malbeclabs · ben-dz · Mar 20, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,13 @@ All notable changes to this project will be documented in this file.
 
 ### Changes
 
+- Onchain Programs
+  - Add `target_update_count` field to GeoProbe account, incremented on `AddTarget` and `RemoveTarget`; uses `BorshDeserializeIncremental` so existing accounts default to 0 (non-breaking)
+- SDK
+  - Add `TargetUpdateCount` field to Go GeoProbe struct with backward-compatible deserialization
+- Telemetry
+  - Skip expensive `GetGeolocationUsers` RPC scan in geoprobe-agent when the probe's `target_update_count` is unchanged, with a forced full refresh every ~5 minutes as safety net
+
 ## [v0.13.0](https://github.com/malbeclabs/doublezero/compare/client/v0.12.0...client/v0.13.0) - 2026-03-20
 
 ### Breaking

diff --git a/controlplane/telemetry/cmd/geoprobe-agent/main.go b/controlplane/telemetry/cmd/geoprobe-agent/main.go
@@ -12,6 +12,7 @@ import (
 	"os/signal"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -533,19 +534,24 @@ func main() {
 		}
 	}()
 
+	// Shared counter: parent discovery writes the GeoProbe target_update_count on each
+	// poll; target discovery reads it to skip expensive full scans when unchanged.
+	var probeTargetUpdateCount atomic.Uint32
+
 	// Run parent DZD discovery if program IDs are configured.
 	if parentDiscoveryEnabled {
 		parentUpdateCh := make(chan geoprobe.ParentUpdate, 1)
 		geoProbeClient := geoprobe.NewRPCGeoProbeClient(rpcClient, geolocationProgramID)
 		deviceResolver := geoprobe.NewRPCDeviceResolver(rpcClient, serviceabilityProgramID)
 
 		pd, err := geoprobe.NewParentDiscovery(&geoprobe.ParentDiscoveryConfig{
-			GeoProbePubkey: geoProbePubkey,
-			Client:         geoProbeClient,
-			Resolver:       deviceResolver,
-			CLIParents:     cliParentAuthorities,
-			Interval:       parentDiscoveryInterval,
-			Logger:         log,
+			GeoProbePubkey:         geoProbePubkey,
+			Client:                 geoProbeClient,
+			Resolver:               deviceResolver,
+			CLIParents:             cliParentAuthorities,
+			Interval:               parentDiscoveryInterval,
+			Logger:                 log,
+			ProbeTargetUpdateCount: &probeTargetUpdateCount,
 		})
 		if err != nil {
 			log.Error("Failed to create parent discovery", "error", err)
@@ -578,12 +584,13 @@ func main() {
 	if !geolocationProgramID.IsZero() {
 		geolocationUserClient := geolocation.New(log, rpcClient, geolocationProgramID)
 		td, err := geoprobe.NewTargetDiscovery(&geoprobe.TargetDiscoveryConfig{
-			GeoProbePubkey: geoProbePubkey,
-			Client:         geolocationUserClient,
-			CLITargets:     targets,
-			CLIAllowedKeys: allowedKeys,
-			Interval:       discoveryInterval,
-			Logger:         log,
+			GeoProbePubkey:         geoProbePubkey,
+			Client:                 geolocationUserClient,
+			CLITargets:             targets,
+			CLIAllowedKeys:         allowedKeys,
+			Interval:               discoveryInterval,
+			Logger:                 log,
+			ProbeTargetUpdateCount: &probeTargetUpdateCount,
 		})
 		if err != nil {
 			log.Error("Failed to create target discovery", "error", err)

diff --git a/controlplane/telemetry/internal/geoprobe/onchain_discovery.go b/controlplane/telemetry/internal/geoprobe/onchain_discovery.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"sync/atomic"
 	"time"
 
 	"github.com/gagliardetto/solana-go"
@@ -38,22 +39,24 @@ type ParentUpdate struct {
 
 // ParentDiscoveryConfig holds configuration for parent discovery.
 type ParentDiscoveryConfig struct {
-	GeoProbePubkey solana.PublicKey
-	Client         GeoProbeAccountClient
-	Resolver       DeviceResolver
-	CLIParents     map[[32]byte][32]byte // static parents from --additional-parent
-	Interval       time.Duration
-	Logger         *slog.Logger
+	GeoProbePubkey         solana.PublicKey
+	Client                 GeoProbeAccountClient
+	Resolver               DeviceResolver
+	CLIParents             map[[32]byte][32]byte // static parents from --additional-parent
+	Interval               time.Duration
+	Logger                 *slog.Logger
+	ProbeTargetUpdateCount *atomic.Uint32 // shared counter for target discovery change detection
 }
 
