Merge branch 'main' into embedded-vnc

client/mdm/changedetector.go

@@ -0,0 +1,34 @@
+package mdm
+
+import "sync"
+
+// ChangeDetector tracks the last observed policy of a Loader so an
+// OS-notification-driven caller can ask whether the managed configuration
+// actually changed before restarting anything.
+type ChangeDetector struct {
+	mu     sync.Mutex
+	loader *Loader
+	prev   *Policy
+}
+
+// NewChangeDetector constructs a ChangeDetector seeded with the loader's
+// current policy, so only a later change reports as changed.
+func NewChangeDetector(loader *Loader) *ChangeDetector {
+	return &ChangeDetector{
+		loader: loader,
+		prev:   loader.Load(),
+	}
+}
+
+// Changed re-reads the policy, logs the per-key diff, and reports whether it
+// diverged from the last observation; the new snapshot becomes the baseline.
+func (d *ChangeDetector) Changed() bool {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	curr := d.loader.Load()
+	if !policyChanged(d.prev, curr) {
+		return false
+	}
+	d.prev = curr
+	return true
+}

client/mdm/conflicts.go

@@ -0,0 +1,116 @@
+package mdm
+
+import (
+	"net/url"
+
+	"github.com/netbirdio/netbird/util"
+)
+
+// PreSharedKeyRedactedSentinel is the redaction mask returned in place of a
+// real pre-shared key; an incoming value equal to it is a round-trip echo,
+// never an override.
+const PreSharedKeyRedactedSentinel = "**********"
+
+// ConflictCheck is a value-aware comparison between a single requested field
+// and the corresponding MDM-enforced value.
+type ConflictCheck struct {
+	Key   string
+	Check func(*Policy) bool
+}
+
+// ConflictBool builds a ConflictCheck for a boolean MDM key.
+func ConflictBool(key string, p *bool) ConflictCheck {
+	return ConflictCheck{
+		Key: key,
+		Check: func(pol *Policy) bool {
+			if p == nil {
+				return true
+			}
+			want, ok := pol.GetBool(key)
+			return ok && want == *p
+		},
+	}
+}
+
+// ConflictStringPtr builds a ConflictCheck for an optional string MDM key,
+// where an explicit empty value is still a request to change the setting. A
+// nil p means "field not set" (no override requested).
+func ConflictStringPtr(key string, p *string) ConflictCheck {
+	return ConflictCheck{
+		Key: key,
+		Check: func(pol *Policy) bool {
+			if p == nil {
+				return true
+			}
+			want, ok := pol.GetString(key)
+			return ok && want == *p
+		},
+	}
+}
+
+// ConflictURL builds a ConflictCheck for a URL-typed MDM key. The two sides are
+// compared as the endpoints they address, not as strings: see
+// util.SameServiceURL.
+func ConflictURL(key, got string) ConflictCheck {
+	return ConflictCheck{
+		Key: key,
+		Check: func(pol *Policy) bool {
+			if got == "" {
+				return true
+			}
+			want, ok := pol.GetString(key)
+			return ok && util.SameServiceURLStrings(want, got)
+		},
+	}
+}
+
+// ConflictInt64 builds a ConflictCheck for an integer MDM key.
+func ConflictInt64(key string, p *int64) ConflictCheck {
+	return ConflictCheck{
+		Key: key,
+		Check: func(pol *Policy) bool {
+			if p == nil {
+				return true
+			}
+			want, ok := pol.GetInt(key)
+			return ok && want == *p
+		},
+	}
+}
+
+// ResolveConflicts returns the names of keys whose requested value diverges
+// from the policy-enforced value; keys the policy does not manage are skipped,
+// a managed key without a Check counts as a conflict.
+func ResolveConflicts(policy *Policy, checks []ConflictCheck) []string {
+	if policy.IsEmpty() {
+		return nil
+	}
+	var conflicts []string
+	for _, c := range checks {
+		if !policy.HasKey(c.Key) {
+			continue
+		}
+		if c.Check == nil || !c.Check(policy) {
+			conflicts = append(conflicts, c.Key)
+		}
+	}
+	return conflicts
+}
+
+// CanonicalURL normalizes a service URL by appending the scheme default port
+// when none is present; unparseable input is returned unchanged.
+func CanonicalURL(s string) string {
+	u, err := url.ParseRequestURI(s)
+	if err != nil {
+		return s
+	}
+	if u.Port() == "" {
+		switch u.Scheme {
+		case "https":
+			u.Host += ":443"
+		case "http":
+			u.Host += ":80"
+		}
+	}
+	return u.String()
+}

