refactor: improve cycle generation code quality and documentation

- Remove Process.sleep calls from integration tests (tests run synchronously in SQL sandbox)
- Improve error handling: membership_fee_type_not_found now returns changeset error instead of just logging
- Clarify partial_failure documentation: successful_cycles are not persisted on rollback
- Update documentation: joined_at → join_date, left_at → exit_date
- Document PostgreSQL advisory locks per member (not whole table lock)
- Document gap handling: explicitly deleted cycles are not recreated

config/test.exs

@@ -47,4 +47,5 @@ config :mv, :session_identifier, :unsafe
 config :mv, :require_token_presence_for_authentication, false
 
 # Enable SQL Sandbox for async LiveView tests
+# This flag controls sync vs async behavior in CycleGenerator after_action hooks
 config :mv, :sql_sandbox, true

docs/membership-fee-architecture.md

@@ -153,8 +153,8 @@ lib/
 
 **Existing Fields Used:**
 
-- `joined_at` - For calculating membership fee start
+- `join_date` - For calculating membership fee start
-- `left_at` - For limiting cycle generation
+- `exit_date` - For limiting cycle generation
 - These fields must remain member fields and should not be replaced by custom fields in the future
 
 ### Settings Integration
@@ -186,8 +186,9 @@ lib/
 
 - Calculate which cycles should exist for a member
 - Generate missing cycles
-- Respect membership_fee_start_date and left_at boundaries
+- Respect membership_fee_start_date and exit_date boundaries
 - Skip existing cycles (idempotent)
+- Use PostgreSQL advisory locks per member to prevent race conditions
 
 **Triggers:**
 
@@ -199,17 +200,20 @@ lib/
 **Algorithm Steps:**
 
 1. Retrieve member with membership fee type and dates
-2. Determine first cycle start (based on membership_fee_start_date)
+2. Determine generation start point:
-3. Calculate all cycle starts from first to today (or left_at)
+   - If NO cycles exist: Start from `membership_fee_start_date` (or calculated from `join_date`)
-4. Query existing cycles for member
+   - If cycles exist: Start from the cycle AFTER the last existing one
-5. Generate missing cycles with current membership fee type's amount
+3. Generate all cycle starts from the determined start point to today (or `exit_date`)
-6. Insert new cycles (batch operation)
+4. Create new cycles with current membership fee type's amount
+5. Use PostgreSQL advisory locks per member to prevent race conditions
 
 **Edge Case Handling:**
 
-- If membership_fee_start_date is NULL: Calculate from joined_at + global setting
+- If membership_fee_start_date is NULL: Calculate from join_date + global setting
-- If left_at is set: Stop generation at left_at
+- If exit_date is set: Stop generation at exit_date
 - If membership fee type changes: Handled separately by regeneration logic
+- **Gap Handling:** If cycles were explicitly deleted (gaps exist), they are NOT recreated.
+  The generator always continues from the cycle AFTER the last existing cycle, regardless of gaps.
 
 ### Calendar Cycle Calculations
 
@@ -381,7 +385,7 @@ lib/
 **AC-M-1:** Member has membership_fee_type_id field (NOT NULL with default)  
 **AC-M-2:** Member has membership_fee_start_date field (nullable)  
 **AC-M-3:** New members get default membership fee type from global setting  
-**AC-M-4:** membership_fee_start_date auto-set based on joined_at and global setting  
+**AC-M-4:** membership_fee_start_date auto-set based on join_date and global setting  
 **AC-M-5:** Admin can manually override membership_fee_start_date  
 **AC-M-6:** Cannot change to membership fee type with different interval (MVP)
 
@@ -391,7 +395,7 @@ lib/
 **AC-CG-2:** Cycles generated when member created (via change hook)  
 **AC-CG-3:** Scheduled job generates missing cycles daily  
 **AC-CG-4:** Generation respects membership_fee_start_date  
-**AC-CG-5:** Generation stops at left_at if member exited  
+**AC-CG-5:** Generation stops at exit_date if member exited  
 **AC-CG-6:** Generation is idempotent (skips existing cycles)  
 **AC-CG-7:** Cycles align to calendar boundaries (1st of month/quarter/half/year)  
 **AC-CG-8:** Amount comes from membership_fee_type at generation time
@@ -472,8 +476,9 @@ lib/
 - Correct cycle_start calculation for all interval types
 - Correct cycle count from start to end date
 - Respects membership_fee_start_date boundary
-- Respects left_at boundary
+- Respects exit_date boundary
 - Skips existing cycles (idempotent)
+- Does not fill gaps when cycles were deleted
 - Handles edge dates (year boundaries, leap years)
 
 **Calendar Cycles Tests:**

docs/membership-fee-overview.md

@@ -120,7 +120,7 @@ This document provides a comprehensive overview of the Membership Fees system. I
 ```
 - membership_fee_type_id (FK → membership_fee_types.id, NOT NULL, default from settings)
 - membership_fee_start_date (Date, nullable) - When to start generating membership fees
-- left_at (Date, nullable) - Exit date (existing)
+- exit_date (Date, nullable) - Exit date (existing)
 ```
 
 **Logic for membership_fee_start_date:**
@@ -167,16 +167,17 @@ value: UUID (Required) - Default membership fee type for new members
 
 **Algorithm:**
 
-Lock the whole cycle table for the duration of the algorithm
+Use PostgreSQL advisory locks per member to prevent race conditions
 
 1. Get `member.membership_fee_start_date` and member's membership fee type
-2. Generate cycles until today (or `left_at` if present):
+2. Determine generation start point:
-    - If no cycle exists:
+   - If NO cycles exist: Start from `membership_fee_start_date`
-      - Generate all cycles from `membership_fee_start_date`
+   - If cycles exist: Start from the cycle AFTER the last existing one
-    - else:
+3. Generate cycles until today (or `exit_date` if present):
-      - Generate all cycles from last existing cycle
+   - Use the interval to generate the cycles
-    - use the interval to generate the cycles
+   - **Note:** If cycles were explicitly deleted (gaps exist), they are NOT recreated.
-3. Set `amount` to current membership fee type's amount
+     The generator always continues from the cycle AFTER the last existing cycle.
+4. Set `amount` to current membership fee type's amount
 
 **Example (Yearly):**
 
@@ -246,7 +247,7 @@ suspended → unpaid
 
 **Logic:**
 
-- Cycles only generated until `member.left_at`
+- Cycles only generated until `member.exit_date`
 - Existing cycles remain visible
 - Unpaid exit cycle can be marked as "suspended"
 

lib/membership/member.ex

@@ -80,7 +80,7 @@ defmodule Mv.Membership.Member do
       argument :user, :map, allow_nil?: true
 
       # Accept member fields plus membership_fee_type_id (belongs_to FK)
-      accept @member_fields ++ [:membership_fee_type_id]
+      accept @member_fields ++ [:membership_fee_type_id, :membership_fee_start_date]
 
       change manage_relationship(:custom_field_values, type: :create)
 
@@ -101,6 +101,42 @@ defmodule Mv.Membership.Member do
       change Mv.EmailSync.Changes.SyncUserEmailToMember do
         where [changing(:user)]
       end
+
+      # Auto-calculate membership_fee_start_date if not manually set
+      # Requires both join_date and membership_fee_type_id to be present
+      change Mv.MembershipFees.Changes.SetMembershipFeeStartDate
+
+      # Trigger cycle generation after member creation
+      # Only runs if membership_fee_type_id is set
+      # Note: Cycle generation runs asynchronously to not block the action,
+      # but in test environment it runs synchronously for DB sandbox compatibility
+      change after_action(fn _changeset, member, _context ->
+               if member.membership_fee_type_id && member.join_date do
+                 generate_fn = fn ->
+                   case Mv.MembershipFees.CycleGenerator.generate_cycles_for_member(member.id) do
+                     {:ok, _cycles} ->
+                       :ok
+
+                     {:error, reason} ->
+                       require Logger
+
+                       Logger.warning(
+                         "Failed to generate cycles for member #{member.id}: #{inspect(reason)}"
+                       )
+                   end
+                 end
+
+                 if Application.get_env(:mv, :sql_sandbox, false) do
+                   # Run synchronously in test environment for DB sandbox compatibility
+                   generate_fn.()
+                 else
+                   # Run asynchronously in other environments
+                   Task.start(generate_fn)
+                 end
+               end
+
+               {:ok, member}
+             end)
     end
 
     update :update_member do
@@ -114,7 +150,7 @@ defmodule Mv.Membership.Member do
       argument :user, :map, allow_nil?: true
 
       # Accept member fields plus membership_fee_type_id (belongs_to FK)
-      accept @member_fields ++ [:membership_fee_type_id]
+      accept @member_fields ++ [:membership_fee_type_id, :membership_fee_start_date]
 
       change manage_relationship(:custom_field_values, on_match: :update, on_no_match: :create)
 
@@ -141,6 +177,46 @@ defmodule Mv.Membership.Member do
       change Mv.EmailSync.Changes.SyncUserEmailToMember do
         where [changing(:user)]
       end
+
+      # Auto-calculate membership_fee_start_date when membership_fee_type_id is set
+      # and membership_fee_start_date is not already set
+      change Mv.MembershipFees.Changes.SetMembershipFeeStartDate do
+        where [changing(:membership_fee_type_id)]
+      end
+
+      # Trigger cycle generation when membership_fee_type_id changes
+      # Note: Cycle generation runs asynchronously to not block the action,
+      # but in test environment it runs synchronously for DB sandbox compatibility
+      change after_action(fn changeset, member, _context ->
+               fee_type_changed =
+                 Ash.Changeset.changing_attribute?(changeset, :membership_fee_type_id)
+
+               if fee_type_changed && member.membership_fee_type_id && member.join_date do
+                 generate_fn = fn ->
+                   case Mv.MembershipFees.CycleGenerator.generate_cycles_for_member(member.id) do
+                     {:ok, _cycles} ->
+                       :ok
+
+                     {:error, reason} ->
+                       require Logger
+
+                       Logger.warning(
+                         "Failed to generate cycles for member #{member.id}: #{inspect(reason)}"
+                       )
+                   end
+                 end
+
+                 if Application.get_env(:mv, :sql_sandbox, false) do
+                   # Run synchronously in test environment for DB sandbox compatibility
+                   generate_fn.()
+                 else
+                   # Run asynchronously in other environments
+                   Task.start(generate_fn)
+                 end
+               end
+
+               {:ok, member}
+             end)
     end
 
     # Action to handle fuzzy search on specific fields

lib/membership/setting.ex

@@ -4,13 +4,15 @@ defmodule Mv.Membership.Setting do
 
   ## Overview
   Settings is a singleton resource that stores global configuration for the association,
-  such as the club name and branding information. There should only ever be one settings
+  such as the club name, branding information, and membership fee settings. There should
-  record in the database.
+  only ever be one settings record in the database.
 
