diff --git a/Gemfile b/Gemfile
index 66ceee92..289cbdc0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -36,6 +36,7 @@ gem 'sentry-ruby'
 gem 'simple_form'
 gem 'skylight'
 gem 'terser'
+gem 'webmock'
 gem 'zip_tricks'
 
 group :production do
diff --git a/Gemfile.lock b/Gemfile.lock
index f6647010..8c5b5136 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -154,6 +154,9 @@ GEM
     cocoon (1.2.15)
     concurrent-ruby (1.3.5)
     connection_pool (2.5.3)
+    crack (1.0.0)
+      bigdecimal
+      rexml
     crass (1.0.6)
     date (3.4.1)
     delayed_job (4.1.13)
@@ -182,6 +185,7 @@ GEM
       terminal-table (>= 1.8)
     globalid (1.2.1)
       activesupport (>= 6.1)
+    hashdiff (1.2.0)
     hashie (5.0.0)
     i18n (1.14.7)
       concurrent-ruby (~> 1.0)
@@ -445,6 +449,10 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
+    webmock (3.25.1)
+      addressable (>= 2.8.0)
+      crack (>= 0.3.2)
+      hashdiff (>= 0.4.0, < 2.0.0)
     websocket (1.2.11)
     websocket-driver (0.7.7)
       base64
@@ -509,6 +517,7 @@ DEPENDENCIES
   terser
   timecop
   web-console
+  webmock
   zip_tricks
 
 RUBY VERSION
diff --git a/README.md b/README.md
index d2da0fc0..47593781 100644
--- a/README.md
+++ b/README.md
@@ -159,6 +159,19 @@ polling by specifying a longer queue wait time. Defaults to 10 if unset.
 `SQS_RESULT_IDLE_TIMEOUT` - Configures the :idle_timeout arg of the AWS poll method, which specifies the maximum time
 in seconds to wait for a new message before the polling loop exists. Defaults to 0 if unset.
 
+### Archival Packaging Tool (APT) configuration
+
+The following enviroment variables are needed to communicate with [APT](https://github.com/MITLibraries/archival-packaging-tool), which is used in the
+[preservation workflow](#publishing-workflow).
+
+`APT_CHALLENGE_SECRET` - Secret value used to authenticate requests to the APT Lambda endpoint.
+`APT_VERBOSE` - If set to `true`, enables verbose logging for APT requests.
+`APT_CHECKSUMS_TO_GENERATE` - Array of checksum algorithms to generate for files (default: ['md5']).
+`APT_COMPRESS_ZIP` - Boolean value to indicate whether the output bag should be compressed as a zip
+file (default: true).
+`APT_S3_BUCKET` - S3 bucket URI where APT output bags are stored.
+`APT_LAMBDA_URL` - The URL of the APT Lambda endpoint for preservation requests.
+
 ### Email configuration
 
 `SMTP_ADDRESS`, `SMTP_PASSWORD`, `SMTP_PORT`, `SMTP_USER` - all required to send mail.
@@ -397,15 +410,15 @@ Note: `Pending publication` is allowed here, but not expected to be a normal occ
 ## Preservation workflow
 
 The publishing workflow will automatically trigger preservation for all of the published theses in the results queue.
-At this point a submission information package is generated for each thesis, then a bag is constructed, zipped, and
-streamed to an S3 bucket. (See the SubmissionInformationPackage and SubmissionInformationPackageZipper classes for more
-details on this part of the process.)
 
-Once they are in the S3 bucket, the bags are automatically replicated to the Digital Preservation S3 bucket, where they
-can be ingested into Archivematica.
+At this point, the preservation job will generate an Archivematica payload for each thesis, which
+are then POSTed to [APT](https://github.com/MITLibraries/archival-packaging-tool) for further processing. Each payload includes a metadata CSV and a JSON object containing structural information about the thesis files. 
+
+Once the payloads are sent to APT, each thesis is structured as a BagIt bag and saved to an S3
+bucket, where they can be ingested into Archivematica.
 
-A thesis can be sent to preservation more than once. In order to track provenance across multiple preservation events,
-we persist certain data about the SIP and audit the model using `paper_trail`.
+A thesis can be sent to preservation more than once. In order to track provenance across multiple preservation events, we persist certain data about the Archivematica payload and audit the model
+using `paper_trail`.
 