client/mdm/conflicts_test.go

@@ -0,0 +1,40 @@
+package mdm
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// The same spellings, through the conflict check that decides whether a request
+// is refused. An enforced URL restated in another spelling addresses the very
+// server the policy names, so it must not be reported as a conflict.
+func TestConflictURLComparesEndpoints(t *testing.T) {
+	policy := NewPolicy(map[string]any{KeyManagementURL: "https://mgmt.example.com"})
+	require.True(t, policy.HasKey(KeyManagementURL))
+
+	for _, restated := range []string{
+		"https://mgmt.example.com",
+		"https://mgmt.example.com:443",
+		"https://mgmt.example.com/",
+		"https://MGMT.example.com",
+		"https://mgmt.example.com:0443",
+	} {
+		conflicts := ResolveConflicts(policy, []ConflictCheck{ConflictURL(KeyManagementURL, restated)})
+		assert.Empty(t, conflicts, "%q is the enforced endpoint written differently", restated)
+	}
+
+	for _, diverging := range []string{
+		"https://other.example.com",
+		"http://mgmt.example.com",
+		"https://mgmt.example.com:8443",
+		"https://mgmt.example.com/other",
+	} {
+		conflicts := ResolveConflicts(policy, []ConflictCheck{ConflictURL(KeyManagementURL, diverging)})
+		assert.Equal(t, []string{KeyManagementURL}, conflicts, "%q addresses another endpoint", diverging)
+	}
+
+	// An unset field is not a request to change anything.
+	assert.Empty(t, ResolveConflicts(policy, []ConflictCheck{ConflictURL(KeyManagementURL, "")}))
+}

client/mdm/jsonloader.go

@@ -0,0 +1,34 @@
+package mdm
+
+import (
+	"encoding/json"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type jsonPolicyFetcher struct {
+	fetch func() string
+}
+
+// NewJSONLoader constructs a Loader whose policy source is a JSON-encoded
+// object string, as produced by the mobile native layers; a nil fetch
+// disables MDM enforcement.
+func NewJSONLoader(fetch func() string) *Loader {
+	if fetch == nil {
+		return NewLoader(nil)
+	}
+	return NewLoader(&jsonPolicyFetcher{fetch: fetch})
+}
+
+func (f *jsonPolicyFetcher) Fetch() map[string]any {
+	raw := f.fetch()
+	if raw == "" {
+		return nil
+	}
+	var out map[string]any
+	if err := json.Unmarshal([]byte(raw), &out); err != nil {
+		log.Warnf("MDM mobile fetcher: invalid JSON payload from native: %v", err)
+		return nil
+	}
+	return out
+}

client/mdm/policy.go

@@ -121,16 +121,46 @@ func NewPolicy(values map[string]any) *Policy {
 	return &Policy{values: values}
 }
 
-// LoadPolicy reads the platform-native MDM configuration. Returns an
-// empty (but non-nil) Policy when no source is present, the source is
-// empty, or the platform is unsupported.
+// PolicyFetcher supplies the managed configuration to a Loader. Mobile
+// platforms (Android / iOS) implement it to push the OS-managed values
+// into the Go runtime. On every platform a non-nil fetcher takes
+// precedence over the native source, which is the test seam for the
+// registry / plist loaders; a nil fetcher leaves the native source in
+// charge, or disables MDM enforcement where there is none.
+type PolicyFetcher interface {
+	Fetch() map[string]any
+}
+
+// Loader is the DI-friendly entry point for reading the active MDM
+// policy. Construct one at the daemon's lifecycle owner (Server on
+// desktop, gomobile-exposed bridge on mobile) and pass it to anything
+// that needs to read MDM state (the reload ticker, profilemanager's
+// Config). Each callsite has the Loader handed in instead of looking
+// up package-level state.
+type Loader struct {
+	fetcher PolicyFetcher
+}
+
+// NewLoader constructs a Loader. A non-nil fetcher takes precedence over
+// the platform-native source; production desktop callers pass nil so the
+// registry / plist stays authoritative.
+func NewLoader(f PolicyFetcher) *Loader {
+	return &Loader{fetcher: f}
+}
+
+// Load reads the platform-native MDM configuration and returns a
+// Policy. Returns an empty (but non-nil) Policy when no source is
+// present, the source is empty, or the platform is unsupported.
 //
 // Diagnostic logging differentiates the three states:
 //   - source absent / unsupported platform: trace log only
 //   - source present, zero keys:             info "MDM enrolled (no managed keys)"
 //   - source present, N keys:                info "MDM enrolled with N managed keys: [...]"
-func LoadPolicy() *Policy {
-	values, err := loadPlatformPolicy()
+func (l *Loader) Load() *Policy {
+	if l == nil {
+		return &Policy{values: map[string]any{}}
+	}
+	values, err := l.loadPlatform()
 	if err != nil {
 		log.Tracef("MDM policy load: %v", err)
 		return &Policy{values: map[string]any{}}
@@ -207,6 +237,8 @@ func (p *Policy) GetBool(key string) (bool, bool) {
 		return t != 0, true
 	case int64:
 		return t != 0, true
+	case float64:
+		return t != 0, true
 	}
 	return false, false
 }
@@ -272,7 +304,7 @@ func (p *Policy) GetStringSlice(key string) ([]string, bool) {
 }
 