   ## Attributes
   - `club_name` - The name of the association/club (required, cannot be empty)
   - `member_field_visibility` - JSONB map storing visibility configuration for member fields
     (e.g., `%{"street" => false, "house_number" => false}`). Fields not in the map default to `true`.
+  - `include_joining_cycle` - Whether to include the joining cycle in membership fee generation (default: true)
+  - `default_membership_fee_type_id` - Default membership fee type for new members (optional)
 
   ## Singleton Pattern
   This resource uses a singleton pattern - there should only be one settings record.
@@ -22,6 +24,12 @@ defmodule Mv.Membership.Setting do
   If set, the environment variable value is used as a fallback when no database
   value exists. Database values always take precedence over environment variables.
 
+  ## Membership Fee Settings
+  - `include_joining_cycle`: When true, members pay from their joining cycle. When false,
+    they pay from the next full cycle after joining.
+  - `default_membership_fee_type_id`: The membership fee type automatically assigned to
+    new members. Can be nil if no default is set.
+
   ## Examples
 
       # Get current settings
@@ -33,6 +41,9 @@ defmodule Mv.Membership.Setting do
 
       # Update member field visibility
       {:ok, updated} = Mv.Membership.update_member_field_visibility(settings, %{"street" => false, "house_number" => false})
+
+      # Update membership fee settings
+      {:ok, updated} = Mv.Membership.update_settings(settings, %{include_joining_cycle: false})
   """
   use Ash.Resource,
     domain: Mv.Membership,
@@ -54,13 +65,24 @@ defmodule Mv.Membership.Setting do
     # Used only as fallback in get_settings/0 if settings don't exist
     # Settings should normally be created via seed script
     create :create do
-      accept [:club_name, :member_field_visibility]
+      accept [
+        :club_name,
+        :member_field_visibility,
+        :include_joining_cycle,
+        :default_membership_fee_type_id
+      ]
     end
 
     update :update do
       primary? true
       require_atomic? false
-      accept [:club_name, :member_field_visibility]
+
+      accept [
+        :club_name,
+        :member_field_visibility,
+        :include_joining_cycle,
+        :default_membership_fee_type_id
+      ]
     end
 
     update :update_member_field_visibility do
@@ -68,6 +90,12 @@ defmodule Mv.Membership.Setting do
       require_atomic? false
       accept [:member_field_visibility]
     end
+
+    update :update_membership_fee_settings do
+      description "Updates the membership fee configuration"
+      require_atomic? false
+      accept [:include_joining_cycle, :default_membership_fee_type_id]
+    end
   end
 
   validations do
@@ -133,6 +161,26 @@ defmodule Mv.Membership.Setting do
       description:
         "Configuration for member field visibility in overview (JSONB map). Keys are member field names (atoms), values are booleans."
 
+    # Membership fee settings
+    attribute :include_joining_cycle, :boolean do
+      allow_nil? false
+      default true
+      public? true
+      description "Whether to include the joining cycle in membership fee generation"
+    end
+
+    attribute :default_membership_fee_type_id, :uuid do
+      allow_nil? true
+      public? true
+      description "Default membership fee type ID for new members"
+    end
+
     timestamps()
   end
+
+  relationships do
+    # Optional relationship to the default membership fee type
+    # Note: We use manual FK (default_membership_fee_type_id attribute) instead of belongs_to
+    # to avoid circular dependency between Membership and MembershipFees domains
+  end
 end

lib/membership_fees/changes/set_membership_fee_start_date.ex

@@ -0,0 +1,174 @@
+defmodule Mv.MembershipFees.Changes.SetMembershipFeeStartDate do
+  @moduledoc """
+  Ash change module that automatically calculates and sets the membership_fee_start_date.
+
+  ## Logic
+
+  1. Only executes if `membership_fee_start_date` is not manually set
+  2. Requires both `join_date` and `membership_fee_type_id` to be present
+  3. Reads `include_joining_cycle` setting from global Settings
+  4. Reads `interval` from the assigned `membership_fee_type`
+  5. Calculates the start date:
+     - If `include_joining_cycle = true`: First day of the joining cycle
+     - If `include_joining_cycle = false`: First day of the next cycle after joining
+
+  ## Usage
+
+  In a Member action:
+
+      create :create_member do
+        # ...
+        change Mv.MembershipFees.Changes.SetMembershipFeeStartDate
+      end
+
+  The change module handles all prerequisite checks internally (join_date, membership_fee_type_id).
+  If any required data is missing, the changeset is returned unchanged with a warning logged.
+  """
+  use Ash.Resource.Change
+
+  require Logger
+
+  alias Mv.MembershipFees.CalendarCycles
+
+  @impl true
+  def change(changeset, _opts, _context) do
+    # Only calculate if membership_fee_start_date is not already set
+    if has_start_date?(changeset) do
+      changeset
+    else
+      calculate_and_set_start_date(changeset)
+    end
+  end
+
+  # Check if membership_fee_start_date is already set (either in changeset or data)
+  defp has_start_date?(changeset) do
+    # Check if it's being set in this changeset
+    case Ash.Changeset.fetch_change(changeset, :membership_fee_start_date) do
+      {:ok, date} when not is_nil(date) ->
+        true
+
+      _ ->
+        # Check if it already exists in the data (for updates)
+        case changeset.data do
+          %{membership_fee_start_date: date} when not is_nil(date) -> true
+          _ -> false
+        end
+    end
+  end
+
+  defp calculate_and_set_start_date(changeset) do
+    with {:ok, join_date} <- get_join_date(changeset),
+         {:ok, membership_fee_type_id} <- get_membership_fee_type_id(changeset),
+         {:ok, interval} <- get_interval(membership_fee_type_id),
+         {:ok, include_joining_cycle} <- get_include_joining_cycle() do
+      start_date = calculate_start_date(join_date, interval, include_joining_cycle)
+      Ash.Changeset.force_change_attribute(changeset, :membership_fee_start_date, start_date)
+    else
+      {:error, :join_date_not_set} ->
+        # Missing join_date is expected for partial creates
+        changeset
+
+      {:error, :membership_fee_type_not_set} ->
+        # Missing membership_fee_type_id is expected for partial creates
+        changeset
+
+      {:error, :membership_fee_type_not_found} ->
+        # This is a data integrity error - membership_fee_type_id references non-existent type
+        # Return changeset error to fail the action
+        Ash.Changeset.add_error(
+          changeset,
+          field: :membership_fee_type_id,
+          message: "not found"
+        )
+
+      {:error, reason} ->
+        # Log warning for other unexpected errors
+        Logger.warning("Could not auto-set membership_fee_start_date: #{inspect(reason)}")
+        changeset
+    end
+  end
+
+  defp get_join_date(changeset) do
+    # First check the changeset for changes
+    case Ash.Changeset.fetch_change(changeset, :join_date) do
+      {:ok, date} when not is_nil(date) ->
+        {:ok, date}
+
+      _ ->
+        # Then check existing data
+        case changeset.data do
+          %{join_date: date} when not is_nil(date) -> {:ok, date}
+          _ -> {:error, :join_date_not_set}
+        end
+    end
+  end
+
+  defp get_membership_fee_type_id(changeset) do
+    # First check the changeset for changes
+    case Ash.Changeset.fetch_change(changeset, :membership_fee_type_id) do
+      {:ok, id} when not is_nil(id) ->
+        {:ok, id}
+
+      _ ->
+        # Then check existing data
+        case changeset.data do
+          %{membership_fee_type_id: id} when not is_nil(id) -> {:ok, id}
+          _ -> {:error, :membership_fee_type_not_set}
+        end
+    end
+  end
+
+  defp get_interval(membership_fee_type_id) do
+    case Ash.get(Mv.MembershipFees.MembershipFeeType, membership_fee_type_id) do
+      {:ok, %{interval: interval}} -> {:ok, interval}
+      {:error, _} -> {:error, :membership_fee_type_not_found}
+    end
+  end
+
+  defp get_include_joining_cycle do
+    case Mv.Membership.get_settings() do
+      {:ok, %{include_joining_cycle: include}} -> {:ok, include}
+      {:error, _} -> {:ok, true}
+    end
+  end
+
+  @doc """
+  Calculates the membership fee start date based on join date, interval, and settings.
+
+  ## Parameters
+
+    - `join_date` - The date the member joined
+    - `interval` - The billing interval (:monthly, :quarterly, :half_yearly, :yearly)
+    - `include_joining_cycle` - Whether to include the joining cycle
+
+  ## Returns
+
+    The calculated start date (first day of the appropriate cycle).
+
+  ## Examples
+
+      iex> calculate_start_date(~D[2024-03-15], :yearly, true)
+      ~D[2024-01-01]
+
+      iex> calculate_start_date(~D[2024-03-15], :yearly, false)
+      ~D[2025-01-01]
+
+      iex> calculate_start_date(~D[2024-03-15], :quarterly, true)
+      ~D[2024-01-01]
+
+      iex> calculate_start_date(~D[2024-03-15], :quarterly, false)
+      ~D[2024-04-01]
+
+  """
+  @spec calculate_start_date(Date.t(), CalendarCycles.interval(), boolean()) :: Date.t()
+  def calculate_start_date(join_date, interval, include_joining_cycle) do
+    if include_joining_cycle do
+      # Start date is the first day of the joining cycle
+      CalendarCycles.calculate_cycle_start(join_date, interval)
+    else
+      # Start date is the first day of the next cycle after joining
+      join_cycle_start = CalendarCycles.calculate_cycle_start(join_date, interval)
+      CalendarCycles.next_cycle_start(join_cycle_start, interval)
+    end
+  end
+end

