readme change

- #1: remove mock alert events that poisoned production responses
- #2: add Notifier interface + Send implementations for all channels
- #3/#4: notification goroutines now carry a 30s context timeout and retry up to 3x with exponential backoff
- #5: schedule email digest in poller via DIGEST_INTERVAL_HOURS (default 24h)
- #6: SystemStatus queries real checkpoint data; returns starting/active/idle with latestBlock and lag
- #7: Ethereum RPC client retries on network errors, 429, and 5xx with 1s/2s backoff
- #8: alert_events dedup index + ON CONFLICT DO NOTHING to prevent duplicate events on poller restart
- #9: PATCH /v1/addresses/{id} for label editing; frontend address list gains inline edit and remove buttons

README.md

@@ -1,9 +1,8 @@
 # Koin Ping
+A lightweight on-chain monitoring and alerting system designed to give users situational awareness over blockchain addresses they care about.
 
-Koin Ping is an MIT-licensed blockchain monitoring system by Steven Jannette
-that polls Ethereum addresses for on-chain activity and delivers real-time
-alerts to users via a Go REST API backend and a React single-page application
-frontend.
+# Overview
+Koin Ping observes on-chain activity and notifies users when predefined conditions are met. It does not execute transactions, manage wallets, or speculate on prices.
 
 ## Getting Started
 

backend-go/cmd/api/main.go

@@ -47,6 +47,7 @@ func main() {
 	addressModel := models.NewAddressModel(pool)
 	alertRuleModel := models.NewAlertRuleModel(pool)
 	alertEventModel := models.NewAlertEventModel(pool)
+	checkpointModel := models.NewCheckpointModel(pool)
 	notifConfigModel := models.NewNotificationConfigModel(pool)
 
 	emailDigestSvc := services.NewEmailDigestService(
@@ -58,13 +59,14 @@ func main() {
 	alertEventHandler := handlers.NewAlertEventHandler(alertEventModel)
 	notifConfigHandler := handlers.NewNotificationConfigHandler(notifConfigModel, cfg)
 	emailDigestHandler := handlers.NewEmailDigestHandler(emailDigestSvc, notifConfigModel)
+	statusHandler := handlers.NewStatusHandler(checkpointModel)
 
 	mux := http.NewServeMux()
 	b := cfg.APIBasePath // e.g. "/v1"
 
 	// Public routes
 	mux.HandleFunc("GET "+b+"/health", handlers.HealthCheck)
-	mux.HandleFunc("GET "+b+"/status", handlers.SystemStatus)
+	mux.HandleFunc("GET "+b+"/status", statusHandler.GetStatus)
 
 	// Authenticated routes — addresses
 	mux.Handle("POST "+b+"/addresses",
@@ -73,6 +75,8 @@ func main() {
 		middleware.Authenticate(http.HandlerFunc(addressHandler.List)))
 	mux.Handle("DELETE "+b+"/addresses/{addressId}",
 		middleware.Authenticate(http.HandlerFunc(addressHandler.Remove)))
+	mux.Handle("PATCH "+b+"/addresses/{addressId}",
+		middleware.Authenticate(http.HandlerFunc(addressHandler.UpdateLabel)))
 
 	// Authenticated routes for alert rules
 	mux.Handle("POST "+b+"/addresses/{addressId}/alerts",

backend-go/cmd/poller/main.go

@@ -62,6 +62,7 @@ func main() {
 		eth, alertRuleModel, alertEventModel, addressModel, notifConfigModel,
 		cfg.ResendAPIKey, cfg.EmailFrom,
 	)
+	digestSvc := services.NewEmailDigestService(cfg.ResendAPIKey, cfg.EmailFrom, alertEventModel, notifConfigModel)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -78,12 +79,14 @@ func main() {
 	}()
 
 	interval := time.Duration(cfg.PollIntervalMS) * time.Millisecond
+	digestInterval := time.Duration(cfg.DigestIntervalHours) * time.Hour
 
 	log.Println(strings.Repeat("=", separatorWidth))
 	log.Println("Koin Ping Observer Poller Starting")
 	log.Println(strings.Repeat("=", separatorWidth))
 	log.Printf("RPC URL: %s", cfg.EthRPCURL)
 	log.Printf("Poll Interval: %dms (%ds)", cfg.PollIntervalMS, cfg.PollIntervalMS/msPerSecond)
+	log.Printf("Digest Interval: %dh", cfg.DigestIntervalHours)
 	log.Println(strings.Repeat("=", separatorWidth))
 
 	runCycle(ctx, observer, evaluator)
@@ -91,6 +94,9 @@ func main() {
 	ticker := time.NewTicker(interval)
 	defer ticker.Stop()
 
