Add server-side query result limit to prevent memory exhaustion (v0.52.11)

- Add ORLY_QUERY_RESULT_LIMIT config (default 256)
- Enforce limit on each REQ filter before database query
- Caps client limit if it exceeds server limit
- Applies server limit if client sends no limit

This prevents unbounded queries from loading millions of events
into memory and causing OOM kills.

Files modified:
- app/config/config.go: Add QueryResultLimit config
- app/handle-req.go: Enforce limit on each filter
- pkg/version/version: Bump to v0.52.11

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/config/config.go

@@ -148,6 +148,9 @@ type C struct {
 	MaxHandlersPerConnection int `env:"ORLY_MAX_HANDLERS_PER_CONN" default:"100" usage:"max concurrent message handlers per WebSocket connection (limits goroutine growth under load)"`
 	MaxConnectionsPerIP      int `env:"ORLY_MAX_CONN_PER_IP" default:"25" usage:"max WebSocket connections per IP address (prevents resource exhaustion, hard limit 40)"`
 
+	// Query result limits (prevents memory exhaustion from unbounded queries)
+	QueryResultLimit int `env:"ORLY_QUERY_RESULT_LIMIT" default:"256" usage:"max events returned per REQ filter (prevents unbounded memory usage, 0=unlimited)"`
+
 	// Adaptive rate limiting (PID-controlled)
 	RateLimitEnabled            bool    `env:"ORLY_RATE_LIMIT_ENABLED" default:"true" usage:"enable adaptive PID-controlled rate limiting for database operations"`
 	RateLimitTargetMB           int     `env:"ORLY_RATE_LIMIT_TARGET_MB" default:"0" usage:"target memory limit in MB (0=auto-detect: 66% of available, min 500MB)"`

app/handle-req.go

@@ -316,8 +316,27 @@ func (l *Listener) HandleReq(msg []byte) (err error) {
 
 	// Collect all events from all filters
 	var allEvents event.S
+
+	// Server-side query result limit to prevent memory exhaustion
+	serverLimit := l.Config.QueryResultLimit
+	if serverLimit <= 0 {
+		serverLimit = 256 // Default if not configured
+	}
+
 	for _, f := range *env.Filters {
 		if f != nil {
+			// Enforce server-side limit on each filter
+			if serverLimit > 0 {
+				if f.Limit == nil {
+					// No client limit - apply server limit
+					limitVal := uint(serverLimit)
+					f.Limit = &limitVal
+				} else if int(*f.Limit) > serverLimit {
+					// Client limit exceeds server limit - cap it
+					limitVal := uint(serverLimit)
+					f.Limit = &limitVal
+				}
+			}
 			// Summarize filter details for diagnostics (avoid internal fields)
 			var kindsLen int
 			if f.Kinds != nil {

pkg/version/version

@@ -1 +1 @@
-v0.52.10
+v0.52.11