diff --git a/cli/analyze.go b/cli/analyze.go
index 169a331..fb40ece 100644
--- a/cli/analyze.go
+++ b/cli/analyze.go
@@ -2,7 +2,6 @@ package cli
 
 import (
 	"fmt"
-	"log"
 	"time"
 
 	"github.com/bubunyo/buildgraph/pkg/diff"
@@ -21,7 +20,7 @@ and outputs which services are affected by the detected changes.`,
 }
 
 func init() {
-	analyzeCmd.Flags().StringP("format", "f", "json", "Output format: json, text")
+	analyzeCmd.Flags().StringP("format", "f", "text", "Output format: text, json")
 	analyzeCmd.Flags().StringP("output", "o", "", "Output file (default: stdout)")
 	analyzeCmd.Flags().BoolP("verbose", "v", false, "Include debug info in output")
 	analyzeCmd.Flags().Bool("no-cache", false, "Ignore baseline, treat everything as new")
@@ -41,8 +40,6 @@ func runAnalyze(cmd *cobra.Command, _ []string) error {
 		return fmt.Errorf("detecting root module: %w", err)
 	}
 
-	log.Printf("Analyzing project: %s", rootModule)
-
 	// Load baseline before parsing so unchanged functions can reuse stored hashes.
 	var previousBaseline *types.Baseline
 	noCache, _ := cmd.Flags().GetBool("no-cache")
@@ -91,11 +88,5 @@ func runAnalyze(cmd *cobra.Command, _ []string) error {
 	output, _ := cmd.Flags().GetString("output")
 	writeOutput(result, format, output)
 
-	if len(changes) > 0 {
-		log.Printf("Changes detected: %d", len(changes))
-		log.Printf("Services to build: %v", impactResult.ServicesToBuild)
-	} else {
-		log.Printf("No changes detected")
-	}
 	return nil
 }
diff --git a/cli/output.go b/cli/output.go
index d9dfe94..1a7fa4f 100644
--- a/cli/output.go
+++ b/cli/output.go
@@ -3,7 +3,6 @@ package cli
 import (
 	"encoding/json"
 	"fmt"
-	"log"
 	"os"
 	"sort"
 	"strings"
@@ -22,13 +21,15 @@ func writeOutput(result *types.Result, format, outputPath string) {
 		var marshalErr error
 		output, marshalErr = json.MarshalIndent(result, "", "  ")
 		if marshalErr != nil {
-			log.Fatalf("failed to marshal result to JSON: %v", marshalErr)
+			fmt.Fprintf(os.Stderr, "failed to marshal result to JSON: %v\n", marshalErr)
+			os.Exit(1)
 		}
 	}
 
 	if outputPath != "" {
 		if err := os.WriteFile(outputPath, output, 0644); err != nil {
-			log.Fatalf("failed to write output: %v", err)
+			fmt.Fprintf(os.Stderr, "failed to write output: %v\n", err)
+			os.Exit(1)
 		}
 		return
 	}
@@ -45,7 +46,7 @@ func formatText(result *types.Result) string {
 	if len(result.Changes) > 0 {
 		fmt.Fprintf(sb, "Changes (%d):\n", len(result.Changes))
 		for _, c := range result.Changes {
-			fmt.Fprintf(sb, "  [%-20s] %s\n", c.Type, c.Function)
+			fmt.Fprintf(sb, "  [%s] %s\n", c.Type, c.Function)
 			if c.Reason != "" {
 				fmt.Fprintf(sb, "    reason : %s\n", c.Reason)
 			}
diff --git a/cli/pipeline.go b/cli/pipeline.go
index c53a040..b87dd8c 100644
--- a/cli/pipeline.go
+++ b/cli/pipeline.go
@@ -2,7 +2,6 @@ package cli
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -30,12 +29,12 @@ func parseProject(
 ) {
 	a := analyzer.New(cfg, rootModule, rootPath)
 
-	log.Printf("Loading packages…")
+	fmt.Fprintln(os.Stderr, "Loading packages…")
 	if err = a.Load(); err != nil {
 		return
 	}
 
