fix: Minor issues #12 and #13 - ASCII mode and performance optimization

This commit addresses the remaining Minor issues from PR #94 code review:

Minor #12: Unicode Symbol Compatibility
- Added CODEAGENT_ASCII_MODE environment variable support
- When set to "true", uses ASCII symbols: PASS/WARN/FAIL
- Default behavior (unset or "false"): Unicode symbols ✓/⚠️/✗
- Updated help text to document the environment variable
- Added tests for both ASCII and Unicode modes

Implementation:
- executor.go:514: New getStatusSymbols() function
- executor.go:531: Dynamic symbol selection in generateFinalOutputWithMode
- main.go:34: useASCIIMode variable declaration
- main.go:495: Environment variable documentation in help
- executor_concurrent_test.go:292: Tests for ASCII mode
- main_integration_test.go:89: Parser updated for both symbol formats

Minor #13: Performance Optimization - Reduce Repeated String Operations
- Optimized Message parsing to split only once per task result
- Added *FromLines() variants of all extractor functions
- Original extract*() functions now wrap *FromLines() for compatibility
- Reduces memory allocations and CPU usage in parallel execution

Implementation:
- utils.go:300: extractCoverageFromLines()
- utils.go:390: extractFilesChangedFromLines()
- utils.go:455: extractTestResultsFromLines()
- utils.go:551: extractKeyOutputFromLines()
- main.go:255: Single split with reuse: lines := strings.Split(...)

Backward Compatibility:
- All original extract*() functions preserved
- Tests updated to handle both symbol formats
- No breaking changes to public API

Test Results:
- All tests pass: go test ./... (40.164s)
- ASCII mode verified: PASS/WARN/FAIL symbols display correctly
- Unicode mode verified: ✓/⚠️/✗ symbols remain default
- Performance: Single split per Message instead of 4+

Usage Examples:
  # Unicode mode (default)
  ./codeagent-wrapper --parallel < tasks.txt

  # ASCII mode (for terminals without Unicode support)
  CODEAGENT_ASCII_MODE=true ./codeagent-wrapper --parallel < tasks.txt

Benefits:
- Improved terminal compatibility across different environments
- Reduced memory allocations in parallel execution
- Better performance for large-scale parallel tasks
- User choice between Unicode aesthetics and ASCII compatibility

Related: #94

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

codeagent-wrapper/utils.go

@@ -297,24 +297,29 @@ func extractMessageSummary(message string, maxLen int) string {
 	return safeTruncate(clean, maxLen)
 }
 
-// extractCoverage extracts coverage percentage from task output
-// Supports common formats: "Coverage: 92%", "92% coverage", "coverage 92%", "TOTAL 92%"
-func extractCoverage(message string) string {
-	if message == "" {
+// extractCoverageFromLines extracts coverage from pre-split lines.
+func extractCoverageFromLines(lines []string) string {
+	if len(lines) == 0 {
 		return ""
 	}
 
-	trimmed := strings.TrimSpace(message)
-	if strings.HasSuffix(trimmed, "%") && !strings.Contains(trimmed, "\n") {
-		if num, err := strconv.ParseFloat(strings.TrimSuffix(trimmed, "%"), 64); err == nil && num >= 0 && num <= 100 {
-			return trimmed
+	end := len(lines)
+	for end > 0 && strings.TrimSpace(lines[end-1]) == "" {
+		end--
+	}
+
+	if end == 1 {
+		trimmed := strings.TrimSpace(lines[0])
+		if strings.HasSuffix(trimmed, "%") {
+			if num, err := strconv.ParseFloat(strings.TrimSuffix(trimmed, "%"), 64); err == nil && num >= 0 && num <= 100 {
+				return trimmed
+			}
 		}
 	}
 
 	coverageKeywords := []string{"file", "stmt", "branch", "line", "coverage", "total"}
 
-	lines := strings.Split(message, "\n")
-	for _, line := range lines {
+	for _, line := range lines[:end] {
 		lower := strings.ToLower(line)
 
 		hasKeyword := false
@@ -359,6 +364,16 @@ func extractCoverage(message string) string {
 	return ""
 }
 
+// extractCoverage extracts coverage percentage from task output
+// Supports common formats: "Coverage: 92%", "92% coverage", "coverage 92%", "TOTAL 92%"
+func extractCoverage(message string) string {
+	if message == "" {
+		return ""
+	}
+
+	return extractCoverageFromLines(strings.Split(message, "\n"))
+}
+
 // extractCoverageNum extracts coverage as a numeric value for comparison
 func extractCoverageNum(coverage string) float64 {
 	if coverage == "" {
@@ -372,10 +387,9 @@ func extractCoverageNum(coverage string) float64 {
 	return 0
 }
 
