diff --git a/src/internal/config/loader.go b/src/internal/config/loader.go
index 851cbbc..2a1fd24 100644
--- a/src/internal/config/loader.go
+++ b/src/internal/config/loader.go
@@ -113,7 +113,18 @@ func defaults() *Config {
 		Pipelines: []PipelineConfig{
 			{
 				Name: "default_pipeline",
-				Flow: &FlowConfig{},
+				Flow: &FlowConfig{
+					RateLimit: &RateLimitConfig{
+						Rate:              5,
+						Burst:             10,
+						Policy:            "drop",
+						MaxEntrySizeBytes: 65536,
+					},
+					Format: &FormatConfig{
+						Type:            "json",
+						SanitizerPolicy: "json",
+					},
+				},
 				PluginSources: []PluginSourceConfig{
 					{
 						ID:   "default_source",
diff --git a/src/internal/config/validate.go b/src/internal/config/validate.go
new file mode 100644
index 0000000..c45a9b0
--- /dev/null
+++ b/src/internal/config/validate.go
@@ -0,0 +1,63 @@
+package config
+
+import (
+	"fmt"
+
+	lconfig "github.com/lixenwraith/config"
+)
+
+// ValidateConfig validates top-level structure only
+// Value range validation is delegated to component constructors
+func ValidateConfig(cfg *Config) error {
+	if cfg == nil {
+		return fmt.Errorf("config is nil")
+	}
+
+	if len(cfg.Pipelines) == 0 {
+		return fmt.Errorf("no pipelines configured")
+	}
+
+	if err := validateLogConfig(cfg.Logging); err != nil {
+		return fmt.Errorf("logging: %w", err)
+	}
+
+	for i, p := range cfg.Pipelines {
+		if err := lconfig.NonEmpty(p.Name); err != nil {
+			return fmt.Errorf("pipeline[%d].name: %w", i, err)
+		}
+		if len(p.PluginSources) == 0 {
+			return fmt.Errorf("pipeline[%d]: no sources defined", i)
+		}
+		if len(p.PluginSinks) == 0 {
+			return fmt.Errorf("pipeline[%d]: no sinks defined", i)
+		}
+	}
+
+	return nil
+}
+
+// validateLogConfig validates application logging settings
+func validateLogConfig(cfg *LogConfig) error {
+	if cfg == nil {
+		return nil
+	}
+
+	validateOutput := lconfig.OneOf("file", "stdout", "stderr", "split", "all", "none")
+	if err := validateOutput(cfg.Output); err != nil {
+		return fmt.Errorf("output: %w", err)
+	}
+
+	validateLevel := lconfig.OneOf("debug", "info", "warn", "error")
+	if err := validateLevel(cfg.Level); err != nil {
+		return fmt.Errorf("level: %w", err)
+	}
+
+	if cfg.Console != nil {
+		validateTarget := lconfig.OneOf("stdout", "stderr", "split")
+		if err := validateTarget(cfg.Console.Target); err != nil {
+			return fmt.Errorf("console.target: %w", err)
+		}
+	}
+
+	return nil
+}
\ No newline at end of file
diff --git a/src/internal/config/validation.go b/src/internal/config/validation.go
deleted file mode 100644
index 8e1b724..0000000
--- a/src/internal/config/validation.go
+++ /dev/null
@@ -1,234 +0,0 @@
-package config
-
-import (
-	"fmt"
-	"path/filepath"
-	"regexp"
-	"strings"
-
-	lconfig "github.com/lixenwraith/config"
-)
-
-// ValidateConfig is the centralized validator for the entire configuration structure
-func ValidateConfig(cfg *Config) error {
-	if cfg == nil {
-		return fmt.Errorf("config is nil")
-	}
-
-	if len(cfg.Pipelines) == 0 {
-		return fmt.Errorf("no pipelines configured")
-	}
-
-	if err := validateLogConfig(cfg.Logging); err != nil {
-		return fmt.Errorf("logging config: %w", err)
-	}
-
-	// // Track used ports across all pipelines
-	// allPorts := make(map[int64]string)
-	// pipelineNames := make(map[string]bool)
-
-	// for i, pipeline := range cfg.Pipelines {
-	// 	if err := validatePipeline(i, &pipeline, pipelineNames, allPorts); err != nil {
-	// 		return err
-	// 	}
-	// }
-
-	return nil
-}
-
-// validateLogConfig validates the application's own logging settings
-func validateLogConfig(cfg *LogConfig) error {
-	validOutputs := map[string]bool{
-		"file": true, "stdout": true, "stderr": true,
-		"split": true, "all": true, "none": true,
-	}
-	if !validOutputs[cfg.Output] {
-		return fmt.Errorf("invalid log output mode: %s", cfg.Output)
-	}
-
-	validLevels := map[string]bool{
-		"debug": true, "info": true, "warn": true, "error": true,
-	}
-	if !validLevels[cfg.Level] {
-		return fmt.Errorf("invalid log level: %s", cfg.Level)
-	}
-
-	if cfg.Console != nil {
-		validTargets := map[string]bool{
-			"stdout": true, "stderr": true, "split": true,
-		}
-		if !validTargets[cfg.Console.Target] {
-			return fmt.Errorf("invalid console target: %s", cfg.Console.Target)
-		}
-	}
-
-	return nil
-}
-
-// validateRateLimit validates the pipeline-level rate limit settings
-func validateRateLimit(pipelineName string, cfg *RateLimitConfig) error {
-	if cfg == nil {
-		return nil
-	}
-
-	if cfg.Rate < 0 {
-		return fmt.Errorf("pipeline '%s': rate limit rate cannot be negative", pipelineName)
-	}
-
-	if cfg.Burst < 0 {
-		return fmt.Errorf("pipeline '%s': rate limit burst cannot be negative", pipelineName)
-	}
-
-	if cfg.MaxEntrySizeBytes < 0 {
-		return fmt.Errorf("pipeline '%s': max entry size bytes cannot be negative", pipelineName)
-	}
-
-	// Validate policy
-	switch strings.ToLower(cfg.Policy) {
-	case "", "pass", "drop":
-		// Valid policies
-	default:
