diff --git a/tools/lite_smoke.cpp b/tools/lite_smoke.cpp
index 41ddbfa..ff0e8b4 100644
--- a/tools/lite_smoke.cpp
+++ b/tools/lite_smoke.cpp
@@ -7,18 +7,22 @@
 // against a real lightwalletd server. The "real backend smoke test" the plan gates behind
 // passing fake-backend tests.
 //
-//   lite_smoke [server-url] [--create] [--refresh] [--full] [--restore-recent]
+//   lite_smoke [server-url] [--create] [--refresh] [--full] [--restore-recent] [--keys]
 //
 // Read-only by default. --create initializes a new wallet. --refresh runs the refresh
 // commands through the parsers (shape check). --full also does a (slow) full sync first.
 // --restore-recent restores a throwaway wallet with a birthday near the tip so the sync is
 // minimal (seconds), then runs the data-shape checks — fast verification of balance/addresses/
-// list shapes without a multi-minute full scan. Always run with an isolated HOME.
+// list shapes without a multi-minute full scan. --keys creates a fresh wallet and checks the
+// M4/M5 spend/backup command shapes (new-address / export / seed / save) — fast, no sync, and
+// SECRET-SAFE (seed/key values are never printed). Always run with an isolated HOME.
 
 #include "wallet/lite_client_bridge.h"
 #include "wallet/lite_connection_service.h"
 #include "wallet/lite_result_parsers.h"
 
+#include <nlohmann/json.hpp>
+
 #include <cstdio>
 #include <string>
 
@@ -68,18 +72,73 @@ static void runDataShapeChecks(LiteClientBridge& bridge)
     }
 }
 
+// Exercise the M4/M5 spend/backup command shapes against the real backend: new-address,
+// export (private keys), seed, and save. SECRET-SAFE — seed/private-key VALUES are never
+// printed; only their presence and JSON shape are reported. (No send/shield here: those would
+// attempt a real broadcast.)
+static void runLiteKeysShapeChecks(LiteClientBridge& bridge)
+{
+    auto parse = [](const std::string& s) { return nlohmann::json::parse(s, nullptr, false); };
+
+    {
+        auto r = bridge.execute("new", "zs");
+        auto j = parse(r.value);
+        const bool shape = j.is_array() && !j.empty() && j[0].is_string() &&
+                           j[0].get<std::string>().rfind("zs", 0) == 0;
+        std::printf("[lite-smoke] new z      bridge_ok=%d shape_ok=%d (addr redacted)\n", r.ok, shape);
+        if (!shape) std::printf("[lite-smoke]   new z RAW = %.80s\n", r.value.c_str());
+    }
+    {
+        auto r = bridge.execute("new", "R");
+        auto j = parse(r.value);
+        const bool shape = j.is_array() && !j.empty() && j[0].is_string() &&
+                           j[0].get<std::string>().rfind("R", 0) == 0;
+        std::printf("[lite-smoke] new t      bridge_ok=%d shape_ok=%d (addr redacted)\n", r.ok, shape);
+        if (!shape) std::printf("[lite-smoke]   new t RAW = %.80s\n", r.value.c_str());
+    }
+    {
+        // seed: {"seed": "...", "birthday": N} — verify shape ONLY; never print the seed.
+        auto r = bridge.execute("seed", "");
+        auto j = parse(r.value);
+        const bool hasSeed = j.is_object() && j.contains("seed") && j["seed"].is_string() &&
+                             !j["seed"].get<std::string>().empty();
+        const bool hasBday = j.is_object() && j.contains("birthday");
+        std::printf("[lite-smoke] seed       bridge_ok=%d has_seed=%d has_birthday=%d (seed REDACTED)\n",
+                    r.ok, hasSeed, hasBday);
+        if (!hasSeed) std::printf("[lite-smoke]   seed shape unexpected (len=%zu)\n", r.value.size());
+    }
+    {
+        // export: [{"address","private_key","viewing_key"}, ...] — shape ONLY; never print keys.
+        auto r = bridge.execute("export", "");
+        auto j = parse(r.value);
+        const bool isArr = j.is_array();
+        const bool hasPk = isArr && !j.empty() && j[0].is_object() && j[0].contains("private_key");
+        std::printf("[lite-smoke] export     bridge_ok=%d is_array=%d count=%zu has_private_key=%d (keys REDACTED)\n",
+                    r.ok, isArr, isArr ? j.size() : 0, hasPk);
+        if (!isArr) std::printf("[lite-smoke]   export shape unexpected (len=%zu)\n", r.value.size());
+    }
+    {
+        auto r = bridge.execute("save", "");
+        auto j = parse(r.value);
+        const bool ok = j.is_object() && j.value("result", std::string()) == "success";
+        std::printf("[lite-smoke] save       bridge_ok=%d result_success=%d\n", r.ok, ok);
+        if (!ok) std::printf("[lite-smoke]   save RAW = %.80s\n", r.value.c_str());
+    }
+}
+
 int main(int argc, char** argv)
 {
     std::setvbuf(stdout, nullptr, _IONBF, 0);  // unbuffered so output survives a timeout kill
 
     std::string server = "https://lite.dragonx.is";
-    bool doCreate = false, doRefresh = false, doFull = false, doRestoreRecent = false;
+    bool doCreate = false, doRefresh = false, doFull = false, doRestoreRecent = false, doKeys = false;
     for (int i = 1; i < argc; ++i) {
         const std::string arg = argv[i];
         if (arg == "--create") doCreate = true;
         else if (arg == "--refresh") doRefresh = true;
         else if (arg == "--full") doFull = true;
         else if (arg == "--restore-recent") doRestoreRecent = true;
+        else if (arg == "--keys") doKeys = true;
         else server = arg;
     }
 
@@ -124,6 +183,24 @@ int main(int argc, char** argv)
         return 0;
     }
 
+    if (doKeys) {
+        // Fast M4/M5 path check: create a fresh wallet (no sync needed for local key ops) and
+        // exercise new-address / export / seed / save shapes. Run with an isolated HOME.
+        std::printf("[lite-smoke] initializeNew() for M4/M5 keys check...\n");
+        auto cr = bridge.initializeNew(false, server);
+        std::printf("[lite-smoke] initializeNew ok=%d\n", cr.ok);
+        if (!cr.ok) {
+            std::printf("[lite-smoke]   error = %s\n", cr.error.c_str());
+            bridge.shutdown();
+            return 1;
+        }
+        std::printf("[lite-smoke] --- M4/M5 shape check (new/export/seed/save) ---\n");
+        runLiteKeysShapeChecks(bridge);
+        bridge.shutdown();
+        std::printf("[lite-smoke] done\n");
+        return 0;
+    }
+
     if (doCreate) {
         std::printf("[lite-smoke] initializeNew() ... (real network + writes wallet state)\n");
         auto result = bridge.initializeNew(false, server);