diff --git a/src/lib/api/habits.triplit.ts b/src/lib/api/habits.triplit.ts
new file mode 100644
index 0000000..dfaf1a5
--- /dev/null
+++ b/src/lib/api/habits.triplit.ts
@@ -0,0 +1,175 @@
+import { triplit, Query } from '../triplit/client';
+import type { Habit, HabitCompletion } from '../triplit/schema';
+
+export type CreateHabitData = Omit<Habit, 'id' | 'active' | 'startDate' | 'createdAt' | 'updatedAt'> & {
+  endDate?: Date;
+};
+
+export type UpdateHabitData = Partial<Omit<Habit, 'id' | 'userId' | 'createdAt'>>;
+
+export type CreateCompletionData = Omit<HabitCompletion, 'id' | 'completedAt'> & {
+  completedAt?: Date;
+};
+
+export async function createHabit(data: CreateHabitData & { active?: boolean; startDate?: Date }) {
+  return await triplit.insert('habits', {
+    userId: data.userId,
+    name: data.name,
+    duration: data.duration,
+    target: data.target,
+    increment: data.increment,
+    unit: data.unit || null,
+    active: data.active ?? true,
+    startDate: data.startDate || new Date(),
+    endDate: data.endDate || null,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+  });
+}
+
+export async function updateHabit(id: string, data: UpdateHabitData) {
+  return await triplit.update('habits', id, {
+    ...data,
+    updatedAt: new Date(),
+  });
+}
+
+export async function deleteHabit(id: string) {
+  // Delete all associated completions
+  const completions = await triplit.fetch(
+    Query('habit_completions').Where('habitId', '=', id)
+  );
+  
+  for (const completion of completions) {
+    await triplit.delete('habit_completions', completion.id);
+  }
+  
+  // Then delete the habit
+  return await triplit.delete('habits', id);
+}
+
+export function getHabits(userId: string) {
+  return Query('habits')
+    .Where('userId', '=', userId)
+    .Order('createdAt', 'ASC');
+}
+
+export function getHabit(id: string) {
+  return Query('habits')
+    .Where('id', '=', id);
+}
+
+export async function createCompletion(data: CreateCompletionData) {
+  return await triplit.insert('habit_completions', {
+    habitId: data.habitId,
+    value: data.value,
+    failed: data.failed || false,
+    completedAt: data.completedAt || new Date(),
+  });
+}
+
+export async function deleteCompletion(id: string) {
+  return await triplit.delete('habit_completions', id);
+}
+
+export function getCompletions(habitId: string, startDate?: Date, endDate?: Date) {
+  let query = Query('habit_completions')
+    .Where('habitId', '=', habitId);
+  
+  if (startDate) {
+    query = query.Where('completedAt', '>=', startDate);
+  }
+  
+  if (endDate) {
+    query = query.Where('completedAt', '<=', endDate);
+  }
+  
+  return query.Order('completedAt', 'DESC');
+}
+
+// Get habits with completions for a date range
+export function getHabitsWithCompletions(userId: string, startDate: Date, endDate: Date) {
+  return Query('habits')
+    .Where('userId', '=', userId)
+    .Where([
+      {
+        exists: Query('habit_completions').Where([
+          ['habitId', '=', '$1.id'],
+          ['completedAt', '>=', startDate],
+          ['completedAt', '<=', endDate]
+        ])
+      }
+    ])
+    .Include('completions')
+    .Order('createdAt', 'ASC');
+}
+
+export function getHabitCompletions(habitId: string, startDate: Date, endDate: Date) {
+  return Query('habit_completions')
+    .Where('habitId', '=', habitId)
+    .Where('completedAt', '>=', startDate)
+    .Where('completedAt', '<=', endDate)
+    .Where('failed', '=', false);
+}
+
+export async function archiveHabit(id: string) {
+  return await updateHabit(id, { active: false });
+}
+
+export async function updateCompletion(id: string, data: Partial<Omit<HabitCompletion, 'id' | 'habitId'>>) {
+  return await triplit.update('habit_completions', id, data);
+}
+
+export async function getCompletionByDate(habitId: string, date: Date) {
+  // Create date range for the specific day (start of day to end of day)
+  const startOfDay = new Date(date);
+  startOfDay.setHours(0, 0, 0, 0);
+  
+  const endOfDay = new Date(date);
+  endOfDay.setHours(23, 59, 59, 999);
+  
+  const completions = await triplit.fetch(
+    Query('habit_completions')
+      .Where('habitId', '=', habitId)
+      .Where('completedAt', '>=', startOfDay)
+      .Where('completedAt', '<=', endOfDay)
+  );
+  
+  return completions[0] || null;
+}
+
+export async function upsertCompletion(habitId: string, date: Date, value: number, failed: boolean = false) {
+  const existing = await getCompletionByDate(habitId, date);
+  
+  if (existing) {
+    return await updateCompletion(existing.id, { value, failed });
+  } else {
+    return await createCompletion({
+      habitId,
+      value,
+      failed,
+      completedAt: date
+    });
+  }
+}
+
+// Reset completions in date range to value 0
+export async function resetCompletions(habitId: string, startDate: Date, endDate: Date) {
+  return await triplit.transact(async (tx) => {
+    const completions = await tx.fetch(
+      Query('habit_completions')
+        .Where('habitId', '=', habitId)
+        .Where('completedAt', '>=', startDate)
+        .Where('completedAt', '<=', endDate)
+    );
+    
+    for (const completion of completions) {
+      await tx.update('habit_completions', completion.id, {
+        value: 0,
+        failed: false
+      });
+    }
+    
+    return completions.length;
+  });
+}
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