fix(telegram): 3 reliability fixes from perf review

1. Health endpoint always returned 503 — defer SetReady() never ran
   during bot lifetime. Changed to immediate call after server start.

2. Data race on HealthServer.ready — read by HTTP handlers, written
   by main goroutine without synchronization. Changed to atomic.Bool.

3. Integer overflow in poller.backoffDuration — 1<<errors overflowed
   when consecutiiveErrors > 30 (extended API outage). Clamped to 30.

Author: molty3000

cmd/odek/telegram.go

@@ -482,8 +482,8 @@ func telegramCmd(args []string) error {
 				fmt.Fprintf(os.Stderr, "odek telegram: health server: %v\n", err)
 			}
 		}()
-		// Mark ready once polling begins.
-		defer healthSrv.SetReady()
+		// Mark ready — the server goroutine is already listening.
+		healthSrv.SetReady()
 	}
 
 	// 15. Handle SIGINT/SIGTERM/SIGHUP.

internal/telegram/health.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"sync/atomic"
 	"time"
 )
 
@@ -15,7 +16,7 @@ import (
 type HealthServer struct {
 	addr      string
 	startTime time.Time
-	ready     bool
+	ready     atomic.Bool
 	log       Logger
 }
 
@@ -39,8 +40,9 @@ func (hs *HealthServer) SetLogger(l Logger) {
 }
 
 // SetReady marks the health server as ready (polling has started).
+// Thread-safe: safe to call from any goroutine.
 func (hs *HealthServer) SetReady() {
-	hs.ready = true
+	hs.ready.Store(true)
 }
 
 // ServeHTTP implements http.Handler.
@@ -52,7 +54,7 @@ func (hs *HealthServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	w.Header().Set("Content-Type", "application/json")
 
-	if !hs.ready {
+	if !hs.ready.Load() {
 		w.WriteHeader(http.StatusServiceUnavailable)
 		json.NewEncoder(w).Encode(map[string]any{
 			"status":  "starting",

internal/telegram/health_test.go

@@ -10,7 +10,7 @@ import (
 
 func TestHealthServer_Returns200(t *testing.T) {
 	hs := NewHealthServer("127.0.0.1:0")
-	hs.ready = true
+	hs.ready.Store(true)
 
 	ts := &http.Server{Addr: hs.addr, Handler: hs}
 	ln, err := net.Listen("tcp", "127.0.0.1:0")

internal/telegram/poller.go

@@ -39,11 +39,15 @@ func (p *Poller) SetLogger(l Logger) {
 // backoffDuration returns the sleep duration after consecutive poll errors.
 // Formula: interval * 2^errors, capped at 60 * interval.
 // Returns 0 for 0 errors (no backoff needed).
+// errors is clamped to 30 to prevent integer overflow in 1<<errors.
 func (p *Poller) backoffDuration(errors int) time.Duration {
 	if errors <= 0 {
 		return 0
 	}
-	shift := 1 << errors // 2^errors
+	if errors > 30 {
+		errors = 30
+	}
+	shift := 1 << errors // 2^errors, safe after clamp
 	d := p.Interval * time.Duration(shift)
 	max := 60 * p.Interval
 	if d > max {