fix fps toggle

Overlord-Client/cmd/agent/capture/flowcontrol.go

@@ -1,16 +1,20 @@
 package capture
 
 import (
+	"os"
+	"strconv"
+	"strings"
 	"sync/atomic"
 	"time"
 )
 
-const maxInFlightFrames int64 = 2
+const defaultMaxInFlightFrames int64 = 2
 
 var (
 	inFlightFrames atomic.Int64
 	frameAckSeen   atomic.Bool
 	lastAckNano    atomic.Int64
+	maxFrameSlots  atomic.Int64
 )
 
 func AcquireFrameSlot() bool {
@@ -20,7 +24,7 @@ func AcquireFrameSlot() bool {
 
 	for {
 		cur := inFlightFrames.Load()
-		if cur >= maxInFlightFrames {
+		if cur >= activeFrameSlotLimit() {
 			lastAck := lastAckNano.Load()
 			if lastAck > 0 && time.Since(time.Unix(0, lastAck)) > time.Second {
 				inFlightFrames.Store(0)
@@ -47,3 +51,33 @@ func ResetFrameSlots() {
 	frameAckSeen.Store(false)
 	lastAckNano.Store(0)
 }
+
+func SetFrameFlowTargetFPS(fps int) {
+	limit := defaultMaxInFlightFrames
+	switch {
+	case fps >= 180:
+		limit = 8
+	case fps >= 120:
+		limit = 4
+	}
+	if env := strings.TrimSpace(os.Getenv("OVERLORD_DESKTOP_IN_FLIGHT_FRAMES")); env != "" {
+		if v, err := strconv.Atoi(env); err == nil {
+			switch {
+			case v < 1:
+				limit = 1
+			case v > 32:
+				limit = 32
+			default:
+				limit = int64(v)
+			}
+		}
+	}
+	maxFrameSlots.Store(limit)
+}
+
+func activeFrameSlotLimit() int64 {
+	if limit := maxFrameSlots.Load(); limit > 0 {
+		return limit
+	}
+	return defaultMaxInFlightFrames
+}