Domain Model & Data Schema

The domain follows the Product Brief’s definitions (§5.1) exactly; the tables below are the Drizzle definitions in src/db/schema.ts.

Entities

• User — a registered person, identified by email and name (users).
• List — a container for Tasks, owned by exactly one User; can be shared with Members and placed in at most one Group (lists).
• Task — an entry in a List with a title and attributes (done, starred, due date, notes, assignee); can be assigned to one Member of its List (tasks).
• Step — a child of a Task with only a title and done state; cannot be starred, assigned, shared, dated, or nested (steps).
• Group — a container that organizes related Lists; cannot nest (groups).
• View — a system-defined, read-only collection of Tasks (“My Day”, “Important”, “Planned”, “Assigned to me”, “Tasks”); aggregates across owned and member Lists and respects the authorization boundary.
• Member — a User a List has been shared with (listMembers); a Member is always a User.

Key domain rules

• A List is owned by exactly one User; only the owner changes memberships; deleting a List permanently deletes its Tasks and Steps (Product Brief §5.2).
• A Task belongs to one List; deleting a Task deletes its Steps; a Task may be assigned to exactly one Member (assigning to the owner is allowed; removing the assignee clears the assignment).
• Steps have only title + done; no nesting.
• A Group holds zero or more Lists and cannot nest; deleting a Group ungroups its Lists rather than deleting them.
• Ordering is custom per scope: per-List for Tasks, per-Task for Steps, per-User for Lists and Groups; sorting is a temporary view, drag-and-drop sets the persisted order.
• The server is the single source of truth; concurrent edits to the same field reconcile last-write-wins at the field level (Product Brief §5.2–§5.3).

Data schema (D1, Drizzle)

The tables defined in src/db/schema.ts:

Table	Represents	Notable columns / relationships
users	Registered users	identity (email, name)
lists	Lists	ownerId, optional groupId, per-owner rank
groups	Groups of Lists	rank; Lists reference via groupId
tasks	Tasks	listId, title, done, starred, dueDate, notes, assigneeId, rank
steps	Steps	taskId, title, done, rank
myDayEntries	”My Day” view membership	per-user daily-focus entries (reset each local day)
listMembers	List sharing	(listId, userId); per-viewer order/group for shared Lists
idempotencyKeys	Replay dedup	stable key per queued mutation for safe outbox replay

Per-member List placement (per-viewer order + group on listMembers) and assignment (assigneeId) come from list-sharing and task-assignment (spec 011, spec 012). The rank columns implement the fractional ordering described in the Fractional Rank Algorithm module guide.