lib/mv/membership_fees/cycle_generation_job.ex

@@ -0,0 +1,174 @@
+defmodule Mv.MembershipFees.CycleGenerationJob do
+  @moduledoc """
+  Scheduled job for generating membership fee cycles.
+
+  This module provides a skeleton for scheduled cycle generation.
+  In the future, this can be integrated with Oban or similar job processing libraries.
+
+  ## Current Implementation
+
+  Currently provides manual execution functions that can be called:
+  - From IEx console for administrative tasks
+  - From a cron job via a Mix task
+  - From the admin UI (future)
+
+  ## Future Oban Integration
+
+  When Oban is added to the project, this module can be converted to an Oban worker:
+
+      defmodule Mv.MembershipFees.CycleGenerationJob do
+        use Oban.Worker,
+          queue: :membership_fees,
+          max_attempts: 3
+
+        @impl Oban.Worker
+        def perform(%Oban.Job{}) do
+          Mv.MembershipFees.CycleGenerator.generate_cycles_for_all_members()
+        end
+      end
+
+  ## Usage
+
+      # Manual execution from IEx
+      Mv.MembershipFees.CycleGenerationJob.run()
+
+      # Check if cycles need to be generated
+      Mv.MembershipFees.CycleGenerationJob.pending_members_count()
+
+  """
+
+  alias Mv.MembershipFees.CycleGenerator
+
+  require Ash.Query
+  require Logger
+
+  @doc """
+  Runs the cycle generation job for all active members.
+
+  This is the main entry point for scheduled execution.
+
+  ## Returns
+
+    - `{:ok, results}` - Map with success/failed counts
+    - `{:error, reason}` - Error with reason
+
+  ## Examples
+
+      iex> Mv.MembershipFees.CycleGenerationJob.run()
+      {:ok, %{success: 45, failed: 0, total: 45}}
+
+  """
+  @spec run() :: {:ok, map()} | {:error, term()}
+  def run do
+    Logger.info("Starting membership fee cycle generation job")
+    start_time = System.monotonic_time(:millisecond)
+
+    result = CycleGenerator.generate_cycles_for_all_members()
+
+    elapsed = System.monotonic_time(:millisecond) - start_time
+
+    case result do
+      {:ok, stats} ->
+        Logger.info(
+          "Cycle generation completed in #{elapsed}ms: #{stats.success} success, #{stats.failed} failed, #{stats.total} total"
+        )
+
+        result
+
+      {:error, reason} ->
+        Logger.error("Cycle generation failed: #{inspect(reason)}")
+        result
+    end
+  end
+
+  @doc """
+  Runs cycle generation with custom options.
+
+  ## Options
+
+    - `:today` - Override today's date (useful for testing or catch-up)
+    - `:batch_size` - Number of members to process in parallel
+
+  ## Examples
+
+      # Generate cycles as if today was a specific date
+      Mv.MembershipFees.CycleGenerationJob.run(today: ~D[2024-12-31])
+
+      # Process with smaller batch size
+      Mv.MembershipFees.CycleGenerationJob.run(batch_size: 5)
+
+  """
+  @spec run(keyword()) :: {:ok, map()} | {:error, term()}
+  def run(opts) when is_list(opts) do
+    Logger.info("Starting membership fee cycle generation job with opts: #{inspect(opts)}")
+    start_time = System.monotonic_time(:millisecond)
+
+    result = CycleGenerator.generate_cycles_for_all_members(opts)
+
+    elapsed = System.monotonic_time(:millisecond) - start_time
+
+    case result do
+      {:ok, stats} ->
+        Logger.info(
+          "Cycle generation completed in #{elapsed}ms: #{stats.success} success, #{stats.failed} failed, #{stats.total} total"
+        )
+
+        result
+
+      {:error, reason} ->
+        Logger.error("Cycle generation failed: #{inspect(reason)}")
+        result
+    end
+  end
+
+  @doc """
+  Returns the count of members that need cycle generation.
+
+  A member needs cycle generation if:
+  - Has a membership_fee_type assigned
+  - Has a join_date set
+  - Is active (no exit_date or exit_date >= today)
+
+  ## Returns
+
+    - `{:ok, count}` - Number of members needing generation
+    - `{:error, reason}` - Error with reason
+
+  """
+  @spec pending_members_count() :: {:ok, non_neg_integer()} | {:error, term()}
+  def pending_members_count do
+    today = Date.utc_today()
+
+    query =
+      Mv.Membership.Member
+      |> Ash.Query.filter(not is_nil(membership_fee_type_id))
+      |> Ash.Query.filter(not is_nil(join_date))
+      |> Ash.Query.filter(is_nil(exit_date) or exit_date >= ^today)
+
+    case Ash.count(query) do
+      {:ok, count} -> {:ok, count}
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  @doc """
+  Generates cycles for a specific member by ID.
+
+  Useful for administrative tasks or manual corrections.
+
+  ## Parameters
+
+    - `member_id` - The UUID of the member
+
+  ## Returns
+
+    - `{:ok, cycles}` - List of newly created cycles
+    - `{:error, reason}` - Error with reason
+
+  """
+  @spec run_for_member(String.t()) :: {:ok, [map()]} | {:error, term()}
+  def run_for_member(member_id) when is_binary(member_id) do
+    Logger.info("Generating cycles for member #{member_id}")
+    CycleGenerator.generate_cycles_for_member(member_id)
+  end
+end