+	digestTicker := time.NewTicker(digestInterval)
+	defer digestTicker.Stop()
+
 	for {
 		select {
 		case <-ctx.Done():
@@ -99,6 +105,13 @@ func main() {
 			return
 		case <-ticker.C:
 			runCycle(ctx, observer, evaluator)
+		case <-digestTicker.C:
+			sent, digestErr := digestSvc.SendDigestsForAllUsers(ctx)
+			if digestErr != nil {
+				log.Printf("Email digest failed: %v", digestErr)
+			} else {
+				log.Printf("Sent %d email digests", sent)
+			}
 		}
 	}
 }

backend-go/go.mod

@@ -42,6 +42,7 @@ require (
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/joho/godotenv v1.5.1 // indirect
 	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
+	github.com/resend/resend-go/v3 v3.1.1 // indirect
 	github.com/spiffe/go-spiffe/v2 v2.6.0 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/contrib/detectors/gcp v1.39.0 // indirect

backend-go/go.sum

@@ -92,6 +92,8 @@ github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/resend/resend-go/v3 v3.1.1 h1:Uwpf/tZU+O/r/3nMWE6zUAMIG9dX/vTBS3wlQzYJKSw=
+github.com/resend/resend-go/v3 v3.1.1/go.mod h1:iI7VA0NoGjWvsNii5iNC5Dy0llsI3HncXPejhniYzwE=
 github.com/spiffe/go-spiffe/v2 v2.6.0 h1:l+DolpxNWYgruGQVV0xsfeya3CsC7m8iBzDnMpsbLuo=
 github.com/spiffe/go-spiffe/v2 v2.6.0/go.mod h1:gm2SeUoMZEtpnzPNs2Csc0D/gX33k1xIx7lEzqblHEs=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

backend-go/infra/migrations/004_alert_event_dedup.sql

@@ -0,0 +1,3 @@
+CREATE UNIQUE INDEX IF NOT EXISTS idx_alert_events_dedup
+    ON alert_events (alert_rule_id, tx_hash)
+    WHERE tx_hash IS NOT NULL;

backend-go/internal/config/config.go

@@ -13,6 +13,7 @@ const (
 	defaultDBPort = 5432
 	defaultPollIntervalMS = 60000
 	minPollIntervalMS = 1000
+	defaultDigestIntervalHours = 24
 )
 
 type Config struct {
@@ -30,6 +31,7 @@ type Config struct {
 	NodeEnv           string
 	ResendAPIKey         string
 	EmailFrom            string
+	DigestIntervalHours  int
 }
 
 // Load reads configuration from environment variables and returns a Config.
@@ -49,6 +51,7 @@ func Load() (*Config, error) {
 		NodeEnv:           getEnv("NODE_ENV", "development"),
 		ResendAPIKey:        os.Getenv("RESEND_API_KEY"),
 		EmailFrom:           getEnv("EMAIL_FROM", "Koin Ping <alerts@koinping.com>"),
+		DigestIntervalHours: getEnvInt("DIGEST_INTERVAL_HOURS", defaultDigestIntervalHours),
 	}
 
 	if cfg.PollIntervalMS < minPollIntervalMS {

backend-go/internal/handlers/address.go

@@ -92,6 +92,44 @@ func (h *AddressHandler) List(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, addresses)
 }
 
+// UpdateLabel handles PATCH requests to update an address label.
+func (h *AddressHandler) UpdateLabel(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+	addressID, ok := parseIntParam(r.PathValue("addressId"))
+	if !ok {
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "Invalid address ID")
+
+		return
+	}
+
+	var body struct {
+		Label *string `json:"label"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "Invalid request body")
+
+		return
+	}
+
+	log.Printf("User %s updating label for address ID: %d", userID, addressID)
+
+	addr, err := h.addresses.UpdateLabel(r.Context(), addressID, userID, body.Label)
+	if err != nil {
+		log.Printf("Error updating address label: %v", err)
+		writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to update address")
+
+		return
+	}
+
+	if addr == nil {
+		writeError(w, http.StatusNotFound, "NOT_FOUND", "Address not found")
+
+		return
+	}
+
+	writeJSON(w, http.StatusOK, addr)
+}
+
 // Remove handles DELETE requests to remove a tracked address.
 func (h *AddressHandler) Remove(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.GetUserID(r.Context())

backend-go/internal/handlers/alert_event.go

@@ -4,7 +4,6 @@ import (
 	"log"
 	"net/http"
 	"strconv"
-	"time"
 
 	"github.com/kjannette/koin-ping/backend-go/internal/domain"
 	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
@@ -51,45 +50,9 @@ func (h *AlertEventHandler) List(w http.ResponseWriter, r *http.Request) {
 
 	log.Printf("Found %d alert events for user", len(events))
 