-		return fmt.Errorf("pipeline '%s': invalid rate limit policy '%s' (must be 'pass' or 'drop')",
-			pipelineName, cfg.Policy)
-	}
-
-	return nil
-}
-
-// validateFilter validates a single filter's configuration
-func validateFilter(pipelineName string, filterIndex int, cfg *FilterConfig) error {
-	// Validate filter type
-	switch cfg.Type {
-	case FilterTypeInclude, FilterTypeExclude, "":
-		// Valid types
-	default:
-		return fmt.Errorf("pipeline '%s' filter[%d]: invalid type '%s' (must be 'include' or 'exclude')",
-			pipelineName, filterIndex, cfg.Type)
-	}
-
-	// Validate filter logic
-	switch cfg.Logic {
-	case FilterLogicOr, FilterLogicAnd, "":
-		// Valid logic
-	default:
-		return fmt.Errorf("pipeline '%s' filter[%d]: invalid logic '%s' (must be 'or' or 'and')",
-			pipelineName, filterIndex, cfg.Logic)
-	}
-
-	// Empty patterns is valid - passes everything
-	if len(cfg.Patterns) == 0 {
-		return nil
-	}
-
-	// Validate regex patterns
-	for i, pattern := range cfg.Patterns {
-		if _, err := regexp.Compile(pattern); err != nil {
-			return fmt.Errorf("pipeline '%s' filter[%d] pattern[%d] '%s': invalid regex: %w",
-				pipelineName, filterIndex, i, pattern, err)
-		}
-	}
-
-	return nil
-}
-
-// validateFileSource validates the settings for a directory source
-func validateFileSource(pipelineName string, index int, opts *FileSourceOptions) error {
-	if err := lconfig.NonEmpty(opts.Directory); err != nil {
-		return fmt.Errorf("pipeline '%s' source[%d]: directory requires 'path'", pipelineName, index)
-	} else {
-		absPath, err := filepath.Abs(opts.Directory)
-		if err != nil {
-			return fmt.Errorf("invalid path %s: %w", opts.Directory, err)
-		}
-		opts.Directory = absPath
-	}
-
-	// Check for directory traversal
-	if strings.Contains(opts.Directory, "..") {
-		return fmt.Errorf("pipeline '%s' source[%d]: path contains directory traversal", pipelineName, index)
-	}
-
-	// Validate pattern if provided
-	if opts.Pattern != "" {
-		if strings.Count(opts.Pattern, "*") == 0 && strings.Count(opts.Pattern, "?") == 0 {
-			// If no wildcards, ensure valid filename
-			if filepath.Base(opts.Pattern) != opts.Pattern {
-				return fmt.Errorf("pipeline '%s' source[%d]: pattern contains path separators", pipelineName, index)
-			}
-		}
-	} else {
-		opts.Pattern = "*"
-	}
-
-	// Validate check interval
-	if opts.CheckIntervalMS < 10 {
-		return fmt.Errorf("pipeline '%s' source[%d]: check_interval_ms must be at least 10ms", pipelineName, index)
-	}
-
-	return nil
-}
-
-// validateConsoleSource validates the settings for a console source
-func validateConsoleSource(pipelineName string, index int, opts *ConsoleSourceOptions) error {
-	if opts.BufferSize < 0 {
-		return fmt.Errorf("pipeline '%s' source[%d]: buffer_size must be positive", pipelineName, index)
-	} else if opts.BufferSize == 0 {
-		opts.BufferSize = 1000
-	}
-	return nil
-}
-
-// validateConsoleSink validates the settings for a console sink
-func validateConsoleSink(pipelineName string, index int, opts *ConsoleSinkOptions) error {
-	if opts.BufferSize < 1 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: buffer_size must be positive", pipelineName, index)
-	}
-	return nil
-}
-
-// validateFileSink validates the settings for a file sink
-func validateFileSink(pipelineName string, index int, opts *FileSinkOptions) error {
-	if err := lconfig.NonEmpty(opts.Directory); err != nil {
-		return fmt.Errorf("pipeline '%s' sink[%d]: file requires 'directory'", pipelineName, index)
-	}
-
-	if err := lconfig.NonEmpty(opts.Name); err != nil {
-		return fmt.Errorf("pipeline '%s' sink[%d]: file requires 'name'", pipelineName, index)
-	}
-
-	if opts.BufferSize <= 0 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: max_size_mb must be positive", pipelineName, index)
-	}
-
-	// Validate sizes
-	if opts.MaxSizeMB < 0 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: max_size_mb must be positive", pipelineName, index)
-	}
-
-	if opts.MaxTotalSizeMB <= 0 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: max_total_size_mb cannot be negative", pipelineName, index)
-	}
-
-	if opts.MinDiskFreeMB < 0 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: min_disk_free_mb must be positive", pipelineName, index)
-	}
-
-	if opts.RetentionHours <= 0 {
-		return fmt.Errorf("pipeline '%s' sink[%d]: retention_hours cannot be negative", pipelineName, index)
-	}
-
-	return nil
-}
-
-// validateHeartbeat validates nested HeartbeatConfig settings
-func validateHeartbeat(pipelineName, location string, hb *HeartbeatConfig) error {
-	if !hb.Enabled {
-		return nil // Skip validation if disabled
-	}
-
-	if hb.IntervalMS < 1000 { // At least 1 second
-		return fmt.Errorf("pipeline '%s' %s: heartbeat interval must be at least 1000ms", pipelineName, location)
-	}
-
-	return nil
-}
\ No newline at end of file
diff --git a/src/internal/filter/filter.go b/src/internal/filter/filter.go
index db6b418..8c9da39 100644
--- a/src/internal/filter/filter.go
+++ b/src/internal/filter/filter.go
@@ -9,6 +9,7 @@ import (
 	"logwisp/src/internal/config"
 	"logwisp/src/internal/core"
 