lib/mv/membership_fees/cycle_generator.ex

@@ -0,0 +1,390 @@
+defmodule Mv.MembershipFees.CycleGenerator do
+  @moduledoc """
+  Module for generating membership fee cycles for members.
+
+  This module provides functions to automatically generate membership fee cycles
+  based on a member's fee type, start date, and exit date.
+
+  ## Algorithm
+
+  1. Load member with relationships (membership_fee_type, membership_fee_cycles)
+  2. Determine the generation start point:
+     - If NO cycles exist: Start from `membership_fee_start_date` (or calculated from `join_date`)
+     - If cycles exist: Start from the cycle AFTER the last existing one
+  3. Generate all cycle starts from the determined start point to today (or `exit_date`)
+  4. Create new cycles with the current amount from `membership_fee_type`
+
+  ## Important: Gap Handling
+
+  **Gaps are NOT filled.** If a cycle was explicitly deleted (e.g., 2023 was deleted
+  but 2022 and 2024 exist), the generator will NOT recreate the deleted cycle.
+  It always continues from the LAST existing cycle, regardless of any gaps.
+
+  This behavior ensures that manually deleted cycles remain deleted and prevents
+  unwanted automatic recreation of intentionally removed cycles.
+
+  ## Concurrency
+
+  Uses PostgreSQL advisory locks to prevent race conditions when generating
+  cycles for the same member concurrently.
+
+  ## Examples
+
+      # Generate cycles for a single member
+      {:ok, cycles} = CycleGenerator.generate_cycles_for_member(member)
+
+      # Generate cycles for all active members
+      {:ok, results} = CycleGenerator.generate_cycles_for_all_members()
+
+  """
+
+  alias Mv.MembershipFees.CalendarCycles
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.Changes.SetMembershipFeeStartDate
+  alias Mv.Membership.Member
+  alias Mv.Repo
+
+  require Ash.Query
+  require Logger
+
+  @type generate_result :: {:ok, [MembershipFeeCycle.t()]} | {:error, term()}
+
+  @doc """
+  Generates membership fee cycles for a single member.
+
+  Uses an advisory lock to prevent concurrent generation for the same member.
+
+  ## Parameters
+
+    - `member` - The member struct or member ID
+    - `opts` - Options:
+      - `:today` - Override today's date (useful for testing)
+
+  ## Returns
+
+    - `{:ok, cycles}` - List of newly created cycles
+    - `{:error, reason}` - Error with reason
+
+  ## Examples
+
+      {:ok, cycles} = CycleGenerator.generate_cycles_for_member(member)
+      {:ok, cycles} = CycleGenerator.generate_cycles_for_member(member_id)
+      {:ok, cycles} = CycleGenerator.generate_cycles_for_member(member, today: ~D[2024-12-31])
+
+  """
+  @spec generate_cycles_for_member(Member.t() | String.t(), keyword()) :: generate_result()
+  def generate_cycles_for_member(member_or_id, opts \\ [])
+
+  def generate_cycles_for_member(member_id, opts) when is_binary(member_id) do
+    case load_member(member_id) do
+      {:ok, member} -> generate_cycles_for_member(member, opts)
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  def generate_cycles_for_member(%Member{} = member, opts) do
+    today = Keyword.get(opts, :today, Date.utc_today())
+
+    # Use advisory lock to prevent concurrent generation
+    # Notifications are handled inside with_advisory_lock after transaction commits
+    with_advisory_lock(member.id, fn ->
+      do_generate_cycles(member, today)
+    end)
+  end
+
+  @doc """
+  Generates membership fee cycles for all members with a fee type assigned.
+
+  This includes both active and inactive (left) members. Inactive members
+  will have cycles generated up to their exit_date if they don't have cycles
+  for that period yet. This allows for catch-up generation of missing cycles.
+
+  Members processed are those who:
+  - Have a membership_fee_type assigned
+  - Have a join_date set
+
+  The exit_date boundary is respected during generation (not in the query),
+  so inactive members will get cycles up to their exit date.
+
+  ## Parameters
+
+    - `opts` - Options:
+      - `:today` - Override today's date (useful for testing)
+      - `:batch_size` - Number of members to process in parallel (default: 10)
+
+  ## Returns
+
+    - `{:ok, results}` - Map with :success and :failed counts
+    - `{:error, reason}` - Error with reason
+
+  """
+  @spec generate_cycles_for_all_members(keyword()) :: {:ok, map()} | {:error, term()}
+  def generate_cycles_for_all_members(opts \\ []) do
+    today = Keyword.get(opts, :today, Date.utc_today())
+    batch_size = Keyword.get(opts, :batch_size, 10)
+
+    # Query ALL members with fee type assigned (including inactive/left members)
+    # The exit_date boundary is applied during cycle generation, not here.
+    # This allows catch-up generation for members who left but are missing cycles.
+    query =
+      Member
+      |> Ash.Query.filter(not is_nil(membership_fee_type_id))
+      |> Ash.Query.filter(not is_nil(join_date))
+
+    case Ash.read(query) do
+      {:ok, members} ->
+        results = process_members_in_batches(members, batch_size, today)
+        {:ok, build_results_summary(results)}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp process_members_in_batches(members, batch_size, today) do
+    members
+    |> Enum.chunk_every(batch_size)
+    |> Enum.flat_map(&process_batch(&1, today))
+  end
+
+  defp process_batch(batch, today) do
+    batch
+    |> Task.async_stream(fn member ->
+      {member.id, generate_cycles_for_member(member, today: today)}
+    end)
+    |> Enum.map(fn
+      {:ok, result} ->
+        result
+
+      {:exit, reason} ->
+        # Task crashed - log and return error tuple
+        Logger.error("Task crashed during cycle generation: #{inspect(reason)}")
+        {nil, {:error, {:task_exit, reason}}}
+    end)
+  end
+
+  defp build_results_summary(results) do
+    success_count = Enum.count(results, fn {_id, result} -> match?({:ok, _}, result) end)
+    failed_count = Enum.count(results, fn {_id, result} -> match?({:error, _}, result) end)
+
+    %{success: success_count, failed: failed_count, total: length(results)}
+  end
+
+  # Private functions
+
+  defp load_member(member_id) do
+    Member
+    |> Ash.Query.filter(id == ^member_id)
+    |> Ash.Query.load([:membership_fee_type, :membership_fee_cycles])
+    |> Ash.read_one()
+    |> case do
+      {:ok, nil} -> {:error, :member_not_found}
+      {:ok, member} -> {:ok, member}
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  defp with_advisory_lock(member_id, fun) do
+    # Convert UUID to integer for advisory lock (use hash)
+    lock_key = :erlang.phash2(member_id)
+
+    result =
+      Repo.transaction(fn ->
+        # Acquire advisory lock for this transaction
+        Ecto.Adapters.SQL.query!(Repo, "SELECT pg_advisory_xact_lock($1)", [lock_key])
+
+        case fun.() do
+          {:ok, result, notifications} when is_list(notifications) ->
+            # Return result and notifications separately
+            {result, notifications}
+
+          {:ok, result} ->
+            # Handle case where no notifications were returned (backward compatibility)
+            {result, []}
+
+          {:error, reason} ->
+            Repo.rollback(reason)
+        end
+      end)
+
+    # Extract result and notifications, send notifications after transaction
+    case result do
+      {:ok, {cycles, notifications}} ->
+        if Enum.any?(notifications) do
+          Ash.Notifier.notify(notifications)
+        end
+
+        {:ok, cycles}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp do_generate_cycles(member, today) do
+    # Reload member with relationships to ensure fresh data
+    case load_member(member.id) do
+      {:ok, member} ->
+        cond do
+          is_nil(member.membership_fee_type_id) ->
+            {:error, :no_membership_fee_type}
+
+          is_nil(member.join_date) ->
+            {:error, :no_join_date}
+
+          true ->
+            generate_missing_cycles(member, today)
+        end
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp generate_missing_cycles(member, today) do
+    fee_type = member.membership_fee_type
+    interval = fee_type.interval
+    amount = fee_type.amount
+    existing_cycles = member.membership_fee_cycles || []
+
+    # Determine start point based on existing cycles
+    # Note: We do NOT fill gaps - only generate from the last existing cycle onwards
+    start_date = determine_generation_start(member, existing_cycles, interval)
+
+    # Determine end date (today or exit_date, whichever is earlier)
+    end_date = determine_end_date(member, today)
+
+    # Only generate if start_date <= end_date
+    if start_date && Date.compare(start_date, end_date) != :gt do
+      cycle_starts = generate_cycle_starts(start_date, end_date, interval)
+      create_cycles(cycle_starts, member.id, fee_type.id, amount)
+    else
+      {:ok, [], []}
+    end
+  end
+
+  # No existing cycles: start from membership_fee_start_date
+  defp determine_generation_start(member, [], interval) do
+    determine_start_date(member, interval)
+  end
+
+  # Has existing cycles: start from the cycle AFTER the last one
+  # This ensures gaps (deleted cycles) are NOT filled
+  defp determine_generation_start(_member, existing_cycles, interval) do
+    last_cycle_start =
+      existing_cycles
+      |> Enum.map(& &1.cycle_start)
+      |> Enum.max(Date)
+
+    CalendarCycles.next_cycle_start(last_cycle_start, interval)
+  end
+
+  defp determine_start_date(member, interval) do
+    if member.membership_fee_start_date do
+      member.membership_fee_start_date
+    else
+      # Calculate from join_date using global settings
+      include_joining_cycle = get_include_joining_cycle()
+
+      SetMembershipFeeStartDate.calculate_start_date(
+        member.join_date,
+        interval,
+        include_joining_cycle
+      )
+    end
+  end
+
+  defp determine_end_date(member, today) do
+    if member.exit_date && Date.compare(member.exit_date, today) == :lt do
+      # Member has left - use the exit date as boundary
+      # Note: If exit_date == cycle_start, the cycle IS still generated.
+      # This means the member is considered a member on the first day of that cycle.
+      # Example: exit_date = 2025-01-01, yearly interval
+      #   -> The 2025 cycle (starting 2025-01-01) WILL be generated
+      member.exit_date
+    else
+      today
+    end
+  end
+
+  defp get_include_joining_cycle do
+    case Mv.Membership.get_settings() do
+      {:ok, %{include_joining_cycle: include}} -> include
+      {:error, _} -> true
+    end
+  end
+
+  @doc """
+  Generates all cycle start dates from a start date to an end date.
+
+  ## Parameters
+
+    - `start_date` - The first cycle start date
+    - `end_date` - The date up to which cycles should be generated
+    - `interval` - The billing interval
+
+  ## Returns
+
+    List of cycle start dates.
+
+  ## Examples
+
+      iex> generate_cycle_starts(~D[2024-01-01], ~D[2024-12-31], :quarterly)
+      [~D[2024-01-01], ~D[2024-04-01], ~D[2024-07-01], ~D[2024-10-01]]
+
+  """
+  @spec generate_cycle_starts(Date.t(), Date.t(), atom()) :: [Date.t()]
+  def generate_cycle_starts(start_date, end_date, interval) do
+    # Ensure start_date is aligned to cycle boundary
+    aligned_start = CalendarCycles.calculate_cycle_start(start_date, interval)
+
+    generate_cycle_starts_acc(aligned_start, end_date, interval, [])
+  end
+
+  defp generate_cycle_starts_acc(current_start, end_date, interval, acc) do
+    if Date.compare(current_start, end_date) == :gt do
+      # Current cycle start is after end date - stop
+      Enum.reverse(acc)
+    else
+      # Include this cycle and continue to next
+      next_start = CalendarCycles.next_cycle_start(current_start, interval)
+      generate_cycle_starts_acc(next_start, end_date, interval, [current_start | acc])
+    end
+  end
+
+  defp create_cycles(cycle_starts, member_id, fee_type_id, amount) do
+    results =
+      Enum.map(cycle_starts, fn cycle_start ->
+        attrs = %{
+          cycle_start: cycle_start,
+          member_id: member_id,
+          membership_fee_type_id: fee_type_id,
+          amount: amount,
+          status: :unpaid
+        }
+
+        # Return notifications to avoid warnings when creating within a transaction
+        case Ash.create(MembershipFeeCycle, attrs, return_notifications?: true) do
+          {:ok, cycle, notifications} -> {:ok, cycle, notifications}
+          {:error, reason} -> {:error, {cycle_start, reason}}
+        end
+      end)
+
+    {successes, errors} = Enum.split_with(results, &match?({:ok, _, _}, &1))
+
+    all_notifications =
+      Enum.flat_map(successes, fn {:ok, _cycle, notifications} -> notifications end)
+
+    if Enum.empty?(errors) do
+      successful_cycles = Enum.map(successes, fn {:ok, cycle, _notifications} -> cycle end)
+      # Return cycles and notifications to be sent after transaction commits
+      {:ok, successful_cycles, all_notifications}
+    else
+      Logger.warning("Some cycles failed to create: #{inspect(errors)}")
+      # Return partial failure with errors
+      # Note: When this error occurs, the transaction will be rolled back,
+      # so no cycles were actually persisted in the database
+      {:error, {:partial_failure, errors}}
+    end
+  end
+end

priv/repo/migrations/20251211195058_add_membership_fee_settings.exs

@@ -0,0 +1,25 @@
+defmodule Mv.Repo.Migrations.AddMembershipFeeSettings do
+  @moduledoc """
+  Adds membership fee settings to the settings table.
+
+  Note: The members table columns (membership_fee_start_date, membership_fee_type_id)
+  were already added in migration 20251211151449_add_membership_fees_tables.
+  """
+
+  use Ecto.Migration
+
+  def up do
+    # Add membership fee settings to the settings table
+    alter table(:settings) do
+      add_if_not_exists :include_joining_cycle, :boolean, null: false, default: true
+      add_if_not_exists :default_membership_fee_type_id, :uuid
+    end
+  end
+
+  def down do
+    alter table(:settings) do
+      remove_if_exists :default_membership_fee_type_id, :uuid
+      remove_if_exists :include_joining_cycle, :boolean
+    end
+  end
+end