-	// MVP scaffolding: return mock data if DB is empty
-	if len(events) == 0 {
-		events = mockEvents(limit)
+	if events == nil {
+		events = []domain.AlertEvent{}
 	}
 
 	writeJSON(w, http.StatusOK, events)
 }
-
-func mockEvents(limit int) []domain.AlertEvent {
-	label1 := "Treasury Wallet"
-	label2 := "Cold Storage"
-
-	mocks := []domain.AlertEvent{
-		{
-			ID:           1,
-			AlertRuleID:  1,
-			Message:      "Incoming transaction detected: 5.5 ETH received",
-			AddressLabel: &label1,
-			Timestamp:    time.Now().Add(-2 * time.Hour),
-		},
-		{
-			ID:           2,           //nolint:mnd
-			AlertRuleID:  2,           //nolint:mnd
-			Message:      "Balance dropped below threshold: Current balance 8.2 ETH",
-			AddressLabel: &label1,
-			Timestamp:    time.Now().Add(-5 * time.Hour),
-		},
-		{
-			ID:           3,           //nolint:mnd
-			AlertRuleID:  3,           //nolint:mnd
-			Message:      "Outgoing transaction detected: 2.0 ETH sent",
-			AddressLabel: &label2,
-			Timestamp:    time.Now().Add(-24 * time.Hour),
-		},
-	}
-
-	if limit < len(mocks) {
-		return mocks[:limit]
-	}
-
-	return mocks
-}

backend-go/internal/handlers/status.go

@@ -1,10 +1,67 @@
 package handlers
 
 import (
+	"log"
 	"net/http"
 	"time"
+
+	"github.com/kjannette/koin-ping/backend-go/internal/models"
 )
 
+// StatusHandler handles the system status endpoint.
+type StatusHandler struct {
+	checkpoints *models.CheckpointModel
+}
+
+// NewStatusHandler creates a new StatusHandler.
+func NewStatusHandler(checkpoints *models.CheckpointModel) *StatusHandler {
+	return &StatusHandler{checkpoints: checkpoints}
+}
+
+// GetStatus returns real-time system status derived from checkpoint data.
+func (h *StatusHandler) GetStatus(w http.ResponseWriter, r *http.Request) {
+	block, checkedAt, err := h.checkpoints.GetLatestBlock(r.Context())
+	if err != nil {
+		log.Printf("Error querying latest block: %v", err)
+		writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to get system status")
+
+		return
+	}
+
+	latestBlock := 0
+	lag := 0
+	status := "starting"
+
+	if checkedAt != nil {
+		lag = int(time.Since(*checkedAt).Seconds())
+		if lag > 600 { //nolint:mnd
+			status = "idle"
+		} else {
+			status = "active"
+		}
+	}
+
+	if block != nil {
+		latestBlock = *block
+	}
+
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"status":        status,
+		"latestBlock":   latestBlock,
+		"lag":           lag,
+		"lastCheckedAt": checkedAtStr(checkedAt),
+		"timestamp":     time.Now().UTC().Format(time.RFC3339),
+	})
+}
+
+func checkedAtStr(t *time.Time) string {
+	if t == nil {
+		return ""
+	}
+
+	return t.UTC().Format(time.RFC3339)
+}
+
 func HealthCheck(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]interface{}{
 		"status":    "ok",
@@ -12,12 +69,3 @@ func HealthCheck(w http.ResponseWriter, r *http.Request) {
 		"service":   "koin-ping-backend",
 	})
 }
-
-func SystemStatus(w http.ResponseWriter, r *http.Request) {
-	writeJSON(w, http.StatusOK, map[string]interface{}{
-		"latestBlock": 0,
-		"lag":         0,
-		"status":      "healthy",
-		"timestamp":   time.Now().UTC().Format(time.RFC3339),
-	})
-}

backend-go/internal/models/address.go

@@ -107,6 +107,24 @@ func (m *AddressModel) FindByID(ctx context.Context, id int, userID *string) (*d
 	return &a, nil
 }
 
+// UpdateLabel updates the label for an address owned by userID.
+// Returns nil, nil if no row matched (address not found or not owned by user).
+func (m *AddressModel) UpdateLabel(ctx context.Context, id int, userID string, label *string) (*domain.Address, error) {
+	var a domain.Address
+	err := m.pool.QueryRow(ctx,
+		`UPDATE addresses SET label = $3 WHERE id = $1 AND user_id = $2
+		 RETURNING id, user_id, address, label, created_at`,
+		id, userID, label,
+	).Scan(&a.ID, &a.UserID, &a.Address, &a.Label, &a.CreatedAt)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return &a, nil
+}
+
 func (m *AddressModel) Remove(ctx context.Context, id int, userID string) (bool, error) {
 	tag, err := m.pool.Exec(ctx,
 		`DELETE FROM addresses WHERE id = $1 AND user_id = $2`,

backend-go/internal/models/alert_event.go

@@ -2,7 +2,9 @@ package models
 
 import (
 	"context"
+	"errors"
 
