feat: save/cancel buttons for task editing (HQ-19)

- EditableText now updates draft state instead of saving immediately
- Panel tracks dirty state across title, description, priority, source
- Save/Cancel bar slides up when any field is modified
- Cancel reverts all changes, Save commits them in one API call
- Slide-up animation for the save/cancel bar

frontend/src/components/TaskDetailPanel.tsx

@@ -124,27 +124,24 @@ function ElapsedTimer({ since }: { since: string }) {
 
 function EditableText({
   value,
-  onSave,
+  onChange,
   multiline = false,
   className = "",
   placeholder = "Click to edit...",
 }: {
   value: string;
-  onSave: (val: string) => void;
+  onChange: (val: string) => void;
   multiline?: boolean;
   className?: string;
   placeholder?: string;
 }) {
   const [editing, setEditing] = useState(false);
-  const [draft, setDraft] = useState(value);
   const ref = useRef<HTMLInputElement | HTMLTextAreaElement>(null);
 
-  useEffect(() => { setDraft(value); }, [value]);
   useEffect(() => { if (editing) ref.current?.focus(); }, [editing]);
 
-  const save = () => {
+  const stopEditing = () => {
     setEditing(false);
-    if (draft.trim() !== value) onSave(draft.trim());
   };
 
   if (!editing) {
@@ -164,10 +161,10 @@ function EditableText({
     return (
       <textarea
         ref={ref as React.RefObject<HTMLTextAreaElement>}
-        value={draft}
+        value={value}
-        onChange={(e) => setDraft(e.target.value)}
+        onChange={(e) => onChange(e.target.value)}
-        onBlur={save}
+        onBlur={stopEditing}
-        onKeyDown={(e) => { if (e.key === "Escape") { setDraft(value); setEditing(false); } }}
+        onKeyDown={(e) => { if (e.key === "Escape") stopEditing(); }}
         className={`w-full rounded-md border border-blue-300 bg-white px-2 py-1 -mx-2 -my-1 text-sm focus:outline-none focus:ring-2 focus:ring-blue-200 resize-y min-h-[60px] ${className}`}
         rows={3}
       />
@@ -177,12 +174,12 @@ function EditableText({
   return (
     <input
       ref={ref as React.RefObject<HTMLInputElement>}
-      value={draft}
+      value={value}
-      onChange={(e) => setDraft(e.target.value)}
+      onChange={(e) => onChange(e.target.value)}
-      onBlur={save}
+      onBlur={stopEditing}
       onKeyDown={(e) => {
-        if (e.key === "Enter") save();
+        if (e.key === "Enter") stopEditing();
-        if (e.key === "Escape") { setDraft(value); setEditing(false); }
+        if (e.key === "Escape") stopEditing();
       }}
       className={`w-full rounded-md border border-blue-300 bg-white px-2 py-1 -mx-2 -my-1 text-sm focus:outline-none focus:ring-2 focus:ring-blue-200 ${className}`}
     />
@@ -248,6 +245,53 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
   const isActive = task.status === "active";
   const [saving, setSaving] = useState(false);
 