 // ParentDiscovery polls the GeoProbe account and resolves parent devices.
 type ParentDiscovery struct {
-	log            *slog.Logger
-	geoProbePubkey solana.PublicKey
-	client         GeoProbeAccountClient
-	resolver       DeviceResolver
-	cliParents     map[[32]byte][32]byte
-	interval       time.Duration
+	log                    *slog.Logger
+	geoProbePubkey         solana.PublicKey
+	client                 GeoProbeAccountClient
+	resolver               DeviceResolver
+	cliParents             map[[32]byte][32]byte
+	interval               time.Duration
+	probeTargetUpdateCount *atomic.Uint32
 
 	cachedParentDevices []solana.PublicKey
 	tickCount           uint64
@@ -83,12 +86,13 @@ func NewParentDiscovery(cfg *ParentDiscoveryConfig) (*ParentDiscovery, error) {
 	}
 
 	return &ParentDiscovery{
-		log:            cfg.Logger,
-		geoProbePubkey: cfg.GeoProbePubkey,
-		client:         cfg.Client,
-		resolver:       cfg.Resolver,
-		cliParents:     cliParents,
-		interval:       cfg.Interval,
+		log:                    cfg.Logger,
+		geoProbePubkey:         cfg.GeoProbePubkey,
+		client:                 cfg.Client,
+		resolver:               cfg.Resolver,
+		cliParents:             cliParents,
+		interval:               cfg.Interval,
+		probeTargetUpdateCount: cfg.ProbeTargetUpdateCount,
 	}, nil
 }
 
@@ -152,6 +156,11 @@ func (d *ParentDiscovery) discover(ctx context.Context) (*ParentUpdate, error) {
 		return d.cliOnlyUpdate(), nil
 	}
 
+	// Publish the probe's target_update_count for target discovery change detection.
+	if d.probeTargetUpdateCount != nil {
+		d.probeTargetUpdateCount.Store(probe.TargetUpdateCount)
+	}
+
 	// Check if parent device set changed since last poll.
 	if !forceFullRefresh && pubkeySlicesEqual(d.cachedParentDevices, probe.ParentDevices) {
 		d.log.Debug("Parent device set unchanged, skipping resolution",

diff --git a/controlplane/telemetry/internal/geoprobe/onchain_discovery_test.go b/controlplane/telemetry/internal/geoprobe/onchain_discovery_test.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"log/slog"
 	"os"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -611,3 +612,46 @@ func TestPubkeySlicesEqual(t *testing.T) {
 		})
 	}
 }
+
+func TestParentDiscovery_StoresTargetUpdateCount(t *testing.T) {
+	t.Parallel()
+
+	geoProbePK := solana.NewWallet().PublicKey()
+	parentDevicePK := solana.NewWallet().PublicKey()
+	var metricsKey [32]byte
+	metricsKey = solana.NewWallet().PublicKey()
+
+	client := &mockGeoProbeAccountClient{
+		probe: &geolocation.GeoProbe{
+			AccountType:       geolocation.AccountTypeGeoProbe,
+			ParentDevices:     []solana.PublicKey{parentDevicePK},
+			TargetUpdateCount: 42,
+		},
+	}
+
+	resolver := &mockDeviceResolver{
+		devices: map[solana.PublicKey]*serviceability.Device{
+			parentDevicePK: {
+				PublicIp:               [4]uint8{10, 0, 0, 1},
+				MetricsPublisherPubKey: metricsKey,
+			},
+		},
+	}
+
+	var counter atomic.Uint32
+	pd, err := NewParentDiscovery(&ParentDiscoveryConfig{
+		Logger:                 slog.New(slog.NewTextHandler(os.Stderr, nil)),
+		Client:                 client,
+		Resolver:               resolver,
+		GeoProbePubkey:         geoProbePK,
+		Interval:               10 * time.Millisecond,
+		ProbeTargetUpdateCount: &counter,
+	})
+	require.NoError(t, err)
+
+	update, err := pd.discover(context.Background())
+	require.NoError(t, err)
+	require.NotNil(t, update)
+
+	assert.Equal(t, uint32(42), counter.Load())
+}
diff --git a/controlplane/telemetry/internal/geoprobe/target_discovery.go b/controlplane/telemetry/internal/geoprobe/target_discovery.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log/slog"
 	"sort"
+	"sync/atomic"
 	"time"
 
 	"github.com/gagliardetto/solana-go"
@@ -27,30 +28,38 @@ type InboundKeyUpdate struct {
 	Keys [][32]byte
 }
 
+// targetDiscoveryFullRefreshEvery controls how often a full GeolocationUser scan
+// is forced regardless of whether the GeoProbe target_update_count has changed.
+// At the default 60s interval, 5 means a full refresh every ~5 minutes.
+const targetDiscoveryFullRefreshEvery = 5
+
 // TargetDiscoveryConfig holds configuration for target discovery.
 type TargetDiscoveryConfig struct {
-	GeoProbePubkey solana.PublicKey
-	Client         GeolocationUserClient
-	CLITargets     []ProbeAddress
-	CLIAllowedKeys [][32]byte
-	Interval       time.Duration
-	Logger         *slog.Logger
+	GeoProbePubkey         solana.PublicKey
+	Client                 GeolocationUserClient
+	CLITargets             []ProbeAddress
+	CLIAllowedKeys         [][32]byte
+	Interval               time.Duration
+	Logger                 *slog.Logger
+	ProbeTargetUpdateCount *atomic.Uint32 // shared counter from parent discovery
 }
 
