style(tools): unify console output with [I/W/E] [Module] color-coded format

- Add ANSI color coding: [I]=green, [W]=yellow, [E]=red
- Format: [Level] [Module] message with 4-char indent for data rows
- Error detail lines use |-> tree connector
- Remove extra blank lines between outputs (except list)
- Modules: CLI, Preview, Builder, Server, Watcher

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/cli/create.go

@@ -49,7 +49,7 @@ func runCreate(c *cli.Context) error {
 
 		if info, err := os.Stat(styleDir); err == nil {
 			if info.IsDir() {
-				fmt.Printf("  [skip] '%s' already exists\n", styleName)
+				fmt.Printf("\033[32m[I]\033[0m [CLI] '%s' already exists, skipped\n", styleName)
 				continue
 			}
 			return fmt.Errorf("'%s' exists but is not a directory", styleName)
@@ -79,7 +79,7 @@ func runCreate(c *cli.Context) error {
 			created++
 		}
 
-		fmt.Printf("  Created style '%s' with %d template files\n", styleName, created)
+		fmt.Printf("\033[32m[I]\033[0m [CLI] Created style '%s' with %d template files\n", styleName, created)
 	}
 
 	return nil

tools/cli/delete.go

@@ -37,14 +37,14 @@ func runDelete(c *cli.Context) error {
 		styleDir := filepath.Join(folder, styleName)
 
 		if _, err := os.Stat(styleDir); os.IsNotExist(err) {
-			fmt.Printf("  [skip] '%s' does not exist\n", styleName)
+			fmt.Printf("\033[33m[W]\033[0m [CLI] '%s' does not exist, skipped\n", styleName)
 			continue
 		}
 
 		if err := os.RemoveAll(styleDir); err != nil {
 			return fmt.Errorf("cannot delete %s: %w", styleDir, err)
 		}
-		fmt.Printf("  Deleted style '%s'\n", styleName)
+		fmt.Printf("\033[32m[I]\033[0m [CLI] Deleted style '%s'\n", styleName)
 	}
 
 	return nil

tools/cli/dev.go

@@ -48,7 +48,7 @@ func runDev(c *cli.Context) error {
 
 	// Verify node_modules are installed
 	if _, err := os.Stat(filepath.Join(serverDir, "node_modules")); os.IsNotExist(err) {
-		fmt.Println("Installing Node.js dependencies...")
+		fmt.Println("\033[32m[I]\033[0m [Builder] Installing Node.js dependencies...")
 		cmd := exec.Command("npm", "install")
 		cmd.Dir = serverDir
 		cmd.Stdout = os.Stdout
@@ -64,7 +64,7 @@ func runDev(c *cli.Context) error {
 	initCmd.Stdout = os.Stdout
 	initCmd.Stderr = os.Stderr
 	if err := initCmd.Run(); err != nil {
-		fmt.Println("Warning: initial preview generation failed, starting anyway...")
+		fmt.Println("\033[33m[W]\033[0m [Builder] Initial preview generation failed, starting anyway")
 	}
 
 	// Start the Node.js dev server
@@ -78,8 +78,8 @@ func runDev(c *cli.Context) error {
 		return fmt.Errorf("failed to start dev server: %w", err)
 	}
 
-	fmt.Printf("\nDev server running at http://localhost:%d\n", port)
-	fmt.Print("Press Ctrl+C to stop.\n\n")
+	fmt.Printf("\033[32m[I]\033[0m [Server] Dev server running at http://localhost:%d\n", port)
+	fmt.Print("\033[32m[I]\033[0m [Server] Press Ctrl+C to stop\n")
 
 	// Handle graceful shutdown
 	sigCh := make(chan os.Signal, 1)
@@ -87,7 +87,7 @@ func runDev(c *cli.Context) error {
 
 	go func() {
 		<-sigCh
-		fmt.Println("\nShutting down...")
+		fmt.Println("\033[32m[I]\033[0m [Server] Shutting down")
 		if err := serverCmd.Process.Signal(os.Interrupt); err != nil {
 			serverCmd.Process.Kill()
 		}

tools/cli/list.go

@@ -37,7 +37,7 @@ func runList(c *cli.Context) error {
 	}
 
 	absDir, _ := filepath.Abs(folder)
-	fmt.Printf("Available styles in '%s' (%d):\n", filepath.Base(absDir), len(themes))
+	fmt.Printf("\033[32m[I]\033[0m [Preview] Available styles in '%s' (%d):\n", filepath.Base(absDir), len(themes))
 
 	sort.Strings(themes)
 	for _, t := range themes {
@@ -51,7 +51,7 @@ func runList(c *cli.Context) error {
 			}
 			return nil
 		})
-		fmt.Printf("  %-16s (%d .tmpl files)\n", t, count)
+		fmt.Printf("\033[32m[I]\033[0m [Preview]    %-16s (%d .tmpl files)\n", t, count)
 	}
 	return nil
 }

tools/cli/preview.go

@@ -2,7 +2,6 @@ package cli
 
 import (
 	"fmt"
-	"log"
 	"path/filepath"
 