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/kjannette/koin-ping/backend-go/internal/domain"
 )
@@ -71,10 +73,15 @@ func (m *AlertEventModel) Create(ctx context.Context, alertRuleID int, message s
 	err := m.pool.QueryRow(ctx,
 		`INSERT INTO alert_events (alert_rule_id, message, address_label, tx_hash)
 		 VALUES ($1, $2, $3, $4)
+		 ON CONFLICT DO NOTHING
 		 RETURNING id, alert_rule_id, message, address_label, tx_hash, timestamp`,
 		alertRuleID, message, addressLabel, txHash,
 	).Scan(&e.ID, &e.AlertRuleID, &e.Message, &e.AddressLabel, &e.TxHash, &e.Timestamp)
 	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			// Duplicate silently skipped by ON CONFLICT DO NOTHING
+			return nil, nil
+		}
 		return nil, err
 	}
 	return &e, nil

backend-go/internal/models/checkpoint.go

@@ -3,6 +3,7 @@ package models
 import (
 	"context"
 	"errors"
+	"time"
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
@@ -17,6 +18,20 @@ func NewCheckpointModel(pool *pgxpool.Pool) *CheckpointModel {
 	return &CheckpointModel{pool: pool}
 }
 
+// GetLatestBlock returns the highest last_checked_block and its timestamp across all addresses.
+// Returns nil, nil, nil when no checkpoints exist yet.
+func (m *CheckpointModel) GetLatestBlock(ctx context.Context) (*int, *time.Time, error) {
+	var block *int
+	var checkedAt *time.Time
+	err := m.pool.QueryRow(ctx,
+		`SELECT MAX(last_checked_block), MAX(last_checked_at) FROM address_checkpoints`,
+	).Scan(&block, &checkedAt)
+	if err != nil {
+		return nil, nil, err
+	}
+	return block, checkedAt, nil
+}
+
 // GetLastCheckedBlock returns the last checked block for an address, or -1 if never checked.
 func (m *CheckpointModel) GetLastCheckedBlock(ctx context.Context, addressID int) (int, bool, error) {
 	var block int

backend-go/internal/notifications/discord.go

@@ -2,6 +2,7 @@ package notifications
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -25,11 +26,15 @@ var discordHTTPClient = &http.Client{ //nolint:gochecknoglobals
 	Timeout: discordHTTPTimeoutSeconds * time.Second,
 }
 
-type AlertMetadata struct {
-	TxHash       string
-	AddressLabel string
-	AlertType    string
-	Address      string
+// DiscordNotifier sends alert notifications via a Discord webhook.
+type DiscordNotifier struct {
+	WebhookURL string
+}
+
+// Send implements Notifier for Discord.
+func (d *DiscordNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
+	_, err := SendDiscordNotification(d.WebhookURL, message, meta)
+	return err
 }
 
 type discordEmbed struct {

backend-go/internal/notifications/email.go

@@ -2,6 +2,7 @@ package notifications
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -9,6 +10,19 @@ import (
 	"time"
 )
 
+// EmailNotifier sends alert notifications via email (Resend).
+type EmailNotifier struct {
+	APIKey string
+	From   string
+	To     string
+}
+
+// Send implements Notifier for email.
+func (e *EmailNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
+	_, err := SendEmailNotification(e.APIKey, e.From, e.To, message, meta)
+	return err
+}
+
 const emailHTTPTimeoutSeconds = 10
 
 var emailHTTPClient = &http.Client{ //nolint:gochecknoglobals

backend-go/internal/notifications/notifier.go

@@ -0,0 +1,16 @@
+package notifications
+
+import "context"
+
+// AlertMetadata holds context about the alert being sent.
+type AlertMetadata struct {
+	TxHash       string
+	AddressLabel string
+	AlertType    string
+	Address      string
+}
+
+// Notifier is the interface implemented by all notification channels.
+type Notifier interface {
+	Send(ctx context.Context, message string, meta AlertMetadata) error
+}

backend-go/internal/notifications/slack.go

@@ -2,6 +2,7 @@ package notifications
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -9,6 +10,17 @@ import (
 	"time"
 )
 
