config/config.exs

@@ -49,7 +49,7 @@ config :spark,
 config :mv,
   ecto_repos: [Mv.Repo],
   generators: [timestamp_type: :utc_datetime],
-  ash_domains: [Mv.Membership, Mv.Accounts]
+  ash_domains: [Mv.Membership, Mv.Accounts, Mv.MembershipFees]
 
 # Configures the endpoint
 config :mv, MvWeb.Endpoint,

docs/database_schema.dbml

@@ -6,8 +6,8 @@
 // - https://dbdocs.io
 // - VS Code Extensions: "DBML Language" or "dbdiagram.io"
 //
-// Version: 1.2
-// Last Updated: 2025-11-13
+// Version: 1.3
+// Last Updated: 2025-12-11
 
 Project mila_membership_management {
   database_type: 'PostgreSQL'
@@ -27,6 +27,7 @@ Project mila_membership_management {
     ## Domains:
     - **Accounts**: User authentication and session management
     - **Membership**: Club member data and custom fields
+    - **MembershipFees**: Membership fee types and billing cycles
     
     ## Required PostgreSQL Extensions:
     - uuid-ossp (UUID generation)
@@ -132,6 +133,8 @@ Table members {
   house_number text [null, note: 'House number']
   postal_code text [null, note: '5-digit German postal code']
   search_vector tsvector [null, note: 'Full-text search index (auto-generated)']
+  membership_fee_type_id uuid [null, note: 'FK to membership_fee_types - assigned fee type']
+  membership_fee_start_date date [null, note: 'Date from which membership fees should be calculated']
   
   indexes {
     email [unique, name: 'members_unique_email_index']
@@ -146,6 +149,7 @@ Table members {
     last_name [name: 'members_last_name_idx', note: 'B-tree index for name sorting']
     join_date [name: 'members_join_date_idx', note: 'B-tree index for date filters']
     (paid) [name: 'members_paid_idx', type: btree, note: 'Partial index WHERE paid IS NOT NULL']
+    membership_fee_type_id [name: 'members_membership_fee_type_id_index', note: 'B-tree index for fee type lookups']
   }
   
   Note: '''
@@ -178,6 +182,8 @@ Table members {
     **Relationships:**
     - Optional 1:1 with users (0..1 ↔ 0..1) - authentication account
     - 1:N with custom_field_values (custom dynamic fields)
+    - Optional N:1 with membership_fee_types - assigned fee type
+    - 1:N with membership_fee_cycles - billing history
     
     **Validation Rules:**
     - first_name, last_name: min 1 character
@@ -281,6 +287,98 @@ Table custom_fields {
   '''
 }
 
+// ============================================
+// MEMBERSHIP_FEES DOMAIN
+// ============================================
+
+Table membership_fee_types {
+  id uuid [pk, not null, default: `uuid_generate_v7()`, note: 'UUIDv7 primary key']
+  name text [not null, unique, note: 'Unique name for the fee type (e.g., "Standard", "Reduced")']
+  amount numeric(10,2) [not null, note: 'Fee amount in default currency (CHECK: >= 0)']
+  interval text [not null, note: 'Billing interval (CHECK: IN monthly, quarterly, half_yearly, yearly) - immutable']
+  description text [null, note: 'Optional description for the fee type']
+  
+  indexes {
+    name [unique, name: 'membership_fee_types_unique_name_index']
+  }
+  
+  Note: '''
+    **Membership Fee Type Definitions**
+    
+    Defines the different types of membership fees with fixed billing intervals.
+    
+    **Attributes:**
+    - `name`: Unique identifier for the fee type
+    - `amount`: Default fee amount (stored per cycle for audit trail)
+    - `interval`: Billing cycle - immutable after creation
+    - `description`: Optional documentation
+    
+    **Interval Values:**
+    - `monthly`: 1st to last day of month
+    - `quarterly`: 1st of Jan/Apr/Jul/Oct to last day of quarter
+    - `half_yearly`: 1st of Jan/Jul to last day of half
+    - `yearly`: Jan 1 to Dec 31
+    
+    **Immutability:**
+    The `interval` field cannot be changed after creation to prevent
+    complex migration scenarios. Create a new fee type to change intervals.
+    
+    **Relationships:**
+    - 1:N with members - members assigned to this fee type
+    - 1:N with membership_fee_cycles - all cycles using this fee type
+    
+    **Deletion Behavior:**
+    - ON DELETE RESTRICT: Cannot delete if members or cycles reference it
+  '''
+}
+
+Table membership_fee_cycles {
+  id uuid [pk, not null, default: `uuid_generate_v7()`, note: 'UUIDv7 primary key']
+  cycle_start date [not null, note: 'Start date of the billing cycle']
+  amount numeric(10,2) [not null, note: 'Fee amount for this cycle (CHECK: >= 0)']
+  status text [not null, default: 'unpaid', note: 'Payment status (CHECK: IN unpaid, paid, suspended)']
+  notes text [null, note: 'Optional notes for this cycle']
+  member_id uuid [not null, note: 'FK to members - the member this cycle belongs to']
+  membership_fee_type_id uuid [not null, note: 'FK to membership_fee_types - fee type for this cycle']
+  
+  indexes {
+    member_id [name: 'membership_fee_cycles_member_id_index']
+    membership_fee_type_id [name: 'membership_fee_cycles_membership_fee_type_id_index']
+    status [name: 'membership_fee_cycles_status_index']
+    cycle_start [name: 'membership_fee_cycles_cycle_start_index']
+    (member_id, cycle_start) [unique, name: 'membership_fee_cycles_unique_cycle_per_member_index', note: 'One cycle per member per cycle_start']
+  }
+  
+  Note: '''
+    **Individual Membership Fee Cycles**
+    
+    Represents a single billing cycle for a member with payment tracking.
+    
+    **Design Decisions:**
+    - `cycle_end` is NOT stored - calculated from cycle_start + interval
+    - `amount` is stored per cycle to preserve historical values when fee type amount changes
+    - Cycles are aligned to calendar boundaries
+    
+    **Status Values:**
+    - `unpaid`: Payment pending (default)
+    - `paid`: Payment received
+    - `suspended`: Payment suspended (e.g., hardship case)
+    
+    **Constraints:**
+    - Unique: One cycle per member per cycle_start date
+    - member_id: Required (belongs_to)
+    - membership_fee_type_id: Required (belongs_to)
+    
+    **Relationships:**
+    - N:1 with members - the member this cycle belongs to
+    - N:1 with membership_fee_types - the fee type for this cycle
+    
+    **Deletion Behavior:**
+    - ON DELETE CASCADE (member_id): Cycles deleted when member deleted
+    - ON DELETE RESTRICT (membership_fee_type_id): Cannot delete fee type if cycles exist
+  '''
+}
+
 // ============================================
 // RELATIONSHIPS
 // ============================================
@@ -306,6 +404,22 @@ Ref: custom_field_values.member_id > members.id [delete: cascade]
 // - ON DELETE RESTRICT: Cannot delete type if custom_field_values exist
 Ref: custom_field_values.custom_field_id > custom_fields.id [delete: restrict]
 
+// Member → MembershipFeeType (N:1)
+// - Many members can be assigned to one fee type
+// - Optional relationship (member can have no fee type)
+// - ON DELETE RESTRICT: Cannot delete fee type if members are assigned
+Ref: members.membership_fee_type_id > membership_fee_types.id [delete: restrict]
+
+// MembershipFeeCycle → Member (N:1)
+// - Many cycles belong to one member
+// - ON DELETE CASCADE: Cycles deleted when member deleted
+Ref: membership_fee_cycles.member_id > members.id [delete: cascade]
+
+// MembershipFeeCycle → MembershipFeeType (N:1)
+// - Many cycles reference one fee type
+// - ON DELETE RESTRICT: Cannot delete fee type if cycles reference it
+Ref: membership_fee_cycles.membership_fee_type_id > membership_fee_types.id [delete: restrict]
+
 // ============================================
 // ENUMS
 // ============================================
@@ -328,6 +442,21 @@ Enum token_purpose {
   email_confirmation [note: 'Email verification tokens']
 }
 
