diff --git a/src/apps/dashboard/tests/integrated/test_sky_views.py b/src/apps/dashboard/tests/integrated/test_sky_views.py
index 98bd2aa..f1f4d29 100644
--- a/src/apps/dashboard/tests/integrated/test_sky_views.py
+++ b/src/apps/dashboard/tests/integrated/test_sky_views.py
@@ -37,6 +37,22 @@ class SkyViewTest(TestCase):
         self.assertContains(response, reverse("sky_preview"))
         self.assertContains(response, reverse("sky_save"))
 
+    def test_tz_input_is_readonly_and_carries_auto_detect_placeholder(self):
+        """Manual TZ edits throw the schedulePreview / PySwiss fetch off (the
+        backend gets a stale TZ for the new lat/lon), so the field is render-
+        readonly like lat/lon — auto-fills from preview, never from a typed
+        override. The old <small id="id_nf_tz_hint"> is gone; its copy lives
+        in the placeholder so an empty field is self-explanatory."""
+        response = self.client.get(reverse("sky"))
+        self.assertContains(response, 'id="id_nf_tz"')
+        # readonly + tabindex:-1 mirrors the lat/lon pattern.
+        self.assertRegex(
+            response.content.decode(),
+            r'id="id_nf_tz"[^>]*\breadonly\b',
+        )
+        self.assertContains(response, 'placeholder="auto-detected from coordinates"')
+        self.assertNotContains(response, 'id="id_nf_tz_hint"')
+
 
 class SkyPreviewTest(TestCase):
     def setUp(self):
diff --git a/src/templates/apps/dashboard/_partials/_applet-my-sky.html b/src/templates/apps/dashboard/_partials/_applet-my-sky.html
index 5326852..abcd77f 100644
--- a/src/templates/apps/dashboard/_partials/_applet-my-sky.html
+++ b/src/templates/apps/dashboard/_partials/_applet-my-sky.html
@@ -54,8 +54,8 @@
             <div class="sky-field">
                 <label for="id_nf_tz">Timezone</label>
                 <input id="id_nf_tz" name="tz" type="text"
-                       placeholder="auto-detected from location">
-                <small id="id_nf_tz_hint"></small>
+                       placeholder="auto-detected from coordinates"
+                       readonly tabindex="-1">
             </div>
 
         </form>
@@ -145,7 +145,6 @@
   const latInput   = document.getElementById('id_nf_lat');
   const lonInput   = document.getElementById('id_nf_lon');
   const tzInput    = document.getElementById('id_nf_tz');
-  const tzHint     = document.getElementById('id_nf_tz_hint');
   const suggestions = document.getElementById('id_nf_suggestions');
 
   const PREVIEW_URL = section.dataset.previewUrl;
@@ -185,7 +184,7 @@
     if (d.place) placeInput.value = d.place;
     if (d.lat)   latInput.value   = d.lat;
     if (d.lon)   lonInput.value   = d.lon;
-    if (d.tz)    { tzInput.value  = d.tz; tzHint.textContent = 'Auto-detected from coordinates.'; }
+    if (d.tz)    { tzInput.value  = d.tz; }
     if (_formReady()) schedulePreview();
   }
 
@@ -250,7 +249,6 @@
     latInput.value   = parseFloat(place.lat).toFixed(4);
     lonInput.value   = parseFloat(place.lon).toFixed(4);
     tzInput.value    = '';
-    tzHint.textContent = '';
     hideSuggestions();
     _saveForm();
     schedulePreview();
@@ -269,7 +267,6 @@
         latInput.value = pos.coords.latitude.toFixed(4);
         lonInput.value = pos.coords.longitude.toFixed(4);
         tzInput.value  = '';
-        tzHint.textContent = '';
         fetch(
           `https://nominatim.openstreetmap.org/reverse?format=json&lat=${latInput.value}&lon=${lonInput.value}`,
           { headers: { 'User-Agent': USER_AGENT } }
@@ -330,7 +327,6 @@
         _lastChartData = d;
         if (!tzInput.value && d.timezone) {
           tzInput.value = d.timezone;
-          tzHint.textContent = 'Auto-detected from coordinates.';
         }
         setStatus('');
         confirmBtn.disabled = false;
diff --git a/src/templates/apps/dashboard/sky.html b/src/templates/apps/dashboard/sky.html
index fbf99aa..cba4e75 100644
--- a/src/templates/apps/dashboard/sky.html
+++ b/src/templates/apps/dashboard/sky.html
@@ -64,9 +64,9 @@
                     <div class="sky-field">
                         <label for="id_nf_tz">Timezone</label>
                         <input id="id_nf_tz" name="tz" type="text"
-                               placeholder="auto-detected from location"
+                               placeholder="auto-detected from coordinates"
+                               readonly tabindex="-1"
                                {% if saved_birth_tz %}value="{{ saved_birth_tz }}"{% endif %}>
-                        <small id="id_nf_tz_hint"></small>
                     </div>
 