 // TargetDiscovery polls GeolocationUser accounts and sends target/key updates
 // when changes are detected. It filters for activated, paid users whose targets
 // reference this probe's pubkey.
 type TargetDiscovery struct {
-	log            *slog.Logger
-	geoProbePubkey solana.PublicKey
-	client         GeolocationUserClient
-	cliTargets     []ProbeAddress
-	cliAllowedKeys [][32]byte
-	interval       time.Duration
-
-	cachedTargets     []ProbeAddress
-	cachedInboundKeys [][32]byte
-	tickCount         uint64
+	log                    *slog.Logger
+	geoProbePubkey         solana.PublicKey
+	client                 GeolocationUserClient
+	cliTargets             []ProbeAddress
+	cliAllowedKeys         [][32]byte
+	interval               time.Duration
+	probeTargetUpdateCount *atomic.Uint32
+
+	cachedTargets             []ProbeAddress
+	cachedInboundKeys         [][32]byte
+	tickCount                 uint64
+	lastSeenTargetUpdateCount uint32
 }
 
 // NewTargetDiscovery creates a new TargetDiscovery instance.
@@ -69,12 +78,13 @@ func NewTargetDiscovery(cfg *TargetDiscoveryConfig) (*TargetDiscovery, error) {
 	}
 
 	return &TargetDiscovery{
-		log:            cfg.Logger,
-		geoProbePubkey: cfg.GeoProbePubkey,
-		client:         cfg.Client,
-		cliTargets:     cfg.CLITargets,
-		cliAllowedKeys: cfg.CLIAllowedKeys,
-		interval:       cfg.Interval,
+		log:                    cfg.Logger,
+		geoProbePubkey:         cfg.GeoProbePubkey,
+		client:                 cfg.Client,
+		cliTargets:             cfg.CLITargets,
+		cliAllowedKeys:         cfg.CLIAllowedKeys,
+		interval:               cfg.Interval,
+		probeTargetUpdateCount: cfg.ProbeTargetUpdateCount,
 	}, nil
 }
 
@@ -111,6 +121,11 @@ func (d *TargetDiscovery) discoverAndSend(ctx context.Context, targetCh chan<- T
 		return
 	}
 
+	// nil targets means the scan was skipped (target_update_count unchanged).
+	if targets == nil && inboundKeys == nil {
+		return
+	}
+
 	if !probeAddressSlicesEqual(targets, d.cachedTargets) {
 		d.cachedTargets = targets
 		select {
@@ -131,10 +146,21 @@ func (d *TargetDiscovery) discoverAndSend(ctx context.Context, targetCh chan<- T
 }
 
 // discover performs a single discovery cycle: fetch users, filter, extract targets/keys,
-// merge with CLI values.
+// merge with CLI values. Returns nil, nil, nil when the scan is skipped.
 func (d *TargetDiscovery) discover(ctx context.Context) ([]ProbeAddress, [][32]byte, error) {
+	forceFullRefresh := d.tickCount%targetDiscoveryFullRefreshEvery == 0
 	d.tickCount++
 
+	if d.probeTargetUpdateCount != nil && !forceFullRefresh {
+		current := d.probeTargetUpdateCount.Load()
+		if current == d.lastSeenTargetUpdateCount && d.tickCount > 1 {
+			d.log.Debug("GeoProbe target_update_count unchanged, skipping target scan",
+				"targetUpdateCount", current)
+			return nil, nil, nil
+		}
+		d.lastSeenTargetUpdateCount = current
+	}
+
 	users, err := d.client.GetGeolocationUsers(ctx)
 	if err != nil {
 		return nil, nil, fmt.Errorf("failed to fetch GeolocationUser accounts: %w", err)
@@ -195,6 +221,11 @@ func (d *TargetDiscovery) discover(ctx context.Context) ([]ProbeAddress, [][32]b
 	mergedTargets := mergeProbes(d.cliTargets, onchainTargets)
 	mergedKeys := mergeKeys(d.cliAllowedKeys, onchainKeys)
 
+	// Sync lastSeenTargetUpdateCount after a full scan (covers forced refresh path).
+	if d.probeTargetUpdateCount != nil {
+		d.lastSeenTargetUpdateCount = d.probeTargetUpdateCount.Load()
+	}
+
 	d.log.Debug("Target discovery tick",
 		"users", len(users),
 		"onchainOutbound", len(onchainTargets),