From 90446b31b07ee6565b955d0290352cf73fe20570 Mon Sep 17 00:00:00 2001
From: Miles Raymond <reukiodo@gmail.com>
Date: Mon, 2 Feb 2026 13:08:53 -0800
Subject: [PATCH] add unique hostname support

---
 .../network/CalibreConnectActivity.cpp        | 18 ++++++++++--
 .../network/CrossPointWebServerActivity.cpp   | 28 ++++++++++++++-----
 2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/src/activities/network/CalibreConnectActivity.cpp b/src/activities/network/CalibreConnectActivity.cpp
index 8aa60c40..6a30fc68 100644
--- a/src/activities/network/CalibreConnectActivity.cpp
+++ b/src/activities/network/CalibreConnectActivity.cpp
@@ -11,7 +11,19 @@
 #include "fontIds.h"
 
 namespace {
-constexpr const char* HOSTNAME = "crosspoint";
+  // Generate hostname dynamically based on device MAC address
+  String getDeviceHostname() {
+    static String deviceHostname;
+    if (deviceHostname.length() == 0) {
+      uint64_t chipId = ESP.getEfuseMac();
+      // Extract last 6 hex digits (24 bits) for serial number
+      uint32_t serialNum = (uint32_t)(chipId & 0xFFFFFF);
+      char hostname[32];
+      snprintf(hostname, sizeof(hostname), "XTeinkX4-%06X", serialNum);
+      deviceHostname = String(hostname);
+    }
+    return deviceHostname;
+  }
 }  // namespace
 
 void CalibreConnectActivity::taskTrampoline(void* param) {
@@ -94,9 +106,9 @@ void CalibreConnectActivity::startWebServer() {
   state = CalibreConnectState::SERVER_STARTING;
   updateRequired = true;
 
-  if (MDNS.begin(HOSTNAME)) {
+  if (MDNS.begin(getDeviceHostname().c_str())) {
     // mDNS is optional for the Calibre plugin but still helpful for users.
-    Serial.printf("[%lu] [CAL] mDNS started: http://%s.local/\n", millis(), HOSTNAME);
+    Serial.printf("[%lu] [CAL] mDNS started: http://%s.local/\n", millis(), getDeviceHostname().c_str());
   }
 
   webServer.reset(new CrossPointWebServer());
diff --git a/src/activities/network/CrossPointWebServerActivity.cpp b/src/activities/network/CrossPointWebServerActivity.cpp
index c6af1497..fe163219 100644
--- a/src/activities/network/CrossPointWebServerActivity.cpp
+++ b/src/activities/network/CrossPointWebServerActivity.cpp
@@ -19,10 +19,24 @@ namespace {
 // AP Mode configuration
 constexpr const char* AP_SSID = "CrossPoint-Reader";
 constexpr const char* AP_PASSWORD = nullptr;  // Open network for ease of use
-constexpr const char* AP_HOSTNAME = "crosspoint";
 constexpr uint8_t AP_CHANNEL = 1;
 constexpr uint8_t AP_MAX_CONNECTIONS = 4;
 
+// Static cached hostname for the device
+static String deviceHostname;
+
+// Generate hostname dynamically based on device MAC address
+String getDeviceHostname() {
+  if (deviceHostname.length() == 0) {
+    // Extract last 6 hex digits (24 bits) for serial number
+    uint32_t serialNum = (uint32_t)(ESP.getEfuseMac() & 0xFFFFFF);
+    char hostname[32];
+    snprintf(hostname, sizeof(hostname), "XTeinkX4-%06X", serialNum);
+    deviceHostname = String(hostname);
+  }
+  return deviceHostname;
+}
+
 // DNS server for captive portal (redirects all DNS queries to our IP)
 DNSServer* dnsServer = nullptr;
 constexpr uint16_t DNS_PORT = 53;
@@ -181,8 +195,8 @@ void CrossPointWebServerActivity::onWifiSelectionComplete(const bool connected)
     exitActivity();
 
     // Start mDNS for hostname resolution
-    if (MDNS.begin(AP_HOSTNAME)) {
-      Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), AP_HOSTNAME);
+    if (MDNS.begin(getDeviceHostname().c_str())) {
+      Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), getDeviceHostname().c_str());
     }
 
     // Start the web server
@@ -234,8 +248,8 @@ void CrossPointWebServerActivity::startAccessPoint() {
   Serial.printf("[%lu] [WEBACT] IP: %s\n", millis(), connectedIP.c_str());
 
   // Start mDNS for hostname resolution
-  if (MDNS.begin(AP_HOSTNAME)) {
-    Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), AP_HOSTNAME);
+  if (MDNS.begin(getDeviceHostname().c_str())) {
+    Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), getDeviceHostname().c_str());
   } else {
     Serial.printf("[%lu] [WEBACT] WARNING: mDNS failed to start\n", millis());
   }
@@ -439,7 +453,7 @@ void CrossPointWebServerActivity::renderServerRunning() const {
 
     startY += 6 * 29 + 3 * LINE_SPACING;
     // Show primary URL (hostname)
-    std::string hostnameUrl = std::string("http://") + AP_HOSTNAME + ".local/";
+    std::string hostnameUrl = std::string("http://") + getDeviceHostname().c_str() + ".local/";
     renderer.drawCenteredText(UI_10_FONT_ID, startY + LINE_SPACING * 3, hostnameUrl.c_str(), true, EpdFontFamily::BOLD);
 
     // Show IP address as fallback
@@ -468,7 +482,7 @@ void CrossPointWebServerActivity::renderServerRunning() const {
     renderer.drawCenteredText(UI_10_FONT_ID, startY + LINE_SPACING * 2, webInfo.c_str(), true, EpdFontFamily::BOLD);
 
     // Also show hostname URL
-    std::string hostnameUrl = std::string("or http://") + AP_HOSTNAME + ".local/";
+    std::string hostnameUrl = std::string("or http://") + getDeviceHostname().c_str() + ".local/";
     renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 3, hostnameUrl.c_str());
 
     renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 4, "Open this URL in your browser");