From 053b39b9ceea03b7f24e49734137c1521fc85ab4 Mon Sep 17 00:00:00 2001
From: Cameron Clark <cameron.clark@hey.com>
Date: Tue, 12 Aug 2025 12:11:54 +0100
Subject: [PATCH 1/2] perf(tspath): optimize `hasRelativePathSegment`
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                                                     │   old.txt   │               new.txt               │
                                                     │   sec/op    │   sec/op     vs base                │
HasRelativePathSegment/foo/bar/baz-12                  29.10n ± 2%   14.79n ± 1%  -49.16% (p=0.000 n=10)
HasRelativePathSegment/./some/path-12                  2.065n ± 0%   2.039n ± 2%   -1.26% (p=0.022 n=10)
HasRelativePathSegment//foo/./bar/../../.-12           7.030n ± 0%   2.025n ± 0%  -71.20% (p=0.000 n=10)
HasRelativePathSegment/foo/foo/foo/foo/foo/...etc-12   9.076n ± 1%   2.308n ± 1%  -74.56% (p=0.000 n=10)
geomean                                                7.869n        3.446n       -56.21%
---
 internal/tspath/path.go | 67 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 56 insertions(+), 11 deletions(-)

diff --git a/internal/tspath/path.go b/internal/tspath/path.go
index a0d722b233..8682fccffd 100644
--- a/internal/tspath/path.go
+++ b/internal/tspath/path.go
@@ -470,28 +470,73 @@ func simpleNormalizePath(path string) (string, bool) {
 	return "", false
 }
 
+// hasRelativePathSegment reports whether p contains ".", "..", "./", "../", "/.", "/..", "//", "/./", or "/../".
 func hasRelativePathSegment(p string) bool {
-	if p == "." || p == ".." {
-		return true
+	n := len(p)
+	if n == 0 {
+		return false
 	}
 
-	if strings.HasPrefix(p, "./") || strings.HasPrefix(p, "../") {
+	if p == "." || p == ".." {
 		return true
 	}
 
-	if strings.HasSuffix(p, "/.") || strings.HasSuffix(p, "/..") {
-		return true
+	// Leading "./" OR "../"
+	if p[0] == '.' {
+		if n >= 2 && p[1] == '/' {
+			return true
+		}
+		// Leading "../"
+		if n >= 3 && p[1] == '.' && p[2] == '/' {
+			return true
+		}
 	}
-
-	if strings.Contains(p, "//") {
-		return true
+	// Trailing "/." OR "/.."
+	if p[n-1] == '.' {
+		if n >= 2 && p[n-2] == '/' {
+			return true
+		}
+		if n >= 3 && p[n-2] == '.' && p[n-3] == '/' {
+			return true
+		}
 	}
 
-	if strings.Contains(p, "/./") || strings.Contains(p, "/../") {
-		return true
+	// Now look for any `//` or `/./` or `/../`
+
+	prevSlash := true // treat start as if preceded by '/'
+	segLen := 0       // length of current segment since last slash
+	dotCount := 0     // consecutive dots at start of the current segment; -1 => not only dots
+
+	for i := range n {
+		c := p[i]
+		if c == '/' {
+			// "//"
+			if prevSlash {
+				return true
+			}
+			// "/./" or "/../"
+			if (segLen == 1 && dotCount == 1) || (segLen == 2 && dotCount == 2) {
+				return true
+			}
+			prevSlash = true
+			segLen = 0
+			dotCount = 0
+			continue
+		}
+
+		if c == '.' {
+			if dotCount >= 0 {
+				dotCount++
+			}
+		} else {
+			dotCount = -1
+		}
+		segLen++
+		prevSlash = false
 	}
 
-	return false
+	// Trailing "/." or "/.."
+	return (segLen == 1 && dotCount == 1) || (segLen == 2 && dotCount == 2)
 }
 
 func NormalizePath(path string) string {

From 7c6c5a0d46d9c41b489f7feaca6069dd867d44c4 Mon Sep 17 00:00:00 2001
From: Cameron Clark <cameron.clark@hey.com>
Date: Tue, 12 Aug 2025 18:50:15 +0100
Subject: [PATCH 2/2] fix case

---
 internal/tspath/path.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/internal/tspath/path.go b/internal/tspath/path.go
index 8682fccffd..7b9cb3dc06 100644
--- a/internal/tspath/path.go
+++ b/internal/tspath/path.go
@@ -503,9 +503,9 @@ func hasRelativePathSegment(p string) bool {
 
 	// Now look for any `//` or `/./` or `/../`
 
-	prevSlash := true // treat start as if preceded by '/'
-	segLen := 0       // length of current segment since last slash
-	dotCount := 0     // consecutive dots at start of the current segment; -1 => not only dots
+	prevSlash := false
+	segLen := 0   // length of current segment since last slash
+	dotCount := 0 // consecutive dots at start of the current segment; -1 => not only dots
 
 	for i := range n {
 		c := p[i]