fix: use Modifier.Set() to maintain AttributeOrder invariant in API handlers

API handlers were populating SetAttributes directly without appending to
AttributeOrder. Since Apply() only iterates AttributeOrder, all updates
via PUT/POST were silently dropped — causing edits to revert and tasks
to disappear on reload.

Adds Modifier.Set() helper, safety net in Apply()/ApplyToNew(), adds
description and status to applyNonDateAttribute, and fixes the
recurrence->recur key mismatch.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

opal-task/internal/engine/keys.go

@@ -4,14 +4,15 @@ package engine
 // Used by parseAddArgs (cmd/add.go), ParseFilter, and ParseModifier
 // to distinguish modifiers from description text.
 var ValidAttributeKeys = map[string]bool{
-	"due":       true,
-	"priority":  true,
-	"project":   true,
-	"recur":     true,
-	"status":    true,
-	"wait":      true,
-	"scheduled": true,
-	"until":     true,
+	"description": true,
+	"due":         true,
+	"priority":    true,
+	"project":     true,
+	"recur":       true,
+	"status":      true,
+	"wait":        true,
+	"scheduled":   true,
+	"until":       true,
 }
 
 // DateKeys is the subset of ValidAttributeKeys that hold date values.

opal-task/internal/engine/modifier.go

@@ -23,6 +23,13 @@ func NewModifier() *Modifier {
 	}
 }
 
+// Set adds an attribute to the modifier, maintaining the SetAttributes and
+// AttributeOrder invariant. Pass nil to clear the attribute.
+func (m *Modifier) Set(key string, value *string) {
+	m.SetAttributes[key] = value
+	m.AttributeOrder = append(m.AttributeOrder, key)
+}
+
 // ParseModifier parses command-line args into Modifier.
 // Only recognized attribute keys (ValidAttributeKeys) are accepted;
 // unrecognized key:value tokens produce an error.
@@ -86,6 +93,14 @@ func (m *Modifier) Apply(task *Task) error {
 	resolvedDates["created"] = task.Created
 	resolvedDates["modified"] = task.Modified
 
+	// Safety net: if SetAttributes were populated without AttributeOrder,
+	// reconstruct order from map keys so updates aren't silently dropped.
+	if len(m.AttributeOrder) == 0 && len(m.SetAttributes) > 0 {
+		for key := range m.SetAttributes {
+			m.AttributeOrder = append(m.AttributeOrder, key)
+		}
+	}
+
 	// Apply attributes in the order they were specified (important for relative references)
 	dateKeys := DateKeys
 
@@ -134,6 +149,14 @@ func (m *Modifier) ApplyToNew(task *Task) error {
 		resolvedDates["created"] = task.Created
 	}
 
+	// Safety net: if SetAttributes were populated without AttributeOrder,
+	// reconstruct order from map keys so updates aren't silently dropped.
+	if len(m.AttributeOrder) == 0 && len(m.SetAttributes) > 0 {
+		for key := range m.SetAttributes {
+			m.AttributeOrder = append(m.AttributeOrder, key)
+		}
+	}
+
 	// Apply attributes in the order they were specified (important for relative references)
 	dateKeys := DateKeys
 
@@ -156,9 +179,17 @@ func (m *Modifier) ApplyToNew(task *Task) error {
 	return nil
 }
 
-// applyNonDateAttribute applies a non-date attribute (priority, project, recur) to a task.
+// applyNonDateAttribute applies a non-date attribute to a task.
 func applyNonDateAttribute(key string, valuePtr *string, task *Task) error {
 	switch key {
+	case "description":
+		if valuePtr != nil {
+			task.Description = *valuePtr
+		}
+	case "status":
+		if valuePtr != nil && len(*valuePtr) > 0 {
+			task.Status = Status((*valuePtr)[0])
+		}
 	case "priority":
 		if valuePtr == nil {
 			task.Priority = PriorityDefault