fix: port allocator scans existing ports to avoid collisions

- Collapse multi-line allocScript to single line (fixes SSH+sudo mangling)
- Scan /etc/ship/ports/* to find highest port in use
- Use max(next_port, highest_used + 1) to prevent collisions
- Fixes issue where stale/missing next_port caused port conflicts

1 files changed, 2 insertions, 8 deletions

diff --git a/cmd/ship/deploy_impl_v2.go b/cmd/ship/deploy_impl_v2.go
index 5b68dc3..ec5c4a3 100644
--- a/cmd/ship/deploy_impl_v2.go
+++ b/cmd/ship/deploy_impl_v2.go
@@ -308,14 +308,8 @@ func allocatePort(client *ssh.Client, name string) (int, error) {
         }
 
         // Allocate new port atomically using flock
-        // This reads next_port, increments it, and writes back while holding a lock
-        allocScript := `
-flock -x /etc/ship/.port.lock sh -c '
-  mkdir -p /etc/ship/ports
-  PORT=$(cat /etc/ship/next_port 2>/dev/null || echo 9000)
-  echo $((PORT + 1)) > /etc/ship/next_port
-  echo $PORT
-'`
+        // Scans existing port files to avoid collisions even if next_port is stale
+        allocScript := `flock -x /etc/ship/.port.lock sh -c 'mkdir -p /etc/ship/ports; NEXT=$(cat /etc/ship/next_port 2>/dev/null || echo 9000); MAX=8999; for f in /etc/ship/ports/*; do [ -f "$f" ] && P=$(cat "$f" 2>/dev/null) && [ "$P" -gt "$MAX" ] 2>/dev/null && MAX=$P; done; PORT=$(( NEXT > MAX ? NEXT : MAX + 1 )); echo $((PORT + 1)) > /etc/ship/next_port; echo $PORT'`
         out, err = client.RunSudo(allocScript)
         if err != nil {
                 return 0, fmt.Errorf("failed to allocate port: %w", err)