diff --git a/cmd/lapp/analyze.go b/cmd/lapp/analyze.go
index 65ab2ae..5d6ef8e 100644
--- a/cmd/lapp/analyze.go
+++ b/cmd/lapp/analyze.go
@@ -2,7 +2,7 @@ package main
 
 import (
 	"bufio"
-	"fmt"
+	"log/slog"
 	"os"
 	"strings"
 
@@ -47,7 +47,7 @@ func runAnalyze(cmd *cobra.Command, args []string) error {
 	}
 
 	// Read all lines
-	fmt.Fprintf(os.Stderr, "Reading logs...\n")
+	slog.Info("Reading logs...")
 	lines, err := readLines(logFile)
 	if err != nil {
 		return errors.Errorf("read log file: %w", err)
@@ -61,7 +61,7 @@ func runAnalyze(cmd *cobra.Command, args []string) error {
 	for i, m := range merged {
 		mergedLines[i] = m.Content
 	}
-	fmt.Fprintf(os.Stderr, "Read %d lines, merged into %d entries\n", len(lines), len(mergedLines))
+	slog.Info("Read lines", "lines", len(lines), "merged_entries", len(mergedLines))
 
 	config := analyzer.Config{
 		APIKey: apiKey,
@@ -73,7 +73,7 @@ func runAnalyze(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	fmt.Println(result)
+	slog.Info(result)
 	return nil
 }
 
diff --git a/cmd/lapp/debug.go b/cmd/lapp/debug.go
index 2516fb3..2ba74be 100644
--- a/cmd/lapp/debug.go
+++ b/cmd/lapp/debug.go
@@ -1,7 +1,7 @@
 package main
 
 import (
-	"fmt"
+	"log/slog"
 	"os"
 
 	"github.com/go-errors/errors"
@@ -41,7 +41,7 @@ files (raw.log, summary.txt, errors.txt) in a local directory for inspection.`,
 func runDebugWorkspace(cmd *cobra.Command, args []string) error {
 	logFile := args[0]
 
-	fmt.Fprintf(os.Stderr, "Reading logs...\n")
+	slog.Info("Reading logs...")
 	lines, err := readLines(logFile)
 	if err != nil {
 		return errors.Errorf("read log file: %w", err)
@@ -55,7 +55,7 @@ func runDebugWorkspace(cmd *cobra.Command, args []string) error {
 	for i, m := range merged {
 		mergedLines[i] = m.Content
 	}
-	fmt.Fprintf(os.Stderr, "Read %d lines, merged into %d entries\n", len(lines), len(mergedLines))
+	slog.Info("Read lines", "lines", len(lines), "merged_entries", len(mergedLines))
 
 	outDir := debugWorkspaceOutput
 	if outDir == "" {
@@ -74,7 +74,7 @@ func runDebugWorkspace(cmd *cobra.Command, args []string) error {
 		return errors.Errorf("drain parser: %w", err)
 	}
 
-	fmt.Fprintf(os.Stderr, "Parsing %d entries...\n", len(mergedLines))
+	slog.Info("Parsing entries", "count", len(mergedLines))
 	if err := drainParser.Feed(mergedLines); err != nil {
 		return errors.Errorf("drain feed: %w", err)
 	}
@@ -87,8 +87,7 @@ func runDebugWorkspace(cmd *cobra.Command, args []string) error {
 		return errors.Errorf("build workspace: %w", err)
 	}
 
-	fmt.Fprintf(os.Stderr, "Workspace created at: %s\n", outDir)
-	fmt.Println(outDir)
+	slog.Info("Workspace created", "dir", outDir)
 	return nil
 }
 
@@ -130,12 +129,12 @@ func runDebugRun(cmd *cobra.Command, args []string) error {
 		Model:  debugRunModel,
 	}
 
-	fmt.Fprintf(os.Stderr, "Running agent on workspace: %s\n", workDir)
+	slog.Info("Running agent on workspace", "dir", workDir)
 	result, err := analyzer.RunAgent(cmd.Context(), config, workDir, question)
 	if err != nil {
 		return err
 	}
 
-	fmt.Println(result)
+	slog.Info(result)
 	return nil
 }
diff --git a/cmd/lapp/ingest.go b/cmd/lapp/ingest.go
index a3c6bca..38a91da 100644
--- a/cmd/lapp/ingest.go
+++ b/cmd/lapp/ingest.go
@@ -2,7 +2,7 @@ package main
 
 import (
 	"context"
-	"fmt"
+	"log/slog"
 	"os"
 	"time"
 