+	lconfig "github.com/lixenwraith/config"
 	"github.com/lixenwraith/log"
 )
 
@@ -27,6 +28,20 @@ type Filter struct {
 
 // NewFilter creates a new filter from a configuration
 func NewFilter(cfg config.FilterConfig, logger *log.Logger) (*Filter, error) {
+	// Validate enums before setting defaults
+	if cfg.Type != "" {
+		validateType := lconfig.OneOf(config.FilterTypeInclude, config.FilterTypeExclude)
+		if err := validateType(cfg.Type); err != nil {
+			return nil, fmt.Errorf("type: %w", err)
+		}
+	}
+	if cfg.Logic != "" {
+		validateLogic := lconfig.OneOf(config.FilterLogicOr, config.FilterLogicAnd)
+		if err := validateLogic(cfg.Logic); err != nil {
+			return nil, fmt.Errorf("logic: %w", err)
+		}
+	}
+
 	// Set defaults
 	if cfg.Type == "" {
 		cfg.Type = config.FilterTypeInclude
@@ -45,7 +60,7 @@ func NewFilter(cfg config.FilterConfig, logger *log.Logger) (*Filter, error) {
 	for i, pattern := range cfg.Patterns {
 		re, err := regexp.Compile(pattern)
 		if err != nil {
-			return nil, fmt.Errorf("invalid regex pattern[%d] '%s': %w", i, pattern, err)
+			return nil, fmt.Errorf("pattern[%d] '%s': %w", i, pattern, err)
 		}
 		f.patterns = append(f.patterns, re)
 	}
diff --git a/src/internal/flow/flow.go b/src/internal/flow/flow.go
index cbee733..b97fa59 100644
--- a/src/internal/flow/flow.go
+++ b/src/internal/flow/flow.go
@@ -63,9 +63,13 @@ func NewFlow(cfg *config.FlowConfig, logger *log.Logger) (*Flow, error) {
 	}
 	f.formatter = formatter
 
-	// Create heartbeat generator with the same formatter
-	if cfg.Heartbeat != nil && cfg.Heartbeat.Enabled {
-		f.heartbeat = NewHeartbeatGenerator(cfg.Heartbeat, formatter, logger)
+	// Create heartbeat generator with the same formatter if configured
+	if cfg.Heartbeat != nil {
+		hb, err := NewHeartbeatGenerator(cfg.Heartbeat, formatter, logger)
+		if err != nil {
+			return nil, fmt.Errorf("heartbeat: %w", err)
+		}
+		f.heartbeat = hb
 	}
 
 	logger.Info("msg", "Flow processor created",
diff --git a/src/internal/flow/heartbeat.go b/src/internal/flow/heartbeat.go
index edc54b4..7d34fbf 100644
--- a/src/internal/flow/heartbeat.go
+++ b/src/internal/flow/heartbeat.go
@@ -3,17 +3,25 @@ package flow
 import (
 	"context"
 	"encoding/json"
-	"logwisp/src/internal/format"
+	"fmt"
 	"sync/atomic"
 	"time"
 