 // sortedKeys returns the keys of m as a deterministic, lexicographically
-// sorted slice. Used internally by Policy.ManagedKeys and LoadPolicy's
+// sorted slice. Used internally by Policy.ManagedKeys and Loader.Load's
 // diagnostic log line so callers see a stable key order across runs
 // regardless of Go's randomised map iteration.
 func sortedKeys(m map[string]any) []string {

client/mdm/policy_darwin.go

@@ -25,8 +25,9 @@ import (
 // writable plist, as a defense against tampered installs.
 const policyPlistPath = "/Library/Managed Preferences/io.netbird.client.plist"
 
-// loadPlatformPolicy reads the MDM-managed configuration from the macOS
-// managed-preferences plist at policyPlistPath. Returns:
+// loadPlatform reads the MDM-managed configuration from the macOS
+// managed-preferences plist at policyPlistPath, unless a fetcher was
+// injected, in which case its values are returned instead. Returns:
 //   - (nil, nil)  when the plist is absent (device not MDM-enrolled for
 //     NetBird, or admin has not yet pushed a payload)
 //   - (map, nil)  with N entries when N managed values are present
@@ -39,13 +40,19 @@ const policyPlistPath = "/Library/Managed Preferences/io.netbird.client.plist"
 // skipped so a stray entry in the payload does not block startup.
 // Native plist value types map naturally onto the Policy accessor
 // expectations (GetString / GetBool / GetInt / GetStringSlice).
-func loadPlatformPolicy() (map[string]any, error) {
+func (l *Loader) loadPlatform() (map[string]any, error) {
+	// Honour the injected fetcher when present so tests (and any
+	// future non-macOS MDM channel) can short-circuit the plist read
+	// with a scripted policy.
+	if l != nil && l.fetcher != nil {
+		return l.fetcher.Fetch(), nil
+	}
 	f, err := os.Open(policyPlistPath)
 	if err != nil {
 		if errors.Is(err, fs.ErrNotExist) {
 			// Not enrolled for NetBird. Caller treats nil as
 			// "no MDM source present".
-			//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
+			//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see Loader.Load.
 			return nil, nil
 		}
 		return nil, fmt.Errorf("open %s: %w", policyPlistPath, err)

client/mdm/policy_mobile.go

@@ -2,13 +2,14 @@
 
 package mdm
 
-// loadPlatformPolicy is unused on mobile: the native layer (Swift on iOS,
-// Kotlin/Java on Android) reads the OS managed-config store and pushes the
-// resulting dictionary in-process via a gomobile entry point that lands in
-// Phase 5 / Phase 6. The stub keeps the package compilable for mobile
-// builds and returns (nil, nil) — the platform-absent sentinel that
-// LoadPolicy in policy.go treats as "no MDM source present".
-func loadPlatformPolicy() (map[string]any, error) {
-	//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
-	return nil, nil
+// loadPlatform reads the OS-managed configuration via the native
+// PolicyFetcher injected at Loader construction. Returns
+// (nil, nil) — the platform-absent sentinel that Loader.Load treats as
+// "no MDM source present" — when no fetcher was provided.
+func (l *Loader) loadPlatform() (map[string]any, error) {
+	if l == nil || l.fetcher == nil {
+		//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see Loader.Load.
+		return nil, nil
+	}
+	return l.fetcher.Fetch(), nil
 }

