fix: use has_time flag for due date time tracking

Replace the hours==0 && minutes==0 heuristic with an explicit has_time
bool field on Task. Existing files without the field deserialize as false
(date-only), preserving current behavior. Frontend components pass and
receive has_time through DateTimePicker's onchange callback.

apps/tauri/src/lib/components/DateTimePicker.svelte

@@ -1,7 +1,8 @@
 <script lang="ts">
-  let { value = null, onchange, onclose }: {
+  let { value = null, has_time = false, onchange, onclose }: {
     value: string | null;
-    onchange: (iso: string | null) => void;
+    has_time: boolean;
+    onchange: (iso: string | null, has_time: boolean) => void;
     onclose: () => void;
   } = $props();
 
@@ -12,7 +13,7 @@
   let viewYear = $state(existing ? existing.getFullYear() : now.getFullYear());
   let viewMonth = $state(existing ? existing.getMonth() : now.getMonth());
   let selectedDay = $state(existing ? existing.getDate() : now.getDate());
-  let includeTime = $state(existing ? (existing.getHours() !== 0 || existing.getMinutes() !== 0) : false);
+  let includeTime = $state(has_time);
   let selectedHour = $state(existing ? existing.getHours() : now.getHours());
   let selectedMinute = $state(existing ? existing.getMinutes() : 0);
   let visible = $state(false);
@@ -66,12 +67,12 @@
     const h = includeTime ? selectedHour : 0;
     const m = includeTime ? selectedMinute : 0;
     const iso = new Date(viewYear, viewMonth, selectedDay, h, m).toISOString();
-    onchange(iso);
+    onchange(iso, includeTime);
     dismiss();
   }
 
   function clear() {
-    onchange(null);
+    onchange(null, false);
     dismiss();
   }
 </script>

apps/tauri/src/lib/components/NewTaskInput.svelte

@@ -10,6 +10,7 @@
   let title = $state("");
   let description = $state("");
   let dueDate = $state<string | null>(null);
+  let dueDateHasTime = $state(false);
   let inputEl = $state<HTMLInputElement | null>(null);
   let showDatePicker = $state(false);
 
@@ -17,11 +18,12 @@
     if (!title.trim()) return;
     const created = await app.createTask(title.trim(), description.trim() || undefined);
     if (dueDate && created) {
-      await app.updateTask({ ...created, due_date: dueDate, updated_at: new Date().toISOString() });
+      await app.updateTask({ ...created, due_date: dueDate, has_time: dueDateHasTime, updated_at: new Date().toISOString() });
     }
     title = "";
     description = "";
     dueDate = null;
+    dueDateHasTime = false;
     newTaskState.open = false;
   }
 
@@ -30,11 +32,13 @@
     title = "";
     description = "";
     dueDate = null;
+    dueDateHasTime = false;
     showDatePicker = false;
   }
 
-  function handleDateChange(iso: string | null) {
+  function handleDateChange(iso: string | null, hasTime: boolean = false) {
     dueDate = iso;
+    dueDateHasTime = hasTime;
   }
 
   function formatDateChip(iso: string): string {
@@ -43,8 +47,7 @@
     const dayNames = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
     const day = dayNames[d.getDay()];
     const pad = (n: number) => String(n).padStart(2, "0");
-    const hasTime = d.getHours() !== 0 || d.getMinutes() !== 0;
+    const timePart = dueDateHasTime ? `, ${pad(d.getHours())}:${pad(d.getMinutes())}` : "";
-    const timePart = hasTime ? `, ${pad(d.getHours())}:${pad(d.getMinutes())}` : "";
     if (d.toDateString() === today.toDateString()) return `Today${timePart}`;
     return `${day}, ${pad(d.getDate())}/${pad(d.getMonth() + 1)}${timePart}`;
   }
@@ -137,6 +140,7 @@
   {#if showDatePicker}
     <DateTimePicker
       value={dueDate}
+      has_time={dueDateHasTime}
       onchange={handleDateChange}
       onclose={() => (showDatePicker = false)}
     />

apps/tauri/src/lib/components/TaskDetailView.svelte

@@ -42,8 +42,8 @@
     debouncedSave({ description });
   }
 
-  function handleDateChange(iso: string | null) {
+  function handleDateChange(iso: string | null, hasTime: boolean = false) {
-    app.updateTask({ ...task, due_date: iso, updated_at: new Date().toISOString() });
+    app.updateTask({ ...task, due_date: iso, has_time: hasTime, updated_at: new Date().toISOString() });
   }
 
   async function handleToggle() {
@@ -79,7 +79,7 @@
     const dayNames = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
     const day = dayNames[d.getDay()];
     const pad = (n: number) => String(n).padStart(2, "0");
-    const hasTime = d.getHours() !== 0 || d.getMinutes() !== 0;
+    const hasTime = task.has_time;
     const timePart = hasTime ? `, ${pad(d.getHours())}:${pad(d.getMinutes())}` : "";
     if (d.toDateString() === today.toDateString()) return `Today${timePart}`;
     return `${day}, ${pad(d.getDate())}/${pad(d.getMonth() + 1)}${timePart}`;
@@ -223,6 +223,7 @@
 {#if showDatePicker}
   <DateTimePicker
     value={task.due_date}
+    has_time={task.has_time}
     onchange={handleDateChange}
     onclose={() => (showDatePicker = false)}
   />

apps/tauri/src/lib/types.ts

@@ -4,6 +4,7 @@ export interface Task {
   description: string;
   status: "backlog" | "completed";
   due_date: string | null;
+  has_time: boolean;
   created_at: string;
   updated_at: string;
   parent_id: string | null;

crates/onyx-core/src/models.rs

@@ -17,6 +17,8 @@ pub struct Task {
     pub status: TaskStatus,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub due_date: Option<DateTime<Utc>>,
+    #[serde(default)]
+    pub has_time: bool,
     pub created_at: DateTime<Utc>,
     pub updated_at: DateTime<Utc>,
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -32,6 +34,7 @@ impl Task {
             description: String::new(),
             status: TaskStatus::Backlog,
             due_date: None,
+            has_time: false,
             created_at: now,
             updated_at: now,
             parent_id: None,

crates/onyx-core/src/storage.rs

@@ -56,6 +56,8 @@ pub struct TaskFrontmatter {
     pub status: TaskStatus,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub due: Option<DateTime<Utc>>,
+    #[serde(default)]
+    pub has_time: bool,
     pub created: DateTime<Utc>,
     pub updated: DateTime<Utc>,
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -68,6 +70,7 @@ impl From<&Task> for TaskFrontmatter {
             id: task.id,
             status: task.status,
             due: task.due_date,
+            has_time: task.has_time,
             created: task.created_at,
             updated: task.updated_at,
             parent: task.parent_id,
@@ -256,6 +259,7 @@ impl Storage for FileSystemStorage {
                         description,
                         status: frontmatter.status,
                         due_date: frontmatter.due,
+                        has_time: frontmatter.has_time,
                         created_at: frontmatter.created,
                         updated_at: frontmatter.updated,
                         parent_id: frontmatter.parent,
@@ -344,6 +348,7 @@ impl Storage for FileSystemStorage {
                     description,
                     status: frontmatter.status,
                     due_date: frontmatter.due,
+                    has_time: frontmatter.has_time,
                     created_at: frontmatter.created,
                     updated_at: frontmatter.updated,
                     parent_id: frontmatter.parent,