+  // Draft state for editable fields
+  const [draftTitle, setDraftTitle] = useState(task.title);
+  const [draftDescription, setDraftDescription] = useState(task.description || "");
+  const [draftPriority, setDraftPriority] = useState(task.priority);
+  const [draftSource, setDraftSource] = useState(task.source);
+
+  // Reset drafts when task changes
+  useEffect(() => {
+    setDraftTitle(task.title);
+    setDraftDescription(task.description || "");
+    setDraftPriority(task.priority);
+    setDraftSource(task.source);
+  }, [task.id, task.title, task.description, task.priority, task.source]);
+
+  // Detect if any field has been modified
+  const isDirty =
+    draftTitle !== task.title ||
+    draftDescription !== (task.description || "") ||
+    draftPriority !== task.priority ||
+    draftSource !== task.source;
+
+  const handleCancel = () => {
+    setDraftTitle(task.title);
+    setDraftDescription(task.description || "");
+    setDraftPriority(task.priority);
+    setDraftSource(task.source);
+  };
+
+  const handleSave = async () => {
+    if (!hasToken || !isDirty) return;
+    setSaving(true);
+    try {
+      const updates: Record<string, string> = {};
+      if (draftTitle !== task.title) updates.title = draftTitle.trim();
+      if (draftDescription !== (task.description || "")) updates.description = draftDescription.trim();
+      if (draftPriority !== task.priority) updates.priority = draftPriority;
+      if (draftSource !== task.source) updates.source = draftSource;
+      await updateTask(task.id, updates, token);
+      onTaskUpdated();
+    } catch (e) {
+      console.error("Failed to update:", e);
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  // Legacy single-field save kept for non-draft fields if needed
   const handleFieldSave = async (field: string, value: string) => {
     if (!hasToken) return;
     setSaving(true);
@@ -294,8 +338,8 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
               </div>
               {hasToken ? (
                 <EditableText
-                  value={task.title}
+                  value={draftTitle}
-                  onSave={(val) => handleFieldSave("title", val)}
+                  onChange={setDraftTitle}
                   className="text-lg font-bold text-gray-900 leading-snug"
                 />
               ) : (
@@ -326,9 +370,9 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
                     {allPriorities.map((p) => (
                       <button
                         key={p}
-                        onClick={() => handleFieldSave("priority", p)}
+                        onClick={() => setDraftPriority(p)}
                         className={`text-xs px-2.5 py-1 rounded-full font-medium transition ${
-                          p === task.priority
+                          p === draftPriority
                             ? priorityColors[p]
                             : "bg-gray-100 text-gray-500 hover:bg-gray-200"
                         }`}
@@ -350,9 +394,9 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
                     {allSources.map((s) => (
                       <button
                         key={s}
-                        onClick={() => handleFieldSave("source", s)}
+                        onClick={() => setDraftSource(s)}
                         className={`text-xs px-2.5 py-1 rounded-full font-medium transition ${
-                          s === task.source
+                          s === draftSource
                             ? sourceColors[s] || sourceColors.other
                             : "bg-gray-100 text-gray-500 hover:bg-gray-200"
                         }`}
@@ -375,8 +419,8 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
             <h3 className="text-xs font-semibold text-gray-400 uppercase tracking-wider mb-2">Description</h3>
             {hasToken ? (
               <EditableText
-                value={task.description || ""}
+                value={draftDescription}
-                onSave={(val) => handleFieldSave("description", val)}
+                onChange={setDraftDescription}
                 multiline
                 className="text-sm text-gray-700 leading-relaxed whitespace-pre-wrap"
                 placeholder="Add a description..."
@@ -461,6 +505,29 @@ export function TaskDetailPanel({ task, onClose, onStatusChange, onTaskUpdated,
           </div>
         </div>
 
+        {/* Save / Cancel Bar */}
+        {hasToken && isDirty && (
+          <div className="px-6 py-3 border-t border-blue-200 bg-blue-50 flex items-center justify-between animate-slide-up">
+            <span className="text-sm text-blue-700 font-medium">Unsaved changes</span>
+            <div className="flex gap-2">
+              <button
+                onClick={handleCancel}
+                disabled={saving}
+                className="text-sm px-4 py-2 rounded-lg border border-gray-300 bg-white text-gray-700 font-medium hover:bg-gray-50 transition disabled:opacity-50"
+              >
+                Cancel
+              </button>
+              <button
+                onClick={handleSave}
+                disabled={saving}
+                className="text-sm px-4 py-2 rounded-lg border border-blue-400 bg-blue-600 text-white font-medium hover:bg-blue-700 transition disabled:opacity-50"
+              >
+                {saving ? "Saving..." : "Save"}
+              </button>
+            </div>
+          </div>
+        )}
+
         {/* Actions Footer */}
         {hasToken && actions.length > 0 && (
           <div className="px-6 py-4 border-t border-gray-200 bg-gray-50">

frontend/src/index.css

@@ -14,3 +14,18 @@
 .animate-slide-in-right {
   animation: slide-in-right 0.25s ease-out;
 }
+
+@keyframes slide-up {
+  from {
+    transform: translateY(100%);
+    opacity: 0;
+  }
+  to {
+    transform: translateY(0);
+    opacity: 1;
+  }
+}
+
+.animate-slide-up {
+  animation: slide-up 0.2s ease-out;
+}