 	"github.com/urfave/cli/v2"
@@ -78,7 +77,7 @@ func runPreview(c *cli.Context) error {
 
 	preview.PrintDetailedSummary(result, folder, cfg)
 
-	log.Printf("Wrote %d themes x %d templates to %s",
+	fmt.Printf("\033[32m[I]\033[0m [Preview] Wrote %d themes x %d templates to %s\n",
 		len(result.Summaries), len(cfg.Templates), outputPath)
 
 	return nil

tools/preview/engine.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"html/template"
-	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -67,7 +66,7 @@ func DiscoverThemes(themesDir string) ([]string, error) {
 func RenderAll(themesDir string, cfg *config.TemplatesConfig, themeFilter map[string]bool) *PreviewResult {
 	themes, err := DiscoverThemes(themesDir)
 	if err != nil {
-		log.Printf("ERROR: %v", err)
+		fmt.Fprintf(os.Stderr, "\033[31m[E]\033[0m [Preview] Error discovering themes: %v\n", err)
 		return nil
 	}
 
@@ -81,7 +80,7 @@ func RenderAll(themesDir string, cfg *config.TemplatesConfig, themeFilter map[st
 		}
 		themes = filtered
 		if len(themes) == 0 {
-			log.Printf("WARN: no themes matched the requested filter")
+			fmt.Println("\033[33m[W]\033[0m [Preview] No themes matched the requested filter")
 			return nil
 		}
 	}
@@ -249,36 +248,35 @@ func WriteRenderedJS(result *PreviewResult, outputPath string) error {
 // PrintDetailedSummary prints a human-readable summary of the preview results.
 func PrintDetailedSummary(result *PreviewResult, themesDir string, cfg *config.TemplatesConfig) {
 	absDir, _ := filepath.Abs(themesDir)
-	fmt.Printf("\nfound %d styles of possible Gitea mail template in '%s' folder:\n\n",
+	fmt.Printf("\033[32m[I]\033[0m [Preview] Found %d styles in '%s':\n",
 		len(result.Summaries), filepath.Base(absDir))
 
 	for _, s := range result.Summaries {
 		if s.MissingCount == 0 && s.ErrorCount == 0 {
-			fmt.Printf("    %-16s all required mail templates are properly rendered, (total %d .tmpl files, %s after, %v)\n",
+			fmt.Printf("\033[32m[I]\033[0m [Preview]    %-16s all required templates OK (total %d .tmpl, %s, %v)\n",
 				s.Name, s.TotalFiles,
 				formatSize(s.RenderedSize),
 				s.RenderDuration.Round(time.Millisecond))
 		} else {
-			fmt.Printf("    %-16s only %d required mail templates are properly rendered:\n",
+			fmt.Printf("\033[33m[W]\033[0m [Preview]    %-16s only %d required templates rendered:\n",
 				s.Name, s.RenderedCount)
 			for _, tplID := range s.Missing {
 				if t, ok := cfg.Templates[tplID]; ok {
-					fmt.Printf("        [%s] not found, expected at 'themes/%s/%s'\n",
+					fmt.Printf("\033[31m[E]\033[0m [Preview]    |-> %s not found, expected at 'themes/%s/%s'\n",
 						filepath.Base(t.PathStr()), s.Name, t.PathStr())
 				} else {
-					fmt.Printf("        [%s] not found\n", tplID)
+					fmt.Printf("\033[31m[E]\033[0m [Preview]    |-> %s not found\n", tplID)
 				}
 			}
 			for _, tplID := range s.Errors {
 				if rr, ok := s.Results[tplID]; ok && rr.Error != "" {
-					fmt.Printf("        [%s] render error: %s\n", tplID, rr.Error)
+					fmt.Printf("\033[31m[E]\033[0m [Preview]    |-> %s render error: %s\n", tplID, rr.Error)
 				} else {
-					fmt.Printf("        [%s] render error\n", tplID)
+					fmt.Printf("\033[31m[E]\033[0m [Preview]    |-> %s render error\n", tplID)
 				}
 			}
 		}
 	}
-	fmt.Println()
 }
 
 // markSafeHTML recursively converts known HTML-containing string fields to

tools/server/server.mjs

@@ -8,6 +8,15 @@ import expressWs from 'express-ws';
 
 import { inlineCSS, stripGmail, stripOutlook } from './inliner.mjs';
 
