feat(web): python -m proteus.web launcher

proteus/web/__main__.py

@@ -0,0 +1,29 @@
+"""`python -m proteus.web` — launch the interactive color-grid play server."""
+from __future__ import annotations
+
+import argparse
+
+import proteus.grid  # noqa: F401  (registers scenarios before any request)
+from proteus.web.server import make_server
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(prog="proteus.web")
+    parser.add_argument("--host", default="127.0.0.1")
+    parser.add_argument("--port", type=int, default=8000)
+    args = parser.parse_args(argv)
+
+    server = make_server(args.host, args.port)
+    host, port = server.server_address[0], server.server_address[1]
+    print(f"PROTEUS arena — open http://{host}:{port}/  (Ctrl-C to stop)")
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        print("\nstopping.")
+    finally:
+        server.server_close()
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

tests/web/test_server.py

@@ -112,3 +112,13 @@ def test_finish_appends_trace_and_returns_metrics(tmp_path):
     assert payload["trace_path"] == str(out)
     assert "survival_fraction" in payload["metrics"]
     assert out.exists() and out.read_text().strip()  # one JSONL line written
+
+
+def test_make_server_binds_and_has_router(tmp_path):
+    srv = server.make_server("127.0.0.1", 0)  # port 0 = ephemeral, no serve_forever
+    try:
+        assert srv.server_address[0] == "127.0.0.1"
+        # the bound handler carries its own fresh registry
+        assert isinstance(srv.RequestHandlerClass.registry, dict)
+    finally:
+        srv.server_close()