+// Billing interval for membership fee types
+Enum membership_fee_interval {
+  monthly [note: '1st to last day of month']
+  quarterly [note: '1st of Jan/Apr/Jul/Oct to last day of quarter']
+  half_yearly [note: '1st of Jan/Jul to last day of half']
+  yearly [note: 'Jan 1 to Dec 31']
+}
+
+// Payment status for membership fee cycles
+Enum membership_fee_status {
+  unpaid [note: 'Payment pending (default)']
+  paid [note: 'Payment received']
+  suspended [note: 'Payment suspended']
+}
+
 // ============================================
 // TABLE GROUPS
 // ============================================
@@ -357,3 +486,17 @@ TableGroup membership_domain {
   '''
 }
 
+TableGroup membership_fees_domain {
+  membership_fee_types
+  membership_fee_cycles
+  
+  Note: '''
+    **Membership Fees Domain**
+    
+    Handles membership fee management including:
+    - Fee type definitions with intervals
+    - Individual billing cycles per member
+    - Payment status tracking
+  '''
+}
+

lib/membership/member.ex

@@ -79,7 +79,8 @@ defmodule Mv.Membership.Member do
       # user_id is NOT in accept list to prevent direct foreign key manipulation
       argument :user, :map, allow_nil?: true
 
-      accept @member_fields
+      # Accept member fields plus membership_fee_type_id (belongs_to FK)
+      accept @member_fields ++ [:membership_fee_type_id]
 
       change manage_relationship(:custom_field_values, type: :create)
 
@@ -112,7 +113,8 @@ defmodule Mv.Membership.Member do
       # user_id is NOT in accept list to prevent direct foreign key manipulation
       argument :user, :map, allow_nil?: true
 
-      accept @member_fields
+      # Accept member fields plus membership_fee_type_id (belongs_to FK)
+      accept @member_fields ++ [:membership_fee_type_id]
 
       change manage_relationship(:custom_field_values, on_match: :update, on_no_match: :create)
 
@@ -394,6 +396,15 @@ defmodule Mv.Membership.Member do
       writable?: false,
       public?: false,
       select_by_default?: false
+
+    # Membership fee fields
+    # membership_fee_start_date: Date from which membership fees should be calculated
+    # If nil, calculated from join_date + global setting
+    attribute :membership_fee_start_date, :date do
+      allow_nil? true
+      public? true
+      description "Date from which membership fees should be calculated"
+    end
   end
 
   relationships do
@@ -402,6 +413,16 @@ defmodule Mv.Membership.Member do
     # This references the User's member_id attribute
     # The relationship is optional (allow_nil? true by default)
     has_one :user, Mv.Accounts.User
+
+    # Membership fee relationships
+    # belongs_to: The fee type assigned to this member
+    # Optional for MVP - can be nil if no fee type assigned yet
+    belongs_to :membership_fee_type, Mv.MembershipFees.MembershipFeeType do
+      allow_nil? true
+    end
+
+    # has_many: All fee cycles for this member
+    has_many :membership_fee_cycles, Mv.MembershipFees.MembershipFeeCycle
   end
 
   # Define identities for upsert operations

lib/membership_fees/membership_fee_cycle.ex

@@ -0,0 +1,102 @@
+defmodule Mv.MembershipFees.MembershipFeeCycle do
+  @moduledoc """
+  Ash resource representing an individual membership fee cycle for a member.
+
+  ## Overview
+  MembershipFeeCycle represents a single billing cycle for a member. Each cycle
+  tracks the payment status and amount for a specific time period.
+
+  ## Attributes
+  - `cycle_start` - Start date of the billing cycle (aligned to calendar boundaries)
+  - `amount` - The fee amount for this cycle (stored for audit trail)
+  - `status` - Payment status: unpaid, paid, or suspended
+  - `notes` - Optional notes for this cycle
+
+  ## Design Decisions
+  - **No cycle_end field**: Calculated from cycle_start + interval (from fee type)
+  - **Amount stored per cycle**: Preserves historical amounts when fee type changes
+  - **Calendar-aligned cycles**: All cycles start on calendar boundaries
+
+  ## Relationships
+  - `belongs_to :member` - The member this cycle belongs to
+  - `belongs_to :membership_fee_type` - The fee type for this cycle
+
+  ## Constraints
+  - Unique constraint on (member_id, cycle_start) - one cycle per period per member
+  - CASCADE delete when member is deleted
+  - RESTRICT delete on membership_fee_type if cycles exist
+  """
+  use Ash.Resource,
+    domain: Mv.MembershipFees,
+    data_layer: AshPostgres.DataLayer
+
+  postgres do
+    table "membership_fee_cycles"
+    repo Mv.Repo
+  end
+
+  resource do
+    description "Individual membership fee cycle for a member"
+  end
+
+  actions do
+    defaults [:read, :destroy]
+
+    create :create do
+      primary? true
+      accept [:cycle_start, :amount, :status, :notes, :member_id, :membership_fee_type_id]
+    end
+
+    update :update do
+      primary? true
+      accept [:status, :notes]
+    end
+  end
+
+  attributes do
+    uuid_v7_primary_key :id
+
+    attribute :cycle_start, :date do
+      allow_nil? false
+      public? true
+      description "Start date of the billing cycle"
+    end
+
+    attribute :amount, :decimal do
+      allow_nil? false
+      public? true
+
+      description "Fee amount for this cycle (stored for audit trail, non-negative, max 2 decimal places)"
+
+      constraints min: 0, scale: 2
+    end
+
+    attribute :status, :atom do
+      allow_nil? false
+      public? true
+      default :unpaid
+      description "Payment status of this cycle"
+      constraints one_of: [:unpaid, :paid, :suspended]
+    end
+
+    attribute :notes, :string do
+      allow_nil? true
+      public? true
+      description "Optional notes for this cycle"
+    end
+  end
+
+  relationships do
+    belongs_to :member, Mv.Membership.Member do
+      allow_nil? false
+    end
+
+    belongs_to :membership_fee_type, Mv.MembershipFees.MembershipFeeType do
+      allow_nil? false
+    end
+  end
+
+  identities do
+    identity :unique_cycle_per_member, [:member_id, :cycle_start]
+  end
+end

lib/membership_fees/membership_fee_type.ex

@@ -0,0 +1,92 @@
+defmodule Mv.MembershipFees.MembershipFeeType do
+  @moduledoc """
+  Ash resource representing a membership fee type definition.
+
+  ## Overview
+  MembershipFeeType defines the different types of membership fees that can be
+  assigned to members. Each type has a fixed interval (billing cycle) and a
+  default amount.
+
+  ## Attributes
+  - `name` - Unique name for the fee type (e.g., "Standard", "Reduced", "Family")
+  - `amount` - The fee amount in the default currency (decimal)
+  - `interval` - Billing interval: monthly, quarterly, half_yearly, or yearly
+  - `description` - Optional description for the fee type
+
+  ## Immutability
+  The `interval` field is immutable after creation. This prevents complex
+  migration scenarios when changing billing cycles. To change intervals,
+  create a new fee type and migrate members.
+
+  ## Relationships
+  - `has_many :members` - Members assigned to this fee type
+  - `has_many :membership_fee_cycles` - All cycles using this fee type
+  """
+  use Ash.Resource,
+    domain: Mv.MembershipFees,
+    data_layer: AshPostgres.DataLayer
+
+  postgres do
+    table "membership_fee_types"
+    repo Mv.Repo
+  end
+
+  resource do
+    description "Membership fee type definition with interval and amount"
+  end
+
+  actions do
+    defaults [:read, :destroy]
+
+    create :create do
+      primary? true
+      accept [:name, :amount, :interval, :description]
+    end
+
+    update :update do
+      primary? true
+      # Note: interval is NOT in accept list - it's immutable after creation
+      # Immutability validation will be added in a future issue
+      accept [:name, :amount, :description]
+    end
+  end
+
+  attributes do
+    uuid_v7_primary_key :id
+
+    attribute :name, :string do
+      allow_nil? false
+      public? true
+      description "Unique name for the membership fee type"
+    end
+
+    attribute :amount, :decimal do
+      allow_nil? false
+      public? true
+      description "Fee amount in default currency (non-negative, max 2 decimal places)"
+      constraints min: 0, scale: 2
+    end
+
+    attribute :interval, :atom do
+      allow_nil? false
+      public? true
+      description "Billing interval (immutable after creation)"
+      constraints one_of: [:monthly, :quarterly, :half_yearly, :yearly]
+    end
+
+    attribute :description, :string do
+      allow_nil? true
+      public? true
+      description "Optional description for the fee type"
+    end
+  end
+
+  relationships do
+    has_many :membership_fee_cycles, Mv.MembershipFees.MembershipFeeCycle
+    has_many :members, Mv.Membership.Member
+  end
+
+  identities do
+    identity :unique_name, [:name]
+  end
+end

