refactor(workflow): co-locate heredoc utils and consolidate any→[]string helpers (#26428)

* Initial plan

* refactor(workflow): consolidate any→[]string helpers and move normalizeHeredocDelimiters to strings.go

Agent-Logs-Url: https://github.com/github/gh-aw/sessions/3f255865-2b14-4042-95a3-b72d8d7b1fd5

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
Co-authored-by: Peli de Halleux <pelikhan@users.noreply.github.com>

Author: Copilot

pkg/workflow/compiler.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"regexp"
 	"slices"
 	"strings"
 	"time"
@@ -20,21 +19,6 @@ import (
 
 var log = logger.New("workflow:compiler")
 
-// heredocDelimiterRE matches randomized heredoc delimiters of the form GH_AW_<NAME>_<16hexchars>_EOF.
-// Used to normalize delimiters when comparing compiled output to skip unnecessary writes.
-var heredocDelimiterRE = regexp.MustCompile(`GH_AW_([A-Z0-9_]+)_[0-9a-f]{16}_EOF`)
-
-// normalizeHeredocDelimiters replaces randomized heredoc delimiter tokens with a stable
-// placeholder so that two compilations of the same workflow compare as equal even though
-// each run embeds different random tokens.
-func normalizeHeredocDelimiters(content string) string {
-	// Fast path: skip regex if content contains no heredoc delimiters
-	if !strings.Contains(content, "GH_AW_") {
-		return content
-	}
-	return heredocDelimiterRE.ReplaceAllString(content, "GH_AW_${1}_NORM_EOF")
-}
-
 const (
 	// MaxLockFileSize is the maximum allowed size for generated lock workflow files (500KB)
 	MaxLockFileSize = 512000 // 500KB in bytes

pkg/workflow/compiler_filters_validation.go

@@ -46,7 +46,6 @@
 package workflow
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 )
@@ -204,25 +203,3 @@ func validateGlobList(eventMap map[string]any, eventName, filterKey string, isPa
 	}
 	return nil
 }
-
-// toStringSlice converts an any value to a []string, supporting []string, []any, and string.
-func toStringSlice(val any) ([]string, error) {
-	switch v := val.(type) {
-	case []string:
-		return v, nil
-	case []any:
-		result := make([]string, 0, len(v))
-		for _, item := range v {
-			s, ok := item.(string)
-			if !ok {
-				return nil, errors.New("non-string item in list")
-			}
-			result = append(result, s)
-		}
-		return result, nil
-	case string:
-		return []string{v}, nil
-	default:
-		return nil, fmt.Errorf("unsupported type %T", val)
-	}
-}

pkg/workflow/role_checks.go

@@ -504,43 +504,6 @@ func (c *Compiler) extractSkipBots(frontmatter map[string]any) []string {
 	return extractSkipField(frontmatter, "skip-bots")
 }
 
-// extractStringSliceField extracts a string slice from various input formats
-// Handles: string, []string, []any (with string elements)
-// Returns nil if the input is empty or invalid
-func extractStringSliceField(value any, fieldName string) []string {
-	switch v := value.(type) {
-	case string:
-		// Single string
-		if v == "" {
-			return nil
-		}
-		roleLog.Printf("Extracted single %s: %s", fieldName, v)
-		return []string{v}
-	case []string:
-		// Already a string slice
-		if len(v) == 0 {
-			return nil
-		}
-		roleLog.Printf("Extracted %d %s: %v", len(v), fieldName, v)
-		return v
-	case []any:
-		// Array of any - extract strings
-		var result []string
-		for _, item := range v {
-			if str, ok := item.(string); ok && str != "" {
-				result = append(result, str)
-			}
-		}
-		if len(result) == 0 {
-			return nil
-		}
-		roleLog.Printf("Extracted %d %s from array: %v", len(result), fieldName, result)
-		return result
-	}
-	roleLog.Printf("No valid %s found or unsupported type: %T", fieldName, value)
-	return nil
-}
-
 // mergeStringSlicesDedup merges two string slices with deduplication (preserving order of first occurrence).
 // Logs the merged result under the given logLabel when the result is non-empty.
 func mergeStringSlicesDedup(top, imported []string, logLabel string) []string {

pkg/workflow/strings.go

@@ -297,6 +297,21 @@ func GenerateHeredocDelimiterFromSeed(name string, seed string) string {
 	return "GH_AW_" + upperName + "_" + tag + "_EOF"
 }
 
