From 1b735c9c30cf32aca206cde7eb8949c47561dbb6 Mon Sep 17 00:00:00 2001
From: David Montero <davidmonterocrespo24@gmail.com>
Date: Tue, 18 Aug 2026 16:04:48 +0200
Subject: [PATCH] seo/analytics: real GA attribution, tight robots.txt, no
 build-date lastmod, GA only on velxio.dev
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- trackClickCTA sent the originating page as the event parameter `source`,
  a reserved traffic-source name in GA4: every landing CTA click rewrote the
  session's acquisition to landing / arduino-simulator / rpi-simulator with
  medium (not set), which put 16% of sessions in the Unassigned channel.
  Renamed to cta_source (register it as a custom dimension in GA4 if the
  click_cta report should keep breaking down by page).
- robots.txt is one group with no blank lines (some parsers end a group at
  a blank line, orphaning the Disallow rules); /login, /register and /admin
  are no longer disallowed — they carry noindex, and a page must be
  crawlable for that tag to take effect. /project/ and /api/ stay out.
- The static sitemap no longer stamps every URL with the build date as
  <lastmod>; an all-identical, ever-changing lastmod is discarded as
  unreliable, so omitting it is the honest option.
- The GA4 tag loads only on velxio.dev / www.velxio.dev / tauri.localhost:
  self-hosted copies of the app (there are >180 hostnames reporting into
  the property) no longer pollute velxio.dev's analytics.
---
 frontend/index.html                   |  25 +++-
 frontend/public/robots.txt            |  18 ++-
 frontend/public/sitemap.xml           | 193 --------------------------
 frontend/scripts/generate-sitemap.mjs |   9 +-
 frontend/src/utils/analytics.ts       |  12 +-
 5 files changed, 42 insertions(+), 215 deletions(-)

diff --git a/frontend/index.html b/frontend/index.html
index 9b24b540..7f936b09 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -20,15 +20,26 @@
 
     <!-- ═══════════════════════════════════════════════
          GOOGLE ANALYTICS 4
-         Replace G-XXXXXXXXXX with your real Measurement ID
-         (analytics.google.com → Admin → Data Streams → Measurement ID)
+         The Measurement ID below is velxio.dev's, so the tag only loads on
+         velxio.dev hostnames (plus the Velxio Desktop shell). Self-hosted
+         copies of the app send nothing — swap in your own ID AND hostname
+         (analytics.google.com → Admin → Data Streams → Measurement ID) if you
+         want analytics on your deployment.
     ═══════════════════════════════════════════════ -->
-    <script async src="https://www.googletagmanager.com/gtag/js?id=G-HPD8HTV3TG"></script>
     <script>
-      window.dataLayer = window.dataLayer || [];
-      function gtag(){dataLayer.push(arguments);}
-      gtag('js', new Date());
-      gtag('config', 'G-HPD8HTV3TG');
+      (function () {
+        var h = location.hostname;
+        if (h !== 'velxio.dev' && h !== 'www.velxio.dev' && h !== 'tauri.localhost') return;
+        var s = document.createElement('script');
+        s.async = true;
+        s.src = 'https://www.googletagmanager.com/gtag/js?id=G-HPD8HTV3TG';
+        document.head.appendChild(s);
+        window.dataLayer = window.dataLayer || [];
+        function gtag(){dataLayer.push(arguments);}
+        window.gtag = gtag;
+        gtag('js', new Date());
+        gtag('config', 'G-HPD8HTV3TG');
+      })();
     </script>
 
     <!-- ═══════════════════════════════════════════════
diff --git a/frontend/public/robots.txt b/frontend/public/robots.txt
index 261bfa5d..33eebceb 100644
--- a/frontend/public/robots.txt
+++ b/frontend/public/robots.txt
@@ -1,17 +1,15 @@
+# One group, no blank lines inside it: some crawlers treat a blank line as
+# the end of a group, which left the Disallow rules below orphaned.
 User-agent: *
 Allow: /
-
-# Auth pages — no useful content for search engines
-Disallow: /login
-Disallow: /register
-
-# UUID-based duplicate of /:username/:slug — keep crawlers on the canonical
-# user-friendly URL instead of the opaque /project/<uuid> alternate.
+# UUID-based duplicate of /:username/:slug (the canonical URL); crawling it
+# is wasted budget.
 Disallow: /project/
-Disallow: /admin
-
-# Prevent crawling of API endpoints
+# API endpoints are not pages.
 Disallow: /api/
+# Auth and admin pages are deliberately NOT disallowed here: they carry a
+# noindex meta tag, and a page has to be crawlable for that tag to be seen —
+# a disallowed URL can still be indexed from links, title-less.
 
 # Sitemaps (static build-time routes + dynamic public projects + the docs
 # portal, which is a separate Astro build shipping its own sitemap index)
diff --git a/frontend/public/sitemap.xml b/frontend/public/sitemap.xml
index adc27b6f..76009aae 100644
--- a/frontend/public/sitemap.xml
+++ b/frontend/public/sitemap.xml
@@ -4,1160 +4,967 @@
 
   <url>
     <loc>https://velxio.dev/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>1</priority>
   </url>
   <url>
     <loc>https://velxio.dev/editor/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.8</priority>
   </url>
   <url>
     <loc>https://velxio.dev/circuit-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.95</priority>
   </url>
   <url>
     <loc>https://velxio.dev/spice-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/electronics-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/custom-chip-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/attiny85-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/arduino-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/arduino-emulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/atmega328p-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/arduino-mega-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/esp32-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/esp32-s3-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/esp32-c3-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/raspberry-pi-pico-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/raspberry-pi-simulator/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
   <url>
     <loc>https://velxio.dev/v2/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/v2-5/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://velxio.dev/v3/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.95</priority>
   </url>
   <url>
     <loc>https://velxio.dev/about/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.7</priority>
   </url>
   <url>
     <loc>https://velxio.dev/classroom/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
 