lib/membership_fees/membership_fees.ex

@@ -0,0 +1,42 @@
+defmodule Mv.MembershipFees do
+  @moduledoc """
+  Ash Domain for membership fee management.
+
+  ## Resources
+  - `MembershipFeeType` - Defines membership fee types with intervals and amounts
+  - `MembershipFeeCycle` - Individual membership fee cycles per member
+
+  ## Overview
+  This domain handles the complete membership fee lifecycle including:
+  - Fee type definitions (monthly, quarterly, half-yearly, yearly)
+  - Individual fee cycles for each member
+  - Payment status tracking (unpaid, paid, suspended)
+
+  ## Architecture Decisions
+  - `interval` field on MembershipFeeType is immutable after creation
+  - `cycle_end` is calculated, not stored (from cycle_start + interval)
+  - `amount` is stored per cycle for audit trail when prices change
+  """
+  use Ash.Domain,
+    extensions: [AshAdmin.Domain, AshPhoenix]
+
+  admin do
+    show? true
+  end
+
+  resources do
+    resource Mv.MembershipFees.MembershipFeeType do
+      define :create_membership_fee_type, action: :create
+      define :list_membership_fee_types, action: :read
+      define :update_membership_fee_type, action: :update
+      define :destroy_membership_fee_type, action: :destroy
+    end
+
+    resource Mv.MembershipFees.MembershipFeeCycle do
+      define :create_membership_fee_cycle, action: :create
+      define :list_membership_fee_cycles, action: :read
+      define :update_membership_fee_cycle, action: :update
+      define :destroy_membership_fee_cycle, action: :destroy
+    end
+  end
+end

lib/mv/constants.ex

@@ -15,7 +15,8 @@ defmodule Mv.Constants do
     :city,
     :street,
     :house_number,
-    :postal_code
+    :postal_code,
+    :membership_fee_start_date
   ]
 
   @custom_field_prefix "custom_field_"