client/mdm/policy_other.go

@@ -2,13 +2,17 @@
 
 package mdm
 
-// loadPlatformPolicy returns no policy on platforms without an MDM channel
-// (Linux, FreeBSD). MDM enforcement is off and the client behaves as if
-// the feature did not exist. Returns (nil, nil) — the platform-absent
-// sentinel the caller (LoadPolicy in policy.go) treats as "no MDM
-// source present"; an error here would just translate to the same
-// outcome with an extra log line.
-func loadPlatformPolicy() (map[string]any, error) {
-	//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
+// loadPlatform reads the MDM policy on platforms without a native MDM
+// channel (Linux, FreeBSD). When no fetcher was injected the policy is
+// (nil, nil) — the platform-absent sentinel that Loader.Load treats as
+// "MDM enforcement disabled". A non-nil fetcher takes precedence: it
+// is the test-seam used by unit tests to inject a scripted policy
+// without touching the OS, and the same hook supports any future
+// non-mobile OS that grows an out-of-band MDM channel.
+func (l *Loader) loadPlatform() (map[string]any, error) {
+	if l != nil && l.fetcher != nil {
+		return l.fetcher.Fetch(), nil
+	}
+	//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see Loader.Load.
 	return nil, nil
 }

client/mdm/policy_test.go

@@ -1,6 +1,7 @@
 package mdm
 
 import (
+	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -95,7 +96,8 @@ func TestPolicy_GetBool(t *testing.T) {
 		{"int64 nonzero", int64(2), true, true},
 		{"int64 zero", int64(0), false, true},
 		{"string garbage", "maybe", false, false},
-		{"float unsupported", 1.0, false, false},
+		{"float nonzero", 1.0, true, true},
+		{"float zero", 0.0, false, true},
 	}
 	for _, c := range cases {
 		t.Run(c.name, func(t *testing.T) {
@@ -155,10 +157,29 @@ func TestPolicy_GetStringSlice(t *testing.T) {
 	})
 }
 
-func TestLoadPolicy_PlatformStubReturnsEmpty(t *testing.T) {
-	// loadPlatformPolicy is a stub on every OS for Phase 1. LoadPolicy must
-	// degrade gracefully and never return nil.
-	p := LoadPolicy()
+// encoding/json decodes every JSON number into float64, so the mobile
+// loaders never see int.
+func TestJSONLoader_BoolFromNumber(t *testing.T) {
+	p := NewJSONLoader(func() string { return `{"blockInbound":1,"disableProfiles":0}` }).Load()
+
+	got, ok := p.GetBool(KeyBlockInbound)
+	assert.True(t, ok)
+	assert.True(t, got)
+
+	got, ok = p.GetBool(KeyDisableProfiles)
+	assert.True(t, ok)
+	assert.False(t, got)
+}
+
+func TestLoader_NilFetcherReturnsEmpty(t *testing.T) {
+	// Loader.Load with no fetcher (desktop construction) must degrade
+	// gracefully and never return nil; on linux loadPlatform is a stub
+	// returning (nil, nil), and Load is expected to translate that
+	// into a non-nil empty Policy.
+	if runtime.GOOS == "windows" || runtime.GOOS == "darwin" {
+		t.Skip("a nil fetcher reads the OS-managed policy on this platform")
+	}
+	p := NewLoader(nil).Load()
 	require.NotNil(t, p)
 	assert.True(t, p.IsEmpty())
 	assert.Empty(t, p.ManagedKeys())

client/mdm/policy_windows.go

@@ -61,8 +61,9 @@ func readRegistryValue(k registry.Key, name, canonical string, out map[string]an
 	}
 }
 
