fix: serialize task all-day flag as isAllDay

CHANGELOG.md

@@ -7,6 +7,9 @@ Version numbers follow [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Fixed
+- `task create/update --not-all-day` now sends `isAllDay` to the Web API.
+
 ## [v0.2.7] - 2026-07-18
 
 ### Added

internal/cli/cli_test.go

@@ -765,8 +765,8 @@ func TestTaskCreateDryRunJSON(t *testing.T) {
 	if items := task["items"].([]any); len(items) != 1 {
 		t.Fatalf("items len = %d, want 1", len(items))
 	}
-	if task["allDay"] != true {
-		t.Fatalf("allDay = %v, want true", task["allDay"])
+	if task["isAllDay"] != true {
+		t.Fatalf("isAllDay = %v, want true", task["isAllDay"])
 	}
 }
 

internal/webapi/tasks.go

@@ -16,7 +16,7 @@ type TaskMutation struct {
 	Title      string        `json:"title,omitempty"`
 	Content    string        `json:"content,omitempty"`
 	Desc       string        `json:"desc,omitempty"`
-	AllDay     *bool         `json:"allDay,omitempty"`
+	AllDay     *bool         `json:"isAllDay,omitempty"`
 	StartDate  string        `json:"startDate,omitempty"`
 	DueDate    string        `json:"dueDate,omitempty"`
 	TimeZone   string        `json:"timeZone,omitempty"`

internal/webapi/tasks_test.go

@@ -82,6 +82,32 @@ func TestTaskUpdateCanSendPriorityZero(t *testing.T) {
 	}
 }
 
+func TestTaskUpdateCanSendAllDayFalse(t *testing.T) {
+	var rawBody string
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		data, err := io.ReadAll(r.Body)
+		if err != nil {
+			t.Fatalf("read request: %v", err)
+		}
+		rawBody = string(data)
+		_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
+	}))
+	defer server.Close()
+
+	client := NewClient("test-token")
+	client.BaseURL = server.URL
+	allDay := false
+	if _, err := client.UpdateTask(context.Background(), TaskMutation{ID: "t1", ProjectID: "p1", AllDay: &allDay}); err != nil {
+		t.Fatalf("UpdateTask() error = %v", err)
+	}
+	if !strings.Contains(rawBody, `"isAllDay":false`) {
+		t.Fatalf("request body missing isAllDay false: %s", rawBody)
+	}
+	if strings.Contains(rawBody, `"allDay"`) {
+		t.Fatalf("request body contains legacy allDay key: %s", rawBody)
+	}
+}
+
 func TestProjectTasksUsesProjectEndpoint(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if got := r.Method + " " + r.URL.Path; got != "GET /project/p1/tasks" {