perf(rules): pre-filter walk by fixed glob filename

internal/detector/rules/engine_test.go

@@ -61,6 +61,8 @@ func fileResult(t *testing.T, scan model.RuleScan, ruleID string) model.RuleFile
 func TestScanRegexMatch(t *testing.T) {
 	dir := t.TempDir()
 	writeFile(t, dir, "proj/.github/setup.js", "const x = eval(atob('benign'))\n")
+	// Decoy: same filename, wrong directory — must be rejected by the full-path check.
+	writeFile(t, dir, "proj/other/setup.js", "const x = eval(atob('benign'))\n")
 
 	rs := prep(t, RuleSet{Rules: []Rule{{
 		ID: "dropper", Revision: "rev1", FileGlobs: []string{"**/.github/setup.js"},
@@ -161,6 +163,20 @@ func TestScanExistenceOnly(t *testing.T) {
 	}
 }
 
+func TestScan_WildcardFilenameGlob(t *testing.T) {
+	dir := t.TempDir()
+	writeFile(t, dir, "nested/payload.mjs", "anything")
+
+	rs := prep(t, RuleSet{Rules: []Rule{{
+		ID: "wildcard", FileGlobs: []string{"**/*.mjs", "**/payload.mjs"},
+	}}})
+	scan := newTestEngine(t, DefaultCaps()).Scan(context.Background(), rs, []string{dir})
+	fm := fileResult(t, scan, "wildcard")
+	if fm.MatchedGlob != "**/*.mjs" {
+		t.Errorf("MatchedGlob got %q, want %q", fm.MatchedGlob, "**/*.mjs")
+	}
+}
+
 func TestScanSizeGuard(t *testing.T) {
 	dir := t.TempDir()
 	big := strings.Repeat("A", 2048)

internal/detector/rules/roots.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"errors"
 	"io/fs"
+	"path"
 	"path/filepath"
+	"strings"
 )
 
 // errWalkStop unwinds filepath.WalkDir when a global budget is hit or the
@@ -45,16 +47,25 @@ type relMatcher struct {
 }
 
 // walkRoots performs one TCC-aware walk per search root, matching each regular
-// file against every relative glob. Symlinks are never followed (the walk does
-// not descend into symlinked directories, and symlinked files are not regular,
-// so they are skipped) — the symlink-escape guard. Sets st.globalStop if a
-// global file/time budget is hit.
+// file against relative globs indexed by fixed filename. A bundle containing a
+// wildcard filename falls back to the original all-glob loop. Symlinks are
+// never followed (the walk does not descend into symlinked directories, and
+// symlinked files are not regular, so they are skipped) — the symlink-escape
+// guard. Sets st.globalStop if a global file/time budget is hit.
 func (e *Engine) walkRoots(ctx context.Context, st *scanState, searchDirs []string) {
+	matchersByName := make(map[string][]relMatcher)
 	var matchers []relMatcher
 	for _, rstate := range st.states {
 		for _, cg := range rstate.rule.globs {
 			if !cg.absolute {
-				matchers = append(matchers, relMatcher{rstate: rstate, cg: cg})
+				matcher := relMatcher{rstate: rstate, cg: cg}
+				matchers = append(matchers, matcher)
+				name := path.Base(cg.raw)
+				if strings.ContainsAny(name, "*?") {
+					matchersByName = nil // preserve original ordering for wildcard filenames
+				} else if matchersByName != nil {
+					matchersByName[name] = append(matchersByName[name], matcher)
+				}
 			}
 		}
 	}
@@ -66,7 +77,7 @@ func (e *Engine) walkRoots(ctx context.Context, st *scanState, searchDirs []stri
 		if root == "" {
 			continue
 		}
-		if e.walkOneRoot(ctx, st, root, matchers) {
+		if e.walkOneRoot(ctx, st, root, matchersByName, matchers) {
 			st.globalStop = true
 			return
 		}
@@ -75,7 +86,7 @@ func (e *Engine) walkRoots(ctx context.Context, st *scanState, searchDirs []stri
 
 // walkOneRoot walks a single root. Returns true if the whole scan should stop
 // (global budget or context cancellation).
-func (e *Engine) walkOneRoot(ctx context.Context, st *scanState, root string, matchers []relMatcher) (stopped bool) {
+func (e *Engine) walkOneRoot(ctx context.Context, st *scanState, root string, matchersByName map[string][]relMatcher, matchers []relMatcher) (stopped bool) {
 	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return nil // unreadable entry — skip, never fail the run
@@ -92,17 +103,22 @@ func (e *Engine) walkOneRoot(ctx context.Context, st *scanState, root string, ma
 		if !d.Type().IsRegular() {
 			return nil // skip symlinks/sockets/etc.
 		}
+		candidates := matchers
+		if matchersByName != nil {
+			candidates = matchersByName[d.Name()]
+			if len(candidates) == 0 {
+				return nil
+			}
+		}
 
 		rel, rerr := filepath.Rel(root, path)
 		if rerr != nil {
 			return nil
 		}
 		relSlashed := filepath.ToSlash(rel)
-		for _, m := range matchers {
-			if m.cg.re.MatchString(relSlashed) {
-				if e.evaluate(st, m.rstate, path, m.cg.raw) {
-					return errWalkStop
-				}
+		for _, m := range candidates {
+			if m.cg.re.MatchString(relSlashed) && e.evaluate(st, m.rstate, path, m.cg.raw) {
+				return errWalkStop
 			}
 		}
 		return nil