+// SlackNotifier sends alert notifications via a Slack webhook.
+type SlackNotifier struct {
+	WebhookURL string
+}
+
+// Send implements Notifier for Slack.
+func (s *SlackNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
+	_, err := SendSlackNotification(s.WebhookURL, message, meta)
+	return err
+}
+
 const slackHTTPTimeoutSeconds = 10
 
 var slackHTTPClient = &http.Client{ //nolint:gochecknoglobals

backend-go/internal/notifications/telegram.go

@@ -2,6 +2,7 @@ package notifications
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -9,6 +10,18 @@ import (
 	"time"
 )
 
+// TelegramNotifier sends alert notifications via Telegram.
+type TelegramNotifier struct {
+	BotToken string
+	ChatID   string
+}
+
+// Send implements Notifier for Telegram.
+func (t *TelegramNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
+	_, err := SendTelegramNotification(t.BotToken, t.ChatID, message, meta)
+	return err
+}
+
 const telegramHTTPTimeoutSeconds = 10
 
 var telegramHTTPClient = &http.Client{ //nolint:gochecknoglobals

backend-go/internal/protocols/ethereum/jsonrpc.go

@@ -4,7 +4,9 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"log"
 	"math/big"
 	"net/http"
 	"strings"
@@ -13,7 +15,11 @@ import (
 	"github.com/kjannette/koin-ping/backend-go/internal/domain"
 )
 
-const rpcTimeoutMS = 30000
+const (
+	rpcTimeoutMS    = 30000
+	rpcMaxRetries   = 3
+	rpcRetryBaseMS  = 1000
+)
 
 type JsonRpcEthereum struct {
 	rpcURL string
@@ -66,6 +72,44 @@ func (j *JsonRpcEthereum) callRPC(ctx context.Context, method string, params ...
 		return nil, fmt.Errorf("marshal RPC request: %w", err)
 	}
 
+	return j.callWithRetry(ctx, method, body)
+}
+
+// callWithRetry executes a JSON-RPC POST with exponential backoff on transient errors.
+// It retries on network errors, HTTP 429, and HTTP 5xx. It does NOT retry on RPC-level
+// errors or other 4xx responses (those are permanent failures).
+func (j *JsonRpcEthereum) callWithRetry(ctx context.Context, method string, body []byte) (json.RawMessage, error) {
+	var lastErr error
+	for attempt := range rpcMaxRetries {
+		if attempt > 0 {
+			wait := time.Duration(rpcRetryBaseMS*(1<<(attempt-1))) * time.Millisecond
+			select {
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			case <-time.After(wait):
+			}
+			log.Printf("Retrying RPC call [%s] (attempt %d/%d)", method, attempt+1, rpcMaxRetries)
+		}
+
+		result, err := j.doRPCCall(ctx, method, body)
+		if err == nil {
+			return result, nil
+		}
+
+		lastErr = err
+
+		// Permanent errors: do not retry
+		if isPermanentRPCError(err) {
+			return nil, err
+		}
+
+		log.Printf("Transient RPC error [%s] (attempt %d/%d): %v", method, attempt+1, rpcMaxRetries, err)
+	}
+
+	return nil, lastErr
+}
+
+func (j *JsonRpcEthereum) doRPCCall(ctx context.Context, method string, body []byte) (json.RawMessage, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodPost, j.rpcURL, bytes.NewReader(body))
 	if err != nil {
 		return nil, fmt.Errorf("create RPC request: %w", err)
@@ -78,8 +122,13 @@ func (j *JsonRpcEthereum) callRPC(ctx context.Context, method string, params ...
 	}
 	defer resp.Body.Close()
 
+	// 429 and 5xx are transient; other non-200 are permanent.
 	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("HTTP %d: %s for %s", resp.StatusCode, resp.Status, method)
+		err := fmt.Errorf("HTTP %d: %s for %s", resp.StatusCode, resp.Status, method)
+		if resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= 500 { //nolint:mnd
+			return nil, err // transient — will be retried
+		}
+		return nil, &permanentRPCError{err}
 	}
 
 	var rpcResp rpcResponse
@@ -88,12 +137,25 @@ func (j *JsonRpcEthereum) callRPC(ctx context.Context, method string, params ...
 	}
 
 	if rpcResp.Error != nil {
-		return nil, fmt.Errorf("RPC Error [%s]: %s (code: %d)", method, rpcResp.Error.Message, rpcResp.Error.Code)
+		// RPC-level errors are permanent (bad params, unsupported method, etc.)
+		return nil, &permanentRPCError{
+			fmt.Errorf("RPC Error [%s]: %s (code: %d)", method, rpcResp.Error.Message, rpcResp.Error.Code),
+		}
 	}
 
 	return rpcResp.Result, nil
 }
 
+type permanentRPCError struct{ cause error }
+
+func (e *permanentRPCError) Error() string { return e.cause.Error() }
+func (e *permanentRPCError) Unwrap() error { return e.cause }
+
+func isPermanentRPCError(err error) bool {
+	var p *permanentRPCError
+	return errors.As(err, &p)
+}
+
 func (j *JsonRpcEthereum) GetLatestBlockNumber(ctx context.Context) (int, error) {
 	result, err := j.callRPC(ctx, "eth_blockNumber")
 	if err != nil {

backend-go/internal/services/evaluator.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"time"
 