priv/resource_snapshots/repo/members/20251211195058.json

@@ -0,0 +1,245 @@
+{
+  "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": "first_name",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "last_name",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "email",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "paid",
+      "type": "boolean"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "phone_number",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "join_date",
+      "type": "date"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "exit_date",
+      "type": "date"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "notes",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "city",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "street",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "house_number",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "postal_code",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "search_vector",
+      "type": "tsvector"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "membership_fee_start_date",
+      "type": "date"
+    },
+    {
+      "allow_nil?": true,
+      "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": "members_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": "6ECD721659E1CC7CB4219293153BCED585111A49765B9DB0D1CAE0B37C54949E",
+  "identities": [
+    {
+      "all_tenants?": false,
+      "base_filter": null,
+      "index_name": "members_unique_email_index",
+      "keys": [
+        {
+          "type": "atom",
+          "value": "email"
+        }
+      ],
+      "name": "unique_email",
+      "nils_distinct?": true,
+      "where": null
+    }
+  ],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.Mv.Repo",
+  "schema": null,
+  "table": "members"
+}

priv/resource_snapshots/repo/membership_fee_cycles/20251211195058.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": 2,
+      "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": "802FB11B08D041501AC395454D84719992B71C0BEAE83B0833F3086486ABD679",
+  "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/20251211195058.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": 2,
+      "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": "C58959BF589FEB75A9F05C2C717C04B641ED14E09FF2503C8B0637392AE5A335",
+  "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"
+}

priv/resource_snapshots/repo/settings/20251211195058.json

@@ -0,0 +1,103 @@
+{
+  "attributes": [
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"gen_random_uuid()\")",
+      "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": "club_name",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "member_field_visibility",
+      "type": "map"
+    },
+    {
+      "allow_nil?": false,
+      "default": "true",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "include_joining_cycle",
+      "type": "boolean"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "default_membership_fee_type_id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"(now() AT TIME ZONE 'utc')\")",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "inserted_at",
+      "type": "utc_datetime_usec"
+    },
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"(now() AT TIME ZONE 'utc')\")",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "updated_at",
+      "type": "utc_datetime_usec"
+    }
+  ],
+  "base_filter": null,
+  "check_constraints": [],
+  "custom_indexes": [],
+  "custom_statements": [],
+  "has_create_action": true,
+  "hash": "CD12EA080677C99D81C2A4A98F0DE419F7BDE1FA8C22206423C9D80305B064D2",
+  "identities": [],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.Mv.Repo",
+  "schema": null,
+  "table": "settings"
+}

test/membership_fees/changes/set_membership_fee_start_date_test.exs

@@ -0,0 +1,268 @@
+defmodule Mv.MembershipFees.Changes.SetMembershipFeeStartDateTest do
+  @moduledoc """
+  Tests for the SetMembershipFeeStartDate change module.
+  """
+  use Mv.DataCase, async: false
+
+  alias Mv.MembershipFees.Changes.SetMembershipFeeStartDate
+
+  # Helper to set up settings with specific include_joining_cycle value
+  defp setup_settings(include_joining_cycle) do
+    {:ok, settings} = Mv.Membership.get_settings()
+
+    settings
+    |> Ash.Changeset.for_update(:update, %{include_joining_cycle: include_joining_cycle})
+    |> Ash.update!()
+  end
+
+  describe "calculate_start_date/3" do
+    test "include_joining_cycle = true: start date is first day of joining cycle (yearly)" do
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :yearly, true)
+      assert result == ~D[2024-01-01]
+    end
+
+    test "include_joining_cycle = false: start date is first day of next cycle (yearly)" do
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :yearly, false)
+      assert result == ~D[2025-01-01]
+    end
+
+    test "include_joining_cycle = true: start date is first day of joining cycle (quarterly)" do
+      # Q1: Jan-Mar, Q2: Apr-Jun, Q3: Jul-Sep, Q4: Oct-Dec
+      # March is in Q1
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :quarterly, true)
+      assert result == ~D[2024-01-01]
+
+      # May is in Q2
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-05-15], :quarterly, true)
+      assert result == ~D[2024-04-01]
+
+      # August is in Q3
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-08-15], :quarterly, true)
+      assert result == ~D[2024-07-01]
+
+      # November is in Q4
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-11-15], :quarterly, true)
+      assert result == ~D[2024-10-01]
+    end
+
+    test "include_joining_cycle = false: start date is first day of next cycle (quarterly)" do
+      # March is in Q1, next is Q2
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :quarterly, false)
+      assert result == ~D[2024-04-01]
+
+      # June is in Q2, next is Q3
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-06-15], :quarterly, false)
+      assert result == ~D[2024-07-01]
+
+      # September is in Q3, next is Q4
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-09-15], :quarterly, false)
+      assert result == ~D[2024-10-01]
+
+      # December is in Q4, next is Q1 of next year
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-12-15], :quarterly, false)
+      assert result == ~D[2025-01-01]
+    end
+
+    test "include_joining_cycle = true: start date is first day of joining cycle (half_yearly)" do
+      # H1: Jan-Jun, H2: Jul-Dec
+      # March is in H1
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :half_yearly, true)
+      assert result == ~D[2024-01-01]
+
+      # September is in H2
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-09-15], :half_yearly, true)
+      assert result == ~D[2024-07-01]
+    end
+
+    test "include_joining_cycle = false: start date is first day of next cycle (half_yearly)" do
+      # March is in H1, next is H2
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :half_yearly, false)
+      assert result == ~D[2024-07-01]
+
+      # September is in H2, next is H1 of next year
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-09-15], :half_yearly, false)
+      assert result == ~D[2025-01-01]
+    end
+
+    test "include_joining_cycle = true: start date is first day of joining cycle (monthly)" do
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :monthly, true)
+      assert result == ~D[2024-03-01]
+    end
+
+    test "include_joining_cycle = false: start date is first day of next cycle (monthly)" do
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-03-15], :monthly, false)
+      assert result == ~D[2024-04-01]
+
+      # December goes to next year
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-12-15], :monthly, false)
+      assert result == ~D[2025-01-01]
+    end
+
+    test "joining on first day of cycle with include_joining_cycle = true" do
+      # When joining exactly on cycle start, should return that date
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-01-01], :yearly, true)
+      assert result == ~D[2024-01-01]
+
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-04-01], :quarterly, true)
+      assert result == ~D[2024-04-01]
+    end
+
+    test "joining on first day of cycle with include_joining_cycle = false" do
+      # When joining exactly on cycle start and include=false, should return next cycle
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-01-01], :yearly, false)
+      assert result == ~D[2025-01-01]
+
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-04-01], :quarterly, false)
+      assert result == ~D[2024-07-01]
+    end
+
+    test "joining on last day of cycle" do
+      # Joining on Dec 31 with yearly cycle
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-12-31], :yearly, true)
+      assert result == ~D[2024-01-01]
+
+      result = SetMembershipFeeStartDate.calculate_start_date(~D[2024-12-31], :yearly, false)
+      assert result == ~D[2025-01-01]
+    end
+  end
+
+  describe "change/3 integration" do
+    test "sets membership_fee_start_date automatically on member creation" do
+      setup_settings(true)
+
+      # Create a fee type
+      fee_type =
+        Mv.MembershipFees.MembershipFeeType
+        |> Ash.Changeset.for_create(:create, %{
+          name: "Test Type #{System.unique_integer([:positive])}",
+          amount: Decimal.new("50.00"),
+          interval: :yearly
+        })
+        |> Ash.create!()
+
+      # Create member with join_date and fee type but no explicit start date
+      member =
+        Mv.Membership.Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2024-03-15],
+          membership_fee_type_id: fee_type.id
+        })
+        |> Ash.create!()
+
+      # Should have auto-calculated start date (2024-01-01 for yearly with include_joining_cycle=true)
+      assert member.membership_fee_start_date == ~D[2024-01-01]
+    end
+
+    test "does not override manually set membership_fee_start_date" do
+      setup_settings(true)
+
+      # Create a fee type
+      fee_type =
+        Mv.MembershipFees.MembershipFeeType
+        |> Ash.Changeset.for_create(:create, %{
+          name: "Test Type #{System.unique_integer([:positive])}",
+          amount: Decimal.new("50.00"),
+          interval: :yearly
+        })
+        |> Ash.create!()
+
+      # Create member with explicit start date
+      manual_start_date = ~D[2024-07-01]
+
+      member =
+        Mv.Membership.Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2024-03-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: manual_start_date
+        })
+        |> Ash.create!()
+
+      # Should keep the manually set date
+      assert member.membership_fee_start_date == manual_start_date
+    end
+
+    test "respects include_joining_cycle = false setting" do
+      setup_settings(false)
+
+      # Create a fee type
+      fee_type =
+        Mv.MembershipFees.MembershipFeeType
+        |> Ash.Changeset.for_create(:create, %{
+          name: "Test Type #{System.unique_integer([:positive])}",
+          amount: Decimal.new("50.00"),
+          interval: :yearly
+        })
+        |> Ash.create!()
+
+      # Create member
+      member =
+        Mv.Membership.Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2024-03-15],
+          membership_fee_type_id: fee_type.id
+        })
+        |> Ash.create!()
+
+      # Should have next cycle start date (2025-01-01 for yearly with include_joining_cycle=false)
+      assert member.membership_fee_start_date == ~D[2025-01-01]
+    end
+
+    test "does not set start date without join_date" do
+      setup_settings(true)
+
+      # Create a fee type
+      fee_type =
+        Mv.MembershipFees.MembershipFeeType
+        |> Ash.Changeset.for_create(:create, %{
+          name: "Test Type #{System.unique_integer([:positive])}",
+          amount: Decimal.new("50.00"),
+          interval: :yearly
+        })
+        |> Ash.create!()
+
+      # Create member without join_date
+      member =
+        Mv.Membership.Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          membership_fee_type_id: fee_type.id
+          # No join_date
+        })
+        |> Ash.create!()
+
+      # Should not have auto-calculated start date
+      assert is_nil(member.membership_fee_start_date)
+    end
+
+    test "does not set start date without membership_fee_type_id" do
+      setup_settings(true)
+
+      # Create member without fee type
+      member =
+        Mv.Membership.Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2024-03-15]
+          # No membership_fee_type_id
+        })
+        |> Ash.create!()
+
+      # Should not have auto-calculated start date
+      assert is_nil(member.membership_fee_start_date)
+    end
+  end
+end

