatedAsUnrestricted proves a
+// policy referencing a guardrail ID absent from the account's set (a stale
+// reference) imposes no model restriction — same as no guardrail.
+func TestSelectPolicy_MissingGuardrailReferenceTreatedAsUnrestricted(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mgr, mockStore := newSelectorMgr(t, ctrl)
+
+	policy := guardedPolicy("pol-A", "acc-1", []string{"grp-eng"}, "prov-1", "g-missing")
+	expectPolicies(mockStore, "acc-1", policy)
+	expectGuardrails(mockStore, "acc-1")
+	expectConsumptionBatch(mockStore, nil)
+
+	res, err := mgr.SelectPolicyForRequest(context.Background(), PolicySelectionInput{
+		AccountID:  "acc-1",
+		GroupIDs:   []string{"grp-eng"},
+		ProviderID: "prov-1",
+		Model:      "anything-goes",
+	})
+	require.NoError(t, err)
+	assert.True(t, res.Allow, "an orphaned guardrail reference must not restrict the model")
+	assert.Equal(t, "pol-A", res.SelectedPolicyID)
+}
+
+// TestSelectPolicy_PartialCandidatesPermittedAfterModelFilter proves the model
+// gate narrows candidates before cap scoring: the permitting policy is selected
+// even though the blocked one has a larger, more attractive cap.
+func TestSelectPolicy_PartialCandidatesPermittedAfterModelFilter(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	mgr, mockStore := newSelectorMgr(t, ctrl)
+
+	polBig := guardedPolicy("pol-big", "acc-1", []string{"grp-eng"}, "prov-1", "g-restrict")
+	polBig.Limits = types.PolicyLimits{
+		TokenLimit: types.PolicyTokenLimit{Enabled: true, GroupCap: 1_000_000, WindowSeconds: 3600},
+	}
+	polSmall := guardedPolicy("pol-small", "acc-1", []string{"grp-eng"}, "prov-1", "g-permit")
+	polSmall.Limits = types.PolicyLimits{
+		TokenLimit: types.PolicyTokenLimit{Enabled: true, GroupCap: 100, WindowSeconds: 3600},
+	}
+	expectPolicies(mockStore, "acc-1", polBig, polSmall)
+	expectGuardrails(mockStore, "acc-1",
+		allowlistGuardrail("g-restrict", "acc-1", "gpt-4o"),
+		allowlistGuardrail("g-permit", "acc-1", "claude-opus-4"),
+	)
+	expectConsumptionBatch(mockStore, nil)
+
+	res, err := mgr.SelectPolicyForRequest(context.Background(), PolicySelectionInput{
+		AccountID:  "acc-1",
+		GroupIDs:   []string{"grp-eng"},
+		ProviderID: "prov-1",
+		Model:      "claude-opus-4", // only pol-small's guardrail permits this
+	})
+	require.NoError(t, err)
+	assert.True(t, res.Allow)
+	assert.Equal(t, "pol-small", res.SelectedPolicyID,
+		"the model filter must exclude pol-big before cap scoring")
+}