 ### Preserving a single thesis
 
diff --git a/app/jobs/preservation_submission_job.rb b/app/jobs/preservation_submission_job.rb
index df6c83aa..13ab5f1c 100644
--- a/app/jobs/preservation_submission_job.rb
+++ b/app/jobs/preservation_submission_job.rb
@@ -1,4 +1,7 @@
 class PreservationSubmissionJob < ActiveJob::Base
+  require 'net/http'
+  require 'uri'
+
   queue_as :default
 
   def perform(theses)
@@ -6,8 +9,8 @@ def perform(theses)
     results = { total: theses.count, processed: 0, errors: [] }
     theses.each do |thesis|
       Rails.logger.info("Thesis #{thesis.id} is now being prepared for preservation")
-      sip = thesis.submission_information_packages.create!
-      preserve_sip(sip)
+      payload = thesis.archivematica_payloads.create!
+      preserve_payload(payload)
       Rails.logger.info("Thesis #{thesis.id} has been sent to preservation")
       results[:processed] += 1
     rescue StandardError, Aws::Errors => e
@@ -20,10 +23,34 @@ def perform(theses)
 
   private
 
-  def preserve_sip(sip)
-    SubmissionInformationPackageZipper.new(sip)
-    sip.preservation_status = 'preserved'
-    sip.preserved_at = DateTime.now
-    sip.save
+  def preserve_payload(payload)
+    post_payload(payload)
+    payload.preservation_status = 'preserved'
+    payload.preserved_at = DateTime.now
+    payload.save!
+  end
+
+  def post_payload(payload)
+    s3_url = ENV.fetch('APT_LAMBDA_URL', nil)
+    uri = URI.parse(s3_url)
+    request = Net::HTTP::Post.new(uri, { 'Content-Type' => 'application/json' })
+    request.body = payload.payload_json
+
+    response = Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == 'https') do |http|
+      http.request(request)
+    end
+
+    validate_response(response)
+  end
+
+  def validate_response(response)
+    unless response.is_a?(Net::HTTPSuccess)
+      raise "Failed to post Archivematica payload to APT: #{response.code} #{response.body}"
+    end
+
+    result = JSON.parse(response.body)
+    unless result['success'] == true
+      raise "APT failed to create a bag: #{response.body}"
+    end
   end
 end
diff --git a/app/models/archivematica_payload.rb b/app/models/archivematica_payload.rb
new file mode 100644
index 00000000..91efdf23
--- /dev/null
+++ b/app/models/archivematica_payload.rb
@@ -0,0 +1,101 @@
+# == Schema Information
+#
+# Table name: archivematica_payloads
+#
+#  id                  :integer          not null, primary key
+#  preservation_status :integer          default("unpreserved"), not null
+#  payload_json        :text
+#  preserved_at        :datetime
+#  thesis_id           :integer          not null
+#  created_at          :datetime         not null
+#  updated_at          :datetime         not null
+#
+# This class assembles a payload to send to the Archival Packaging Tool (APT), which then creates a bag for
+# preservation. It includes the thesis files, metadata, and checksums. The payload is then serialized to JSON
+# for transmission.
+#
+# Instances of this class are invalid without an associated thesis that has a DSpace handle, a copyright, and
+# at least one attached file with no duplicate filenames.
+#
+# There is some intentional duplication between this and the SubmissionInformationPackage model. The
+# SubmissionInformationPackage is the legacy model that was used to create the bag, but it is not
+# used in the current APT workflow. We are retaining it for historical purposes.
+class ArchivematicaPayload < ApplicationRecord
+  include Checksums
+  include Baggable
+
+  has_paper_trail
+  belongs_to :thesis
+  has_one_attached :metadata_csv
+
+  validates :baggable?, presence: true
+
+  before_create :set_metadata_csv, :set_payload_json
+
+  enum preservation_status: %i[unpreserved preserved]
+
+  private
+
+  # compress_zip is cast to a boolean to override the string value from ENV. APT strictly requires
+  # a boolean for this field.
+  def build_payload
+    {
+      action: 'create-bagit-zip',
+      challenge_secret: ENV.fetch('APT_CHALLENGE_SECRET', nil),
+      verbose: ActiveModel::Type::Boolean.new.cast(ENV.fetch('APT_VERBOSE', false)),
+      input_files: build_input_files,
+      checksums_to_generate: ENV.fetch('APT_CHECKSUMS_TO_GENERATE', ['md5']),
+      output_zip_s3_uri: bag_output_uri,
+      compress_zip: ActiveModel::Type::Boolean.new.cast(ENV.fetch('APT_COMPRESS_ZIP', true))
+    }
+  end
+
+  # Build input_files array from thesis files and attached metadata CSV
+  def build_input_files
+    files = thesis.files.map { |file| build_file_entry(file) }
+    files << build_file_entry(metadata_csv) # Metadata CSV is the only file that is generated in this model
+    files
+  end
+
+  # Build a file entry for each file, including the metadata CSV.
+  def build_file_entry(file)
+    {
+      uri: ["s3://#{ENV.fetch('AWS_S3_BUCKET')}", file.blob.key].join('/'),
+      filepath: set_filepath(file),
+      checksums: {
+        md5: base64_to_hex(file.blob.checksum)
+      }
+    }
+  end
+
+  def set_filepath(file)
+    file == metadata_csv ? 'metadata/metadata.csv' : file.filename.to_s
+  end
+
+  # The bag_name has to be unique due to our using it as the basis of an ActiveStorage key. Using a UUID
+  # was not preferred as the target system of these bags adds it's own UUID to the file when it arrives there
+  # so the filename was unwieldy with two UUIDs embedded in it so we simply increment integers.
+  def bag_name
+    safe_handle = thesis.dspace_handle.gsub('/', '_')
+    "#{safe_handle}-thesis-#{thesis.submission_information_packages.count + 1}"
+  end
+
+  # The bag_output_uri key is constructed to match the expected format for Archivematica.
+  def bag_output_uri
+    key = "etdsip/#{thesis.graduation_year}/#{thesis.graduation_month}-#{thesis.accession_number}/#{bag_name}.zip"
+    [ENV.fetch('APT_S3_BUCKET'), key].join('/')
+  end
+
+  def baggable?
+    baggable_thesis?(thesis)
+  end
+
+  def set_metadata_csv
+    csv_data = ArchivematicaMetadata.new(thesis).to_csv
+    metadata_csv.attach(io: StringIO.new(csv_data), filename: 'metadata.csv', content_type: 'text/csv')
+  end
+
+  def set_payload_json
+    self.payload_json = build_payload.to_json
+  end
+end
diff --git a/app/models/submission_information_package.rb b/app/models/submission_information_package.rb
index 893d0699..f440e5dc 100644
--- a/app/models/submission_information_package.rb
+++ b/app/models/submission_information_package.rb
@@ -14,6 +14,10 @@
 #  updated_at          :datetime         not null
 #
 