-// loadPlatformPolicy reads the MDM-managed configuration from the
-// Windows registry under HKLM\Software\Policies\NetBird. Returns:
+// loadPlatform reads the MDM-managed configuration from the Windows
+// registry under HKLM\Software\Policies\NetBird, unless a fetcher was
+// injected, in which case its values are returned instead. Returns:
 //   - (nil, nil)  when the key is absent (device not MDM-enrolled for NetBird)
 //   - (map, nil)  with N entries when N managed values are set (N may be 0)
 //   - (nil, err)  on open / enumerate registry errors
@@ -70,12 +71,18 @@ func readRegistryValue(k registry.Key, name, canonical string, out map[string]an
 // Per-value type coercion + skip-on-error is delegated to
 // readRegistryValue. Unknown value names are logged and skipped so a
 // malformed deployment does not block startup.
-func loadPlatformPolicy() (map[string]any, error) {
+func (l *Loader) loadPlatform() (map[string]any, error) {
+	// Honour the injected fetcher when present so tests (and any
+	// future non-Windows MDM channel) can short-circuit the registry
+	// read with a scripted policy.
+	if l != nil && l.fetcher != nil {
+		return l.fetcher.Fetch(), nil
+	}
 	k, err := registry.OpenKey(registry.LOCAL_MACHINE, policyRegistryPath, registry.QUERY_VALUE)
 	if err != nil {
 		if errors.Is(err, registry.ErrNotExist) {
 			// Not enrolled. Caller treats nil as "no MDM source present".
-			//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see LoadPolicy.
+			//nolint:nilnil // (nil, nil) is the documented platform-absent sentinel; see Loader.Load.
 			return nil, nil
 		}
 		return nil, fmt.Errorf("open %s: %w", policyRegistryPath, err)

client/mdm/restrictions.go

@@ -0,0 +1,91 @@
+package mdm
+
+import "encoding/json"
+
+// Fields carries the per-key MDM enforcement state for a UI: value-typed
+// fields hold the enforced value (nil pointer = not managed), boolean
+// fields report that the key is managed.
+type Fields struct {
+	ManagementURL            string `json:"managementURL"`
+	PreSharedKey             bool   `json:"preSharedKey"`
+	WireguardPort            bool   `json:"wireguardPort"`
+	RosenpassEnabled         bool   `json:"rosenpassEnabled"`
+	RosenpassPermissive      bool   `json:"rosenpassPermissive"`
+	DisableClientRoutes      bool   `json:"disableClientRoutes"`
+	DisableServerRoutes      bool   `json:"disableServerRoutes"`
+	AllowServerSSH           *bool  `json:"allowServerSSH"`
+	AllowServerVNC           *bool  `json:"allowServerVNC"`
+	DisableVNCApproval       bool   `json:"disableVNCApproval"`
+	DisableAutoConnect       bool   `json:"disableAutoConnect"`
+	DisableAutostart         bool   `json:"disableAutostart"`
+	BlockInbound             bool   `json:"blockInbound"`
+	DisableMetricsCollection bool   `json:"disableMetricsCollection"`
+	SplitTunnelMode          bool   `json:"splitTunnelMode"`
+	SplitTunnelApps          bool   `json:"splitTunnelApps"`
+	DisableAdvancedView      *bool  `json:"disableAdvancedView"`
+}
+
+// Features carries the feature gates a UI must honor.
+type Features struct {
+	DisableProfiles       bool `json:"disableProfiles"`
+	DisableNetworks       bool `json:"disableNetworks"`
+	DisableUpdateSettings bool `json:"disableUpdateSettings"`
+}
+
+// Restrictions is the UI-facing enforcement snapshot; the JSON shape is
+// shared by the desktop frontend and the mobile bridges.
+type Restrictions struct {
+	MDM      Fields   `json:"mdm"`
+	Features Features `json:"features"`
+}
+
+// BuildRestrictions derives the UI enforcement snapshot from the active
+// policy.
+func BuildRestrictions(policy *Policy) Restrictions {
+	var r Restrictions
+	if policy.IsEmpty() {
+		return r
+	}
+
+	if v, ok := policy.GetString(KeyManagementURL); ok {
+		r.MDM.ManagementURL = CanonicalURL(v)
+	}
+	r.MDM.PreSharedKey = policy.HasKey(KeyPreSharedKey)
+	r.MDM.WireguardPort = policy.HasKey(KeyWireguardPort)
+	r.MDM.RosenpassEnabled = policy.HasKey(KeyRosenpassEnabled)
+	r.MDM.RosenpassPermissive = policy.HasKey(KeyRosenpassPermissive)
+	r.MDM.DisableClientRoutes = policy.HasKey(KeyDisableClientRoutes)
+	r.MDM.DisableServerRoutes = policy.HasKey(KeyDisableServerRoutes)
+	r.MDM.DisableAutoConnect = policy.HasKey(KeyDisableAutoConnect)
+	r.MDM.DisableAutostart = policy.HasKey(KeyDisableAutostart)
+	r.MDM.BlockInbound = policy.HasKey(KeyBlockInbound)
+	r.MDM.DisableMetricsCollection = policy.HasKey(KeyDisableMetricsCollection)
+	r.MDM.SplitTunnelMode = policy.HasKey(KeySplitTunnelMode)
+	r.MDM.SplitTunnelApps = policy.HasKey(KeySplitTunnelApps)
+	if v, ok := policy.GetBool(KeyAllowServerSSH); ok {
+		r.MDM.AllowServerSSH = &v
+	}
+	if v, ok := policy.GetBool(KeyDisableAdvancedView); ok {
+		r.MDM.DisableAdvancedView = &v
+	}
+
+	if v, ok := policy.GetBool(KeyDisableProfiles); ok {
+		r.Features.DisableProfiles = v
+	}
+	if v, ok := policy.GetBool(KeyDisableNetworks); ok {
+		r.Features.DisableNetworks = v
+	}
+	if v, ok := policy.GetBool(KeyDisableUpdateSettings); ok {
+		r.Features.DisableUpdateSettings = v
+	}
+	return r
+}
+
+// JSON renders the snapshot in the shared UI JSON shape.
+func (r Restrictions) JSON() (string, error) {
+	b, err := json.Marshal(r)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}