management/internals/shared/grpc/proxy_llm_policy_limits_test.go

@@ -0,0 +1,138 @@
+package grpc
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc/codes"
+	grpcstatus "google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/management/internals/modules/agentnetwork"
+	"github.com/netbirdio/netbird/shared/management/proto"
+)
+
+// fakeAgentNetworkLimits records the PolicySelectionInput it was invoked with
+// and returns a pre-programmed result, so tests can assert what the handler
+// forwards to the selector.
+type fakeAgentNetworkLimits struct {
+	gotInput agentnetwork.PolicySelectionInput
+	result   *agentnetwork.PolicySelectionResult
+	err      error
+}
+
+func (f *fakeAgentNetworkLimits) SelectPolicyForRequest(_ context.Context, in agentnetwork.PolicySelectionInput) (*agentnetwork.PolicySelectionResult, error) {
+	f.gotInput = in
+	if f.err != nil {
+		return nil, f.err
+	}
+	return f.result, nil
+}
+
+func (f *fakeAgentNetworkLimits) RecordUsage(_ context.Context, _ agentnetwork.RecordUsageInput) error {
+	return nil
+}
+
+// TestCheckLLMPolicyLimits_ForwardsModelToSelector proves the wiring added here:
+// the model the proxy extracted must reach the selector's Model unchanged,
+// alongside the account/user/group/provider fields.
+func TestCheckLLMPolicyLimits_ForwardsModelToSelector(t *testing.T) {
+	fake := &fakeAgentNetworkLimits{result: &agentnetwork.PolicySelectionResult{Allow: true, SelectedPolicyID: "pol-1"}}
+	s := &ProxyServiceServer{}
+	s.SetAgentNetworkLimitsService(fake)
+
+	req := &proto.CheckLLMPolicyLimitsRequest{
+		AccountId:  "acc-1",
+		UserId:     "user-1",
+		GroupIds:   []string{"grp-a", "grp-b"},
+		ProviderId: "prov-1",
+		Model:      "claude-opus-4",
+	}
+
+	resp, err := s.CheckLLMPolicyLimits(context.Background(), req)
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+
+	assert.Equal(t, "acc-1", fake.gotInput.AccountID)
+	assert.Equal(t, "user-1", fake.gotInput.UserID)
+	assert.Equal(t, []string{"grp-a", "grp-b"}, fake.gotInput.GroupIDs)
+	assert.Equal(t, "prov-1", fake.gotInput.ProviderID)
+	assert.Equal(t, "claude-opus-4", fake.gotInput.Model,
+		"the request's model must be forwarded to the selector")
+}
+
+// TestCheckLLMPolicyLimits_EmptyModelForwardedAsEmpty proves an undetermined
+// model (empty string) is forwarded as-is; the selector decides how to treat it.
+func TestCheckLLMPolicyLimits_EmptyModelForwardedAsEmpty(t *testing.T) {
+	fake := &fakeAgentNetworkLimits{result: &agentnetwork.PolicySelectionResult{Allow: true}}
+	s := &ProxyServiceServer{}
+	s.SetAgentNetworkLimitsService(fake)
+
+	req := &proto.CheckLLMPolicyLimitsRequest{
+		AccountId:  "acc-1",
+		ProviderId: "prov-1",
+	}
+
+	_, err := s.CheckLLMPolicyLimits(context.Background(), req)
+	require.NoError(t, err)
+	assert.Equal(t, "", fake.gotInput.Model, "an absent model must be forwarded as empty, not fabricated")
+}
+
+// TestCheckLLMPolicyLimits_DenyResponseCarriesModelBlockedCode proves the deny
+// envelope surfaces the model-allowlist deny code + reason through the response.
+func TestCheckLLMPolicyLimits_DenyResponseCarriesModelBlockedCode(t *testing.T) {
+	fake := &fakeAgentNetworkLimits{result: &agentnetwork.PolicySelectionResult{
+		Allow:      false,
+		DenyCode:   "llm_policy.model_blocked",
+		DenyReason: `model "claude-opus-4" is not permitted by any applicable policy allowlist`,
+	}}
+	s := &ProxyServiceServer{}
+	s.SetAgentNetworkLimitsService(fake)
+
+	resp, err := s.CheckLLMPolicyLimits(context.Background(), &proto.CheckLLMPolicyLimitsRequest{
+		AccountId:  "acc-1",
+		ProviderId: "prov-1",
+		Model:      "claude-opus-4",
+	})
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+	assert.Equal(t, "deny", resp.Decision)
+	assert.Equal(t, "llm_policy.model_blocked", resp.DenyCode)
+	assert.NotEmpty(t, resp.DenyReason)
+	assert.Empty(t, resp.SelectedPolicyId, "a denied request must carry no selected policy")
+}
+
+// TestCheckLLMPolicyLimits_SelectorErrorSurfacesAsInternal proves a selector
+// failure surfaces as an Internal gRPC error rather than a silent allow.
+func TestCheckLLMPolicyLimits_SelectorErrorSurfacesAsInternal(t *testing.T) {
+	fake := &fakeAgentNetworkLimits{err: errors.New("boom")}
+	s := &ProxyServiceServer{}
+	s.SetAgentNetworkLimitsService(fake)
+
+	_, err := s.CheckLLMPolicyLimits(context.Background(), &proto.CheckLLMPolicyLimitsRequest{
+		AccountId:  "acc-1",
+		ProviderId: "prov-1",
+		Model:      "gpt-4o",
+	})
+	require.Error(t, err)
+	st, ok := grpcstatus.FromError(err)
+	require.True(t, ok)
+	assert.Equal(t, codes.Internal, st.Code(), "selector errors must never fail open on the hot path")
+}
+
+// TestCheckLLMPolicyLimits_UnconfiguredServiceReturnsUnimplemented locks the
+// fallback: with no limits service wired the RPC returns Unimplemented.
+func TestCheckLLMPolicyLimits_UnconfiguredServiceReturnsUnimplemented(t *testing.T) {
+	s := &ProxyServiceServer{}
+
+	_, err := s.CheckLLMPolicyLimits(context.Background(), &proto.CheckLLMPolicyLimitsRequest{
+		AccountId:  "acc-1",
+		ProviderId: "prov-1",
+	})
+	require.Error(t, err)
+	st, ok := grpcstatus.FromError(err)
+	require.True(t, ok)
+	assert.Equal(t, codes.Unimplemented, st.Code())
+}