 	"logwisp/src/internal/config"
 	"logwisp/src/internal/core"
+	"logwisp/src/internal/format"
 
+	lconfig "github.com/lixenwraith/config"
 	"github.com/lixenwraith/log"
 	"github.com/lixenwraith/log/formatter"
 )
 
+const (
+	MinHeartbeatIntervalMS     = 100
+	DefaultHeartbeatIntervalMS = 1000
+	DefaultHeartbeatFormat     = "txt"
+)
+
 // HeartbeatGenerator produces periodic heartbeat events
 type HeartbeatGenerator struct {
 	config    *config.HeartbeatConfig
@@ -24,14 +32,35 @@ type HeartbeatGenerator struct {
 }
 
 // NewHeartbeatGenerator creates a new heartbeat generator
-func NewHeartbeatGenerator(cfg *config.HeartbeatConfig, formatter format.Formatter, logger *log.Logger) *HeartbeatGenerator {
+func NewHeartbeatGenerator(cfg *config.HeartbeatConfig, formatter format.Formatter, logger *log.Logger) (*HeartbeatGenerator, error) {
+	if cfg == nil || !cfg.Enabled {
+		return nil, nil
+	}
+
+	// Validate
+	if cfg.IntervalMS == 0 {
+		cfg.IntervalMS = DefaultHeartbeatIntervalMS
+	} else if cfg.IntervalMS < MinHeartbeatIntervalMS {
+		return nil, fmt.Errorf("interval_ms: must be >= %d, got %d", MinHeartbeatIntervalMS, cfg.IntervalMS)
+	}
+
+	validateFormat := lconfig.OneOf("txt", "json", "raw", "")
+	if err := validateFormat(cfg.Format); err != nil {
+		return nil, fmt.Errorf("format: %w", err)
+	}
+
+	// Defaults
+	if cfg.Format == "" {
+		cfg.Format = DefaultHeartbeatFormat
+	}
+
 	hg := &HeartbeatGenerator{
 		config:    cfg,
 		formatter: formatter,
 		logger:    logger,
 	}
 	hg.lastBeat.Store(time.Time{})
-	return hg
+	return hg, nil
 }
 
 // Start begins generating heartbeat events
diff --git a/src/internal/flow/ratelimiter.go b/src/internal/flow/ratelimiter.go
index 47f3021..9e56778 100644
--- a/src/internal/flow/ratelimiter.go
+++ b/src/internal/flow/ratelimiter.go
@@ -1,6 +1,7 @@
 package flow
 
 import (
+	"fmt"
 	"strings"
 	"sync/atomic"
 
@@ -8,6 +9,7 @@ import (
 	"logwisp/src/internal/core"
 	"logwisp/src/internal/tokenbucket"
 
+	lconfig "github.com/lixenwraith/config"
 	"github.com/lixenwraith/log"
 )
 
@@ -25,21 +27,36 @@ type RateLimiter struct {
 
 // NewRateLimiter creates a new pipeline-level rate limiter from configuration
 func NewRateLimiter(cfg config.RateLimitConfig, logger *log.Logger) (*RateLimiter, error) {
+	// Rate <= 0 means disabled
 	if cfg.Rate <= 0 {
 		return nil, nil // No rate limit
 	}
 
+	// Validate
+	if err := lconfig.NonNegative(cfg.Rate); err != nil {
+		return nil, fmt.Errorf("rate: %w", err)
+	}
+	if err := lconfig.NonNegative(cfg.Burst); err != nil {
+		return nil, fmt.Errorf("burst: %w", err)
+	}
+	if err := lconfig.NonNegative(cfg.MaxEntrySizeBytes); err != nil {
+		return nil, fmt.Errorf("max_entry_size_bytes: %w", err)
+	}
+
+	// Defaults
 	burst := cfg.Burst
 	if burst <= 0 {
-		burst = cfg.Rate // Default burst to rate
+		burst = cfg.Rate
 	}
 
 	var policy config.RateLimitPolicy
 	switch strings.ToLower(cfg.Policy) {
 	case "drop":
 		policy = config.PolicyDrop
-	default:
+	case "pass", "":
 		policy = config.PolicyPass
+	default:
+		return nil, fmt.Errorf("policy: must be one of [drop, pass], got %s", cfg.Policy)
 	}
 
 	l := &RateLimiter{
diff --git a/src/internal/format/adapter.go b/src/internal/format/adapter.go
index 48f332b..373c90e 100644
--- a/src/internal/format/adapter.go
+++ b/src/internal/format/adapter.go
@@ -2,13 +2,20 @@ package format
 
 import (
 	"encoding/json"
+	"fmt"
+
 	"logwisp/src/internal/config"
 	"logwisp/src/internal/core"
 