lib/mv/membership_fees/calendar_cycles.ex

@@ -0,0 +1,329 @@
+defmodule Mv.MembershipFees.CalendarCycles do
+  @moduledoc """
+  Calendar-based cycle calculation functions for membership fees.
+
+  This module provides functions for calculating cycle boundaries
+  based on interval types (monthly, quarterly, half-yearly, yearly).
+
+  The calculation functions (`calculate_cycle_start/3`, `calculate_cycle_end/2`,
+  `next_cycle_start/2`) are pure functions with no side effects.
+
+  The time-dependent functions (`current_cycle?/3`, `last_completed_cycle?/3`)
+  depend on a date parameter for testability. Their 2-argument variants
+  (`current_cycle?/2`, `last_completed_cycle?/2`) use `Date.utc_today()` and
+  are not referentially transparent.
+
+  ## Interval Types
+
+  - `:monthly` - Cycles from 1st to last day of each month
+  - `:quarterly` - Cycles from 1st of Jan/Apr/Jul/Oct to last day of quarter
+  - `:half_yearly` - Cycles from 1st of Jan/Jul to last day of half-year
+  - `:yearly` - Cycles from Jan 1st to Dec 31st
+
+  ## Examples
+
+      iex> date = ~D[2024-03-15]
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(date, :monthly)
+      ~D[2024-03-01]
+
+      iex> cycle_start = ~D[2024-01-01]
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(cycle_start, :yearly)
+      ~D[2024-12-31]
+
+      iex> cycle_start = ~D[2024-01-01]
+      iex> Mv.MembershipFees.CalendarCycles.next_cycle_start(cycle_start, :yearly)
+      ~D[2025-01-01]
+  """
+
+  @typedoc """
+  Interval type for membership fee cycles.
+
+  - `:monthly` - Monthly cycles (1st to last day of month)
+  - `:quarterly` - Quarterly cycles (1st of quarter to last day of quarter)
+  - `:half_yearly` - Half-yearly cycles (1st of half-year to last day of half-year)
+  - `:yearly` - Yearly cycles (Jan 1st to Dec 31st)
+  """
+  @type interval :: :monthly | :quarterly | :half_yearly | :yearly
+
+  @doc """
+  Calculates the start date of the cycle that contains the reference date.
+
+  ## Parameters
+
+    - `date` - Ignored in this 3-argument version (kept for API consistency)
+    - `interval` - The interval type (`:monthly`, `:quarterly`, `:half_yearly`, `:yearly`)
+    - `reference_date` - The date used to determine which cycle to calculate
+
+  ## Returns
+
+    The start date of the cycle containing the reference date.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-03-15], :monthly, ~D[2024-05-20])
+      ~D[2024-05-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-03-15], :quarterly, ~D[2024-05-20])
+      ~D[2024-04-01]
+  """
+  @spec calculate_cycle_start(Date.t(), interval(), Date.t()) :: Date.t()
+  def calculate_cycle_start(_date, interval, reference_date) do
+    case interval do
+      :monthly -> monthly_cycle_start(reference_date)
+      :quarterly -> quarterly_cycle_start(reference_date)
+      :half_yearly -> half_yearly_cycle_start(reference_date)
+      :yearly -> yearly_cycle_start(reference_date)
+    end
+  end
+
+  @doc """
+  Calculates the start date of the cycle that contains the given date.
+
+  This is a convenience function that calls `calculate_cycle_start/3` with `date` as both
+  the input and reference date.
+
+  ## Parameters
+
+    - `date` - The date used to determine which cycle to calculate
+    - `interval` - The interval type (`:monthly`, `:quarterly`, `:half_yearly`, `:yearly`)
+
+  ## Returns
+
+    The start date of the cycle containing the given date.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-03-15], :monthly)
+      ~D[2024-03-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-05-15], :quarterly)
+      ~D[2024-04-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-09-15], :half_yearly)
+      ~D[2024-07-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_start(~D[2024-12-15], :yearly)
+      ~D[2024-01-01]
+  """
+  @spec calculate_cycle_start(Date.t(), interval()) :: Date.t()
+  def calculate_cycle_start(date, interval) do
+    calculate_cycle_start(date, interval, date)
+  end
+
+  @doc """
+  Calculates the end date of a cycle based on its start date and interval.
+
+  ## Parameters
+
+    - `cycle_start` - The start date of the cycle
+    - `interval` - The interval type
+
+  ## Returns
+
+    The end date of the cycle.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(~D[2024-03-01], :monthly)
+      ~D[2024-03-31]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(~D[2024-02-01], :monthly)
+      ~D[2024-02-29]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(~D[2024-01-01], :quarterly)
+      ~D[2024-03-31]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(~D[2024-01-01], :half_yearly)
+      ~D[2024-06-30]
+
+      iex> Mv.MembershipFees.CalendarCycles.calculate_cycle_end(~D[2024-01-01], :yearly)
+      ~D[2024-12-31]
+  """
+  @spec calculate_cycle_end(Date.t(), interval()) :: Date.t()
+  def calculate_cycle_end(cycle_start, interval) do
+    case interval do
+      :monthly -> monthly_cycle_end(cycle_start)
+      :quarterly -> quarterly_cycle_end(cycle_start)
+      :half_yearly -> half_yearly_cycle_end(cycle_start)
+      :yearly -> yearly_cycle_end(cycle_start)
+    end
+  end
+
+  @doc """
+  Calculates the start date of the next cycle.
+
+  ## Parameters
+
+    - `cycle_start` - The start date of the current cycle
+    - `interval` - The interval type
+
+  ## Returns
+
+    The start date of the next cycle.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.next_cycle_start(~D[2024-01-01], :monthly)
+      ~D[2024-02-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.next_cycle_start(~D[2024-01-01], :quarterly)
+      ~D[2024-04-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.next_cycle_start(~D[2024-01-01], :half_yearly)
+      ~D[2024-07-01]
+
+      iex> Mv.MembershipFees.CalendarCycles.next_cycle_start(~D[2024-01-01], :yearly)
+      ~D[2025-01-01]
+  """
+  @spec next_cycle_start(Date.t(), interval()) :: Date.t()
+  def next_cycle_start(cycle_start, interval) do
+    cycle_end = calculate_cycle_end(cycle_start, interval)
+    next_date = Date.add(cycle_end, 1)
+    calculate_cycle_start(next_date, interval)
+  end
+
+  @doc """
+  Checks if the cycle contains the given date.
+
+  ## Parameters
+
+    - `cycle_start` - The start date of the cycle
+    - `interval` - The interval type
+    - `today` - The date to check (defaults to today's date)
+
+  ## Returns
+
+    `true` if the given date is within the cycle, `false` otherwise.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.current_cycle?(~D[2024-03-01], :monthly, ~D[2024-03-15])
+      true
+
+      iex> Mv.MembershipFees.CalendarCycles.current_cycle?(~D[2024-02-01], :monthly, ~D[2024-03-15])
+      false
+
+      iex> Mv.MembershipFees.CalendarCycles.current_cycle?(~D[2024-03-01], :monthly, ~D[2024-03-01])
+      true
+
+      iex> Mv.MembershipFees.CalendarCycles.current_cycle?(~D[2024-03-01], :monthly, ~D[2024-03-31])
+      true
+  """
+  @spec current_cycle?(Date.t(), interval(), Date.t()) :: boolean()
+  def current_cycle?(cycle_start, interval, today) do
+    cycle_end = calculate_cycle_end(cycle_start, interval)
+
+    Date.compare(cycle_start, today) in [:lt, :eq] and
+      Date.compare(today, cycle_end) in [:lt, :eq]
+  end
+
+  @spec current_cycle?(Date.t(), interval()) :: boolean()
+  def current_cycle?(cycle_start, interval) do
+    current_cycle?(cycle_start, interval, Date.utc_today())
+  end
+
+  @doc """
+  Checks if the cycle is the last completed cycle.
+
+  A cycle is considered the last completed cycle if:
+  - The cycle has ended (cycle_end < today)
+  - The next cycle has not ended yet (today <= next_end)
+
+  In other words: `cycle_end < today <= next_end`
+
+  ## Parameters
+
+    - `cycle_start` - The start date of the cycle
+    - `interval` - The interval type
+    - `today` - The date to check against (defaults to today's date)
+
+  ## Returns
+
+    `true` if the cycle is the last completed cycle, `false` otherwise.
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CalendarCycles.last_completed_cycle?(~D[2024-03-01], :monthly, ~D[2024-04-01])
+      true
+
+      iex> Mv.MembershipFees.CalendarCycles.last_completed_cycle?(~D[2024-03-01], :monthly, ~D[2024-03-15])
+      false
+
+      iex> Mv.MembershipFees.CalendarCycles.last_completed_cycle?(~D[2024-02-01], :monthly, ~D[2024-04-15])
+      false
+  """
+  @spec last_completed_cycle?(Date.t(), interval(), Date.t()) :: boolean()
+  def last_completed_cycle?(cycle_start, interval, today) do
+    cycle_end = calculate_cycle_end(cycle_start, interval)
+
+    # Cycle must have ended (cycle_end < today)
+    case Date.compare(today, cycle_end) do
+      :gt ->
+        # Check if this is the most recent completed cycle
+        # by verifying that the next cycle hasn't ended yet (today <= next_end)
+        next_start = next_cycle_start(cycle_start, interval)
+        next_end = calculate_cycle_end(next_start, interval)
+
+        Date.compare(today, next_end) in [:lt, :eq]
+
+      _ ->
+        false
+    end
+  end
+
+  @spec last_completed_cycle?(Date.t(), interval()) :: boolean()
+  def last_completed_cycle?(cycle_start, interval) do
+    last_completed_cycle?(cycle_start, interval, Date.utc_today())
+  end
+
+  # Private helper functions
+
+  defp monthly_cycle_start(date) do
+    Date.new!(date.year, date.month, 1)
+  end
+
+  defp monthly_cycle_end(cycle_start) do
+    Date.end_of_month(cycle_start)
+  end
+
+  defp quarterly_cycle_start(date) do
+    quarter_start_month =
+      case date.month do
+        m when m in [1, 2, 3] -> 1
+        m when m in [4, 5, 6] -> 4
+        m when m in [7, 8, 9] -> 7
+        m when m in [10, 11, 12] -> 10
+      end
+
+    Date.new!(date.year, quarter_start_month, 1)
+  end
+
+  defp quarterly_cycle_end(cycle_start) do
+    case cycle_start.month do
+      1 -> Date.new!(cycle_start.year, 3, 31)
+      4 -> Date.new!(cycle_start.year, 6, 30)
+      7 -> Date.new!(cycle_start.year, 9, 30)
+      10 -> Date.new!(cycle_start.year, 12, 31)
+    end
+  end
+
+  defp half_yearly_cycle_start(date) do
+    half_start_month = if date.month in 1..6, do: 1, else: 7
+    Date.new!(date.year, half_start_month, 1)
+  end
+
+  defp half_yearly_cycle_end(cycle_start) do
+    case cycle_start.month do
+      1 -> Date.new!(cycle_start.year, 6, 30)
+      7 -> Date.new!(cycle_start.year, 12, 31)
+    end
+  end
+
+  defp yearly_cycle_start(date) do
+    Date.new!(date.year, 1, 1)
+  end
+
+  defp yearly_cycle_end(cycle_start) do
+    Date.new!(cycle_start.year, 12, 31)
+  end
+end

mix.lock

@@ -30,7 +30,7 @@
   "file_system": {:hex, :file_system, "1.1.1", "31864f4685b0148f25bd3fbef2b1228457c0c89024ad67f7a81a3ffbc0bbad3a", [:mix], [], "hexpm", "7a15ff97dfe526aeefb090a7a9d3d03aa907e100e262a0f8f7746b78f8f87a5d"},
   "finch": {:hex, :finch, "0.20.0", "5330aefb6b010f424dcbbc4615d914e9e3deae40095e73ab0c1bb0968933cadf", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.6.2 or ~> 1.7", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "2658131a74d051aabfcba936093c903b8e89da9a1b63e430bee62045fa9b2ee2"},
   "fine": {:hex, :fine, "0.1.4", "b19a89c1476c7c57afb5f9314aed5960b5bc95d5277de4cb5ee8e1d1616ce379", [:mix], [], "hexpm", "be3324cc454a42d80951cf6023b9954e9ff27c6daa255483b3e8d608670303f5"},
-  "gettext": {:hex, :gettext, "0.26.2", "5978aa7b21fada6deabf1f6341ddba50bc69c999e812211903b169799208f2a8", [:mix], [{:expo, "~> 0.5.1 or ~> 1.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "aa978504bcf76511efdc22d580ba08e2279caab1066b76bb9aa81c4a1e0a32a5"},
+  "gettext": {:hex, :gettext, "1.0.2", "5457e1fd3f4abe47b0e13ff85086aabae760497a3497909b8473e0acee57673b", [:mix], [{:expo, "~> 0.5.1 or ~> 1.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "eab805501886802071ad290714515c8c4a17196ea76e5afc9d06ca85fb1bfeb3"},
   "glob_ex": {:hex, :glob_ex, "0.1.11", "cb50d3f1ef53f6ca04d6252c7fde09fd7a1cf63387714fe96f340a1349e62c93", [:mix], [], "hexpm", "342729363056e3145e61766b416769984c329e4378f1d558b63e341020525de4"},
   "heroicons": {:git, "https://github.com/tailwindlabs/heroicons.git", "0435d4ca364a608cc75e2f8683d374e55abbae26", [tag: "v2.2.0", sparse: "optimized", depth: 1]},
   "hpax": {:hex, :hpax, "1.0.3", "ed67ef51ad4df91e75cc6a1494f851850c0bd98ebc0be6e81b026e765ee535aa", [:mix], [], "hexpm", "8eab6e1cfa8d5918c2ce4ba43588e894af35dbd8e91e6e55c817bca5847df34a"},

