perf: fix CompileSimpleWorkflow regression (+177.5% slowdown)

pkg/workflow/claude_engine.go

@@ -423,7 +423,9 @@ func (e *ClaudeEngine) GetExecutionSteps(workflowData *WorkflowData, logFile str
 	stepLines = append(stepLines, "        id: agentic_execution")
 
 	// Add allowed tools comment before the run section
-	allowedToolsComment := e.generateAllowedToolsComment(e.computeAllowedClaudeToolsString(toolsWithMountedCLIs, workflowData.SafeOutputs, workflowData.CacheMemoryConfig, workflowData.MCPScripts), "        ")
+	// Reuse the already-computed allowedTools string (computed earlier for --allowed-tools flag)
+	// to avoid redundant allocations from calling computeAllowedClaudeToolsString twice.
+	allowedToolsComment := e.generateAllowedToolsComment(allowedTools, "        ")
 	if allowedToolsComment != "" {
 		// Split the comment into lines and add each line
 		commentLines := strings.Split(strings.TrimSuffix(allowedToolsComment, "\n"), "\n")

pkg/workflow/claude_tools.go

@@ -463,10 +463,27 @@ func (e *ClaudeEngine) generateAllowedToolsComment(allowedToolsStr string, inden
 		return ""
 	}
 
+	// Pre-size the builder using the exact output size:
+	//   - header line:  indent + "# Allowed tools (sorted):\n"
+	//   - per tool:     indent + "# - " + toolName + "\n"
+	// allowedToolsStr is comma-separated, so subtracting (len(tools)-1) gives the
+	// total bytes contributed by tool names alone.
+	toolNameBytes := len(allowedToolsStr) - (len(tools) - 1)
 	var comment strings.Builder
-	comment.WriteString(indent + "# Allowed tools (sorted):\n")
+	comment.Grow(
+		len(indent) +
+			len("# Allowed tools (sorted):\n") +
+			len(tools)*len(indent) +
+			len(tools)*len("# - \n") +
+			toolNameBytes,
+	)
+	comment.WriteString(indent)
+	comment.WriteString("# Allowed tools (sorted):\n")
 	for _, tool := range tools {
-		fmt.Fprintf(&comment, "%s# - %s\n", indent, tool)
+		comment.WriteString(indent)
+		comment.WriteString("# - ")
+		comment.WriteString(tool)
+		comment.WriteByte('\n')
 	}
 
 	return comment.String()

pkg/workflow/features.go

@@ -17,40 +17,51 @@ var featuresLog = logger.New("workflow:features")
 // If workflowData is nil or has no features, it falls back to checking the environment variable only.
 func isFeatureEnabled(flag constants.FeatureFlag, workflowData *WorkflowData) bool {
 	flagLower := strings.ToLower(strings.TrimSpace(string(flag)))
-	featuresLog.Printf("Checking if feature is enabled: %s", flagLower)
+	logEnabled := featuresLog.Enabled()
+	if logEnabled {
+		featuresLog.Printf("Checking if feature is enabled: %s", flagLower)
+	}
 
 	// First, check if the feature is explicitly set in frontmatter.
 	// Frontmatter values always take precedence.
-	if enabled, found := getFeatureValueFromFrontmatter(flagLower, workflowData); found {
+	if enabled, found := getFeatureValueFromFrontmatter(flagLower, workflowData, logEnabled); found {
 		return enabled
 	}
 
 	// Fall back to checking the environment variable
-	if isFeatureInEnvironment(flagLower) {
-		featuresLog.Printf("Feature found in GH_AW_FEATURES: %s=true", flagLower)
+	if isFeatureInEnvironment(flagLower, logEnabled) {
+		if logEnabled {
+			featuresLog.Printf("Feature found in GH_AW_FEATURES: %s=true", flagLower)
+		}
 		return true
 	}
 
-	featuresLog.Printf("Feature not found: %s=false", flagLower)
+	if logEnabled {
+		featuresLog.Printf("Feature not found: %s=false", flagLower)
+	}
 	return false
 }
 
-func getFeatureValueFromFrontmatter(flagLower string, workflowData *WorkflowData) (bool, bool) {
+func getFeatureValueFromFrontmatter(flagLower string, workflowData *WorkflowData, logEnabled bool) (bool, bool) {
 	if workflowData == nil || workflowData.Features == nil {
 		return false, false
 	}
 
 	if value, exists := workflowData.Features[flagLower]; exists {
 		if enabled, found := parseFeatureValue(value); found {
-			featuresLog.Printf("Feature found in frontmatter: %s=%v", flagLower, enabled)
+			if logEnabled {
+				featuresLog.Printf("Feature found in frontmatter: %s=%v", flagLower, enabled)
+			}
 			return enabled, true
 		}
 	}
 
 	for key, value := range workflowData.Features {
 		if strings.ToLower(key) == flagLower {
 			if enabled, found := parseFeatureValue(value); found {
-				featuresLog.Printf("Feature found in frontmatter (case-insensitive): %s=%v", flagLower, enabled)
+				if logEnabled {
+					featuresLog.Printf("Feature found in frontmatter (case-insensitive): %s=%v", flagLower, enabled)
+				}
 				return enabled, true
 			}
 		}
@@ -69,14 +80,18 @@ func parseFeatureValue(value any) (bool, bool) {
 	return false, false
 }
 
-func isFeatureInEnvironment(flagLower string) bool {
+func isFeatureInEnvironment(flagLower string, logEnabled bool) bool {
 	features := os.Getenv("GH_AW_FEATURES")
 	if features == "" {
-		featuresLog.Printf("Feature not found, GH_AW_FEATURES empty: %s=false", flagLower)
+		if logEnabled {
+			featuresLog.Printf("Feature not found, GH_AW_FEATURES empty: %s=false", flagLower)
+		}
 		return false
 	}
 
-	featuresLog.Printf("Checking GH_AW_FEATURES environment variable: %s", features)
+	if logEnabled {
+		featuresLog.Printf("Checking GH_AW_FEATURES environment variable: %s", features)
+	}
 	for feature := range strings.SplitSeq(features, ",") {
 		if strings.ToLower(strings.TrimSpace(feature)) == flagLower {
 			return true