@@ -97,9 +97,12 @@ func runIngest(cmd *cobra.Command, args []string, model string) error {
 		return err
 	}
 
-	fmt.Fprintf(os.Stderr, "Ingested %d lines, discovered %d patterns (%d with 2+ matches)\n",
-		len(lines), templateCount, patternCount)
-	fmt.Fprintf(os.Stderr, "Database: %s\n", dbPath)
+	slog.Info("Ingestion complete",
+		"lines", len(lines),
+		"templates", templateCount,
+		"patterns_with_2+_matches", patternCount,
+	)
+	slog.Info("Database stored", "path", dbPath)
 	return nil
 }
 
@@ -148,7 +151,7 @@ func discoverAndSavePatterns(
 	// Build labeler inputs with sample lines from in-memory data
 	inputs := buildLabelInputs(filtered, lines)
 
-	fmt.Fprintf(os.Stderr, "Labeling %d patterns...\n", len(inputs))
+	slog.Info("Labeling patterns", "count", len(inputs))
 
 	labels, err := semantic.Label(ctx, labelCfg, inputs)
 	if err != nil {
diff --git a/cmd/lapp/templates.go b/cmd/lapp/templates.go
index b50b38c..99a5158 100644
--- a/cmd/lapp/templates.go
+++ b/cmd/lapp/templates.go
@@ -1,7 +1,7 @@
 package main
 
 import (
-	"fmt"
+	"log/slog"
 
 	"github.com/go-errors/errors"
 	"github.com/spf13/cobra"
@@ -45,8 +45,6 @@ func runTemplates(cmd *cobra.Command, _ []string) error {
 	}
 
 	if hasLabels {
-		fmt.Printf("%-12s %-6s %-22s %-6s %s\n", "ID", "TYPE", "SEMANTIC_ID", "COUNT", "DESCRIPTION")
-		fmt.Println("------------ ------ ---------------------- ------ ----------------------------------------")
 		for _, ts := range summaries {
 			semanticID := ts.SemanticID
 			if semanticID == "" {
@@ -60,17 +58,26 @@ func runTemplates(cmd *cobra.Command, _ []string) error {
 			if pType == "" {
 				pType = "-"
 			}
-			fmt.Printf("%-12s %-6s %-22s %-6d %s\n", ts.PatternUUIDString, pType, semanticID, ts.Count, desc)
+			slog.Info("template",
+				"id", ts.PatternUUIDString,
+				"type", pType,
+				"semantic_id", semanticID,
+				"count", ts.Count,
+				"description", desc,
+			)
 		}
 	} else {
-		fmt.Printf("%-12s %-6s %-6s %s\n", "ID", "TYPE", "COUNT", "PATTERN")
-		fmt.Println("------------ ------ ------ ----------------------------------------")
 		for _, ts := range summaries {
 			pType := ts.PatternType
 			if pType == "" {
 				pType = "-"
 			}
-			fmt.Printf("%-12s %-6s %-6d %s\n", ts.PatternUUIDString, pType, ts.Count, ts.Pattern)
+			slog.Info("template",
+				"id", ts.PatternUUIDString,
+				"type", pType,
+				"count", ts.Count,
+				"pattern", ts.Pattern,
+			)
 		}
 	}
 	return nil
diff --git a/pkg/analyzer/analyzer.go b/pkg/analyzer/analyzer.go
index e785cbb..eb034c8 100644
--- a/pkg/analyzer/analyzer.go
+++ b/pkg/analyzer/analyzer.go
@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -73,7 +74,7 @@ func Analyze(ctx context.Context, config Config, lines []string, question string
 		return "", errors.Errorf("drain parser: %w", err)
 	}
 
-	fmt.Fprintf(os.Stderr, "Parsing %d lines...\n", len(lines))
+	slog.Info("Parsing lines", "count", len(lines))
 	if err := drainParser.Feed(lines); err != nil {
 		return "", errors.Errorf("drain feed: %w", err)
 	}
@@ -98,7 +99,7 @@ func RunAgent(ctx context.Context, config Config, workDir, question string) (str
 		return "", errors.Errorf("resolve workspace dir: %w", err)
 	}
 
-	fmt.Fprintf(os.Stderr, "Analyzing with model %s...\n", config.Model)
+	slog.Info("Analyzing with model", "model", config.Model)
 
 	// Preflight check: verify API key works
 	if err := preflightCheck(ctx, config); err != nil {