priv/repo/migrations/20251211151449_add_membership_fees_tables.exs

@@ -0,0 +1,142 @@
+defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
+  @moduledoc """
+  Updates resources based on their most recent snapshots.
+
+  This file was autogenerated with `mix ash_postgres.generate_migrations`
+  """
+
+  use Ecto.Migration
+
+  def up do
+    create table(:membership_fee_types, primary_key: false) do
+      add :id, :uuid, null: false, default: fragment("uuid_generate_v7()"), primary_key: true
+      add :name, :text, null: false
+      # Precision: 10 digits total, 2 decimal places (max 99,999,999.99)
+      add :amount, :numeric, null: false, precision: 10, scale: 2
+      add :interval, :text, null: false
+      add :description, :text
+    end
+
+    create unique_index(:membership_fee_types, [:name],
+             name: "membership_fee_types_unique_name_index"
+           )
+
+    # CHECK constraint for interval values (enforced at DB level)
+    create constraint(:membership_fee_types, :membership_fee_types_interval_check,
+             check: "interval IN ('monthly', 'quarterly', 'half_yearly', 'yearly')"
+           )
+
+    # CHECK constraint for non-negative amount
+    create constraint(:membership_fee_types, :membership_fee_types_amount_check,
+             check: "amount >= 0"
+           )
+
+    create table(:membership_fee_cycles, primary_key: false) do
+      add :id, :uuid, null: false, default: fragment("uuid_generate_v7()"), primary_key: true
+      add :cycle_start, :date, null: false
+      # Precision: 10 digits total, 2 decimal places (max 99,999,999.99)
+      add :amount, :numeric, null: false, precision: 10, scale: 2
+      add :status, :text, null: false, default: "unpaid"
+      add :notes, :text
+
+      # CASCADE: Delete cycles when member is deleted
+      add :member_id,
+          references(:members,
+            column: :id,
+            name: "membership_fee_cycles_member_id_fkey",
+            type: :uuid,
+            prefix: "public",
+            on_delete: :delete_all
+          ),
+          null: false
+
+      # RESTRICT: Cannot delete fee type if cycles reference it
+      add :membership_fee_type_id,
+          references(:membership_fee_types,
+            column: :id,
+            name: "membership_fee_cycles_membership_fee_type_id_fkey",
+            type: :uuid,
+            prefix: "public",
+            on_delete: :restrict
+          ),
+          null: false
+    end
+
+    # CHECK constraint for status values (enforced at DB level)
+    create constraint(:membership_fee_cycles, :membership_fee_cycles_status_check,
+             check: "status IN ('unpaid', 'paid', 'suspended')"
+           )
+
+    # CHECK constraint for non-negative amount
+    create constraint(:membership_fee_cycles, :membership_fee_cycles_amount_check,
+             check: "amount >= 0"
+           )
+
+    # Indexes as specified in architecture document
+    create index(:membership_fee_cycles, [:member_id])
+    create index(:membership_fee_cycles, [:membership_fee_type_id])
+    create index(:membership_fee_cycles, [:status])
+    create index(:membership_fee_cycles, [:cycle_start])
+
+    # Composite unique index: one cycle per member per cycle_start
+    create unique_index(:membership_fee_cycles, [:member_id, :cycle_start],
+             name: "membership_fee_cycles_unique_cycle_per_member_index"
+           )
+
+    # Extend members table with membership fee fields
+    alter table(:members) do
+      add :membership_fee_start_date, :date
+
+      # RESTRICT: Cannot delete fee type if members are assigned to it
+      add :membership_fee_type_id,
+          references(:membership_fee_types,
+            column: :id,
+            name: "members_membership_fee_type_id_fkey",
+            type: :uuid,
+            prefix: "public",
+            on_delete: :restrict
+          )
+    end
+
+    # Index for efficient lookup of members by fee type
+    create index(:members, [:membership_fee_type_id])
+  end
+
+  def down do
+    # First: Remove members extension (depends on membership_fee_types)
+    drop_if_exists index(:members, [:membership_fee_type_id])
+    drop constraint(:members, "members_membership_fee_type_id_fkey")
+
+    alter table(:members) do
+      remove :membership_fee_type_id
+      remove :membership_fee_start_date
+    end
+
+    # Second: Drop cycles table (depends on membership_fee_types)
+    drop_if_exists unique_index(:membership_fee_cycles, [:member_id, :cycle_start],
+                     name: "membership_fee_cycles_unique_cycle_per_member_index"
+                   )
+
+    drop_if_exists index(:membership_fee_cycles, [:cycle_start])
+    drop_if_exists index(:membership_fee_cycles, [:status])
+    drop_if_exists index(:membership_fee_cycles, [:membership_fee_type_id])
+    drop_if_exists index(:membership_fee_cycles, [:member_id])
+
+    drop constraint(:membership_fee_cycles, "membership_fee_cycles_member_id_fkey")
+    drop constraint(:membership_fee_cycles, "membership_fee_cycles_membership_fee_type_id_fkey")
+    drop_if_exists constraint(:membership_fee_cycles, :membership_fee_cycles_status_check)
+    drop_if_exists constraint(:membership_fee_cycles, :membership_fee_cycles_amount_check)
+
+    drop table(:membership_fee_cycles)
+
+    # Third: Drop fee types table
+    drop_if_exists unique_index(:membership_fee_types, [:name],
+                     name: "membership_fee_types_unique_name_index"
+                   )
+
+    drop_if_exists constraint(:membership_fee_types, :membership_fee_types_interval_check)
+    drop_if_exists constraint(:membership_fee_types, :membership_fee_types_amount_check)
+
+    drop table(:membership_fee_types)
+  end
+end

priv/resource_snapshots/repo/membership_fee_cycles/20251211151449.json

@@ -0,0 +1,160 @@
+{
+  "attributes": [
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"uuid_generate_v7()\")",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": true,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "cycle_start",
+      "type": "date"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "amount",
+      "type": "decimal"
+    },
+    {
+      "allow_nil?": false,
+      "default": "\"unpaid\"",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "status",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "notes",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": {
+        "deferrable": false,
+        "destination_attribute": "id",
+        "destination_attribute_default": null,
+        "destination_attribute_generated": null,
+        "index?": false,
+        "match_type": null,
+        "match_with": null,
+        "multitenancy": {
+          "attribute": null,
+          "global": null,
+          "strategy": null
+        },
+        "name": "membership_fee_cycles_member_id_fkey",
+        "on_delete": null,
+        "on_update": null,
+        "primary_key?": true,
+        "schema": "public",
+        "table": "members"
+      },
+      "scale": null,
+      "size": null,
+      "source": "member_id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": {
+        "deferrable": false,
+        "destination_attribute": "id",
+        "destination_attribute_default": null,
+        "destination_attribute_generated": null,
+        "index?": false,
+        "match_type": null,
+        "match_with": null,
+        "multitenancy": {
+          "attribute": null,
+          "global": null,
+          "strategy": null
+        },
+        "name": "membership_fee_cycles_membership_fee_type_id_fkey",
+        "on_delete": null,
+        "on_update": null,
+        "primary_key?": true,
+        "schema": "public",
+        "table": "membership_fee_types"
+      },
+      "scale": null,
+      "size": null,
+      "source": "membership_fee_type_id",
+      "type": "uuid"
+    }
+  ],
+  "base_filter": null,
+  "check_constraints": [],
+  "custom_indexes": [],
+  "custom_statements": [],
+  "has_create_action": true,
+  "hash": "43EA9EA365C09D423249AC4B6757A9AC07788C6C1E4BC7C50F8EF2CE01DE5684",
+  "identities": [
+    {
+      "all_tenants?": false,
+      "base_filter": null,
+      "index_name": "membership_fee_cycles_unique_cycle_per_member_index",
+      "keys": [
+        {
+          "type": "atom",
+          "value": "member_id"
+        },
+        {
+          "type": "atom",
+          "value": "cycle_start"
+        }
+      ],
+      "name": "unique_cycle_per_member",
+      "nils_distinct?": true,
+      "where": null
+    }
+  ],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.Mv.Repo",
+  "schema": null,
+  "table": "membership_fee_cycles"
+}

