fix(discovery): skip hidden directories during workspace scans

Dot-prefixed directories are tool state, caches, and generated fixtures
rather than portfolio checkouts, so scanning them manufactured hundreds
of anchor findings for synthetic trees. Keep .git as the discoverable
boundary while skipping every other dot-directory.

Author: rldyourmnd

core/discovery/local.go

@@ -306,9 +306,15 @@ func pathDepth(relative string) int {
 }
 
 func excludedDirectory(name string) bool {
+	// Hidden directories other than a repository's own .git boundary are tool
+	// state, caches, or generated fixtures (".tmp", ".idea", ".venv", ...) —
+	// never portfolio checkouts. Scanning them manufactures anchor findings
+	// for synthetic trees and burns time on ignored content.
+	if name != ".git" && strings.HasPrefix(name, ".") {
+		return true
+	}
 	switch name {
-	case ".cache", ".idea", ".pytest_cache", ".ruff_cache", ".tox", ".venv",
-		"__pycache__", "node_modules", "target", "vendor":
+	case "__pycache__", "node_modules", "target", "vendor":
 		return true
 	default:
 		return false

core/discovery/local_test.go

@@ -190,3 +190,28 @@ func TestDiscoverAcceptsIdentityPinnedBySuperprojectAndCheckedOutStandalone(t *t
 		}
 	}
 }
+
+func TestDiscoverSkipsHiddenDirectoryTrees(t *testing.T) {
+	t.Parallel()
+	root := t.TempDir()
+	plain := filepath.Join(root, "plain")
+	fixture := filepath.Join(root, ".tmp", "native-linux", "fixture-repo")
+	for _, path := range []string{plain, fixture} {
+		if err := os.MkdirAll(path, 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if output, err := exec.Command("git", "init", "-q", path).CombinedOutput(); err != nil {
+			t.Fatalf("git init %s: %v\n%s", path, err, output)
+		}
+	}
+
+	result, err := newTestDiscovery(t).Discover(
+		context.Background(), root, Options{MaxDepth: 8, MaxRepositories: 10, Concurrency: 2},
+	)
+	if err != nil {
+		t.Fatalf("Discover() error = %v", err)
+	}
+	if len(result.Boundaries) != 1 || result.Boundaries[0].Path != plain {
+		t.Fatalf("boundaries = %#v, want only %s", result.Boundaries, plain)
+	}
+}