-	log.Printf("Building call graph…")
+	fmt.Fprintln(os.Stderr, "Building call graph…")
 	functions, graph, err = a.BuildGraph()
 	if err != nil {
 		return
@@ -48,14 +47,14 @@ func parseProject(
 		prevFuncHashes = prevBaseline.FunctionHashes
 	}
 
-	log.Printf("Computing hashes for %d functions…", len(functions))
+	fmt.Fprintf(os.Stderr, "Computing hashes for %d functions…\n", len(functions))
 	if err = a.ComputeHashes(functions, prevSrcHashes, prevFuncHashes); err != nil {
 		return
 	}
 
 	extDeps, extHash, err = a.ExtractExternalDeps()
 	if err != nil {
-		log.Printf("Warning: could not extract external deps: %v", err)
+		fmt.Fprintf(os.Stderr, "Warning: could not extract external deps: %v\n", err)
 		extDeps = map[string]string{}
 		extHash = ""
 		err = nil //nolint:ineffassign
@@ -63,7 +62,7 @@ func parseProject(
 
 	sourceHashes, err = a.ComputeSourceHashes()
 	if err != nil {
-		log.Printf("Warning: could not compute source hashes: %v", err)
+		fmt.Fprintf(os.Stderr, "Warning: could not compute source hashes: %v\n", err)
 		sourceHashes = map[string]string{}
 		err = nil //nolint:ineffassign
 	}
diff --git a/cli/root.go b/cli/root.go
index 8c5ea90..739e4b0 100644
--- a/cli/root.go
+++ b/cli/root.go
@@ -4,7 +4,7 @@ package cli
 
 import (
 	"errors"
-	"log"
+	"fmt"
 	"os"
 	"strings"
 
@@ -71,7 +71,8 @@ func initConfig() {
 		// errors.Is(err, os.ErrNotExist) to correctly catch the missing-file
 		// case and only fatal on genuine read errors (bad permissions, etc.).
 		if !errors.Is(err, os.ErrNotExist) {
-			log.Fatalf("error reading config file %s: %v", cfgFile, err)
+			fmt.Fprintf(os.Stderr, "error reading config file %s: %v\n", cfgFile, err)
+			os.Exit(1)
 		}
 	}
 }
@@ -80,7 +81,8 @@ func initConfig() {
 func loadConfig() *config.Config {
 	cfg := config.Default()
 	if err := viper.Unmarshal(cfg); err != nil {
-		log.Fatalf("invalid configuration: %v", err)
+		fmt.Fprintf(os.Stderr, "invalid configuration: %v\n", err)
+		os.Exit(1)
 	}
 	if len(cfg.Services) == 0 {
 		cfg.Services = config.Default().Services
diff --git a/pkg/impact/impact.go b/pkg/impact/impact.go
index db72af8..718595c 100644
--- a/pkg/impact/impact.go
+++ b/pkg/impact/impact.go
@@ -27,7 +27,6 @@ func (a *Analyzer) ComputeImpact(changes []types.Change) types.Impact {
 		AffectedFunctions: make(map[string][]string),
 		AffectReasons:     make(map[string][]string),
 		ServicesToBuild:   []string{},
-		Changes:           changes,
 	}
 
 	// Get initial changed functions
diff --git a/pkg/types/types.go b/pkg/types/types.go
index 36ead50..56d6675 100644
--- a/pkg/types/types.go
+++ b/pkg/types/types.go
@@ -70,10 +70,9 @@ type Change struct {
 }
 
 type Impact struct {
-	AffectedFunctions map[string][]string `json:"affected_functions"`
-	AffectReasons     map[string][]string `json:"affect_reasons"`
+	AffectedFunctions map[string][]string `json:"-"`
+	AffectReasons     map[string][]string `json:"-"`
 	ServicesToBuild   []string            `json:"services_to_build"`
-	Changes           []Change            `json:"changes"`
 }
 
 type DebugInfo struct {