priv/resource_snapshots/repo/membership_fee_types/20251211151449.json

@@ -0,0 +1,94 @@
+{
+  "attributes": [
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"uuid_generate_v7()\")",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": true,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "name",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "amount",
+      "type": "decimal"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "interval",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "description",
+      "type": "text"
+    }
+  ],
+  "base_filter": null,
+  "check_constraints": [],
+  "custom_indexes": [],
+  "custom_statements": [],
+  "has_create_action": true,
+  "hash": "E93A7A1EE90E5CEAC98CEA57C99C6330465716248642D5E2949EF578DE514E99",
+  "identities": [
+    {
+      "all_tenants?": false,
+      "base_filter": null,
+      "index_name": "membership_fee_types_unique_name_index",
+      "keys": [
+        {
+          "type": "atom",
+          "value": "name"
+        }
+      ],
+      "name": "unique_name",
+      "nils_distinct?": true,
+      "where": null
+    }
+  ],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.Mv.Repo",
+  "schema": null,
+  "table": "membership_fee_types"
+}

test/membership_fees/foreign_key_test.exs

@@ -0,0 +1,220 @@
+defmodule Mv.MembershipFees.ForeignKeyTest do
+  @moduledoc """
+  Tests for foreign key behaviors (CASCADE and RESTRICT).
+  """
+  use Mv.DataCase, async: true
+
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+  alias Mv.Membership.Member
+
+  describe "CASCADE behavior" do
+    test "deleting member deletes associated membership_fee_cycles" do
+      # Create member
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "Cascade",
+          last_name: "Test",
+          email: "cascade.test.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      # Create fee type
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Cascade Test Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :monthly
+        })
+
+      # Create multiple cycles for this member
+      {:ok, cycle1} =
+        Ash.create(MembershipFeeCycle, %{
+          cycle_start: ~D[2025-01-01],
+          amount: Decimal.new("100.00"),
+          member_id: member.id,
+          membership_fee_type_id: fee_type.id
+        })
+
+      {:ok, cycle2} =
+        Ash.create(MembershipFeeCycle, %{
+          cycle_start: ~D[2025-02-01],
+          amount: Decimal.new("100.00"),
+          member_id: member.id,
+          membership_fee_type_id: fee_type.id
+        })
+
+      # Verify cycles exist
+      assert {:ok, _} = Ash.get(MembershipFeeCycle, cycle1.id)
+      assert {:ok, _} = Ash.get(MembershipFeeCycle, cycle2.id)
+
+      # Delete member
+      assert :ok = Ash.destroy(member)
+
+      # Verify cycles are also deleted (CASCADE)
+      # NotFound is wrapped in Ash.Error.Invalid
+      assert {:error, %Ash.Error.Invalid{}} = Ash.get(MembershipFeeCycle, cycle1.id)
+      assert {:error, %Ash.Error.Invalid{}} = Ash.get(MembershipFeeCycle, cycle2.id)
+    end
+  end
+
+  describe "RESTRICT behavior" do
+    test "cannot delete membership_fee_type if cycles reference it" do
+      # Create member
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "Restrict",
+          last_name: "Test",
+          email: "restrict.test.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      # Create fee type
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Restrict Test Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :monthly
+        })
+
+      # Create a cycle referencing this fee type
+      {:ok, _cycle} =
+        Ash.create(MembershipFeeCycle, %{
+          cycle_start: ~D[2025-01-01],
+          amount: Decimal.new("100.00"),
+          member_id: member.id,
+          membership_fee_type_id: fee_type.id
+        })
+
+      # Try to delete fee type - should fail due to RESTRICT
+      assert {:error, error} = Ash.destroy(fee_type)
+
+      # Check that it's a foreign key violation error
+      assert is_struct(error, Ash.Error.Invalid) or is_struct(error, Ash.Error.Unknown)
+    end
+
+    test "can delete membership_fee_type if no cycles reference it" do
+      # Create fee type without any cycles
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Deletable Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :monthly
+        })
+
+      # Should be able to delete
+      assert :ok = Ash.destroy(fee_type)
+
+      # Verify it's gone (NotFound is wrapped in Ash.Error.Invalid)
+      assert {:error, %Ash.Error.Invalid{}} = Ash.get(MembershipFeeType, fee_type.id)
+    end
+
+    test "cannot delete membership_fee_type if members reference it" do
+      # Create fee type
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Member Ref Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :monthly
+        })
+
+      # Create member with this fee type
+      {:ok, _member} =
+        Ash.create(Member, %{
+          first_name: "FeeType",
+          last_name: "Reference",
+          email: "feetype.ref.#{System.unique_integer([:positive])}@example.com",
+          membership_fee_type_id: fee_type.id
+        })
+
+      # Try to delete fee type - should fail due to RESTRICT
+      assert {:error, error} = Ash.destroy(fee_type)
+      assert is_struct(error, Ash.Error.Invalid) or is_struct(error, Ash.Error.Unknown)
+    end
+  end
+
+  describe "member extensions" do
+    test "member can be created with membership_fee_type_id" do
+      # Create fee type first
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Create Test Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :yearly
+        })
+
+      # Create member with fee type
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "With",
+          last_name: "FeeType",
+          email: "with.feetype.#{System.unique_integer([:positive])}@example.com",
+          membership_fee_type_id: fee_type.id
+        })
+
+      assert member.membership_fee_type_id == fee_type.id
+    end
+
+    test "member can be created with membership_fee_start_date" do
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "With",
+          last_name: "StartDate",
+          email: "with.startdate.#{System.unique_integer([:positive])}@example.com",
+          membership_fee_start_date: ~D[2025-01-01]
+        })
+
+      assert member.membership_fee_start_date == ~D[2025-01-01]
+    end
+
+    test "member can be created without membership fee fields" do
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "No",
+          last_name: "FeeFields",
+          email: "no.feefields.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      assert member.membership_fee_type_id == nil
+      assert member.membership_fee_start_date == nil
+    end
+
+    test "member can be updated with membership_fee_type_id" do
+      # Create fee type
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Update Test Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("100.00"),
+          interval: :yearly
+        })
+
+      # Create member without fee type
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "Update",
+          last_name: "Test",
+          email: "update.test.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      assert member.membership_fee_type_id == nil
+
+      # Update member with fee type
+      {:ok, updated_member} = Ash.update(member, %{membership_fee_type_id: fee_type.id})
+
+      assert updated_member.membership_fee_type_id == fee_type.id
+    end
+
+    test "member can be updated with membership_fee_start_date" do
+      {:ok, member} =
+        Ash.create(Member, %{
+          first_name: "Start",
+          last_name: "Date",
+          email: "start.date.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      assert member.membership_fee_start_date == nil
+
+      {:ok, updated_member} = Ash.update(member, %{membership_fee_start_date: ~D[2025-06-01]})
+
+      assert updated_member.membership_fee_start_date == ~D[2025-06-01]
+    end
+  end
+end