   <url>
     <loc>https://velxio.dev/examples/uno-oled-4pin-i2c/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/esp32-oled-4pin-i2c/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/esp32-idf-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-oled-4pin-i2c/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-oled-4pin-i2c/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/ky-040-rotary-encoder/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-serial-counter/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-f4-discovery-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-olimex-h405-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-netduino-plus2-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-netduino2-serial/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-blackpill-f401-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-f103cb-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-uno-gpio-mirror/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-uno-serial-link/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-esp32-gpio-sync/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-blackpill-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-blackpill-gpio/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-bmp280/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-oled/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-mpu6050/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-rtc/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-blackpill-oled/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-weather-station/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-7segment/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-rgb/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-button/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-switch/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/stm32-bluepill-stepper/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/uno-stepper-a4988/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/esp32-stepper-a4988/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-stepper-a4988/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/blink-led/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/traffic-light/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/button-led/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/fade-led/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/serial-hello/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/rgb-led/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/simon-says/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-doom-raycaster/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/tft-display/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/lcd-hello/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/serial-echo/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/serial-led-control/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/i2c-scanner/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/i2c-rtc-read/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/i2c-eeprom-rw/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/spi-loopback/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/multi-protocol/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-blink/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-serial-echo/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-serial-led-control/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-i2c-scanner/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-i2c-rtc-read/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-i2c-eeprom-rw/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-spi-loopback/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/pico-adc-read/</loc>
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-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/logic-probe/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/relay-led-switch/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/optocoupler-signal/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/l293d-motor-control/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/l293d-speed-pwm/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/power-supply-7805/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/lm317-adjustable-psu/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/battery-voltage-monitor/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/esp32-dual-adc/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/mega-multi-led/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/nano-sensor-station/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
   <url>
     <loc>https://velxio.dev/examples/esp32-pwm-led-rgb/</loc>
-    <lastmod>2026-08-15</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>
diff --git a/frontend/scripts/generate-sitemap.mjs b/frontend/scripts/generate-sitemap.mjs
index fd6f7fe6..2d44ecfd 100644
--- a/frontend/scripts/generate-sitemap.mjs
+++ b/frontend/scripts/generate-sitemap.mjs
@@ -76,11 +76,16 @@ if (process.env.VITE_PRO_BUILD && process.env.PRO_OVERLAY_PATH) {
 
 const exampleUrls = exampleIds.map((id) => ({
   loc: `${DOMAIN}/examples/${id}`,
-  lastmod: TODAY,
   changefreq: 'monthly',
   priority: 0.6,
 }));
 
+// No <lastmod>: this runs at build time with no per-page history to draw
+// on, so every URL used to carry the build date. A lastmod that changes on
+// every deploy for every page is provably unreliable and search engines
+// discard the whole signal; omitting it is the honest option (the projects
+// sitemap, which has real updated_at timestamps, keeps its lastmod).
+
 // Every <loc> carries a trailing slash. nginx serves the prerendered route
 // files as `<route>/index.html` and 301-redirects the slash-less form to add
 // the slash, so a slash-less sitemap URL is fetched as a redirect and filed
@@ -94,7 +99,6 @@ ${indexable
     (r) => `
   <url>
     <loc>${DOMAIN}${r.path}${r.path.endsWith('/') ? '' : '/'}</loc>
-    <lastmod>${TODAY}</lastmod>
     <changefreq>${r.changefreq ?? 'monthly'}</changefreq>
     <priority>${r.priority ?? 0.5}</priority>
   </url>`
@@ -105,7 +109,6 @@ ${exampleUrls
     (u) => `
   <url>
     <loc>${u.loc}/</loc>
-    <lastmod>${u.lastmod}</lastmod>
     <changefreq>${u.changefreq}</changefreq>
     <priority>${u.priority}</priority>
   </url>`
diff --git a/frontend/src/utils/analytics.ts b/frontend/src/utils/analytics.ts
index f832897f..489282f7 100644
--- a/frontend/src/utils/analytics.ts
+++ b/frontend/src/utils/analytics.ts
@@ -130,9 +130,17 @@ export function trackProductPageClick(componentId: string, brand?: string, href?
 
 // ── CTA / Conversion ────────────────────────────────────────────────────────
 
-/** Fired when a user clicks a CTA button on a landing/SEO page. */
+/**
+ * Fired when a user clicks a CTA button on a landing/SEO page.
+ *
+ * The originating page is sent as `cta_source`, NOT `source`: `source`
+ * (like `medium` and `campaign`) is a reserved traffic-source parameter in
+ * GA4, so every CTA click was rewriting the session's acquisition source to
+ * "landing" / "arduino-simulator" / "rpi-simulator" with medium "(not set)"
+ * — 16% of sessions landed in the Unassigned channel with no real origin.
+ */
 export function trackClickCTA(source: string, destination: string): void {
-  fireEvent('click_cta', { event_category: 'conversion', source, destination });
+  fireEvent('click_cta', { event_category: 'conversion', cta_source: source, destination });
 }
 
 // ── Library Manager ─────────────────────────────────────────────────────────