                 </form>
@@ -114,7 +114,6 @@
   const latInput    = document.getElementById('id_nf_lat');
   const lonInput    = document.getElementById('id_nf_lon');
   const tzInput     = document.getElementById('id_nf_tz');
-  const tzHint      = document.getElementById('id_nf_tz_hint');
   const suggestions = document.getElementById('id_nf_suggestions');
 
   const PREVIEW_URL = overlay.dataset.previewUrl;
@@ -191,7 +190,6 @@
     latInput.value   = parseFloat(place.lat).toFixed(4);
     lonInput.value   = parseFloat(place.lon).toFixed(4);
     tzInput.value    = '';
-    tzHint.textContent = '';
     hideSuggestions();
     schedulePreview();
   }
@@ -209,7 +207,6 @@
         latInput.value = pos.coords.latitude.toFixed(4);
         lonInput.value = pos.coords.longitude.toFixed(4);
         tzInput.value  = '';
-        tzHint.textContent = '';
         fetch(`https://nominatim.openstreetmap.org/reverse?format=json&lat=${latInput.value}&lon=${lonInput.value}`, {
           headers: { 'User-Agent': USER_AGENT },
         })
@@ -267,7 +264,6 @@
         _lastChartData = data;
         if (!tzInput.value && data.timezone) {
           tzInput.value = data.timezone;
-          tzHint.textContent = 'Auto-detected from coordinates.';
         }
         setStatus('');
         confirmBtn.disabled = false;
diff --git a/src/templates/apps/gameboard/_partials/_sky_overlay.html b/src/templates/apps/gameboard/_partials/_sky_overlay.html
index bb76e3d..358d7ce 100644
--- a/src/templates/apps/gameboard/_partials/_sky_overlay.html
+++ b/src/templates/apps/gameboard/_partials/_sky_overlay.html
@@ -71,8 +71,8 @@
                         <div class="sky-field">
                             <label for="id_nf_tz">Timezone</label>
                             <input id="id_nf_tz" name="tz" type="text"
-                                   placeholder="auto-detected from location">
-                            <small id="id_nf_tz_hint"></small>
+                                   placeholder="auto-detected from coordinates"
+                                   readonly tabindex="-1">
                         </div>
 
                     </form>
@@ -122,7 +122,6 @@
   const latInput     = document.getElementById('id_nf_lat');
   const lonInput     = document.getElementById('id_nf_lon');
   const tzInput      = document.getElementById('id_nf_tz');
-  const tzHint       = document.getElementById('id_nf_tz_hint');
   const suggestions  = document.getElementById('id_nf_suggestions');
 
   const PREVIEW_URL  = overlay.dataset.previewUrl;
@@ -166,7 +165,7 @@
     if (data.place) placeInput.value = data.place;
     if (data.lat)   latInput.value   = data.lat;
     if (data.lon)   lonInput.value   = data.lon;
-    if (data.tz)    { tzInput.value  = data.tz; tzHint.textContent = 'Auto-detected from coordinates.'; }
+    if (data.tz)    { tzInput.value  = data.tz; }
   }
 
   // ── Open / Close ──────────────────────────────────────────────────────────
@@ -251,7 +250,6 @@
     latInput.value   = parseFloat(place.lat).toFixed(4);
     lonInput.value   = parseFloat(place.lon).toFixed(4);
     tzInput.value    = '';
-    tzHint.textContent = '';
     hideSuggestions();
     _saveForm();
     schedulePreview();
@@ -270,7 +268,6 @@
         latInput.value = pos.coords.latitude.toFixed(4);
         lonInput.value = pos.coords.longitude.toFixed(4);
         tzInput.value  = '';
-        tzHint.textContent = '';
         fetch(`https://nominatim.openstreetmap.org/reverse?format=json&lat=${latInput.value}&lon=${lonInput.value}`, {
           headers: { 'User-Agent': USER_AGENT },
         })
@@ -335,7 +332,6 @@
         // Back-fill timezone field from proxy response (first render)
         if (!tzInput.value && data.timezone) {
           tzInput.value = data.timezone;
-          tzHint.textContent = 'Auto-detected from coordinates.';
         }
 
         setStatus('');
@@ -429,7 +425,6 @@
         latInput.value = '';
         lonInput.value = '';
         tzInput.value  = '';
-        tzHint.textContent = '';
         _lastChartData = null;
         confirmBtn.disabled = true;
         setStatus('');