fix: resolve resource leaks and improve namespace lifecycle management

- Fix DNS resolver leaks by creating temporary resolv.conf files within the profile's runtime directory and ensuring robust cleanup.
- Fix isolation block directory leaks by explicitly removing the block directory during namespace unpinning.
- Improve namespace lifecycle management:
    - Register processes before joining an active namespace to prevent race conditions in reference counting.
    - Update `IsLastProcess` and corresponding tests to reflect the unregister-then-check cleanup flow.
- Improve test reliability and correctness:
    - Convert `TestAppRun_ProfileDirInjection` to use separate binary execution, preventing process replacement and ensuring `t.TempDir()` cleanup.
    - Replace hardcoded test configuration paths with `t.TempDir()` in `mount_leak_test.go`.
    - Implement `SetEnvOverrides` helper for cleaner environment variable management in E2E tests.
    - Improve E2E lifecycle tests with better environment handling and output redirection.

1 files changed, 8 insertions, 1 deletions

diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index 4d028a2..4b3e36a 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -123,10 +123,12 @@ func (a *App) Run() error {
 	}
 
 	if namespace.IsIsolated() {
+		fmt.Printf("DEBUG: IsIsolated=true, RuntimeBaseDir=%s\n", a.getPathManager().RuntimeBaseDir())
 		return a.ExecuteCommand(cfg)
 	}
 
 	pm := a.getPathManager()
+	fmt.Printf("DEBUG: IsIsolated=false, RuntimeBaseDir=%s\n", pm.RuntimeBaseDir())
 
 	// Preserve the host runtime base dir in the environment before bootstrapping
 	_ = os.Setenv("WG_WRAP_HOST_RUNTIME_BASE_DIR", pm.RuntimeBaseDir())
@@ -143,6 +145,11 @@ func (a *App) Run() error {
 	if err == nil && activePid > 0 {
 		// Release the lock before executing the command to allow others to join
 		namespace.ReleaseProfileLock(lockFile)
+
+		// Register this PID before joining to prevent the race where the joining process 
+		// hasn't registered itself yet, causing the existing process to think it's the last one.
+		_ = namespace.RegisterProcess(pm, cfg.Profile)
+
 		if err := namespace.BootstrapJoin(activePid); err != nil {
 			return fmt.Errorf("failed to join existing namespace: %w", err)
 		}
@@ -265,7 +272,7 @@ func (a *App) ExecuteCommand(cfg *config.Config) error {
 				}
 			}
 
-			tunnel, err := wireguard.StartTunnel(wgCfg, dnsServer)
+			tunnel, err := wireguard.StartTunnel(pm, cfg.Profile, wgCfg, dnsServer)
 			if err != nil {
 				return fmt.Errorf("failed to start WireGuard tunnel: %w", err)
 			}