-// extractFilesChanged extracts list of changed files from task output
-// Looks for common patterns like "Modified: file.ts", "Created: file.ts", file paths in output
-func extractFilesChanged(message string) []string {
-	if message == "" {
+// extractFilesChangedFromLines extracts files from pre-split lines.
+func extractFilesChangedFromLines(lines []string) []string {
+	if len(lines) == 0 {
 		return nil
 	}
 
@@ -383,7 +397,6 @@ func extractFilesChanged(message string) []string {
 	seen := make(map[string]bool)
 	exts := []string{".ts", ".tsx", ".js", ".jsx", ".go", ".py", ".rs", ".java", ".vue", ".css", ".scss", ".md", ".json", ".yaml", ".yml", ".toml"}
 
-	lines := strings.Split(message, "\n")
 	for _, line := range lines {
 		line = strings.TrimSpace(line)
 
@@ -429,21 +442,30 @@ func extractFilesChanged(message string) []string {
 	return files
 }
 
-// extractTestResults extracts test pass/fail counts from task output
-func extractTestResults(message string) (passed, failed int) {
+// extractFilesChanged extracts list of changed files from task output
+// Looks for common patterns like "Modified: file.ts", "Created: file.ts", file paths in output
+func extractFilesChanged(message string) []string {
 	if message == "" {
-		return 0, 0
+		return nil
 	}
 
-	lower := strings.ToLower(message)
+	return extractFilesChangedFromLines(strings.Split(message, "\n"))
+}
+
+// extractTestResultsFromLines extracts test results from pre-split lines.
+func extractTestResultsFromLines(lines []string) (passed, failed int) {
+	if len(lines) == 0 {
+		return 0, 0
+	}
 
 	// Common patterns:
 	// pytest: "12 passed, 2 failed"
 	// jest: "Tests: 2 failed, 12 passed"
 	// go: "ok ... 12 tests"
 
-	lines := strings.Split(lower, "\n")
 	for _, line := range lines {
+		line = strings.ToLower(line)
+
 		// Look for test result lines
 		if !strings.Contains(line, "pass") && !strings.Contains(line, "fail") && !strings.Contains(line, "test") {
 			continue
@@ -485,6 +507,15 @@ func extractTestResults(message string) (passed, failed int) {
 	return passed, failed
 }
 
+// extractTestResults extracts test pass/fail counts from task output
+func extractTestResults(message string) (passed, failed int) {
+	if message == "" {
+		return 0, 0
+	}
+
+	return extractTestResultsFromLines(strings.Split(message, "\n"))
+}
+
 // extractNumberBefore extracts a number that appears before the given index
 func extractNumberBefore(s string, idx int) int {
 	if idx <= 0 {
@@ -517,15 +548,12 @@ func extractNumberBefore(s string, idx int) int {
 	return 0
 }
 
-// extractKeyOutput extracts a brief summary of what the task accomplished
-// Looks for summary lines, first meaningful sentence, or truncates message
-func extractKeyOutput(message string, maxLen int) string {
-	if message == "" || maxLen <= 0 {
+// extractKeyOutputFromLines extracts key output from pre-split lines.
+func extractKeyOutputFromLines(lines []string, maxLen int) string {
+	if len(lines) == 0 || maxLen <= 0 {
 		return ""
 	}
 
-	lines := strings.Split(message, "\n")
-
 	// Priority 1: Look for explicit summary lines
 	for _, line := range lines {
 		line = strings.TrimSpace(line)
@@ -560,10 +588,19 @@ func extractKeyOutput(message string, maxLen int) string {
 	}
 
 	// Fallback: truncate entire message
-	clean := strings.TrimSpace(message)
+	clean := strings.TrimSpace(strings.Join(lines, "\n"))
 	return safeTruncate(clean, maxLen)
 }
 
+// extractKeyOutput extracts a brief summary of what the task accomplished
+// Looks for summary lines, first meaningful sentence, or truncates message
+func extractKeyOutput(message string, maxLen int) string {
+	if message == "" || maxLen <= 0 {
+		return ""
+	}
+	return extractKeyOutputFromLines(strings.Split(message, "\n"), maxLen)
+}
+
 // extractCoverageGap extracts what's missing from coverage reports
 // Looks for uncovered lines, branches, or functions
 func extractCoverageGap(message string) string {