test/membership_fees/member_cycle_integration_test.exs

@@ -0,0 +1,211 @@
+defmodule Mv.MembershipFees.MemberCycleIntegrationTest do
+  @moduledoc """
+  Integration tests for membership fee cycle generation triggered by member actions.
+  """
+  use Mv.DataCase, async: false
+
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+  alias Mv.Membership.Member
+
+  require Ash.Query
+
+  # Helper to create a membership fee type
+  defp create_fee_type(attrs) do
+    default_attrs = %{
+      name: "Test Fee Type #{System.unique_integer([:positive])}",
+      amount: Decimal.new("50.00"),
+      interval: :yearly
+    }
+
+    attrs = Map.merge(default_attrs, attrs)
+
+    MembershipFeeType
+    |> Ash.Changeset.for_create(:create, attrs)
+    |> Ash.create!()
+  end
+
+  # Helper to set up settings
+  defp setup_settings(include_joining_cycle) do
+    {:ok, settings} = Mv.Membership.get_settings()
+
+    settings
+    |> Ash.Changeset.for_update(:update, %{include_joining_cycle: include_joining_cycle})
+    |> Ash.update!()
+  end
+
+  # Helper to get cycles for a member
+  defp get_member_cycles(member_id) do
+    MembershipFeeCycle
+    |> Ash.Query.filter(member_id == ^member_id)
+    |> Ash.Query.sort(cycle_start: :asc)
+    |> Ash.read!()
+  end
+
+  describe "member creation triggers cycle generation" do
+    test "creates cycles when member is created with fee type and join_date" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2023-03-15],
+          membership_fee_type_id: fee_type.id
+        })
+        |> Ash.create!()
+
+      cycles = get_member_cycles(member.id)
+
+      # Should have cycles for 2023 and 2024 (and possibly current year)
+      assert length(cycles) >= 2
+
+      # Verify cycles have correct data
+      Enum.each(cycles, fn cycle ->
+        assert cycle.member_id == member.id
+        assert cycle.membership_fee_type_id == fee_type.id
+        assert Decimal.equal?(cycle.amount, fee_type.amount)
+        assert cycle.status == :unpaid
+      end)
+    end
+
+    test "does not create cycles when member has no fee type" do
+      setup_settings(true)
+
+      member =
+        Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2023-03-15]
+          # No membership_fee_type_id
+        })
+        |> Ash.create!()
+
+      cycles = get_member_cycles(member.id)
+
+      assert cycles == []
+    end
+
+    test "does not create cycles when member has no join_date" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          membership_fee_type_id: fee_type.id
+          # No join_date
+        })
+        |> Ash.create!()
+
+      cycles = get_member_cycles(member.id)
+
+      assert cycles == []
+    end
+  end
+
+  describe "member update triggers cycle generation" do
+    test "generates cycles when fee type is assigned to existing member" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member without fee type
+      member =
+        Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2023-03-15]
+        })
+        |> Ash.create!()
+
+      # Verify no cycles yet
+      assert get_member_cycles(member.id) == []
+
+      # Update to assign fee type
+      member
+      |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+      |> Ash.update!()
+
+      cycles = get_member_cycles(member.id)
+
+      # Should have generated cycles
+      assert length(cycles) >= 2
+    end
+  end
+
+  describe "concurrent cycle generation" do
+    test "handles multiple members being created concurrently" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create multiple members concurrently
+      tasks =
+        Enum.map(1..5, fn i ->
+          Task.async(fn ->
+            Member
+            |> Ash.Changeset.for_create(:create_member, %{
+              first_name: "Test#{i}",
+              last_name: "User#{i}",
+              email: "test#{System.unique_integer([:positive])}@example.com",
+              join_date: ~D[2023-03-15],
+              membership_fee_type_id: fee_type.id
+            })
+            |> Ash.create!()
+          end)
+        end)
+
+      members = Enum.map(tasks, &Task.await/1)
+
+      # Each member should have cycles
+      Enum.each(members, fn member ->
+        cycles = get_member_cycles(member.id)
+        assert length(cycles) >= 2, "Member #{member.id} should have at least 2 cycles"
+      end)
+    end
+  end
+
+  describe "idempotent cycle generation" do
+    test "running generation multiple times does not create duplicate cycles" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        Member
+        |> Ash.Changeset.for_create(:create_member, %{
+          first_name: "Test",
+          last_name: "User",
+          email: "test#{System.unique_integer([:positive])}@example.com",
+          join_date: ~D[2023-03-15],
+          membership_fee_type_id: fee_type.id
+        })
+        |> Ash.create!()
+
+      initial_cycles = get_member_cycles(member.id)
+      initial_count = length(initial_cycles)
+
+      # Use a fixed "today" date to avoid date dependency
+      # Use a date far enough in the future to ensure all cycles are generated
+      today = ~D[2025-12-31]
+
+      # Manually trigger generation again with fixed "today" date
+      {:ok, _} =
+        Mv.MembershipFees.CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      final_cycles = get_member_cycles(member.id)
+      final_count = length(final_cycles)
+
+      # Should have same number of cycles (idempotent)
+      assert final_count == initial_count
+    end
+  end
+end

