fix double stop regression

Author: argyleink

src/components/Presets.svelte

@@ -296,8 +296,8 @@
 						kind: 'stop',
 						color: stop.color,
 						auto: null,
-						position1: stop.position1 || null,
-						position2: stop.position2 || null,
+						position1: (stop.position1 ?? null),
+						position2: (stop.position2 ?? null),
 				}
 			}
 			else return stop

src/utils/gradientString.ts

@@ -95,9 +95,8 @@ function stopsToStrings(stops: any[], { convert_colors, new_lines }: { convert_c
         let p1 = s.position1
         let p2 = s.position2
 
-        // If position equals computed auto position, omit it
-        if (p1 != null && s.auto != null && p1 == s.auto) p1 = null
-        if (p2 != null && s.auto != null && p2 == s.auto) p2 = null
+        // If first position equals computed auto position, omit it (keep explicit second positions)
+        if (p1 != null && s.auto != null && String(p1) == String(s.auto)) p1 = null
 
         // Omit default endpoints
         if (i === firstStopIdx && isPctZero(p1)) p1 = null

src/utils/stops.ts

@@ -3,25 +3,36 @@ export function updateStops(stops) {
 
   let updated = stops.map((stop, i) => {
     let autoVal = autoStops[i]
-    
+
     if (stop.kind == 'stop') {
       if (stops.length === 1) {
+        // For a single color stop, span the entire line
         stop.position1 = 0
-        stop.position2 = 100 
+        stop.position2 = 100
       }
-      else if (!stop._manual && (!stop.position1 || stop.position1 === stop.auto)) {
-        stop.position1 = autoVal
-        stop.position2 = autoVal
+      else if (!stop._manual) {
+        // Treat null/undefined as unset; 0 is a valid value and must be preserved
+        const p1Unset = (stop.position1 == null) || (stop.auto != null && String(stop.position1) == String(stop.auto))
+        const p2UnsetOrAuto = (stop.position2 == null) || (stop.auto != null && String(stop.position2) == String(stop.auto))
+
+        // Only assign auto for position1 when it is unset or previously auto-managed
+        if (p1Unset) stop.position1 = autoVal
+
+        // Only assign auto for position2 when it's unset or previously auto-managed.
+        // Preserve any explicitly provided second position (e.g., from presets) to avoid regressions.
+        if (p2UnsetOrAuto) stop.position2 = p1Unset ? autoVal : stop.position1
       }
       // Clear the manual flag after one normalization pass so future edits behave normally
       if (stop._manual) delete stop._manual
     }
     // is a hint
     else {
-      if (!stop.percentage || stop.percentage === stop.auto)
+      // Only auto-assign hint percentage when it's unset or previously auto-managed
+      if (stop.percentage == null || (stop.auto != null && String(stop.percentage) == String(stop.auto)))
         stop.percentage = autoVal
     }
 
+    // Persist the computed auto value for future comparisons
     stop.auto = autoVal
     return stop
   })