fix(alert): add context to Provider.Send, log alert failures

Provider.Send now accepts context.Context for timeout/cancellation.
HTTPProvider and NtfyProvider use NewRequestWithContext so HTTP alerts
respect the 30s deadline. triggerAlert logs send failures and config
load errors instead of silently swallowing them.

internal/alert/alert.go

@@ -2,6 +2,7 @@ package alert
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"go-upkeep/internal/models"
@@ -15,7 +16,7 @@ import (
 var alertClient = &http.Client{Timeout: 10 * time.Second}
 
 type Provider interface {
-	Send(title, message string) error
+	Send(ctx context.Context, title, message string) error
 }
 
 type PayloadFunc func(title, message string) ([]byte, error)
@@ -25,12 +26,17 @@ type HTTPProvider struct {
 	Payload PayloadFunc
 }
 
-func (h *HTTPProvider) Send(title, message string) error {
+func (h *HTTPProvider) Send(ctx context.Context, title, message string) error {
 	body, err := h.Payload(title, message)
 	if err != nil {
 		return err
 	}
-	resp, err := alertClient.Post(h.URL, "application/json", bytes.NewBuffer(body))
+	req, err := http.NewRequestWithContext(ctx, "POST", h.URL, bytes.NewBuffer(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := alertClient.Do(req)
 	if err != nil {
 		return err
 	}
@@ -170,7 +176,12 @@ type EmailProvider struct {
 	Host, Port, User, Pass, To, From string
 }
 
-func (e *EmailProvider) Send(title, message string) error {
+func (e *EmailProvider) Send(ctx context.Context, title, message string) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	default:
+	}
 	auth := smtp.PlainAuth("", e.User, e.Pass, e.Host)
 	msg := []byte("To: " + e.To + "\r\n" +
 		"Subject: Go-Upkeep: " + title + "\r\n" +
@@ -187,9 +198,9 @@ type NtfyProvider struct {
 	Password  string
 }
 
-func (n *NtfyProvider) Send(title, message string) error {
+func (n *NtfyProvider) Send(ctx context.Context, title, message string) error {
 	url := strings.TrimRight(n.ServerURL, "/") + "/" + n.Topic
-	req, err := http.NewRequest("POST", url, strings.NewReader(message))
+	req, err := http.NewRequestWithContext(ctx, "POST", url, strings.NewReader(message))
 	if err != nil {
 		return err
 	}

internal/alert/alert_test.go

@@ -1,6 +1,7 @@
 package alert
 
 import (
+	"context"
 	"encoding/json"
 	"go-upkeep/internal/models"
 	"net/http"
@@ -17,7 +18,7 @@ func TestHTTPProviderDiscord(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "discord", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Test Title", "Test Body"); err != nil {
+	if err := p.Send(context.Background(), "Test Title", "Test Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -35,7 +36,7 @@ func TestHTTPProviderSlack(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "slack", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Alert", "Message"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Message"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -53,7 +54,7 @@ func TestHTTPProviderWebhook(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "webhook", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Title", "Body"); err != nil {
+	if err := p.Send(context.Background(), "Title", "Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -69,7 +70,7 @@ func TestHTTPProviderErrorOnHTTP4xx(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "discord", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Test", "Test"); err == nil {
+	if err := p.Send(context.Background(), "Test", "Test"); err == nil {
 		t.Fatal("expected error on 403 response")
 	}
 }
@@ -89,7 +90,7 @@ func TestNtfyProvider(t *testing.T) {
 		"url":   srv.URL,
 		"topic": "test",
 	}})
-	if err := p.Send("Alert Title", "Alert Body"); err != nil {
+	if err := p.Send(context.Background(), "Alert Title", "Alert Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -110,7 +111,7 @@ func TestHTTPProviderTelegram(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: telegramPayload("12345")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["chat_id"] != "12345" {
@@ -133,7 +134,7 @@ func TestHTTPProviderPagerDuty(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: pagerdutyPayload("test-key", "critical")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["routing_key"] != "test-key" {
@@ -160,7 +161,7 @@ func TestHTTPProviderPushover(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: pushoverPayload("app-tok", "user-key")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["token"] != "app-tok" {
@@ -183,7 +184,7 @@ func TestHTTPProviderGotify(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: gotifyPayload("8")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["title"] != "Alert" || received["message"] != "Down" {

internal/monitor/monitor.go

@@ -25,7 +25,7 @@ type Engine struct {
 	histMu    sync.RWMutex
 	histories map[int]*SiteHistory
 
-	tokenIndex map[string]int
+	tokenIndex map[string]int // protected by mu
 
 	probeResultsMu sync.RWMutex
 	probeResults   map[int]map[string]NodeResult
@@ -433,6 +433,7 @@ func (e *Engine) handleStatusChange(site models.Site, rawStatus string, code int
 func (e *Engine) triggerAlert(alertID int, title, message string) {
 	cfg, err := e.db.GetAlert(alertID)
 	if err != nil {
+		e.AddLog(fmt.Sprintf("Failed to load alert config %d: %v", alertID, err))
 		return
 	}
 	provider := alert.GetProvider(cfg)
@@ -440,8 +441,9 @@ func (e *Engine) triggerAlert(alertID int, title, message string) {
 		go func() {
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 			defer cancel()
-			_ = ctx
+			if err := provider.Send(ctx, title, message); err != nil {
-			_ = provider.Send(title, message)
+				e.AddLog(fmt.Sprintf("Alert send failed (%s): %v", cfg.Name, err))
+			}
 		}()
 	}
 }