test/mv/membership_fees/cycle_generator_edge_cases_test.exs

@@ -0,0 +1,644 @@
+defmodule Mv.MembershipFees.CycleGeneratorEdgeCasesTest do
+  @moduledoc """
+  Edge case tests for the CycleGenerator module.
+
+  Tests cover:
+  - Member joins today
+  - Member left yesterday
+  - Year boundary handling
+  - Leap year handling
+  - Members with no existing cycles
+  - Members with existing cycles
+  """
+  use Mv.DataCase, async: false
+
+  alias Mv.MembershipFees.CycleGenerator
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+  alias Mv.Membership.Member
+
+  require Ash.Query
+
+  # Helper to create a membership fee type
+  defp create_fee_type(attrs) do
+    default_attrs = %{
+      name: "Test Fee Type #{System.unique_integer([:positive])}",
+      amount: Decimal.new("50.00"),
+      interval: :yearly
+    }
+
+    attrs = Map.merge(default_attrs, attrs)
+
+    MembershipFeeType
+    |> Ash.Changeset.for_create(:create, attrs)
+    |> Ash.create!()
+  end
+
+  # Helper to create a member. Note: If membership_fee_type_id is provided,
+  # cycles will be auto-generated during creation in test environment.
+  defp create_member(attrs) do
+    default_attrs = %{
+      first_name: "Test",
+      last_name: "User",
+      email: "test#{System.unique_integer([:positive])}@example.com"
+    }
+
+    attrs = Map.merge(default_attrs, attrs)
+
+    Member
+    |> Ash.Changeset.for_create(:create_member, attrs)
+    |> Ash.create!()
+  end
+
+  # Helper to create a member and explicitly generate cycles with a fixed "today" date.
+  # This avoids date dependency issues in tests.
+  #
+  # Note: We first create the member without fee_type_id, then assign it via update,
+  # which triggers the after_action hook. However, we then explicitly regenerate
+  # cycles with the fixed "today" date to ensure consistency.
+  defp create_member_with_cycles(attrs, today) do
+    # Extract membership_fee_type_id if present
+    fee_type_id = Map.get(attrs, :membership_fee_type_id)
+
+    # Create member WITHOUT fee type first to avoid auto-generation with real today
+    attrs_without_fee_type = Map.delete(attrs, :membership_fee_type_id)
+
+    member =
+      create_member(attrs_without_fee_type)
+
+    # Assign fee type if provided (this will trigger auto-generation with real today)
+    member =
+      if fee_type_id do
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type_id})
+        |> Ash.update!()
+      else
+        member
+      end
+
+    # Explicitly regenerate cycles with fixed "today" date to override any auto-generated cycles
+    # This ensures the test uses the fixed date, not the real current date
+    if fee_type_id && member.join_date do
+      # Delete any existing cycles first to ensure clean state
+      existing_cycles = get_member_cycles(member.id)
+      Enum.each(existing_cycles, &Ash.destroy!(&1))
+
+      # Generate cycles with fixed "today" date
+      {:ok, _} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+    end
+
+    member
+  end
+
+  # Helper to get cycles for a member
+  defp get_member_cycles(member_id) do
+    MembershipFeeCycle
+    |> Ash.Query.filter(member_id == ^member_id)
+    |> Ash.Query.sort(cycle_start: :asc)
+    |> Ash.read!()
+  end
+
+  # Helper to set up settings
+  defp setup_settings(include_joining_cycle) do
+    {:ok, settings} = Mv.Membership.get_settings()
+
+    settings
+    |> Ash.Changeset.for_update(:update, %{include_joining_cycle: include_joining_cycle})
+    |> Ash.update!()
+  end
+
+  describe "member joins today" do
+    test "current cycle is generated (yearly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+
+      # Create member WITHOUT fee type first to avoid auto-generation with real today
+      member =
+        create_member(%{
+          join_date: today,
+          membership_fee_start_date: ~D[2024-01-01]
+        })
+
+      # Assign fee type
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Explicitly generate cycles with fixed "today" date
+      {:ok, _} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have the current year's cycle
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year)
+      assert 2024 in cycle_years
+    end
+
+    test "current cycle is generated (monthly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :monthly})
+
+      today = ~D[2024-06-15]
+
+      # Create member WITHOUT fee type first to avoid auto-generation with real today
+      member =
+        create_member(%{
+          join_date: today,
+          membership_fee_start_date: ~D[2024-06-01]
+        })
+
+      # Assign fee type
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Explicitly generate cycles with fixed "today" date
+      {:ok, _} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have June 2024 cycle
+      assert Enum.any?(cycles, fn c -> c.cycle_start == ~D[2024-06-01] end)
+    end
+
+    test "current cycle is generated (quarterly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :quarterly})
+
+      today = ~D[2024-05-15]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: today,
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2024-04-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have Q2 2024 cycle
+      assert Enum.any?(cycles, fn c -> c.cycle_start == ~D[2024-04-01] end)
+    end
+  end
+
+  describe "member left yesterday" do
+    test "no future cycles are generated" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+      yesterday = Date.add(today, -1)
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2022-03-15],
+            exit_date: yesterday,
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2022-01-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # 2024 should be included because the member was still active during that cycle
+      assert 2022 in cycle_years
+      assert 2023 in cycle_years
+      assert 2024 in cycle_years
+
+      # 2025 should NOT be included
+      refute 2025 in cycle_years
+    end
+
+    test "exit during first month of year stops at that year (monthly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :monthly})
+
+      # Create member - cycles will be auto-generated
+      member =
+        create_member(%{
+          join_date: ~D[2024-01-15],
+          exit_date: ~D[2024-03-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2024-01-01]
+        })
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_months = Enum.map(cycles, & &1.cycle_start.month) |> Enum.sort()
+
+      assert 1 in cycle_months
+      assert 2 in cycle_months
+      assert 3 in cycle_months
+
+      # April and beyond should NOT be included
+      refute 4 in cycle_months
+      refute 5 in cycle_months
+    end
+  end
+
+  describe "member has no cycles initially" do
+    test "returns error when fee type is not assigned" do
+      setup_settings(true)
+
+      # Create member WITHOUT fee type (no auto-generation)
+      member =
+        create_member(%{
+          join_date: ~D[2022-03-15],
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      # Verify no cycles exist initially
+      initial_cycles = get_member_cycles(member.id)
+      assert initial_cycles == []
+
+      # Trying to generate cycles without fee type should return error
+      result = CycleGenerator.generate_cycles_for_member(member.id)
+      assert result == {:error, :no_membership_fee_type}
+    end
+
+    test "generates all cycles when member is created with fee type" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2022-03-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2022-01-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have generated all cycles from 2022 to 2024 (3 cycles)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+      assert 2022 in cycle_years
+      assert 2023 in cycle_years
+      assert 2024 in cycle_years
+      # Should NOT have 2025 (today is 2024-06-15)
+      refute 2025 in cycle_years
+    end
+  end
+
+  describe "member has existing cycles" do
+    test "generates from last cycle (not duplicating existing)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member WITHOUT fee type first
+      member =
+        create_member(%{
+          join_date: ~D[2022-03-15],
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      # Manually create an existing cycle for 2022
+      MembershipFeeCycle
+      |> Ash.Changeset.for_create(:create, %{
+        cycle_start: ~D[2022-01-01],
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        amount: fee_type.amount,
+        status: :paid
+      })
+      |> Ash.create!()
+
+      # Now assign fee type
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Explicitly generate cycles with fixed "today" date
+      today = ~D[2024-06-15]
+      {:ok, _} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Check all cycles
+      all_cycles = get_member_cycles(member.id)
+      all_cycle_years = Enum.map(all_cycles, & &1.cycle_start.year) |> Enum.sort() |> Enum.uniq()
+
+      # Should have 2022 (manually created), 2023 and 2024 (auto-generated)
+      assert 2022 in all_cycle_years
+      assert 2023 in all_cycle_years
+      assert 2024 in all_cycle_years
+
+      # Verify no duplicates
+      assert length(all_cycles) == length(all_cycle_years)
+    end
+  end
+
+  describe "year boundary handling" do
+    test "cycles span across year boundaries correctly (yearly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2023-11-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2023-01-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # Should have 2023 and 2024
+      assert 2023 in cycle_years
+      assert 2024 in cycle_years
+    end
+
+    test "cycles span across year boundaries correctly (quarterly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :quarterly})
+
+      today = ~D[2024-12-15]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2024-10-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2024-10-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_starts = Enum.map(cycles, & &1.cycle_start) |> Enum.sort(Date)
+
+      # Should have Q4 2024
+      assert ~D[2024-10-01] in cycle_starts
+    end
+
+    test "December to January transition (monthly)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :monthly})
+
+      today = ~D[2024-12-31]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2024-12-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2024-12-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_starts = Enum.map(cycles, & &1.cycle_start) |> Enum.sort(Date)
+
+      # Should have Dec 2024
+      assert ~D[2024-12-01] in cycle_starts
+    end
+  end
+
+  describe "leap year handling" do
+    test "February cycles in leap year" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :monthly})
+
+      today = ~D[2024-03-15]
+
+      # 2024 is a leap year
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2024-02-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2024-02-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have February 2024 cycle
+      feb_cycle = Enum.find(cycles, fn c -> c.cycle_start == ~D[2024-02-01] end)
+
+      assert feb_cycle != nil
+    end
+
+    test "February cycles in non-leap year" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :monthly})
+
+      today = ~D[2023-03-15]
+
+      # 2023 is NOT a leap year
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2023-02-15],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2023-02-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have February 2023 cycle
+      feb_cycle = Enum.find(cycles, fn c -> c.cycle_start == ~D[2023-02-01] end)
+
+      assert feb_cycle != nil
+    end
+
+    test "yearly cycle in leap year" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-12-31]
+
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2024-02-29],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2024-01-01]
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+
+      # Should have 2024 cycle
+      cycle_2024 = Enum.find(cycles, fn c -> c.cycle_start == ~D[2024-01-01] end)
+
+      assert cycle_2024 != nil
+    end
+  end
+
+  describe "include_joining_cycle variations" do
+    test "include_joining_cycle = true starts from joining cycle" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+
+      # Member joins mid-2023, should get 2023 cycle with include_joining_cycle=true
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2023-06-15],
+            membership_fee_type_id: fee_type.id
+            # membership_fee_start_date will be auto-calculated
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # Should include 2023 (joining year)
+      assert 2023 in cycle_years
+    end
+
+    test "include_joining_cycle = false starts from next cycle" do
+      setup_settings(false)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-06-15]
+
+      # Member joins mid-2023, should start from 2024 with include_joining_cycle=false
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2023-06-15],
+            membership_fee_type_id: fee_type.id
+            # membership_fee_start_date will be auto-calculated
+          },
+          today
+        )
+
+      # Check all cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # Should NOT include 2023 (joining year)
+      refute 2023 in cycle_years
+
+      # Should start from 2024
+      assert 2024 in cycle_years
+    end
+  end
+
+  describe "inactive member processing" do
+    test "inactive members receive cycles up to exit_date via generate_cycles_for_all_members" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create an inactive member (left in 2023) WITHOUT fee type initially
+      # This simulates a member that was created before the fee system existed
+      member =
+        create_member(%{
+          join_date: ~D[2021-03-15],
+          exit_date: ~D[2023-06-15]
+        })
+
+      # Now assign fee type (simulating a retroactive assignment)
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2021-01-01]
+        })
+        |> Ash.update!()
+
+      # Run batch generation with a "today" date after the member left
+      today = ~D[2024-06-15]
+      {:ok, results} = CycleGenerator.generate_cycles_for_all_members(today: today)
+
+      # The inactive member should have been processed
+      assert results.total >= 1
+
+      # Check the member's cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort() |> Enum.uniq()
+
+      # Should have 2021, 2022, 2023 (exit year included)
+      assert 2021 in cycle_years
+      assert 2022 in cycle_years
+      assert 2023 in cycle_years
+
+      # Should NOT have 2024 (after exit)
+      refute 2024 in cycle_years
+    end
+
+    test "exit_date on cycle_start still generates that cycle" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      today = ~D[2024-12-31]
+
+      # Member exits exactly on cycle start (2024-01-01)
+      # Create member and generate cycles with fixed "today" date
+      member =
+        create_member_with_cycles(
+          %{
+            join_date: ~D[2022-03-15],
+            exit_date: ~D[2024-01-01],
+            membership_fee_type_id: fee_type.id,
+            membership_fee_start_date: ~D[2022-01-01]
+          },
+          today
+        )
+
+      # Check cycles
+      cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # 2024 should be included because exit_date == cycle_start means
+      # the member was still a member on that day
+      assert 2022 in cycle_years
+      assert 2023 in cycle_years
+      assert 2024 in cycle_years
+
+      # 2025 should NOT be included
+      refute 2025 in cycle_years
+    end
+  end
+end