 	"github.com/kjannette/koin-ping/backend-go/internal/domain"
 	"github.com/kjannette/koin-ping/backend-go/internal/models"
@@ -12,6 +13,12 @@ import (
 	"github.com/kjannette/koin-ping/backend-go/internal/wei"
 )
 
+const (
+	notificationTimeout    = 30 * time.Second
+	notificationMaxRetries = 3
+	notificationRetryBase  = time.Second
+)
+
 type EvaluatorService struct {
 	eth          ethereum.EthereumObserver
 	alertRules   *models.AlertRuleModel
@@ -167,25 +174,85 @@ func (s *EvaluatorService) fireAlert(ctx context.Context, rule domain.AlertRule,
 	message := s.buildMessage(rule, obs)
 	txHash := &obs.Hash
 
-	_, err = s.alertEvents.Create(ctx, rule.ID, message, &addressLabel, txHash)
+	event, err := s.alertEvents.Create(ctx, rule.ID, message, &addressLabel, txHash)
 	if err != nil {
 		return err
 	}
 
+	if event == nil {
+		log.Printf("[ALERT DEDUP] Rule %d (%s) - duplicate event skipped for TX: %s", rule.ID, rule.Type, obs.Hash)
+		return nil
+	}
+
 	log.Printf("[ALERT FIRED] Rule %d (%s) - %s - TX: %s", rule.ID, rule.Type, message, obs.Hash)
 
-	// Send Discord notification (non-fatal on failure)
 	if addr != nil {
+		userID := addr.UserID
+		address := addr.Address
 		go func() {
-			s.sendNotification(
-				ctx, addr.UserID, message, obs, addressLabel, rule, addr.Address,
-			)
+			notifCtx, cancel := context.WithTimeout(context.Background(), notificationTimeout)
+			defer cancel()
+			s.sendNotification(notifCtx, userID, message, obs, addressLabel, rule, address)
 		}()
 	}
 
 	return nil
 }
 
+func (s *EvaluatorService) buildNotifiers(cfg *domain.NotificationConfig) []notifications.Notifier {
+	var notifiers []notifications.Notifier
+
+	if cfg.DiscordWebhookURL != nil && *cfg.DiscordWebhookURL != "" {
+		notifiers = append(notifiers, &notifications.DiscordNotifier{WebhookURL: *cfg.DiscordWebhookURL})
+	}
+
+	if cfg.TelegramBotToken != nil && *cfg.TelegramBotToken != "" &&
+		cfg.TelegramChatID != nil && *cfg.TelegramChatID != "" {
+		notifiers = append(notifiers, &notifications.TelegramNotifier{
+			BotToken: *cfg.TelegramBotToken,
+			ChatID:   *cfg.TelegramChatID,
+		})
+	}
+
+	if cfg.SlackWebhookURL != nil && *cfg.SlackWebhookURL != "" {
+		notifiers = append(notifiers, &notifications.SlackNotifier{WebhookURL: *cfg.SlackWebhookURL})
+	}
+
+	if cfg.Email != nil && *cfg.Email != "" {
+		notifiers = append(notifiers, &notifications.EmailNotifier{
+			APIKey: s.resendAPIKey,
+			From:   s.emailFrom,
+			To:     *cfg.Email,
+		})
+	}
+
+	return notifiers
+}
+
+func sendWithRetry(ctx context.Context, n notifications.Notifier, message string, meta notifications.AlertMetadata) error {
+	var lastErr error
+	for attempt := range notificationMaxRetries {
+		if attempt > 0 {
+			wait := notificationRetryBase * time.Duration(1<<(attempt-1))
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-time.After(wait):
+			}
+		}
+
+		if err := n.Send(ctx, message, meta); err != nil {
+			log.Printf("Notification attempt %d/%d failed: %v", attempt+1, notificationMaxRetries, err)
+			lastErr = err
+			continue
+		}
+
+		return nil
+	}
+
+	return lastErr
+}
+
 func (s *EvaluatorService) sendNotification(ctx context.Context, userID, message string, obs domain.ObservedTx, addressLabel string, rule domain.AlertRule, address string) {
 	notifConfig, err := s.notifConfigs.GetConfig(ctx, userID)
 	if err != nil {
@@ -204,44 +271,11 @@ func (s *EvaluatorService) sendNotification(ctx context.Context, userID, message
 		Address:      address,
 	}
 