+	lconfig "github.com/lixenwraith/config"
 	"github.com/lixenwraith/log/formatter"
 	"github.com/lixenwraith/log/sanitizer"
 )
 
+const (
+	DefaultFormatType = "raw"
+)
+
 // FormatterAdapter wraps log/formatter for logwisp compatibility
 type FormatterAdapter struct {
 	formatter *formatter.Formatter
@@ -18,6 +25,26 @@ type FormatterAdapter struct {
 
 // NewFormatterAdapter creates adapter from config
 func NewFormatterAdapter(cfg *config.FormatConfig) (*FormatterAdapter, error) {
+	// Validate
+	if cfg.Type != "" {
+		validateType := lconfig.OneOf("json", "txt", "text", "raw")
+		if err := validateType(cfg.Type); err != nil {
+			return nil, fmt.Errorf("type: %w", err)
+		}
+	}
+
+	if cfg.SanitizerPolicy != "" {
+		validatePolicy := lconfig.OneOf("raw", "json", "txt", "shell")
+		if err := validatePolicy(cfg.SanitizerPolicy); err != nil {
+			return nil, fmt.Errorf("sanitizer_policy: %w", err)
+		}
+	}
+
+	// Defaults
+	if cfg.Type == "" {
+		cfg.Type = DefaultFormatType
+	}
+
 	// Create sanitizer based on policy
 	var s *sanitizer.Sanitizer
 	if cfg.SanitizerPolicy != "" {
@@ -44,7 +71,6 @@ func NewFormatterAdapter(cfg *config.FormatConfig) (*FormatterAdapter, error) {
 	// Build flags from config
 	flags := cfg.Flags
 	if flags == 0 {
-		// Set default flags based on format type
 		if cfg.Type == "raw" {
 			flags = formatter.FlagRaw
 		} else {
diff --git a/src/internal/format/format.go b/src/internal/format/format.go
index 956ee9a..6a3ea81 100644
--- a/src/internal/format/format.go
+++ b/src/internal/format/format.go
@@ -14,17 +14,15 @@ type Formatter interface {
 	Name() string
 }
 
-// NewFormatter creates a Formatter using the new formatter/sanitizer packages
+// NewFormatter creates a Formatter using formatter/sanitizer packages
 func NewFormatter(cfg *config.FormatConfig) (Formatter, error) {
 	if cfg == nil {
-		// Default config
 		cfg = &config.FormatConfig{
-			Type:            "raw",
+			Type:            DefaultFormatType,
 			Flags:           0,
 			SanitizerPolicy: "raw",
 		}
 	}
 
-	// Use the new FormatterAdapter that integrates formatter and sanitizer
 	return NewFormatterAdapter(cfg)
 }
\ No newline at end of file
diff --git a/src/internal/sink/console/console.go b/src/internal/sink/console/console.go
index 97105b6..b03ecba 100644
--- a/src/internal/sink/console/console.go
+++ b/src/internal/sink/console/console.go
@@ -49,6 +49,12 @@ type ConsoleSink struct {
 	lastProcessed  atomic.Value // time.Time
 }
 
+const (
+	// Defaults
+	DefaultConsoleTarget     = "stdout"
+	DefaultConsoleBufferSize = 1000
+)
+
 // NewConsoleSinkPlugin creates a console sink through plugin factory
 func NewConsoleSinkPlugin(
 	id string,
@@ -56,10 +62,7 @@ func NewConsoleSinkPlugin(
 	logger *log.Logger,
 	proxy *session.Proxy,
 ) (sink.Sink, error) {
-	// Create empty config struct with defaults
-	opts := &config.ConsoleSinkOptions{
-		Target: DefaultConsoleTarget,
-	}
+	opts := &config.ConsoleSinkOptions{}
 
 	// Scan config map into struct
 	if err := lconfig.ScanMap(configMap, opts); err != nil {
@@ -67,21 +70,28 @@ func NewConsoleSinkPlugin(
 	}
 
