chore: init commit

in worker.../repo/GITFOLDER.zip is the .git folder.

worker-toolkit-stocks-in-the-future/repo/app/models/classroom_enrollment.rb

@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+# Represents a student's enrollment in a classroom, supporting multiple
+# enrollments over time with historical tracking.
+#
+# A student can have multiple enrollment records for the same classroom
+# (e.g., enrolled in Fall 2023, then again in Spring 2024), and can be
+# enrolled in multiple classrooms simultaneously.
+#
+# @example Find a student's current enrollments
+#   student.classroom_enrollments.current
+#
+# @example Find a student's enrollment history
+#   student.classroom_enrollments.historical
+#
+# @example Get a student's primary classroom
+#   student.primary_enrollment&.classroom
+class ClassroomEnrollment < ApplicationRecord
+  belongs_to :student, class_name: "Student"
+  belongs_to :classroom
+
+  validates :enrolled_at, presence: true
+  validate :unenrolled_at_after_enrolled_at
+  validate :only_one_primary_per_student, if: :primary?
+
+  scope :current, -> { where(unenrolled_at: nil) }
+  scope :historical, -> { where.not(unenrolled_at: nil) }
+  scope :primary_enrollment, -> { where(primary: true) }
+  scope :for_student, ->(student) { where(student: student) }
+  scope :for_classroom, ->(classroom) { where(classroom: classroom) }
+
+  # Mark this enrollment as the primary enrollment for the student
+  # and demote any other primary enrollments
+  #
+  # @return [self]
+  def make_primary!
+    transaction do
+      ClassroomEnrollment.where(student: student, primary: true)
+        .where.not(id: id)
+        .find_each { |enrollment| enrollment.update!(primary: false) }
+      update!(primary: true)
+    end
+    self
+  end
+
+  # Unenroll the student from this classroom
+  #
+  # @param at [DateTime] when the student was unenrolled (defaults to now)
+  # @return [self]
+  def unenroll!(at: Time.current)
+    update!(unenrolled_at: at, primary: false)
+    self
+  end
+
+  # Check if this enrollment is currently active
+  #
+  # @return [Boolean]
+  def current?
+    unenrolled_at.nil?
+  end
+
+  # Check if this enrollment is historical (no longer active)
+  #
+  # @return [Boolean]
+  def historical?
+    !current?
+  end
+
+  private
+
+  def unenrolled_at_after_enrolled_at
+    return if unenrolled_at.blank? || enrolled_at.blank?
+    return if unenrolled_at >= enrolled_at
+
+    errors.add(:unenrolled_at, "must be after enrolled_at")
+  end
+
+  def only_one_primary_per_student
+    return if student_id.blank?
+
+    existing = ClassroomEnrollment.where(student_id: student_id, primary: true)
+      .where.not(id: id)
+      .exists?
+
+    errors.add(:primary, "student can only have one primary enrollment") if existing
+  end
+end