client/mdm/ticker.go

@@ -15,33 +15,33 @@ import (
 // instead, hence anticipating the ticker mechanism entirely.
 const DefaultReloadInterval = 1 * time.Minute
 
-// policyLoader is the indirection through which the ticker reads the
-// OS-native policy, both for the initial observation and on every tick.
-// Production points it at LoadPolicy; tests in this package override it to
-// feed a scripted sequence of policies without touching the real OS store.
-var policyLoader = LoadPolicy
-
-// Ticker periodically re-reads the OS-native MDM policy via LoadPolicy and
-// invokes the onChange callback (supplied to Run) whenever the observed
-// Policy diverges from the last observation (added / removed / changed
-// keys). Launch with Run from a goroutine; cancel the supplied context
-// to stop.
+// Ticker periodically re-reads the OS-native MDM policy via the
+// injected Loader and invokes the onChange callback (supplied to Run)
+// whenever the observed Policy diverges from the last observation
+// (added / removed / changed keys). Launch with Run from a goroutine;
+// cancel the supplied context to stop.
 type Ticker struct {
 	interval time.Duration
+	loader   *Loader
 	prev     *Policy
 }
 
 // NewTicker constructs a Ticker that will re-read the OS-native policy
-// every reloadInterval once Run is called.
-// The initial snapshot is populated by calling policyLoader at
+// every reloadInterval once Run is called. The Loader is injected so
+// the ticker doesn't depend on any package-level state — production
+// passes the daemon-owned Loader, tests pass a fake Loader (built with
+// a fake PolicyFetcher).
+//
+// The initial snapshot is populated by calling loader.Load() at
 // construction time so the first tick only fires
 // onChange when the policy actually changed since boot — without
 // this baseline the first tick would report every currently-managed
 // key as "added" and trigger a spurious engine restart.
-func NewTicker(reloadInterval time.Duration) *Ticker {
+func NewTicker(reloadInterval time.Duration, loader *Loader) *Ticker {
 	return &Ticker{
 		interval: reloadInterval,
-		prev:     policyLoader(),
+		loader:   loader,
+		prev:     loader.Load(),
 	}
 }
 
@@ -58,13 +58,10 @@ func (t *Ticker) Run(ctx context.Context, onChange func(prev, curr *Policy) erro
 			log.Info("MDM policy reload ticker stopped")
 			return
 		case <-tk.C:
-			curr := policyLoader()
-			if policiesEqual(t.prev, curr) {
+			curr := t.loader.Load()
+			if !policyChanged(t.prev, curr) {
 				continue
 			}
-			added, removed, changed := diffPolicies(t.prev, curr)
-			log.Infof("MDM policy changed: added=%v removed=%v changed=%v",
-				added, removed, changed)
 			prev := t.prev
 			if err := onChange(prev, curr); err != nil {
 				log.Errorf("MDM policy change handler failed (retrying in 1 minute): %v", err)
@@ -127,3 +124,12 @@ func mapOf(p *Policy) map[string]any {
 	}
 	return out
 }
+
+func policyChanged(prev, curr *Policy) bool {
+	if policiesEqual(prev, curr) {
+		return false
+	}
+	added, removed, changed := diffPolicies(prev, curr)
+	log.Infof("MDM policy changed: added=%v removed=%v changed=%v", added, removed, changed)
+	return true
+}

client/mdm/ticker_test.go

@@ -13,28 +13,40 @@ import (
 // testReloadInterval for speeding up the ticker cadence under `go test`
 const testReloadInterval = 1 * time.Second
 