 	// Validate and apply defaults
+	if opts.Target == "" {
+		opts.Target = DefaultConsoleTarget
+	} else {
+		validateTarget := lconfig.OneOf("stdout", "stderr")
+		if err := validateTarget(opts.Target); err != nil {
+			return nil, fmt.Errorf("target: %w", err)
+		}
+	}
+
 	var output io.Writer
 	switch opts.Target {
 	case "stdout":
 		output = os.Stdout
 	case "stderr":
 		output = os.Stderr
-	default:
-		return nil, fmt.Errorf("invalid console target: %s (must be 'stdout' or 'stderr')", opts.Target)
 	}
 
 	if opts.BufferSize <= 0 {
 		opts.BufferSize = DefaultConsoleBufferSize
 	}
 
-	// Step 4: Create and return plugin instance
+	// Create and return plugin instance
 	cs := &ConsoleSink{
 		id:     id,
 		proxy:  proxy,
diff --git a/src/internal/sink/console/const.go b/src/internal/sink/console/const.go
deleted file mode 100644
index a1e2fbc..0000000
--- a/src/internal/sink/console/const.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package console
-
-const (
-	// Defaults
-	DefaultConsoleTarget     = "stdout"
-	DefaultConsoleBufferSize = 1000
-)
\ No newline at end of file
diff --git a/src/internal/sink/file/const.go b/src/internal/sink/file/const.go
deleted file mode 100644
index a6cb39b..0000000
--- a/src/internal/sink/file/const.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package file
-
-const (
-	// Defaults
-	DefaultFileMaxSizeMB       = 100
-	DefaultFileMaxTotalSizeMB  = 1000
-	DefaultFileMinDiskFreeMB   = 100
-	DefaultFileRetentionHours  = 168 // 7 days
-	DefaultFileBufferSize      = 1000
-	DefaultFileFlushIntervalMs = 100
-)
\ No newline at end of file
diff --git a/src/internal/sink/file/file.go b/src/internal/sink/file/file.go
index 0bdef24..088778d 100644
--- a/src/internal/sink/file/file.go
+++ b/src/internal/sink/file/file.go
@@ -47,6 +47,16 @@ type FileSink struct {
 	lastProcessed  atomic.Value // time.Time
 }
 
+const (
+	// Defaults
+	DefaultFileMaxSizeMB       = 100
+	DefaultFileMaxTotalSizeMB  = 1000
+	DefaultFileMinDiskFreeMB   = 100
+	DefaultFileRetentionHours  = 168 // 7 days
+	DefaultFileBufferSize      = 1000
+	DefaultFileFlushIntervalMs = 100
+)
+
 // NewFileSinkPlugin creates a file sink through plugin factory
 func NewFileSinkPlugin(
 	id string,
@@ -62,13 +72,15 @@ func NewFileSinkPlugin(
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Validate required fields and apply defaults
-	if opts.Directory == "" {
-		return nil, fmt.Errorf("directory is required")
+	// Validate
+	if err := lconfig.NonEmpty(opts.Directory); err != nil {
+		return nil, fmt.Errorf("directory: %w", err)
 	}
-	if opts.Name == "" {
-		return nil, fmt.Errorf("name is required")
+	if err := lconfig.NonEmpty(opts.Name); err != nil {
+		return nil, fmt.Errorf("name: %w", err)
 	}
+
+	// Defaults
 	if opts.MaxSizeMB <= 0 {
 		opts.MaxSizeMB = DefaultFileMaxSizeMB
 	}
@@ -88,7 +100,6 @@ func NewFileSinkPlugin(
 		opts.FlushIntervalMs = DefaultFileFlushIntervalMs
 	}
 
-	// Step 4: Create and return plugin instance
 	// Create configuration for the internal log writer
 	writerConfig := log.DefaultConfig()
 	writerConfig.Directory = opts.Directory
diff --git a/src/internal/sink/http/const.go b/src/internal/sink/http/const.go
deleted file mode 100644
index 4eb68e2..0000000
--- a/src/internal/sink/http/const.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package http
-
-import "time"
-
-const (
-	// Server lifecycle
-	HttpServerStartTimeout    = 100 * time.Millisecond
-	HttpServerShutdownTimeout = 2 * time.Second
-
-	// Defaults
-	DefaultHTTPHost       = "0.0.0.0"
-	DefaultHTTPBufferSize = 1000
-	DefaultHTTPStreamPath = "/stream"
-	DefaultHTTPStatusPath = "/status"
-	HTTPMaxPort           = 65535
-)
\ No newline at end of file
diff --git a/src/internal/sink/http/http.go b/src/internal/sink/http/http.go
index 91b6f74..ba05954 100644
--- a/src/internal/sink/http/http.go
+++ b/src/internal/sink/http/http.go
@@ -66,6 +66,19 @@ type HTTPSink struct {
 	lastProcessed  atomic.Value // time.Time
 }
 