test/membership_fees/membership_fee_cycle_test.exs

@@ -0,0 +1,282 @@
+defmodule Mv.MembershipFees.MembershipFeeCycleTest do
+  @moduledoc """
+  Tests for MembershipFeeCycle resource.
+  """
+  use Mv.DataCase, async: true
+
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+  alias Mv.Membership.Member
+
+  setup do
+    # Create a member for testing
+    {:ok, member} =
+      Ash.create(Member, %{
+        first_name: "Test",
+        last_name: "Member",
+        email: "test.member.#{System.unique_integer([:positive])}@example.com"
+      })
+
+    # Create a fee type for testing
+    {:ok, fee_type} =
+      Ash.create(MembershipFeeType, %{
+        name: "Test Fee Type #{System.unique_integer([:positive])}",
+        amount: Decimal.new("100.00"),
+        interval: :monthly
+      })
+
+    %{member: member, fee_type: fee_type}
+  end
+
+  describe "create MembershipFeeCycle" do
+    test "can create cycle with valid attributes", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, %MembershipFeeCycle{} = cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.cycle_start == ~D[2025-01-01]
+      assert Decimal.equal?(cycle.amount, Decimal.new("100.00"))
+      assert cycle.member_id == member.id
+      assert cycle.membership_fee_type_id == fee_type.id
+    end
+
+    test "can create cycle with notes", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        notes: "First payment cycle"
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.notes == "First payment cycle"
+    end
+
+    test "requires cycle_start", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :cycle_start)
+    end
+
+    test "requires amount", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "requires member_id", %{fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :member_id) or error_on_field?(error, :member)
+    end
+
+    test "requires membership_fee_type_id", %{member: member} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+
+      assert error_on_field?(error, :membership_fee_type_id) or
+               error_on_field?(error, :membership_fee_type)
+    end
+
+    test "status defaults to :unpaid", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.status == :unpaid
+    end
+
+    test "validates status enum values - unpaid", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        status: :unpaid
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.status == :unpaid
+    end
+
+    test "validates status enum values - paid", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-02-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        status: :paid
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.status == :paid
+    end
+
+    test "validates status enum values - suspended", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-03-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        status: :suspended
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert cycle.status == :suspended
+    end
+
+    test "rejects invalid status values", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        status: :cancelled
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :status)
+    end
+
+    test "rejects negative amount", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-04-01],
+        amount: Decimal.new("-50.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "accepts zero amount", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-05-01],
+        amount: Decimal.new("0.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert Decimal.equal?(cycle.amount, Decimal.new("0.00"))
+    end
+  end
+
+  describe "uniqueness constraint" do
+    test "cannot create duplicate cycle for same member and cycle_start", %{
+      member: member,
+      fee_type: fee_type
+    } do
+      attrs = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, _cycle1} = Ash.create(MembershipFeeCycle, attrs)
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+
+      # Should fail due to uniqueness constraint
+      assert is_struct(error, Ash.Error.Invalid)
+    end
+
+    test "can create cycles for same member with different cycle_start", %{
+      member: member,
+      fee_type: fee_type
+    } do
+      attrs1 = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      attrs2 = %{
+        cycle_start: ~D[2025-02-01],
+        amount: Decimal.new("100.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, _cycle1} = Ash.create(MembershipFeeCycle, attrs1)
+      assert {:ok, _cycle2} = Ash.create(MembershipFeeCycle, attrs2)
+    end
+
+    test "can create cycles for different members with same cycle_start", %{fee_type: fee_type} do
+      {:ok, member1} =
+        Ash.create(Member, %{
+          first_name: "Member",
+          last_name: "One",
+          email: "member.one.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      {:ok, member2} =
+        Ash.create(Member, %{
+          first_name: "Member",
+          last_name: "Two",
+          email: "member.two.#{System.unique_integer([:positive])}@example.com"
+        })
+
+      attrs1 = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member1.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      attrs2 = %{
+        cycle_start: ~D[2025-01-01],
+        amount: Decimal.new("100.00"),
+        member_id: member2.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, _cycle1} = Ash.create(MembershipFeeCycle, attrs1)
+      assert {:ok, _cycle2} = Ash.create(MembershipFeeCycle, attrs2)
+    end
+  end
+
+  # Helper to check if an error occurred on a specific field
+  defp error_on_field?(%Ash.Error.Invalid{} = error, field) do
+    Enum.any?(error.errors, fn e ->
+      case e do
+        %{field: ^field} -> true
+        %{fields: fields} when is_list(fields) -> field in fields
+        _ -> false
+      end
+    end)
+  end
+
+  defp error_on_field?(_, _), do: false
+end

test/membership_fees/membership_fee_type_test.exs

@@ -0,0 +1,172 @@
+defmodule Mv.MembershipFees.MembershipFeeTypeTest do
+  @moduledoc """
+  Tests for MembershipFeeType resource.
+  """
+  use Mv.DataCase, async: true
+
+  alias Mv.MembershipFees.MembershipFeeType
+
+  describe "create MembershipFeeType" do
+    test "can create membership fee type with valid attributes" do
+      attrs = %{
+        name: "Standard Membership",
+        amount: Decimal.new("120.00"),
+        interval: :yearly,
+        description: "Standard yearly membership fee"
+      }
+
+      assert {:ok, %MembershipFeeType{} = fee_type} =
+               Ash.create(MembershipFeeType, attrs)
+
+      assert fee_type.name == "Standard Membership"
+      assert Decimal.equal?(fee_type.amount, Decimal.new("120.00"))
+      assert fee_type.interval == :yearly
+      assert fee_type.description == "Standard yearly membership fee"
+    end
+
+    test "can create membership fee type without description" do
+      attrs = %{
+        name: "Basic",
+        amount: Decimal.new("60.00"),
+        interval: :monthly
+      }
+
+      assert {:ok, %MembershipFeeType{}} = Ash.create(MembershipFeeType, attrs)
+    end
+
+    test "requires name" do
+      attrs = %{
+        amount: Decimal.new("100.00"),
+        interval: :yearly
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :name)
+    end
+
+    test "requires amount" do
+      attrs = %{
+        name: "Test Fee",
+        interval: :yearly
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "requires interval" do
+      attrs = %{
+        name: "Test Fee",
+        amount: Decimal.new("100.00")
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :interval)
+    end
+
+    test "validates interval enum values - monthly" do
+      attrs = %{name: "Monthly", amount: Decimal.new("10.00"), interval: :monthly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert fee_type.interval == :monthly
+    end
+
+    test "validates interval enum values - quarterly" do
+      attrs = %{name: "Quarterly", amount: Decimal.new("30.00"), interval: :quarterly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert fee_type.interval == :quarterly
+    end
+
+    test "validates interval enum values - half_yearly" do
+      attrs = %{name: "Half Yearly", amount: Decimal.new("60.00"), interval: :half_yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert fee_type.interval == :half_yearly
+    end
+
+    test "validates interval enum values - yearly" do
+      attrs = %{name: "Yearly", amount: Decimal.new("120.00"), interval: :yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert fee_type.interval == :yearly
+    end
+
+    test "rejects invalid interval values" do
+      attrs = %{name: "Invalid", amount: Decimal.new("100.00"), interval: :weekly}
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :interval)
+    end
+
+    test "name must be unique" do
+      attrs = %{name: "Unique Name", amount: Decimal.new("100.00"), interval: :yearly}
+
+      assert {:ok, _} = Ash.create(MembershipFeeType, attrs)
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+
+      # Check for uniqueness error
+      assert error_on_field?(error, :name)
+    end
+
+    test "rejects negative amount" do
+      attrs = %{name: "Negative Test", amount: Decimal.new("-10.00"), interval: :yearly}
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "accepts zero amount" do
+      attrs = %{name: "Zero Amount", amount: Decimal.new("0.00"), interval: :yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert Decimal.equal?(fee_type.amount, Decimal.new("0.00"))
+    end
+
+    test "amount respects scale of 2 decimal places" do
+      attrs = %{name: "Scale Test", amount: Decimal.new("100.50"), interval: :yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert Decimal.equal?(fee_type.amount, Decimal.new("100.50"))
+    end
+  end
+
+  describe "update MembershipFeeType" do
+    setup do
+      {:ok, fee_type} =
+        Ash.create(MembershipFeeType, %{
+          name: "Original Name",
+          amount: Decimal.new("100.00"),
+          interval: :yearly,
+          description: "Original description"
+        })
+
+      %{fee_type: fee_type}
+    end
+
+    test "can update name", %{fee_type: fee_type} do
+      assert {:ok, updated} = Ash.update(fee_type, %{name: "Updated Name"})
+      assert updated.name == "Updated Name"
+    end
+
+    test "can update amount", %{fee_type: fee_type} do
+      assert {:ok, updated} = Ash.update(fee_type, %{amount: Decimal.new("150.00")})
+      assert Decimal.equal?(updated.amount, Decimal.new("150.00"))
+    end
+
+    test "can update description", %{fee_type: fee_type} do
+      assert {:ok, updated} = Ash.update(fee_type, %{description: "Updated description"})
+      assert updated.description == "Updated description"
+    end
+
+    test "can clear description", %{fee_type: fee_type} do
+      assert {:ok, updated} = Ash.update(fee_type, %{description: nil})
+      assert updated.description == nil
+    end
+  end
+
+  # Helper to check if an error occurred on a specific field
+  defp error_on_field?(%Ash.Error.Invalid{} = error, field) do
+    Enum.any?(error.errors, fn e ->
+      case e do
+        %{field: ^field} -> true
+        %{fields: fields} when is_list(fields) -> field in fields
+        _ -> false
+      end
+    end)
+  end
+
+  defp error_on_field?(_, _), do: false
+end