+// ANSI color helpers
+const G = '\x1b[32m';   // green (Info)
+const Y = '\x1b[33m';   // yellow (Warn)
+const R = '\x1b[31m';   // red (Error)
+const Z = '\x1b[0m';    // reset
+const I = `${G}[I]${Z}`;
+const W = `${Y}[W]${Z}`;
+const E = `${R}[E]${Z}`;
+
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const ROOT = resolve(__dirname, '..', '..');       // project root
 const TOOLS = join(ROOT, 'tools');                   // tools/ (for go run)
@@ -55,13 +64,13 @@ async function rebuild() {
   CHANGED_THEMES.clear();
 
   const start = Date.now();
-  console.log(`\n[rebuild] ${themes.length > 0 ? themes.join(', ') : 'all'} changed`);
+  console.log(`${I} [Builder] Rebuilding: ${themes.length > 0 ? themes.join(', ') : 'all'} changed`);
 
   // Step 1: Go render
   try {
     await goPreview(themes.length > 0 ? themes : ['all']);
   } catch (err) {
-    console.error('[rebuild] go render failed:', err.message);
+    console.error(`${E} [Builder] Go render failed: ${err.message}`);
     building = false;
     broadcast('error', { message: err.message });
     return;
@@ -73,11 +82,11 @@ async function rebuild() {
     const juiced = await juiceRenderedOutput(renderedJS);
     writeFileSync(RENDERED_JS, juiced, 'utf8');
   } catch (err) {
-    console.error('[rebuild] juice step failed:', err.message);
+    console.error(`${E} [Builder] Juice step failed: ${err.message}`);
   }
 
   const elapsed = Date.now() - start;
-  console.log(`[rebuild] done in ${elapsed}ms`);
+  console.log(`${I} [Builder] Rebuild done in ${elapsed}ms`);
 
   building = false;
 
@@ -190,19 +199,19 @@ try {
     const fullPath = join(THEMES, fname);
     // event is 'rename' for both create and delete; 'change' for modifications
     if (event === 'change') {
-      console.log('[watch] ' + relPath(fullPath) + ' edited');
+      console.log(`${I} [Watcher] ${relPath(fullPath)} changed`);
       scheduleRebuild(fullPath);
     } else if (event === 'rename') {
       if (existsSync(fullPath)) {
-        console.log('[watch] ' + relPath(fullPath) + ' created');
+        console.log(`${I} [Watcher] ${relPath(fullPath)} created`);
       } else {
-        console.log('[watch] ' + relPath(fullPath) + ' deleted');
+        console.log(`${I} [Watcher] ${relPath(fullPath)} deleted`);
       }
     }
   });
-  console.log('[watch] themes/ (recursive)');
+  console.log(`${I} [Watcher] Watching themes/ (recursive)`);
 } catch (err) {
-  console.error('[watch] failed:', err.message);
+  console.error(`${E} [Watcher] File watch failed: ${err.message}`);
 }
 
 // Initial Juice pass
@@ -213,9 +222,9 @@ try {
     const js = readFileSync(RENDERED_JS, 'utf8');
     const juiced = await juiceRenderedOutput(js);
     writeFileSync(RENDERED_JS, juiced, 'utf8');
-    console.log('[init] juice inlining applied');
+    console.log(`${I} [Builder] CSS inlining applied`);
   } catch (err) {
-    console.error('[init] juice failed:', err.message);
+    console.error(`${E} [Builder] CSS inlining failed: ${err.message}`);
   }
 })();
 
@@ -223,8 +232,8 @@ try {
 app.get('/health', (_req, res) => res.json({ status: 'ok', port: PORT }));
 
 app.listen(PORT, () => {
-  console.log(`\n  Gitea Mail Templates — Dev Server`);
-  console.log(`  http://localhost:${PORT}\n`);
-  console.log(`  Watching themes/ for changes...`);
-  console.log(`  WebSocket  ws://localhost:${PORT}/ws`);
+  console.log(`${I} [Server] Gitea Mail Templates — Dev Server`);
+  console.log(`${I} [Server] http://localhost:${PORT}`);
+  console.log(`${I} [Watcher] Watching themes/ for changes`);
+  console.log(`${I} [Server] WebSocket ws://localhost:${PORT}/ws\n`);
 });

tools/tools.go

@@ -24,7 +24,7 @@ func main() {
 	}
 
 	if err := app.Run(os.Args); err != nil {
-		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		fmt.Fprintf(os.Stderr, "\033[31m[E]\033[0m [CLI] %v\n", err)
 		os.Exit(1)
 	}
 }