+const (
+	// Server lifecycle
+	HttpServerStartTimeout    = 100 * time.Millisecond
+	HttpServerShutdownTimeout = 2 * time.Second
+
+	// Defaults
+	DefaultHTTPHost       = "0.0.0.0"
+	DefaultHTTPBufferSize = 1000
+	DefaultHTTPStreamPath = "/stream"
+	DefaultHTTPStatusPath = "/status"
+	HTTPMaxPort           = 65535
+)
+
 // NewHTTPSinkPlugin creates an HTTP sink through plugin factory
 func NewHTTPSinkPlugin(
 	id string,
@@ -83,10 +96,12 @@ func NewHTTPSinkPlugin(
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Validate and apply defaults
+	// Validate
 	if opts.Port <= 0 || opts.Port > HTTPMaxPort {
 		return nil, fmt.Errorf("port must be between 1 and %d", HTTPMaxPort)
 	}
+
+	// Defaults
 	if opts.BufferSize <= 0 {
 		opts.BufferSize = DefaultHTTPBufferSize
 	}
diff --git a/src/internal/sink/tcp/const.go b/src/internal/sink/tcp/const.go
deleted file mode 100644
index 4d49712..0000000
--- a/src/internal/sink/tcp/const.go
+++ /dev/null
@@ -1,21 +0,0 @@
-package tcp
-
-import (
-	"time"
-)
-
-const (
-	// Server lifecycle
-	TCPServerStartTimeout    = 100 * time.Millisecond
-	TCPServerShutdownTimeout = 2 * time.Second
-
-	// Connection management
-	TCPMaxConsecutiveWriteErrors = 3
-	TCPMaxPort                   = 65535
-
-	// Defaults
-	DefaultTCPHost            = "0.0.0.0"
-	DefaultTCPBufferSize      = 1000
-	DefaultTCPWriteTimeoutMS  = 5000
-	DefaultTCPKeepAlivePeriod = 30000
-)
\ No newline at end of file
diff --git a/src/internal/sink/tcp/tcp.go b/src/internal/sink/tcp/tcp.go
index c890ea8..9436399 100644
--- a/src/internal/sink/tcp/tcp.go
+++ b/src/internal/sink/tcp/tcp.go
@@ -61,6 +61,22 @@ type TCPSink struct {
 	errorMu                sync.Mutex
 }
 
+const (
+	// Server lifecycle
+	TCPServerStartTimeout    = 100 * time.Millisecond
+	TCPServerShutdownTimeout = 2 * time.Second
+
+	// Connection management
+	TCPMaxConsecutiveWriteErrors = 3
+	TCPMaxPort                   = 65535
+
+	// Defaults
+	DefaultTCPHost            = "0.0.0.0"
+	DefaultTCPBufferSize      = 1000
+	DefaultTCPWriteTimeoutMS  = 5000
+	DefaultTCPKeepAlivePeriod = 30000
+)
+
 // NewTCPSinkPlugin creates a TCP sink through plugin factory
 func NewTCPSinkPlugin(
 	id string,
@@ -80,11 +96,12 @@ func NewTCPSinkPlugin(
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Validate required fields
-	// Validate and apply defaults
-	if opts.Port <= 0 || opts.Port > TCPMaxPort {
-		return nil, fmt.Errorf("port must be between 1 and %d", TCPMaxPort)
+	// Validate
+	if err := lconfig.Port(opts.Port); err != nil {
+		return nil, fmt.Errorf("port: %w", err)
 	}
+
+	// Defaults
 	if opts.BufferSize <= 0 {
 		opts.BufferSize = DefaultTCPBufferSize
 	}
diff --git a/src/internal/source/console/console.go b/src/internal/source/console/console.go
index cc2e659..1a43cd5 100644
--- a/src/internal/source/console/console.go
+++ b/src/internal/source/console/console.go
@@ -56,6 +56,10 @@ type ConsoleSource struct {
 	lastEntryTime  atomic.Value // time.Time
 }
 
+const (
+	DefaultConsoleSourceBufferSize = 1000
+)
+
 // NewConsoleSourcePlugin creates a console source through plugin factory
 func NewConsoleSourcePlugin(
 	id string,
@@ -63,22 +67,19 @@ func NewConsoleSourcePlugin(
 	logger *log.Logger,
 	proxy *session.Proxy,
 ) (source.Source, error) {
-	// Step 1: Create empty config struct with defaults
-	opts := &config.ConsoleSourceOptions{
-		BufferSize: 1000, // Default buffer size
-	}
+	opts := &config.ConsoleSourceOptions{}
 
-	// Step 2: Use lconfig to scan map into struct (overriding defaults)
+	// Scan config map
 	if err := lconfig.ScanMap(configMap, opts); err != nil {
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Step 3: Validate required fields
+	// Validate and apply defaults
 	if opts.BufferSize <= 0 {
-		opts.BufferSize = 1000
+		opts.BufferSize = DefaultConsoleSourceBufferSize
 	}
 
-	// Step 4: Create and return plugin instance
+	// Create and return plugin instance
 	cs := &ConsoleSource{
 		id:          id,
 		proxy:       proxy,
@@ -89,7 +90,7 @@ func NewConsoleSourcePlugin(
 	}
 	cs.lastEntryTime.Store(time.Time{})
 
