⚡ Bolt: Use strings.Cut to avoid string allocations in CompareVersions

.jules/bolt.md

@@ -21,3 +21,7 @@
 ## 2025-05-10 - fmt.Sscanf is lenient, strconv.Atoi is strict
 **Learning:** In Go, `fmt.Sscanf("%d")` parses digits until it encounters a non-digit character (e.g., `"2beta"` parses as `2`), while `strconv.Atoi` fails and returns `0` for the entire string. If you need the lenient parsing behavior of `fmt.Sscanf` for performance optimization, implement a custom byte-traversal loop to extract leading digits rather than relying on `strconv.Atoi` or regex, as it is over 10x faster and maintains exact functional parity.
 **Action:** When replacing `fmt.Sscanf` for performance, always evaluate whether the leniency of the parser is being implicitly relied upon by the surrounding code.
+
+## 2024-05-22 - Avoid strings.Split in hot loops
+**Learning:** Using `strings.Split` to parse strings separated by a known single-byte delimiter causes unnecessary slice allocations, memory pressure, and slows down performance.
+**Action:** When iterating over segments of a delimited string, use a `for` loop with `strings.Cut` to avoid intermediate slice allocations and improve parsing speed.

internal/plugin/manager.go

@@ -832,24 +832,20 @@ func parseLenientAtoi(s string) int {
 // CompareVersions compares two semver strings
 // Returns -1 if a < b, 0 if a == b, 1 if a > b
 func CompareVersions(a, b string) int {
-	partsA := strings.Split(a, ".")
-	partsB := strings.Split(b, ".")
+	for a != "" || b != "" {
+		var partA, partB string
 
-	maxLen := len(partsA)
-	if len(partsB) > maxLen {
-		maxLen = len(partsB)
-	}
-
-	for i := 0; i < maxLen; i++ {
-		var numA, numB int
-		if i < len(partsA) {
-			// Bolt optimization: using a custom loop is ~14x faster than fmt.Sscanf
-			numA = parseLenientAtoi(partsA[i])
+		if a != "" {
+			partA, a, _ = strings.Cut(a, ".")
 		}
-		if i < len(partsB) {
-			numB = parseLenientAtoi(partsB[i])
+		if b != "" {
+			partB, b, _ = strings.Cut(b, ".")
 		}
 
+		// Bolt optimization: using a custom loop is ~14x faster than fmt.Sscanf
+		numA := parseLenientAtoi(partA)
+		numB := parseLenientAtoi(partB)
+
 		if numA < numB {
 			return -1
 		}