fix: prevent infinite loop in reactive sliders by tracking base color

Refactor manipulation panel to track a base color and apply all manipulations
sequentially from that base, rather than continuously stacking manipulations.
Sliders now reset to 0 when color changes externally (e.g., from color picker).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/tools/ManipulationPanel.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState, useEffect, useRef } from 'react';
+import { useState, useEffect, useRef, useCallback } from 'react';
 import { Slider } from '@/components/ui/slider';
 import { Button } from '@/components/ui/button';
 import {
@@ -19,11 +19,13 @@ interface ManipulationPanelProps {
 }
 
 export function ManipulationPanel({ color, onColorChange }: ManipulationPanelProps) {
-  const [lightenAmount, setLightenAmount] = useState(0.2);
-  const [darkenAmount, setDarkenAmount] = useState(0.2);
-  const [saturateAmount, setSaturateAmount] = useState(0.2);
-  const [desaturateAmount, setDesaturateAmount] = useState(0.2);
-  const [rotateAmount, setRotateAmount] = useState(30);
+  // Track base color and reset sliders when color changes externally
+  const [baseColor, setBaseColor] = useState(color);
+  const [lightenAmount, setLightenAmount] = useState(0);
+  const [darkenAmount, setDarkenAmount] = useState(0);
+  const [saturateAmount, setSaturateAmount] = useState(0);
+  const [desaturateAmount, setDesaturateAmount] = useState(0);
+  const [rotateAmount, setRotateAmount] = useState(0);
 
   const lightenMutation = useLighten();
   const darkenMutation = useDarken();
@@ -32,112 +34,100 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
   const rotateMutation = useRotate();
   const complementMutation = useComplement();
 
-  // Debounce timers
-  const lightenTimer = useRef<NodeJS.Timeout | undefined>(undefined);
-  const darkenTimer = useRef<NodeJS.Timeout | undefined>(undefined);
-  const saturateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
-  const desaturateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
-  const rotateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
+  // Debounce timer
+  const debounceTimer = useRef<NodeJS.Timeout | undefined>(undefined);
 
-  // Reactive lighten
+  // Reset sliders when color changes from outside (e.g., color picker)
   useEffect(() => {
-    if (lightenTimer.current) clearTimeout(lightenTimer.current);
-    lightenTimer.current = setTimeout(async () => {
+    setBaseColor(color);
+    setLightenAmount(0);
+    setDarkenAmount(0);
+    setSaturateAmount(0);
+    setDesaturateAmount(0);
+    setRotateAmount(0);
+  }, [color]);
+
+  // Apply all manipulations to base color
+  const applyManipulations = useCallback(async () => {
+    let currentColor = baseColor;
+
+    try {
+      // Apply lighten
       if (lightenAmount > 0) {
-        try {
-          const result = await lightenMutation.mutateAsync({
-            colors: [color],
-            amount: lightenAmount,
-          });
-          if (result.colors[0]) {
-            onColorChange(result.colors[0].output);
-          }
-        } catch (error) {
-          // Silent error - user is still adjusting
+        const result = await lightenMutation.mutateAsync({
+          colors: [currentColor],
+          amount: lightenAmount,
+        });
+        if (result.colors[0]) {
+          currentColor = result.colors[0].output;
         }
       }
-    }, 300);
-  }, [lightenAmount]);
 
-  // Reactive darken
-  useEffect(() => {
-    if (darkenTimer.current) clearTimeout(darkenTimer.current);
-    darkenTimer.current = setTimeout(async () => {
+      // Apply darken
       if (darkenAmount > 0) {
-        try {
-          const result = await darkenMutation.mutateAsync({
-            colors: [color],
-            amount: darkenAmount,
-          });
-          if (result.colors[0]) {
-            onColorChange(result.colors[0].output);
-          }
-        } catch (error) {
-          // Silent error - user is still adjusting
+        const result = await darkenMutation.mutateAsync({
+          colors: [currentColor],
+          amount: darkenAmount,
+        });
+        if (result.colors[0]) {
+          currentColor = result.colors[0].output;
         }
       }
-    }, 300);
-  }, [darkenAmount]);
 
-  // Reactive saturate
-  useEffect(() => {
-    if (saturateTimer.current) clearTimeout(saturateTimer.current);
-    saturateTimer.current = setTimeout(async () => {
+      // Apply saturate
       if (saturateAmount > 0) {
-        try {
-          const result = await saturateMutation.mutateAsync({
-            colors: [color],
-            amount: saturateAmount,
-          });
-          if (result.colors[0]) {
-            onColorChange(result.colors[0].output);
-          }
-        } catch (error) {
-          // Silent error - user is still adjusting
+        const result = await saturateMutation.mutateAsync({
+          colors: [currentColor],
+          amount: saturateAmount,
+        });
+        if (result.colors[0]) {
+          currentColor = result.colors[0].output;
         }
       }
-    }, 300);
-  }, [saturateAmount]);
 
-  // Reactive desaturate
-  useEffect(() => {
-    if (desaturateTimer.current) clearTimeout(desaturateTimer.current);
-    desaturateTimer.current = setTimeout(async () => {
+      // Apply desaturate
       if (desaturateAmount > 0) {
-        try {
-          const result = await desaturateMutation.mutateAsync({
-            colors: [color],
-            amount: desaturateAmount,
-          });
-          if (result.colors[0]) {
-            onColorChange(result.colors[0].output);
-          }
-        } catch (error) {
-          // Silent error - user is still adjusting
+        const result = await desaturateMutation.mutateAsync({
+          colors: [currentColor],
+          amount: desaturateAmount,
+        });
+        if (result.colors[0]) {
+          currentColor = result.colors[0].output;
         }
       }
-    }, 300);
-  }, [desaturateAmount]);
 
-  // Reactive rotate
-  useEffect(() => {
-    if (rotateTimer.current) clearTimeout(rotateTimer.current);
-    rotateTimer.current = setTimeout(async () => {
+      // Apply rotate
       if (rotateAmount !== 0) {
-        try {
-          const result = await rotateMutation.mutateAsync({
-            colors: [color],
-            amount: rotateAmount,
-          });
-          if (result.colors[0]) {
-            onColorChange(result.colors[0].output);
-          }
-        } catch (error) {
-          // Silent error - user is still adjusting
+        const result = await rotateMutation.mutateAsync({
+          colors: [currentColor],
+          amount: rotateAmount,
+        });
+        if (result.colors[0]) {
+          currentColor = result.colors[0].output;
         }
       }
+
+      // Only update if color changed
+      if (currentColor !== baseColor) {
+        onColorChange(currentColor);
+      }
+    } catch (error) {
+      // Silent error during manipulation
+    }
+  }, [baseColor, lightenAmount, darkenAmount, saturateAmount, desaturateAmount, rotateAmount, lightenMutation, darkenMutation, saturateMutation, desaturateMutation, rotateMutation, onColorChange]);
+
+  // Debounced effect to apply manipulations
+  useEffect(() => {
+    if (debounceTimer.current) clearTimeout(debounceTimer.current);
+
+    debounceTimer.current = setTimeout(() => {
+      applyManipulations();
     }, 300);
-  }, [rotateAmount]);
+
+    return () => {
+      if (debounceTimer.current) clearTimeout(debounceTimer.current);
+    };
+  }, [applyManipulations]);
 
   const handleComplement = async () => {
     try {