-// withPolicyLoader overrides the package-level policyLoader for the duration
-// of the test so the ticker observes a scripted policy instead of the real
-// OS-native store. The original loader is restored on cleanup.
-func withPolicyLoader(t *testing.T, fn func() *Policy) {
-	t.Helper()
-	prev := policyLoader
-	policyLoader = fn
-	t.Cleanup(func() { policyLoader = prev })
+// fakePolicyFetcher implements PolicyFetcher returning a scripted
+// policy map. Goroutine-safe so the test can mutate the script while
+// the ticker is observing it.
+type fakePolicyFetcher struct {
+	mu     sync.Mutex
+	values map[string]any
+}
+
+func (f *fakePolicyFetcher) Fetch() map[string]any {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if f.values == nil {
+		return nil
+	}
+	out := make(map[string]any, len(f.values))
+	for k, v := range f.values {
+		out[k] = v
+	}
+	return out
+}
+
+func (f *fakePolicyFetcher) set(values map[string]any) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.values = values
 }
 
 func TestTicker_FiresOnChangeWithDelta(t *testing.T) {
-	var mu sync.Mutex
-	current := NewPolicy(nil) // initial observation: empty (no enforcement)
-	withPolicyLoader(t, func() *Policy {
-		mu.Lock()
-		defer mu.Unlock()
-		return current
-	})
+	fetcher := &fakePolicyFetcher{} // initial observation: empty (no enforcement)
+	loader := NewLoader(fetcher)
 
 	type change struct{ prev, curr *Policy }
 	changes := make(chan change, 1)
-	tk := NewTicker(testReloadInterval)
+	tk := NewTicker(testReloadInterval, loader)
 	require.Equal(t, testReloadInterval, tk.interval)
 
 	ctx, cancel := context.WithCancel(context.Background())
@@ -49,15 +61,13 @@ func TestTicker_FiresOnChangeWithDelta(t *testing.T) {
 		})
 		close(done)
 	}()
-	// Stop Run and wait for it to exit before returning, so the policyLoader
-	// restore in t.Cleanup can't race the ticker goroutine still reading it.
+	// Stop Run and wait for it to exit before returning, so the test
+	// goroutine doesn't race the still-running ticker.
 	defer func() { cancel(); <-done }()
 
-	// Flip the OS-observed policy from empty to one managed key. The next
-	// tick must detect the diff and invoke onChange.
-	mu.Lock()
-	current = NewPolicy(map[string]any{KeyManagementURL: "https://mdm.example.com:443"})
-	mu.Unlock()
+	// Flip the OS-observed policy from empty to one managed key. The
+	// next tick must detect the diff and invoke onChange.
+	fetcher.set(map[string]any{KeyManagementURL: "https://mdm.example.com:443"})
 
 	select {
 	case c := <-changes:
@@ -69,12 +79,11 @@ func TestTicker_FiresOnChangeWithDelta(t *testing.T) {
 }
 
 func TestTicker_NoCallbackWhenPolicyUnchanged(t *testing.T) {
-	withPolicyLoader(t, func() *Policy {
-		return NewPolicy(map[string]any{KeyBlockInbound: true})
-	})
+	fetcher := &fakePolicyFetcher{values: map[string]any{KeyBlockInbound: true}}
+	loader := NewLoader(fetcher)
 
 	fired := make(chan struct{}, 1)
-	tk := NewTicker(testReloadInterval)
+	tk := NewTicker(testReloadInterval, loader)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	done := make(chan struct{})
@@ -90,8 +99,8 @@ func TestTicker_NoCallbackWhenPolicyUnchanged(t *testing.T) {
 	}()
 	defer func() { cancel(); <-done }()
 
-	// Over ~2 ticks at the 1s test cadence the policy never changes, so the
-	// diff guard must suppress the callback entirely.
+	// Over ~2 ticks at the 1s test cadence the policy never changes,
+	// so the diff guard must suppress the callback entirely.
 	select {
 	case <-fired:
 		t.Fatal("onChange fired despite an unchanged policy")