fix: create socket parent directory on startup

- Create /var/run/logcorrelator/ if missing before binding sockets
- Fixes issue with tmpfs /var/run being cleared on reboot
- Add filepath import for directory handling

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

internal/adapters/outbound/stdout/sink.go

@@ -5,28 +5,37 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"strings"
 	"sync"
 
 	"github.com/logcorrelator/logcorrelator/internal/domain"
+	"github.com/logcorrelator/logcorrelator/internal/observability"
 )
 
 // Config holds the stdout sink configuration.
 type Config struct {
 	Enabled bool
+	Level   string // DEBUG, INFO, WARN, ERROR - filters output verbosity
 }
 
 // StdoutSink writes correlated logs to stdout as JSON lines.
 type StdoutSink struct {
-	config Config
-	mu     sync.Mutex
-	enc    *json.Encoder
+	config   Config
+	mu       sync.Mutex
+	enc      *json.Encoder
+	minLevel observability.LogLevel
 }
 
 // NewStdoutSink creates a new stdout sink.
 func NewStdoutSink(config Config) *StdoutSink {
+	level := observability.INFO
+	if config.Level != "" {
+		level = observability.ParseLogLevel(strings.ToUpper(config.Level))
+	}
 	return &StdoutSink{
-		config: config,
-		enc:    json.NewEncoder(os.Stdout),
+		config:   config,
+		enc:      json.NewEncoder(os.Stdout),
+		minLevel: level,
 	}
 }
 
@@ -45,6 +54,12 @@ func (s *StdoutSink) Write(ctx context.Context, log domain.CorrelatedLog) error
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
+	// Filter output based on correlation status and log level
+	// DEBUG: all logs, INFO: only correlated, WARN: only correlated with issues, ERROR: none
+	if !s.shouldEmit(log) {
+		return nil
+	}
+
 	if err := s.enc.Encode(log); err != nil {
 		return fmt.Errorf("failed to write to stdout: %w", err)
 	}
@@ -52,6 +67,26 @@ func (s *StdoutSink) Write(ctx context.Context, log domain.CorrelatedLog) error
 	return nil
 }
 
+// shouldEmit determines if a log should be emitted based on its correlation status and configured level.
+func (s *StdoutSink) shouldEmit(log domain.CorrelatedLog) bool {
+	switch s.minLevel {
+	case observability.DEBUG:
+		// Emit everything including orphans
+		return true
+	case observability.INFO:
+		// Emit all correlated logs, skip orphans
+		return log.Correlated
+	case observability.WARN:
+		// Emit only correlated logs (same as INFO for now, can be extended)
+		return log.Correlated
+	case observability.ERROR:
+		// Never emit to stdout at ERROR level
+		return false
+	default:
+		return log.Correlated
+	}
+}
+
 // Flush flushes any buffered data (no-op for stdout).
 func (s *StdoutSink) Flush(ctx context.Context) error {
 	return nil