fix: security-audit remediation (15 findings), empty-wallet warning, and send/chat/console/shutdown UX

Security audit remediation (15 confirmed findings from the codebase audit):
- H-02: scrub+delete the decrypt-flow plaintext key export on ALL exit paths
  (RAII guard) and purge stale obsidiandecryptexport* files at startup.
- M-01/L-03/L-04/L-05/L-07: sodium_memzero the Set-PIN and encrypt-PIN worker
  passphrase/PIN copies, the RPC Basic-auth string (auth_), the exported/imported
  key buffers (App::wipeSecrets, called from ~App and before main's _Exit), and
  the first-run wizard "Skip" buffers.
- M-03/M-04/M-05/L-06: return locked COPIES from XmrigManager/EmbeddedDaemon
  getters (dedicated error_mutex_; DaemonController::lastError now by value),
  route xmrig last_error_ writes through a locked setter, and wrap
  shutdown_status_/wizard_stop_status_ in a locking GuardedStatus
  (wizard_stopping_external_ -> std::atomic).
- M-02: persist after a console send/shield/import in the lite backend.
- L-01: require the confirm click for z_shieldcoinbase/z_mergetoaddress.
- L-02: quote/escape each Windows daemon argv per the MSDN CommandLineToArgvW rules.
- L-08: pin json/tomlplusplus/libwebp FetchContent to immutable commit SHAs.
- I-01: extract updater archives from the already-verified in-memory buffer
  (no disk re-read TOCTOU).

Feature: warn once (full-node) when the active wallet loads empty while a sibling
wallet file in the datadir holds keys. A funded salvage wallet.<ts>.bak routes to
the recovery/Restore flow; a funded sibling .dat routes to the wallet manager.
Per-wallet-file dismissal; gated on synced + address-list-loaded to avoid false
positives on warm reconnect / spent-down wallets.

UX fixes:
- send: show the TOTAL balance (with a spendable "available" note) in the source
  dropdown and keep pending-change addresses visible.
- chat: insert emoji at the cursor position; restrict new-chat recipients to
  shielded (z) addresses.
- console: optional auto-focus of the command input on tab open (off by default).
- shutdown: when "stop external daemon" is on, keep the shutdown screen up until
  the external node actually exits, showing live status.

Adversarially reviewed; verified across full-node, lite, and Windows builds; tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/daemon/daemon_controller.cpp

@@ -71,9 +71,11 @@ DaemonController::State DaemonController::state() const
     return daemon_->getState();
 }
 
-const std::string& DaemonController::lastError() const
+std::string DaemonController::lastError() const
 {
-    return daemon_->getLastError();
+    // By value — getLastError() now returns a mutex-locked COPY, so forwarding it by reference would
+    // dangle (bind a reference to that temporary). (M-04 follow-through)
+    return daemon_ ? daemon_->getLastError() : std::string();
 }
 
 int DaemonController::crashCount() const

src/daemon/daemon_controller.h

@@ -95,7 +95,7 @@ public:
     bool externalDaemonDetected() const;
     void clearExternalDaemonDetected();
     State state() const;
-    const std::string& lastError() const;
+    std::string lastError() const;   // by value: EmbeddedDaemon::getLastError() returns a locked copy (M-04)
     int crashCount() const;
     int lastBlockHeight() const;
     double memoryUsageMB() const;

src/daemon/embedded_daemon.cpp

@@ -224,12 +224,11 @@ std::vector<std::string> EmbeddedDaemon::getChainParams()
 void EmbeddedDaemon::setState(State s, const std::string& message)
 {
     state_ = s;
-    if (!message.empty()) {
-        if (s == State::Error) {
-            last_error_ = message;
-        }
+    if (!message.empty() && s == State::Error) {
+        std::lock_guard<std::mutex> lk(error_mutex_);   // dedicated mutex — never taken with output_mutex_ held
+        last_error_ = message;
     }
-    
+
     if (state_callback_) {
         state_callback_(s, message);
     }
@@ -621,12 +620,28 @@ bool EmbeddedDaemon::start(const std::string& binary_path)
 // Forward declaration — defined after startProcess
 static DWORD findProcessByName(const char* name);
 