test/mv/membership_fees/cycle_generator_test.exs

@@ -0,0 +1,428 @@
+defmodule Mv.MembershipFees.CycleGeneratorTest do
+  @moduledoc """
+  Tests for the CycleGenerator module.
+  """
+  use Mv.DataCase, async: false
+
+  alias Mv.MembershipFees.CycleGenerator
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+  alias Mv.Membership.Member
+
+  require Ash.Query
+
+  # Helper to create a membership fee type
+  defp create_fee_type(attrs) do
+    default_attrs = %{
+      name: "Test Fee Type #{System.unique_integer([:positive])}",
+      amount: Decimal.new("50.00"),
+      interval: :yearly
+    }
+
+    attrs = Map.merge(default_attrs, attrs)
+
+    MembershipFeeType
+    |> Ash.Changeset.for_create(:create, attrs)
+    |> Ash.create!()
+  end
+
+  # Helper to create a member without triggering cycle generation
+  defp create_member_without_cycles(attrs) do
+    default_attrs = %{
+      first_name: "Test",
+      last_name: "User",
+      email: "test#{System.unique_integer([:positive])}@example.com"
+    }
+
+    attrs = Map.merge(default_attrs, attrs)
+
+    Member
+    |> Ash.Changeset.for_create(:create_member, attrs)
+    |> Ash.create!()
+  end
+
+  # Helper to set up settings with specific include_joining_cycle value
+  defp setup_settings(include_joining_cycle) do
+    {:ok, settings} = Mv.Membership.get_settings()
+
+    settings
+    |> Ash.Changeset.for_update(:update, %{include_joining_cycle: include_joining_cycle})
+    |> Ash.update!()
+  end
+
+  # Helper to get cycles for a member
+  defp get_member_cycles(member_id) do
+    MembershipFeeCycle
+    |> Ash.Query.filter(member_id == ^member_id)
+    |> Ash.Query.sort(cycle_start: :asc)
+    |> Ash.read!()
+  end
+
+  describe "generate_cycles_for_member/2" do
+    test "generates cycles from start date to today" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member WITHOUT fee type first to avoid auto-generation
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2022-03-15],
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      # Assign fee type
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Explicitly generate cycles with fixed "today" date to avoid date dependency
+      today = ~D[2024-06-15]
+      {:ok, _} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Verify cycles were generated
+      all_cycles = get_member_cycles(member.id)
+      cycle_years = Enum.map(all_cycles, & &1.cycle_start.year) |> Enum.sort() |> Enum.uniq()
+
+      # With include_joining_cycle=true and join_date=2022-03-15,
+      # start_date should be 2022-01-01
+      # Should have cycles for 2022, 2023, 2024
+      assert 2022 in cycle_years
+      assert 2023 in cycle_years
+      assert 2024 in cycle_years
+    end
+
+    test "generates cycles from last existing cycle" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member without fee type first to avoid auto-generation
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2022-03-15],
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      # Manually create a cycle for 2022
+      MembershipFeeCycle
+      |> Ash.Changeset.for_create(:create, %{
+        cycle_start: ~D[2022-01-01],
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id,
+        amount: fee_type.amount,
+        status: :paid
+      })
+      |> Ash.create!()
+
+      # Now assign fee type to member
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Generate cycles with specific "today" date
+      today = ~D[2024-06-15]
+      {:ok, new_cycles} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Should generate only 2023 and 2024 (2022 already exists)
+      new_cycle_years = Enum.map(new_cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      assert 2022 not in new_cycle_years
+    end
+
+    test "respects left_at boundary (stops generation)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2022-03-15],
+          exit_date: ~D[2023-06-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      # Generate cycles with specific "today" date far in the future
+      today = ~D[2025-06-15]
+      {:ok, cycles} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # With exit_date in 2023, should only generate 2022 and 2023 cycles
+      cycle_years = Enum.map(cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # Should not have 2024 or 2025 cycles
+      assert 2024 not in cycle_years
+      assert 2025 not in cycle_years
+    end
+
+    test "skips existing cycles (idempotent)" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2023-03-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2023-01-01]
+        })
+
+      today = ~D[2024-06-15]
+
+      # First generation
+      {:ok, _first_cycles} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Second generation (should be idempotent)
+      {:ok, second_cycles} = CycleGenerator.generate_cycles_for_member(member.id, today: today)
+
+      # Second call should return empty list (no new cycles)
+      assert second_cycles == []
+    end
+
+    test "does not fill gaps when cycles were deleted" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member without fee type first to control which cycles exist
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2020-03-15],
+          membership_fee_start_date: ~D[2020-01-01]
+        })
+
+      # Manually create cycles for 2020, 2021, 2022, 2023
+      for year <- [2020, 2021, 2022, 2023] do
+        MembershipFeeCycle
+        |> Ash.Changeset.for_create(:create, %{
+          cycle_start: Date.new!(year, 1, 1),
+          member_id: member.id,
+          membership_fee_type_id: fee_type.id,
+          amount: fee_type.amount,
+          status: :unpaid
+        })
+        |> Ash.create!()
+      end
+
+      # Delete the 2021 cycle (create a gap)
+      cycle_2021 =
+        MembershipFeeCycle
+        |> Ash.Query.filter(member_id == ^member.id and cycle_start == ^~D[2021-01-01])
+        |> Ash.read_one!()
+
+      Ash.destroy!(cycle_2021)
+
+      # Now assign fee type to member (this triggers generation)
+      # Since cycles already exist (2020, 2022, 2023), the generator will
+      # start from the last existing cycle (2023) and go forward
+      member =
+        member
+        |> Ash.Changeset.for_update(:update_member, %{membership_fee_type_id: fee_type.id})
+        |> Ash.update!()
+
+      # Verify gap was NOT filled and new cycles were generated from last existing
+      all_cycles = get_member_cycles(member.id)
+      all_cycle_years = Enum.map(all_cycles, & &1.cycle_start.year) |> Enum.sort()
+
+      # 2021 should NOT exist (gap was not filled)
+      refute 2021 in all_cycle_years, "Gap at 2021 should NOT be filled"
+
+      # 2020, 2022, 2023 should exist (original cycles)
+      assert 2020 in all_cycle_years
+      assert 2022 in all_cycle_years
+      assert 2023 in all_cycle_years
+
+      # 2024 and 2025 should exist (generated after last existing cycle 2023)
+      assert 2024 in all_cycle_years
+      assert 2025 in all_cycle_years
+    end
+
+    test "sets correct amount from membership fee type" do
+      setup_settings(true)
+      amount = Decimal.new("75.50")
+      fee_type = create_fee_type(%{interval: :yearly, amount: amount})
+
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2024-03-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2024-01-01]
+        })
+
+      # Verify cycles were generated with correct amount
+      all_cycles = get_member_cycles(member.id)
+      refute Enum.empty?(all_cycles), "Expected cycles to be generated"
+
+      # All cycles should have the correct amount
+      Enum.each(all_cycles, fn cycle ->
+        assert Decimal.equal?(cycle.amount, amount)
+      end)
+    end
+
+    test "handles NULL membership_fee_start_date by calculating from join_date" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :quarterly})
+
+      # Create member without membership_fee_start_date - it will be auto-calculated
+      # and cycles will be auto-generated
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2024-02-15],
+          membership_fee_type_id: fee_type.id
+          # No membership_fee_start_date - should be calculated
+        })
+
+      # Verify cycles were auto-generated
+      all_cycles = get_member_cycles(member.id)
+
+      # With include_joining_cycle=true and join_date=2024-02-15 (quarterly),
+      # start_date should be 2024-01-01 (Q1 start)
+      # Should have Q1, Q2, Q3, Q4 2024 cycles (based on current date)
+      refute Enum.empty?(all_cycles), "Expected cycles to be generated"
+
+      cycle_starts = Enum.map(all_cycles, & &1.cycle_start) |> Enum.sort(Date)
+      first_cycle_start = List.first(cycle_starts)
+
+      # First cycle should start in Q1 2024 (2024-01-01)
+      assert first_cycle_start == ~D[2024-01-01]
+    end
+
+    test "returns error when member has no membership_fee_type" do
+      # Create member without fee type - no auto-generation will occur
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2024-03-15]
+          # No membership_fee_type_id
+        })
+
+      {:error, reason} = CycleGenerator.generate_cycles_for_member(member.id)
+      assert reason == :no_membership_fee_type
+    end
+
+    test "returns error when member has no join_date" do
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create member without join_date - no auto-generation will occur
+      # (after_action hook checks for join_date)
+      member =
+        create_member_without_cycles(%{
+          membership_fee_type_id: fee_type.id
+          # No join_date
+        })
+
+      {:error, reason} = CycleGenerator.generate_cycles_for_member(member.id)
+      assert reason == :no_join_date
+    end
+
+    test "returns error when member not found" do
+      fake_id = Ash.UUID.generate()
+      {:error, reason} = CycleGenerator.generate_cycles_for_member(fake_id)
+      assert reason == :member_not_found
+    end
+  end
+
+  describe "generate_cycle_starts/3" do
+    test "generates correct cycle starts for yearly interval" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2022-01-01], ~D[2024-06-15], :yearly)
+
+      assert starts == [~D[2022-01-01], ~D[2023-01-01], ~D[2024-01-01]]
+    end
+
+    test "generates correct cycle starts for quarterly interval" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2024-01-01], ~D[2024-09-15], :quarterly)
+
+      assert starts == [~D[2024-01-01], ~D[2024-04-01], ~D[2024-07-01]]
+    end
+
+    test "generates correct cycle starts for monthly interval" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2024-01-01], ~D[2024-03-15], :monthly)
+
+      assert starts == [~D[2024-01-01], ~D[2024-02-01], ~D[2024-03-01]]
+    end
+
+    test "generates correct cycle starts for half_yearly interval" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2023-01-01], ~D[2024-09-15], :half_yearly)
+
+      assert starts == [~D[2023-01-01], ~D[2023-07-01], ~D[2024-01-01], ~D[2024-07-01]]
+    end
+
+    test "returns empty list when start_date is after end_date" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2025-01-01], ~D[2024-06-15], :yearly)
+
+      assert starts == []
+    end
+
+    test "includes cycle when end_date is on cycle start" do
+      starts = CycleGenerator.generate_cycle_starts(~D[2024-01-01], ~D[2024-01-01], :yearly)
+
+      assert starts == [~D[2024-01-01]]
+    end
+  end
+
+  describe "generate_cycles_for_all_members/1" do
+    test "generates cycles for multiple members" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      # Create multiple members
+      _member1 =
+        create_member_without_cycles(%{
+          join_date: ~D[2024-01-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2024-01-01]
+        })
+
+      _member2 =
+        create_member_without_cycles(%{
+          join_date: ~D[2024-02-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2024-01-01]
+        })
+
+      today = ~D[2024-06-15]
+      {:ok, results} = CycleGenerator.generate_cycles_for_all_members(today: today)
+
+      assert is_map(results)
+      assert Map.has_key?(results, :success)
+      assert Map.has_key?(results, :failed)
+      assert Map.has_key?(results, :total)
+    end
+  end
+
+  describe "lock mechanism" do
+    test "prevents concurrent generation for same member" do
+      setup_settings(true)
+      fee_type = create_fee_type(%{interval: :yearly})
+
+      member =
+        create_member_without_cycles(%{
+          join_date: ~D[2022-03-15],
+          membership_fee_type_id: fee_type.id,
+          membership_fee_start_date: ~D[2022-01-01]
+        })
+
+      today = ~D[2024-06-15]
+
+      # Run two concurrent generations
+      task1 =
+        Task.async(fn -> CycleGenerator.generate_cycles_for_member(member.id, today: today) end)
+
+      task2 =
+        Task.async(fn -> CycleGenerator.generate_cycles_for_member(member.id, today: today) end)
+
+      result1 = Task.await(task1)
+      result2 = Task.await(task2)
+
+      # Both should succeed
+      assert match?({:ok, _}, result1)
+      assert match?({:ok, _}, result2)
+
+      # One should have created cycles, the other should have empty list (idempotent)
+      {:ok, cycles1} = result1
+      {:ok, cycles2} = result2
+
+      # Combined should not have duplicates
+      all_cycles = cycles1 ++ cycles2
+      unique_starts = all_cycles |> Enum.map(& &1.cycle_start) |> Enum.uniq()
+
+      assert length(all_cycles) == length(unique_starts)
+    end
+  end
+end