-	if notifConfig.DiscordWebhookURL != nil && *notifConfig.DiscordWebhookURL != "" {
-		sent, sendErr := notifications.SendDiscordNotification(*notifConfig.DiscordWebhookURL, message, meta)
-		if sendErr != nil || !sent {
-			log.Printf("Discord notification failed for user %s: %v", userID, sendErr)
+	for _, n := range s.buildNotifiers(notifConfig) {
+		if err := sendWithRetry(ctx, n, message, meta); err != nil {
+			log.Printf("Notification channel failed for user %s after retries: %v", userID, err)
 		} else {
-			log.Printf("Discord notification sent to user %s", userID)
-		}
-	}
-
-	if notifConfig.TelegramBotToken != nil && *notifConfig.TelegramBotToken != "" &&
-		notifConfig.TelegramChatID != nil && *notifConfig.TelegramChatID != "" {
-		sent, sendErr := notifications.SendTelegramNotification(
-			*notifConfig.TelegramBotToken, *notifConfig.TelegramChatID, message, meta,
-		)
-		if sendErr != nil || !sent {
-			log.Printf("Telegram notification failed for user %s: %v", userID, sendErr)
-		} else {
-			log.Printf("Telegram notification sent to user %s", userID)
-		}
-	}
-
-	if notifConfig.SlackWebhookURL != nil && *notifConfig.SlackWebhookURL != "" {
-		sent, sendErr := notifications.SendSlackNotification(*notifConfig.SlackWebhookURL, message, meta)
-		if sendErr != nil || !sent {
-			log.Printf("Slack notification failed for user %s: %v", userID, sendErr)
-		} else {
-			log.Printf("Slack notification sent to user %s", userID)
-		}
-	}
-
-	if notifConfig.Email != nil && *notifConfig.Email != "" {
-		sent, sendErr := notifications.SendEmailNotification(
-			s.resendAPIKey, s.emailFrom, *notifConfig.Email, message, meta,
-		)
-		if sendErr != nil || !sent {
-			log.Printf("Email notification failed for user %s: %v", userID, sendErr)
-		} else {
-			log.Printf("Email notification sent to user %s", userID)
+			log.Printf("Notification sent to user %s via %T", userID, n)
 		}
 	}
 }

frontend/src/api/addresses.jsx

@@ -80,6 +80,41 @@ export async function getAddresses() {
     }
 }
 
+/**
+ * Update an address (e.g. change its label)
+ * @param {number} addressId - Address ID to update
+ * @param {Object} data - Fields to update (e.g. { label: "New Label" })
+ * @returns {Promise<Object>} Updated address
+ */
+export async function updateAddress(addressId, data) {
+    try {
+        const headers = await getAuthHeaders();
+        const response = await fetch(`${API_BASE}/addresses/${addressId}`, {
+            method: "PATCH",
+            headers: headers,
+            body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+            let errorMessage = "Failed to update address";
+            try {
+                const error = await response.json();
+                errorMessage = error.message || errorMessage;
+            } catch {
+                errorMessage = `Server error: ${response.status} ${response.statusText}`;
+            }
+            throw new Error(errorMessage);
+        }
+
+        return response.json();
+    } catch (error) {
+        if (error.message.includes("fetch")) {
+            throw new Error("Cannot connect to server. Is the backend running?");
+        }
+        throw error;
+    }
+}
+
 /**
  * Delete a tracked address
  * @param {number} addressId - Address ID to delete

frontend/src/pages/Addresses.jsx

@@ -1,11 +1,13 @@
 import { useState, useEffect } from "react";
 import AddressForm from "../components/AddressForm";
-import { getAddresses, createAddress } from "../api/addresses";
+import { getAddresses, createAddress, deleteAddress, updateAddress } from "../api/addresses";
 
 export default function Addresses() {
     const [addresses, setAddresses] = useState([]);
     const [loading, setLoading] = useState(true);
     const [error, setError] = useState(null);
+    const [editingId, setEditingId] = useState(null);
+    const [editLabel, setEditLabel] = useState("");
 
     // Load addresses on mount
     useEffect(() => {
@@ -29,15 +31,52 @@ export default function Addresses() {
     async function handleAddressSubmit(data) {
         try {
             const newAddress = await createAddress(data);
-            // Append new address to state
             setAddresses((prev) => [...prev, newAddress]);
-            setError(null); // Clear any previous errors
+            setError(null);
         } catch (err) {
             setError(err.message);
             console.error("Failed to create address:", err);
         }
     }
 