+// Quote a single argument per the CommandLineToArgvW rules (MSDN) so a value containing a space or a
+// quote is delivered as ONE argv token to the daemon instead of splitting/corrupting argv (L-02).
+static std::string quoteWinArg(const std::string& arg) {
+    if (!arg.empty() && arg.find_first_of(" \t\n\v\"") == std::string::npos) return arg;
+    std::string out = "\"";
+    for (size_t i = 0; ; ++i) {
+        size_t nbs = 0;
+        while (i < arg.size() && arg[i] == '\\') { ++nbs; ++i; }
+        if (i == arg.size()) { out.append(nbs * 2, '\\'); break; }
+        if (arg[i] == '"')   { out.append(nbs * 2 + 1, '\\'); out.push_back('"'); }
+        else                 { out.append(nbs, '\\'); out.push_back(arg[i]); }
+    }
+    out.push_back('"');
+    return out;
+}
+
 bool EmbeddedDaemon::startProcess(const std::string& binary_path, const std::vector<std::string>& args)
 {
-    // Build command line
+    // Build command line (binary path always quoted; each arg quoted/escaped per Windows rules — L-02)
     std::string cmd = "\"" + binary_path + "\"";
     for (const auto& arg : args) {
-        cmd += " " + arg;
+        cmd += " " + quoteWinArg(arg);
     }
     DEBUG_LOGF("[INFO] Starting daemon: %s\n", cmd.c_str());
     

src/daemon/embedded_daemon.h

@@ -79,7 +79,9 @@ public:
     /**
      * @brief Get last error message
      */
-    const std::string& getLastError() const { return last_error_; }
+    // Copy under lock: last_error_ is written from the monitor thread (setState on an unexpected exit)
+    // while the UI thread reads it — a reference would be a torn-read / use-after-free race (M-04).
+    std::string getLastError() const { std::lock_guard<std::mutex> lk(error_mutex_); return last_error_; }
     
     /**
      * @brief Get dragonxd process output (thread-safe copy)
@@ -286,6 +288,7 @@ private:
     std::atomic<State> state_{State::Stopped};
     std::atomic<bool> external_daemon_detected_{false};
     std::string last_error_;
+    mutable std::mutex error_mutex_;    // protects last_error_ (written by main + monitor threads)
     mutable std::mutex output_mutex_;  // protects process_output_
     std::string process_output_;
     StateCallback state_callback_;

src/daemon/xmrig_manager.cpp

@@ -210,7 +210,7 @@ bool XmrigManager::generateConfig(const Config& cfg, const std::string& outPath)
         fs::create_directories(fs::path(outPath).parent_path());
         std::ofstream ofs(outPath, std::ios::trunc);
         if (!ofs.is_open()) {
-            last_error_ = "Cannot write xmrig config: " + outPath;
+            setLastError("Cannot write xmrig config: " + outPath);
             DEBUG_LOGF("[ERROR] XmrigManager: %s\n", last_error_.c_str());
             return false;
         }
@@ -224,7 +224,7 @@ bool XmrigManager::generateConfig(const Config& cfg, const std::string& outPath)
         ofs.close();
         return true;
     } catch (const std::exception& e) {
-        last_error_ = std::string("Config write error: ") + e.what();
+        setLastError(std::string("Config write error: ") + e.what());
         DEBUG_LOGF("[ERROR] XmrigManager: %s\n", last_error_.c_str());
         return false;
     }
@@ -236,19 +236,22 @@ bool XmrigManager::generateConfig(const Config& cfg, const std::string& outPath)
 
 bool XmrigManager::start(const Config& cfg) {
     if (state_ == State::Running || state_ == State::Starting) {
-        last_error_ = "Already running";
+        setLastError("Already running");
         DEBUG_LOGF("[WARN] XmrigManager: %s\n", last_error_.c_str());
         return false;
     }
 
     state_ = State::Starting;
     should_stop_ = false;
-    last_error_.clear();
+    setLastError(std::string());
     {
         std::lock_guard<std::mutex> lk(output_mutex_);
         process_output_.clear();
     }
-    stats_ = PoolStats{};
+    {
+        std::lock_guard<std::mutex> lk(stats_mutex_);
+        stats_ = PoolStats{};
+    }
 
     // Extract pool hostname for stats API queries
     {
@@ -265,7 +268,7 @@ bool XmrigManager::start(const Config& cfg) {
     // Find binary
     std::string binary = findXmrigBinary();
     if (binary.empty()) {
-        last_error_ = "xmrig binary not found";
+        setLastError("xmrig binary not found");
         state_ = State::Error;
         DEBUG_LOGF("[ERROR] XmrigManager: xmrig binary not found\n");
         return false;
@@ -368,7 +371,7 @@ bool XmrigManager::startProcess(const std::string& xmrigPath, const std::string&
 