proxy/internal/middleware/builtin/llm_guardrail/middleware_test.go

@@ -207,6 +207,36 @@ func TestRestrictionsButNoResolvedProviderFailsClosed(t *testing.T) {
 	assert.Equal(t, "llm_policy.model_unknown", out.DenyReason.Code, "deny code must be model_unknown")
 }
 
+func TestEnabledButEmptyAllowlistDeniesEveryModel(t *testing.T) {
+	// An allowlist-enabled provider with zero models is distinct from an
+	// unrestricted (absent) provider: it must deny every model.
+	mw := New(providerCfg())
+	out, err := mw.Invoke(context.Background(), newInputProvider(testProvider,
+		middleware.KV{Key: middleware.KeyLLMModel, Value: "gpt-4o"},
+	))
+	require.NoError(t, err)
+	require.NotNil(t, out)
+	assert.Equal(t, middleware.DecisionDeny, out.Decision, "an enabled-but-empty allowlist must deny every model")
+	require.NotNil(t, out.DenyReason)
+	assert.Equal(t, "llm_policy.model_blocked", out.DenyReason.Code, "deny code must be model_blocked, not model_unknown")
+}
+
+func TestFactoryAllEmptyEntriesDenyEveryModel(t *testing.T) {
+	// All the provider's entries are blank; they collapse to a non-nil empty
+	// list (deny everything for that provider), not "no restriction".
+	raw := []byte(`{"provider_allowlists":{"prov-1":["","   "]}}`)
+	mw, err := Factory{}.New(raw)
+	require.NoError(t, err)
+	out, err := mw.Invoke(context.Background(), newInputProvider(testProvider,
+		middleware.KV{Key: middleware.KeyLLMModel, Value: "gpt-4o"},
+	))
+	require.NoError(t, err)
+	require.NotNil(t, out)
+	assert.Equal(t, middleware.DecisionDeny, out.Decision, "all-blank allowlist entries must still restrict the provider")
+	require.NotNil(t, out.DenyReason)
+	assert.Equal(t, "llm_policy.model_blocked", out.DenyReason.Code, "deny code must be model_blocked")
+}
+
 func TestPromptCaptureDisabledEmitsNoPrompt(t *testing.T) {
 	mw := New(Config{})
 	out, err := mw.Invoke(context.Background(), newInput(