revert: restore button-based manipulation controls

Revert to the original button-based approach for color manipulation.
The reactive slider implementation was causing infinite loops and page
reloads. Buttons provide stable, predictable behavior.

🤖 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, useCallback } from 'react';
+import { useState } from 'react';
 import { Slider } from '@/components/ui/slider';
 import { Button } from '@/components/ui/button';
 import {
@@ -19,11 +19,11 @@ interface ManipulationPanelProps {
 }
 
 export function ManipulationPanel({ color, onColorChange }: ManipulationPanelProps) {
-  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 [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);
 
   const lightenMutation = useLighten();
   const darkenMutation = useDarken();
@@ -32,101 +32,80 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
   const rotateMutation = useRotate();
   const complementMutation = useComplement();
 
-  // Track if we're applying our own changes to prevent feedback loop
-  const isApplyingRef = useRef(false);
-  const baseColorRef = useRef(color);
-
-  // Update base color only when not applying our own changes
-  useEffect(() => {
-    if (!isApplyingRef.current) {
-      baseColorRef.current = color;
-      // Reset sliders when color changes externally
-      setLightenAmount(0);
-      setDarkenAmount(0);
-      setSaturateAmount(0);
-      setDesaturateAmount(0);
-      setRotateAmount(0);
+  const handleLighten = async () => {
+    try {
+      const result = await lightenMutation.mutateAsync({
+        colors: [color],
+        amount: lightenAmount,
+      });
+      if (result.colors[0]) {
+        onColorChange(result.colors[0].output);
+        toast.success(`Lightened by ${(lightenAmount * 100).toFixed(0)}%`);
+      }
+    } catch (error) {
+      toast.error('Failed to lighten color');
     }
-  }, [color]);
+  };
 
-  // Debounced effect to apply manipulations
-  useEffect(() => {
-    const timer = setTimeout(async () => {
-      // Skip if all sliders are at neutral position
-      if (lightenAmount === 0 && darkenAmount === 0 && saturateAmount === 0 &&
-          desaturateAmount === 0 && rotateAmount === 0) {
-        return;
+  const handleDarken = async () => {
+    try {
+      const result = await darkenMutation.mutateAsync({
+        colors: [color],
+        amount: darkenAmount,
+      });
+      if (result.colors[0]) {
+        onColorChange(result.colors[0].output);
+        toast.success(`Darkened by ${(darkenAmount * 100).toFixed(0)}%`);
       }
+    } catch (error) {
+      toast.error('Failed to darken color');
+    }
+  };
 
-      isApplyingRef.current = true;
-      let currentColor = baseColorRef.current;
-
-      try {
-        // Apply lighten
-        if (lightenAmount > 0) {
-          const result = await lightenMutation.mutateAsync({
-            colors: [currentColor],
-            amount: lightenAmount,
-          });
-          if (result.colors[0]) {
-            currentColor = result.colors[0].output;
-          }
-        }
-
-        // Apply darken
-        if (darkenAmount > 0) {
-          const result = await darkenMutation.mutateAsync({
-            colors: [currentColor],
-            amount: darkenAmount,
-          });
-          if (result.colors[0]) {
-            currentColor = result.colors[0].output;
-          }
-        }
-
-        // Apply saturate
-        if (saturateAmount > 0) {
-          const result = await saturateMutation.mutateAsync({
-            colors: [currentColor],
-            amount: saturateAmount,
-          });
-          if (result.colors[0]) {
-            currentColor = result.colors[0].output;
-          }
-        }
-
-        // Apply desaturate
-        if (desaturateAmount > 0) {
-          const result = await desaturateMutation.mutateAsync({
-            colors: [currentColor],
-            amount: desaturateAmount,
-          });
-          if (result.colors[0]) {
-            currentColor = result.colors[0].output;
-          }
-        }
-
-        // Apply rotate
-        if (rotateAmount !== 0) {
-          const result = await rotateMutation.mutateAsync({
-            colors: [currentColor],
-            amount: rotateAmount,
-          });
-          if (result.colors[0]) {
-            currentColor = result.colors[0].output;
-          }
-        }
-
-        onColorChange(currentColor);
-      } catch (error) {
-        // Silent error during manipulation
-      } finally {
-        isApplyingRef.current = false;
+  const handleSaturate = async () => {
+    try {
+      const result = await saturateMutation.mutateAsync({
+        colors: [color],
+        amount: saturateAmount,
+      });
+      if (result.colors[0]) {
+        onColorChange(result.colors[0].output);
+        toast.success(`Saturated by ${(saturateAmount * 100).toFixed(0)}%`);
       }
-    }, 300);
+    } catch (error) {
+      toast.error('Failed to saturate color');
+    }
+  };
 
-    return () => clearTimeout(timer);
-  }, [lightenAmount, darkenAmount, saturateAmount, desaturateAmount, rotateAmount]);
+  const handleDesaturate = async () => {
+    try {
+      const result = await desaturateMutation.mutateAsync({
+        colors: [color],
+        amount: desaturateAmount,
+      });
+      if (result.colors[0]) {
+        onColorChange(result.colors[0].output);
+        toast.success(`Desaturated by ${(desaturateAmount * 100).toFixed(0)}%`);
+      }
+    } catch (error) {
+      toast.error('Failed to desaturate color');
+    }
+  };
+
+  const handleRotate = async () => {
+    try {
+      const result = await rotateMutation.mutateAsync({
+        colors: [color],
+        amount: rotateAmount,
+      });
+      if (result.colors[0]) {
+        onColorChange(result.colors[0].output);
+        toast.success(`Rotated hue by ${rotateAmount}°`);
+      }
+    } catch (error) {
+      toast.error('Failed to rotate hue');
+    }
+  };
 
   const handleComplement = async () => {
     try {
@@ -151,7 +130,7 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
   return (
     <div className="space-y-6">
       {/* Lighten */}
-      <div>
+      <div className="space-y-3">
         <Slider
           label="Lighten"
           min={0}
@@ -162,10 +141,13 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
           suffix="%"
           showValue
         />
+        <Button onClick={handleLighten} disabled={isLoading} className="w-full">
+          Apply Lighten
+        </Button>
       </div>
 
       {/* Darken */}
-      <div>
+      <div className="space-y-3">
         <Slider
           label="Darken"
           min={0}
@@ -176,10 +158,13 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
           suffix="%"
           showValue
         />
+        <Button onClick={handleDarken} disabled={isLoading} className="w-full">
+          Apply Darken
+        </Button>
       </div>
 
       {/* Saturate */}
-      <div>
+      <div className="space-y-3">
         <Slider
           label="Saturate"
           min={0}
@@ -190,10 +175,13 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
           suffix="%"
           showValue
         />
+        <Button onClick={handleSaturate} disabled={isLoading} className="w-full">
+          Apply Saturate
+        </Button>
       </div>
 
       {/* Desaturate */}
-      <div>
+      <div className="space-y-3">
         <Slider
           label="Desaturate"
           min={0}
@@ -204,10 +192,13 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
           suffix="%"
           showValue
         />
+        <Button onClick={handleDesaturate} disabled={isLoading} className="w-full">
+          Apply Desaturate
+        </Button>
       </div>
 
       {/* Rotate Hue */}
-      <div>
+      <div className="space-y-3">
         <Slider
           label="Rotate Hue"
           min={-180}
@@ -218,6 +209,9 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
           suffix="°"
           showValue
         />
+        <Button onClick={handleRotate} disabled={isLoading} className="w-full">
+          Apply Rotation
+        </Button>
       </div>
 
       {/* Quick Actions */}