+    async function handleDelete(id, label) {
+        const displayName = label || "this address";
+        if (!window.confirm(`Remove "${displayName}"? This will also delete all associated alert rules.`)) {
+            return;
+        }
+        try {
+            await deleteAddress(id);
+            setAddresses((prev) => prev.filter((a) => a.id !== id));
+            setError(null);
+        } catch (err) {
+            setError(err.message);
+            console.error("Failed to delete address:", err);
+        }
+    }
+
+    function handleEditStart(addr) {
+        setEditingId(addr.id);
+        setEditLabel(addr.label ?? "");
+    }
+
+    async function handleEditSave(id) {
+        try {
+            const updated = await updateAddress(id, { label: editLabel || null });
+            setAddresses((prev) => prev.map((a) => (a.id === id ? updated : a)));
+            setEditingId(null);
+            setEditLabel("");
+            setError(null);
+        } catch (err) {
+            setError(err.message);
+            console.error("Failed to update address:", err);
+        }
+    }
+
+    function handleEditCancel() {
+        setEditingId(null);
+        setEditLabel("");
+    }
+
     return (
         <div style={{ maxWidth: "800px", margin: "0 auto", padding: "2rem" }}>
             <h1>Tracked Addresses</h1>
@@ -68,14 +107,62 @@ export default function Addresses() {
                                     backgroundColor: "#333",
                                 }}
                             >
-                                <div
+                                <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center" }}>
+                                    <div style={{ flex: 1 }}>
+                                        {editingId === addr.id ? (
+                                            <div style={{ display: "flex", gap: "0.5rem", alignItems: "center", marginBottom: "0.25rem" }}>
+                                                <input
+                                                    value={editLabel}
+                                                    onChange={(e) => setEditLabel(e.target.value)}
+                                                    placeholder="Label (optional)"
                                                     style={{
-                                        fontWeight: "bold",
-                                        marginBottom: "0.25rem",
+                                                        background: "#444",
+                                                        border: "1px solid #666",
+                                                        borderRadius: "3px",
+                                                        color: "#fff",
+                                                        padding: "0.25rem 0.5rem",
+                                                        fontSize: "0.9rem",
+                                                    }}
+                                                    onKeyDown={(e) => {
+                                                        if (e.key === "Enter") handleEditSave(addr.id);
+                                                        if (e.key === "Escape") handleEditCancel();
+                                                    }}
+                                                    autoFocus
+                                                />
+                                                <button
+                                                    onClick={() => handleEditSave(addr.id)}
+                                                    style={{ cursor: "pointer", padding: "0.25rem 0.6rem", fontSize: "0.85rem" }}
+                                                >
+                                                    Save
+                                                </button>
+                                                <button
+                                                    onClick={handleEditCancel}
+                                                    style={{ cursor: "pointer", padding: "0.25rem 0.6rem", fontSize: "0.85rem", background: "transparent", color: "#aaa", border: "1px solid #555" }}
+                                                >
+                                                    Cancel
+                                                </button>
+                                            </div>
+                                        ) : (
+                                            <div style={{ display: "flex", alignItems: "center", gap: "0.5rem", marginBottom: "0.25rem" }}>
+                                                <span style={{ fontWeight: "bold" }}>
+                                                    {addr.label || "Unlabeled"}
+                                                </span>
+                                                <button
+                                                    onClick={() => handleEditStart(addr)}
+                                                    style={{
+                                                        cursor: "pointer",
+                                                        background: "transparent",
+                                                        border: "none",
+                                                        color: "#6699cc",
+                                                        fontSize: "0.8rem",
+                                                        padding: "0",
+                                                        textDecoration: "underline",
                                                     }}
                                                 >
-                                    {addr.label || "Unlabeled"}
+                                                    Edit
+                                                </button>
                                             </div>
+                                        )}
                                         <div
                                             style={{
                                                 fontFamily: "monospace",
@@ -85,6 +172,24 @@ export default function Addresses() {
                                         >
                                             {addr.address}
                                         </div>
+                                    </div>
+                                    <button
+                                        onClick={() => handleDelete(addr.id, addr.label)}
+                                        style={{
+                                            cursor: "pointer",
+                                            background: "transparent",
+                                            border: "1px solid #884444",
+                                            color: "#cc6666",
+                                            borderRadius: "3px",
+                                            padding: "0.3rem 0.7rem",
+                                            fontSize: "0.85rem",
+                                            marginLeft: "1rem",
+                                            flexShrink: 0,
+                                        }}
+                                    >
+                                        Remove
+                                    </button>
+                                </div>
                             </li>
                         ))}
                     </ul>