-	// Create session for console
+	// Create session
 	cs.session = proxy.CreateSession(
 		"console_stdin",
 		map[string]any{
diff --git a/src/internal/source/console/const.go b/src/internal/source/console/const.go
deleted file mode 100644
index 178a9d5..0000000
--- a/src/internal/source/console/const.go
+++ /dev/null
@@ -1 +0,0 @@
-package console
\ No newline at end of file
diff --git a/src/internal/source/file/file.go b/src/internal/source/file/file.go
index c02c7bb..aa5f69f 100644
--- a/src/internal/source/file/file.go
+++ b/src/internal/source/file/file.go
@@ -57,6 +57,12 @@ type FileSource struct {
 	lastEntryTime  atomic.Value // time.Time
 }
 
+const (
+	DefaultFileSourcePattern         = "*"
+	DefaultFileSourceCheckIntervalMS = 100
+	MinFileSourceCheckIntervalMS     = 10
+)
+
 // NewFileSourcePlugin creates a file source through plugin factory
 func NewFileSourcePlugin(
 	id string,
@@ -64,28 +70,28 @@ func NewFileSourcePlugin(
 	logger *log.Logger,
 	proxy *session.Proxy,
 ) (source.Source, error) {
-	// Step 1: Create empty config struct with defaults
-	opts := &config.FileSourceOptions{
-		Directory:       "",  // Required field - no default
-		Pattern:         "*", // Default pattern
-		CheckIntervalMS: 100, // Default check interval
-	}
+	opts := &config.FileSourceOptions{}
 
-	// Step 2: Use lconfig to scan map into struct (overriding defaults)
+	// Use lconfig to scan map into struct (overriding defaults)
 	if err := lconfig.ScanMap(configMap, opts); err != nil {
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Step 3: Validate required fields
-	if opts.Directory == "" {
-		return nil, fmt.Errorf("directory is mandatory")
+	// Validate and apply defaults
+	if err := lconfig.NonEmpty(opts.Directory); err != nil {
+		return nil, fmt.Errorf("directory: %w", err)
 	}
 
-	if opts.CheckIntervalMS < 10 {
-		return nil, fmt.Errorf("check_interval_ms must be at least 10ms")
+	if opts.Pattern == "" {
+		opts.Pattern = DefaultFileSourcePattern
+	}
+	if opts.CheckIntervalMS <= 0 {
+		opts.CheckIntervalMS = DefaultFileSourceCheckIntervalMS
+	} else if opts.CheckIntervalMS < MinFileSourceCheckIntervalMS {
+		return nil, fmt.Errorf("check_interval_ms: must be >= %d", MinFileSourceCheckIntervalMS)
 	}
 
-	// Step 4: Create and return plugin instance
+	// Create and return plugin instance
 	fs := &FileSource{
 		id:          id,
 		proxy:       proxy,
diff --git a/src/internal/source/random/random.go b/src/internal/source/random/random.go
index 594898a..2dd1850 100644
--- a/src/internal/source/random/random.go
+++ b/src/internal/source/random/random.go
@@ -53,6 +53,12 @@ type RandomSource struct {
 	lastEntryTime  atomic.Value // time.Time
 }
 
+const (
+	DefaultRandomSourceIntervalMS = 500
+	DefaultRandomSourceFormat     = "txt"
+	DefaultRandomSourceLength     = 20
+)
+
 // NewRandomSourcePlugin creates a random source through plugin factory
 func NewRandomSourcePlugin(
 	id string,
@@ -69,26 +75,33 @@ func NewRandomSourcePlugin(
 		Special:    false,
 	}
 
-	// Step 2: Use lconfig to scan map into struct (overriding defaults)
+	// Scan config map
 	if err := lconfig.ScanMap(configMap, opts); err != nil {
 		return nil, fmt.Errorf("failed to parse config: %w", err)
 	}
 
-	// Step 3: Validate
+	// Defaults
 	if opts.IntervalMS <= 0 {
-		return nil, fmt.Errorf("interval_ms must be positive")
+		opts.IntervalMS = DefaultRandomSourceIntervalMS
 	}
+	if opts.Format == "" {
+		opts.Format = DefaultRandomSourceFormat
+	}
+	if opts.Length <= 0 {
+		opts.Length = DefaultRandomSourceLength
+	}
+
+	// Validate
 	if opts.JitterMS < 0 {
 		return nil, fmt.Errorf("jitter_ms cannot be negative")
 	}
 	if opts.JitterMS > opts.IntervalMS {
 		opts.JitterMS = opts.IntervalMS
 	}
-	if opts.Length <= 0 {
-		return nil, fmt.Errorf("length must be positive")
-	}
-	if opts.Format != "raw" && opts.Format != "txt" && opts.Format != "json" {
-		return nil, fmt.Errorf("format must be 'raw', 'txt', or 'json'")
+
+	validateFormat := lconfig.OneOf("raw", "txt", "json")
+	if err := validateFormat(opts.Format); err != nil {
+		return nil, fmt.Errorf("format: %w", err)
 	}
 
 	rs := &RandomSource{