diff --git a/experimental/dsh-everything-edition/flake.nix b/experimental/dsh-everything-edition/flake.nix
index a2d440a..5b542b9 100644
--- a/experimental/dsh-everything-edition/flake.nix
+++ b/experimental/dsh-everything-edition/flake.nix
@@ -132,6 +132,21 @@
               description = "dsh web preloaded with this checkout's dsh-plugins/plugins.cordis.yml";
             };
           };
+
+          # dsh-main with `--port 0`, so a second run gets an OS-assigned free
+          # port instead of colliding on 3080. A user-supplied `--port` still
+          # wins, because it lands after this one on the composed command line.
+          dsh-main-any-port = pkgs.writeShellApplication {
+            name = "dsh-main-any-port";
+            runtimeInputs = [ dsh-main ];
+            text = ''
+              exec dsh-main --port 0 "$@"
+            '';
+            meta = {
+              mainProgram = "dsh-main-any-port";
+              description = "dsh-main on an OS-assigned free port";
+            };
+          };
         in
         {
           # `nix run .#dsh-vanilla-with-pnpm`: plain dsh with pnpm + node on PATH.
@@ -140,6 +155,9 @@
           # `nix run` (or `nix run .#main`): dsh web with this checkout's plugins loaded.
           default = dsh-main;
           main = dsh-main;
+
+          # `nix run .#main-any-port`: `#main`, but on an OS-assigned free port.
+          main-any-port = dsh-main-any-port;
         }
       );
     };