test/mv/membership_fees/calendar_cycles_test.exs

@@ -0,0 +1,181 @@
+defmodule Mv.MembershipFees.CalendarCyclesTest do
+  @moduledoc """
+  Tests for CalendarCycles module.
+  """
+  use ExUnit.Case, async: true
+
+  alias Mv.MembershipFees.CalendarCycles
+
+  doctest Mv.MembershipFees.CalendarCycles
+
+  describe "calculate_cycle_start/3" do
+    test "uses reference_date when provided" do
+      date = ~D[2024-03-15]
+      reference = ~D[2024-05-20]
+
+      assert CalendarCycles.calculate_cycle_start(date, :monthly, reference) == ~D[2024-05-01]
+      assert CalendarCycles.calculate_cycle_start(date, :quarterly, reference) == ~D[2024-04-01]
+    end
+  end
+
+  describe "current_cycle?/3" do
+    # Basic examples are covered by doctests
+
+    test "works for all interval types" do
+      today = ~D[2024-03-15]
+
+      for interval <- [:monthly, :quarterly, :half_yearly, :yearly] do
+        cycle_start = CalendarCycles.calculate_cycle_start(today, interval)
+        result = CalendarCycles.current_cycle?(cycle_start, interval, today)
+
+        assert result == true, "Expected current cycle for #{interval} with start #{cycle_start}"
+      end
+    end
+  end
+
+  describe "current_cycle?/2 wrapper" do
+    test "calls current_cycle?/3 with Date.utc_today()" do
+      today = Date.utc_today()
+      cycle_start = CalendarCycles.calculate_cycle_start(today, :monthly)
+
+      # This test verifies the wrapper works, but uses actual today
+      # The real testing happens in current_cycle?/3 tests above
+      result = CalendarCycles.current_cycle?(cycle_start, :monthly)
+
+      assert result == true
+    end
+  end
+
+  describe "last_completed_cycle?/3" do
+    # Basic examples are covered by doctests
+
+    test "returns false when next cycle has also ended" do
+      # Two cycles ago: cycle ended, but next cycle also ended
+      today = ~D[2024-05-15]
+      cycle_start = ~D[2024-03-01]
+      # Cycle ended 2024-03-31, next cycle ended 2024-04-30, today is 2024-05-15
+
+      assert CalendarCycles.last_completed_cycle?(cycle_start, :monthly, today) == false
+    end
+
+    test "works correctly for quarterly intervals" do
+      # Q1 2024 ended on 2024-03-31
+      # Q2 2024 ends on 2024-06-30
+      # Today is 2024-04-15 (after Q1 ended, before Q2 ended)
+      today = ~D[2024-04-15]
+      past_quarter_start = ~D[2024-01-01]
+
+      assert CalendarCycles.last_completed_cycle?(past_quarter_start, :quarterly, today) == true
+    end
+
+    test "returns false when cycle ended on the given date" do
+      # Cycle ends on today, so it's still current, not completed
+      today = ~D[2024-03-31]
+      cycle_start = ~D[2024-03-01]
+
+      assert CalendarCycles.last_completed_cycle?(cycle_start, :monthly, today) == false
+    end
+  end
+
+  describe "last_completed_cycle?/2 wrapper" do
+    test "calls last_completed_cycle?/3 with Date.utc_today()" do
+      today = Date.utc_today()
+      cycle_start = CalendarCycles.calculate_cycle_start(today, :monthly)
+
+      # This test verifies the wrapper works, but uses actual today
+      # The real testing happens in last_completed_cycle?/3 tests above
+      result = CalendarCycles.last_completed_cycle?(cycle_start, :monthly)
+
+      # Result depends on actual today, so we just verify it's a boolean
+      assert is_boolean(result)
+    end
+  end
+
+  describe "edge cases" do
+    test "leap year: February has 29 days" do
+      # 2024 is a leap year
+      assert CalendarCycles.calculate_cycle_end(~D[2024-02-01], :monthly) == ~D[2024-02-29]
+
+      # 2023 is not a leap year
+      assert CalendarCycles.calculate_cycle_end(~D[2023-02-01], :monthly) == ~D[2023-02-28]
+    end
+
+    test "year boundary: December 31 to January 1" do
+      # Yearly cycle
+      assert CalendarCycles.next_cycle_start(~D[2024-01-01], :yearly) == ~D[2025-01-01]
+
+      # Monthly cycle across year boundary
+      assert CalendarCycles.next_cycle_start(~D[2024-12-01], :monthly) == ~D[2025-01-01]
+
+      # Half-yearly cycle across year boundary
+      assert CalendarCycles.next_cycle_start(~D[2024-07-01], :half_yearly) == ~D[2025-01-01]
+
+      # Quarterly cycle across year boundary
+      assert CalendarCycles.next_cycle_start(~D[2024-10-01], :quarterly) == ~D[2025-01-01]
+    end
+
+    test "month boundary: different month lengths" do
+      # 31-day months
+      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :monthly) == ~D[2024-01-31]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-03-01], :monthly) == ~D[2024-03-31]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-05-01], :monthly) == ~D[2024-05-31]
+
+      # 30-day months
+      assert CalendarCycles.calculate_cycle_end(~D[2024-04-01], :monthly) == ~D[2024-04-30]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-06-01], :monthly) == ~D[2024-06-30]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-09-01], :monthly) == ~D[2024-09-30]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-11-01], :monthly) == ~D[2024-11-30]
+    end
+
+    test "date in middle of cycle: all functions work correctly" do
+      middle_date = ~D[2024-03-15]
+
+      # calculate_cycle_start
+      assert CalendarCycles.calculate_cycle_start(middle_date, :monthly) == ~D[2024-03-01]
+      assert CalendarCycles.calculate_cycle_start(middle_date, :quarterly) == ~D[2024-01-01]
+      assert CalendarCycles.calculate_cycle_start(middle_date, :half_yearly) == ~D[2024-01-01]
+      assert CalendarCycles.calculate_cycle_start(middle_date, :yearly) == ~D[2024-01-01]
+
+      # calculate_cycle_end
+      monthly_start = CalendarCycles.calculate_cycle_start(middle_date, :monthly)
+      assert CalendarCycles.calculate_cycle_end(monthly_start, :monthly) == ~D[2024-03-31]
+
+      # next_cycle_start
+      assert CalendarCycles.next_cycle_start(monthly_start, :monthly) == ~D[2024-04-01]
+    end
+
+    test "quarterly: all quarter boundaries correct" do
+      # Q1 boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-01-15], :quarterly) == ~D[2024-01-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :quarterly) == ~D[2024-03-31]
+
+      # Q2 boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-05-15], :quarterly) == ~D[2024-04-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-04-01], :quarterly) == ~D[2024-06-30]
+
+      # Q3 boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-08-15], :quarterly) == ~D[2024-07-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-07-01], :quarterly) == ~D[2024-09-30]
+
+      # Q4 boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-11-15], :quarterly) == ~D[2024-10-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-10-01], :quarterly) == ~D[2024-12-31]
+    end
+
+    test "half_yearly: both half boundaries correct" do
+      # First half boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-03-15], :half_yearly) == ~D[2024-01-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :half_yearly) == ~D[2024-06-30]
+
+      # Second half boundaries
+      assert CalendarCycles.calculate_cycle_start(~D[2024-09-15], :half_yearly) == ~D[2024-07-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-07-01], :half_yearly) == ~D[2024-12-31]
+    end
+
+    test "yearly: full year boundaries" do
+      assert CalendarCycles.calculate_cycle_start(~D[2024-06-15], :yearly) == ~D[2024-01-01]
+      assert CalendarCycles.calculate_cycle_end(~D[2024-01-01], :yearly) == ~D[2024-12-31]
+      assert CalendarCycles.next_cycle_start(~D[2024-01-01], :yearly) == ~D[2025-01-01]
+    end
+  end
+end