+// heredocDelimiterRE matches randomized heredoc delimiters of the form GH_AW_<NAME>_<16hexchars>_EOF.
+// Used to normalize delimiters when comparing compiled output to skip unnecessary writes.
+var heredocDelimiterRE = regexp.MustCompile(`GH_AW_([A-Z0-9_]+)_[0-9a-f]{16}_EOF`)
+
+// normalizeHeredocDelimiters replaces randomized heredoc delimiter tokens with a stable
+// placeholder so that two compilations of the same workflow compare as equal even though
+// each run embeds different random tokens.
+func normalizeHeredocDelimiters(content string) string {
+	// Fast path: skip regex if content contains no heredoc delimiters
+	if !strings.Contains(content, "GH_AW_") {
+		return content
+	}
+	return heredocDelimiterRE.ReplaceAllString(content, "GH_AW_${1}_NORM_EOF")
+}
+
 // ValidateHeredocContent checks that content does not contain the heredoc delimiter
 // anywhere (substring match). The check is intentionally stricter than what shell
 // heredocs require (delimiter on its own line) — rejecting any occurrence eliminates

pkg/workflow/validation_helpers.go

@@ -11,6 +11,12 @@
 //   - validateMountStringFormat() - Parses and validates a "source:dest:mode" mount string
 //   - containsTrigger() - Reports whether an 'on:' section includes a named trigger
 //
+// # Type Conversion Helpers (any → []string)
+//
+//   - parseStringSliceAny() - Canonical coercion of []string/[]any to []string; skips non-strings
+//   - toStringSlice() - Strict variant: returns error on non-string elements; also accepts bare string
+//   - extractStringSliceField() - Accepts string/[]string/[]any; skips empty strings; wraps bare string
+//
 // # Design Rationale
 //
 // These helpers consolidate 76+ duplicate validation patterns identified in the
@@ -189,6 +195,67 @@ func parseStringSliceAny(raw any, log *logger.Logger) []string {
 	}
 }
 
+// toStringSlice converts an any value to a []string, supporting []string, []any, and string.
+// Unlike parseStringSliceAny, this function returns an error when a []any element is not a string,
+// and also accepts a bare string value (wrapping it in a single-element slice).
+func toStringSlice(val any) ([]string, error) {
+	switch v := val.(type) {
+	case []string:
+		return v, nil
+	case []any:
+		result := make([]string, 0, len(v))
+		for _, item := range v {
+			s, ok := item.(string)
+			if !ok {
+				return nil, errors.New("non-string item in list")
+			}
+			result = append(result, s)
+		}
+		return result, nil
+	case string:
+		return []string{v}, nil
+	default:
+		return nil, fmt.Errorf("unsupported type %T", val)
+	}
+}
+
+// extractStringSliceField extracts a string slice from various input formats.
+// Handles: string, []string, []any (with string elements).
+// Returns nil if the input is empty or invalid.
+func extractStringSliceField(value any, fieldName string) []string {
+	switch v := value.(type) {
+	case string:
+		// Single string
+		if v == "" {
+			return nil
+		}
+		validationHelpersLog.Printf("Extracted single %s: %s", fieldName, v)
+		return []string{v}
+	case []string:
+		// Already a string slice
+		if len(v) == 0 {
+			return nil
+		}
+		validationHelpersLog.Printf("Extracted %d %s: %v", len(v), fieldName, v)
+		return v
+	case []any:
+		// Array of any - extract strings
+		var result []string
+		for _, item := range v {
+			if str, ok := item.(string); ok && str != "" {
+				result = append(result, str)
+			}
+		}
+		if len(result) == 0 {
+			return nil
+		}
+		validationHelpersLog.Printf("Extracted %d %s from array: %v", len(result), fieldName, result)
+		return result
+	}
+	validationHelpersLog.Printf("No valid %s found or unsupported type: %T", fieldName, value)
+	return nil
+}
+
 // validateNoDuplicateIDs checks that all items have unique IDs extracted by idFunc.
 // The onDuplicate callback creates the error to return when a duplicate is found.
 func validateNoDuplicateIDs[T any](items []T, idFunc func(T) string, onDuplicate func(string) error) error {