From 8bd1242156872eeada67300086a60af57b43b422 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 3 Apr 2026 13:48:56 +0000
Subject: [PATCH 1/2] Initial plan


From 25c17654023e1eaeb8deeca17767f3798a12de10 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 3 Apr 2026 14:00:06 +0000
Subject: [PATCH 2/2] fix: prevent double-format wrapping for pre-formatted
 compiler errors
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- pkg/parser/schema_compiler.go: return &FormattedParserError{} instead of
  errors.New() so isFormattedCompilerError() recognises them and compiler.go
  does not re-wrap with a spurious file:1:1: error: prefix
- pkg/parser/import_error.go: add NewFormattedParserError constructor for
  external packages to create FormattedParserError values
- pkg/workflow/frontmatter_error.go: return parser.NewFormattedParserError()
  for pre-formatted YAML error strings instead of fmt.Errorf()
- pkg/workflow/compiler_error_formatter_test.go: cover NewFormattedParserError path

Fixes #<issue> — compiler error messages double-format with wrong line number

Agent-Logs-Url: https://github.com/github/gh-aw/sessions/a25ffcf4-a170-4618-8c25-3837826bef98

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
---
 pkg/parser/import_error.go                    | 7 +++++++
 pkg/parser/schema_compiler.go                 | 4 ++--
 pkg/workflow/compiler_error_formatter_test.go | 5 +++++
 pkg/workflow/frontmatter_error.go             | 4 ++--
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/pkg/parser/import_error.go b/pkg/parser/import_error.go
index ad3e1edbe4a..62e596aec5b 100644
--- a/pkg/parser/import_error.go
+++ b/pkg/parser/import_error.go
@@ -84,6 +84,13 @@ type FormattedParserError struct {
 func (e *FormattedParserError) Error() string { return e.formatted }
 func (e *FormattedParserError) Unwrap() error { return e.cause }
 
+// NewFormattedParserError creates a FormattedParserError with the given pre-formatted
+// message string. Use this in external packages (e.g. pkg/workflow) to return an error
+// that isFormattedCompilerError can detect without double-wrapping.
+func NewFormattedParserError(formatted string) *FormattedParserError {
+	return &FormattedParserError{formatted: formatted}
+}
+
 // FormatImportError formats an import error as a compilation error with source location
 func FormatImportError(err *ImportError, yamlContent string) error {
 	importErrorLog.Printf("Formatting import error: path=%s, file=%s, line=%d", err.ImportPath, err.FilePath, err.Line)
diff --git a/pkg/parser/schema_compiler.go b/pkg/parser/schema_compiler.go
index fb18aa7b048..96ced941deb 100644
--- a/pkg/parser/schema_compiler.go
+++ b/pkg/parser/schema_compiler.go
@@ -354,7 +354,7 @@ func validateWithSchemaAndLocation(frontmatter map[string]any, schemaJSON, conte
 
 				// Format and return the error
 				formattedErr := console.FormatError(compilerErr)
-				return errors.New(formattedErr)
+				return &FormattedParserError{formatted: formattedErr}
 			}
 		}
 
@@ -382,7 +382,7 @@ func validateWithSchemaAndLocation(frontmatter map[string]any, schemaJSON, conte
 
 		// Format and return the error
 		formattedErr := console.FormatError(compilerErr)
-		return errors.New(formattedErr)
+		return &FormattedParserError{formatted: formattedErr}
 	}
 
 	// Fallback to the original error if we can't format it nicely
diff --git a/pkg/workflow/compiler_error_formatter_test.go b/pkg/workflow/compiler_error_formatter_test.go
index d1277af54e0..d631ee16da9 100644
--- a/pkg/workflow/compiler_error_formatter_test.go
+++ b/pkg/workflow/compiler_error_formatter_test.go
@@ -45,6 +45,11 @@ func TestIsFormattedCompilerError(t *testing.T) {
 			}, "imports:\n  - missing.md"),
 			expected: true,
 		},
+		{
+			name:     "error from parser.NewFormattedParserError is detected as formatted",
+			err:      parser.NewFormattedParserError("workflow.md:5:3: error: bad value"),
+			expected: true,
+		},
 		{
 			name:     "plain error is not formatted",
 			err:      errors.New("plain error"),
diff --git a/pkg/workflow/frontmatter_error.go b/pkg/workflow/frontmatter_error.go
index 2d90c92a35d..076046d12b7 100644
--- a/pkg/workflow/frontmatter_error.go
+++ b/pkg/workflow/frontmatter_error.go
@@ -73,11 +73,11 @@ func (c *Compiler) createFrontmatterError(filePath, content string, err error, f
 				context := errorStr[loc[0]+1:] // +1 to skip the leading newline
 				// Return VSCode-compatible format on first line, followed by source context only
 				frontmatterErrorLog.Print("Formatting error for VSCode compatibility")
-				return fmt.Errorf("%s\n%s", vscodeFormat, context)
+				return parser.NewFormattedParserError(fmt.Sprintf("%s\n%s", vscodeFormat, context))
 			}
 
 			// If we can't extract source context, return just the VSCode format
-			return fmt.Errorf("%s", vscodeFormat)
+			return parser.NewFormattedParserError(vscodeFormat)
 		}
 
 		// Fallback if we can't parse the line/col