     HANDLE hRead = nullptr, hWrite = nullptr;
     if (!CreatePipe(&hRead, &hWrite, &sa, 0)) {
-        last_error_ = "CreatePipe failed";
+        setLastError("CreatePipe failed");
         DEBUG_LOGF("[ERROR] XmrigManager: %s\n", last_error_.c_str());
         return false;
     }
@@ -400,7 +403,7 @@ bool XmrigManager::startProcess(const std::string& xmrigPath, const std::string&
         char errBuf[256];
         FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                        NULL, err, 0, errBuf, sizeof(errBuf), NULL);
-        last_error_ = "CreateProcess failed for xmrig (error " + std::to_string(err) + "): " + errBuf;
+        setLastError("CreateProcess failed for xmrig (error " + std::to_string(err) + "): " + errBuf);
         DEBUG_LOGF("[ERROR] XmrigManager: %s\nCommand: %s\n", last_error_.c_str(), cmdLine.c_str());
         return false;
     }
@@ -451,14 +454,14 @@ void XmrigManager::drainOutput() {
 bool XmrigManager::startProcess(const std::string& xmrigPath, const std::string& cfgPath, int threads) {
     int pipefd[2];
     if (pipe(pipefd) != 0) {
-        last_error_ = "pipe() failed";
+        setLastError("pipe() failed");
         DEBUG_LOGF("[ERROR] XmrigManager: %s\n", last_error_.c_str());
         return false;
     }
 
     pid_t pid = fork();
     if (pid < 0) {
-        last_error_ = "fork() failed";
+        setLastError("fork() failed");
         DEBUG_LOGF("[ERROR] XmrigManager: %s\n", last_error_.c_str());
         close(pipefd[0]);
         close(pipefd[1]);
@@ -629,7 +632,7 @@ void XmrigManager::monitorProcess() {
             if (GetExitCodeProcess(process_handle_, &exitCode) && exitCode != STILL_ACTIVE) {
                 DEBUG_LOGF("[ERROR] XmrigManager: process exited (code %lu)\n", exitCode);
                 state_ = State::Error;
-                last_error_ = "xmrig process exited unexpectedly";
+                setLastError("xmrig process exited unexpectedly");
                 break;
             }
         }
@@ -640,7 +643,7 @@ void XmrigManager::monitorProcess() {
             if (ret == process_pid_ || ret < 0) {
                 DEBUG_LOGF("[ERROR] XmrigManager: process exited (waitpid=%d)\n", ret);
                 state_ = State::Error;
-                last_error_ = "xmrig process exited unexpectedly";
+                setLastError("xmrig process exited unexpectedly");
                 break;
             }
         }

src/daemon/xmrig_manager.h

@@ -86,8 +86,10 @@ public:
     bool  isRunning() const;
     State getState() const { return state_.load(std::memory_order_relaxed); }
 
-    const PoolStats& getStats() const { return stats_; }
-    const std::string& getLastError() const { return last_error_; }
+    // Return COPIES under lock: stats_ and last_error_ are mutated by the monitor thread while the UI
+    // thread reads them, so handing out a reference is a torn-read / use-after-free race (M-03, M-04).
+    PoolStats getStats() const { std::lock_guard<std::mutex> lk(stats_mutex_); return stats_; }
+    std::string getLastError() const { std::lock_guard<std::mutex> lk(error_mutex_); return last_error_; }
 
     /// Thread count requested at start() — available immediately, unlike
     /// PoolStats::threads_active which requires an API response.
@@ -156,11 +158,14 @@ private:
     void monitorProcess();
     void drainOutput();
     void appendOutput(const char* data, size_t len);
+    // Set last_error_ under error_mutex_ (writers run on both the main thread and the monitor thread).
+    void setLastError(std::string e) { std::lock_guard<std::mutex> lk(error_mutex_); last_error_ = std::move(e); }
     void fetchStatsHttp();  // Blocking HTTP call — runs on monitor thread only
     void fetchPoolApiStats();  // Fetch pool-side stats (hashrate) from pool HTTP API
 
     std::atomic<State> state_{State::Stopped};
     std::string last_error_;
+    mutable std::mutex error_mutex_;   // guards last_error_ (written by main + monitor threads)
 
     mutable std::mutex output_mutex_;
     std::string process_output_;