From 53ad34cbee460b0758129020a24d18e1b9a04ff7 Mon Sep 17 00:00:00 2001
From: Tien Dung Dao <tiendungdev@gmail.com>
Date: Fri, 21 Aug 2026 16:57:29 +0700
Subject: [PATCH] fix(mcp): match fidelity globs with path.Match, not
 filepath.Match
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matchFidelityGlob normalizes both the pattern and the path to forward
slashes, then hands them to filepath.Match — whose separator is the
platform's. On Windows '/' is an ordinary character to that matcher, so a
single `*` crosses it:

    matchFidelityGlob("internal/*.go", "internal/sub/x.go")
      = true on windows, false on linux/macos

The file's own doc-comment states the assumption this breaks: "Go's
filepath.Match never crosses `/`". That holds on POSIX and is why the
linux/macos matrix has never seen it.

Everything around it already works in slash space — ToSlash on entry,
Split(rel, "/"), the `**` prefix and suffix handling — so path.Match and
path.Base are the matching primitives that space calls for. Identical to
filepath.Match on POSIX, where the separator already is '/'.

fidelity_globs is a public tool parameter on read_file and
get_editing_context, so on Windows a documented `internal/*.go` rule
silently applied to the whole subtree beneath internal/.

Whole package on windows: TestMatchFidelityGlob flips, newly-broken set
empty.
---
 internal/mcp/fidelity_globs.go | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/internal/mcp/fidelity_globs.go b/internal/mcp/fidelity_globs.go
index 61313aa0a..c30023533 100644
--- a/internal/mcp/fidelity_globs.go
+++ b/internal/mcp/fidelity_globs.go
@@ -1,6 +1,7 @@
 package mcp
 
 import (
+	"path"
 	"path/filepath"
 	"strings"
 
@@ -89,7 +90,8 @@ func fidelityDecideForPath(rules []fidelityRule, relPath string) func(elide.Decl
 // matchFidelityGlob matches a glob against a forward-slash relative
 // path. It extends matchPathPattern's basename/prefix semantics with
 // explicit `**` support so the documented `internal/**` / `**/*.go`
-// forms work as written (Go's filepath.Match never crosses `/`).
+// forms work as written (a single `*` never crosses `/` — see
+// matchSegmentGlob for why that requires path.Match, not filepath.Match).
 func matchFidelityGlob(pattern, rel string) bool {
 	pattern = filepath.ToSlash(pattern)
 	rel = filepath.ToSlash(rel)
@@ -125,13 +127,20 @@ func matchFidelityGlob(pattern, rel string) bool {
 }
 
 // matchSegmentGlob applies the single-segment glob semantics shared
-// with matchPathPattern: filepath.Match against the full path and the
+// with matchPathPattern: a glob match against the full path and the
 // basename, plus a bare directory-prefix shortcut.
+//
+// path.Match, not filepath.Match. Both callers hand this function a
+// forward-slash path, and filepath.Match's separator is the platform's:
+// on Windows '/' is an ordinary character there, so `*` crosses it and
+// `internal/*.go` matches `internal/sub/x.go`. path.Match's separator is
+// always '/', which is the semantics this file's `**` handling — and its
+// own doc-comment — already assume.
 func matchSegmentGlob(pattern, rel string) bool {
-	if ok, _ := filepath.Match(pattern, rel); ok {
+	if ok, _ := path.Match(pattern, rel); ok {
 		return true
 	}
-	if ok, _ := filepath.Match(pattern, filepath.Base(rel)); ok {
+	if ok, _ := path.Match(pattern, path.Base(rel)); ok {
 		return true
 	}
 	if strings.HasSuffix(pattern, "/*") {