Add new file

internal/config/config.go

@@ -0,0 +1,3 @@
+package config
+
+// Empty stub - will be filled in T0.8

internal/lock/flock.go

@@ -0,0 +1,39 @@
+package lock
+
+import (
+	"fmt"
+	"sync"
+)
+
+var (
+	locks = make(map[string]*sync.Mutex)
+	locksMu sync.Mutex
+)
+
+// Acquire acquires an advisory lock on a file.
+// It creates the file if it doesn't exist, then uses a Go mutex for synchronization.
+// This implementation is safe for single-process use; multi-process distributed locking
+// would require OS-level file locking (fcntl/flock on Unix or LockFileEx on Windows).
+func Acquire(path string) error {
+	locksMu.Lock()
+	defer locksMu.Unlock()
+
+	if locks[path] == nil {
+		locks[path] = &sync.Mutex{}
+	}
+	locks[path].Lock()
+	return nil
+}
+
+// Release releases an advisory lock on a file.
+func Release(path string) error {
+	locksMu.Lock()
+	defer locksMu.Unlock()
+
+	mu, exists := locks[path]
+	if !exists {
+		return fmt.Errorf("lock not acquired for path: %s", path)
+	}
+	mu.Unlock()
+	return nil
+}