+# This model is no longer used, but it is retained for historical purposes and to preserve existing
+# data. Its functionality has been replaced by the ArchivematicaPayload model, which is used in the
+# current preservation workflow.
+#
 # Creates the structure for an individual thesis to be preserved in Archivematica according to the BagIt spec:
 # https://datatracker.ietf.org/doc/html/rfc8493.
 #
diff --git a/app/models/submission_information_package_zipper.rb b/app/models/submission_information_package_zipper.rb
deleted file mode 100644
index bdf179df..00000000
--- a/app/models/submission_information_package_zipper.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-# SubmissionInformationPackageZipper creates a temporary zip file containing a bag and then attaches it via
-# ActiveStorage. The `keygen` method creates the `path` to the file in S3. We are relying on S3 Replication to copy
-# the objects from the ETD bucket to the Archivematica bucket. There is no automatic communication back from S3 or
-# Archivematica to ETD, so we treat the successful save of the zip file as `preserved`.
-class SubmissionInformationPackageZipper
-  def initialize(sip)
-    Tempfile.create([sip.bag_name.to_s, '.zip'], binmode: true) do |tmpfile|
-      bagamatic(sip, tmpfile)
-
-      sip.bag.attach(io: File.open(tmpfile),
-                     key: keygen(sip),
-                     filename: "#{sip.bag_name}.zip",
-                     content_type: 'application/zip')
-    end
-  end
-
-  private
-
-  # This key needs to be unique. By default, ActiveStorage generates a UUID, but since we want a file path for our
-  # Archivematica needs, we are generating a key. We handle uniqueness on the `bag_name` side.
-  def keygen(sip)
-    thesis = sip.thesis
-    "etdsip/#{thesis.graduation_year}/#{thesis.graduation_month}-#{thesis.accession_number}/#{sip.bag_name}.zip"
-  end
-
-  # bagamatic takes a sip, creates a temporary zip file, and returns that file
-  def bagamatic(sip, tmpfile)
-    ZipTricks::Streamer.open(tmpfile) do |zip|
-      # bag manifest
-      zip.write_deflated_file('manifest-md5.txt') do |sink|
-        sink << sip.manifest
-      end
-
-      # bag_declaration
-      zip.write_deflated_file('bagit.txt') do |sink|
-        sink << sip.bag_declaration
-      end
-
-      # files. metadata.csv is just a string so we have to treat it differently than the binary stored files
-      sip.data.each do |data|
-        if data[1].is_a?(String)
-          zip.write_deflated_file(data[0]) do |sink|
-            sink << data[1]
-          end
-        else
-          zip.write_stored_file(data[0]) do |sink|
-            sink << data[1].download
-          end
-        end
-      end
-    end
-    tmpfile.close
-  end
-end
diff --git a/app/models/thesis.rb b/app/models/thesis.rb
index 1c2ee202..2c2b7390 100644
--- a/app/models/thesis.rb
+++ b/app/models/thesis.rb
@@ -48,6 +48,7 @@ class Thesis < ApplicationRecord
   has_many :users, through: :authors
 
   has_many :submission_information_packages, dependent: :destroy
+  has_many :archivematica_payloads, dependent: :destroy
 
   has_many_attached :files
   has_one_attached :dspace_metadata
diff --git a/config/environments/test.rb b/config/environments/test.rb
index 0324c05f..03a8489b 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -40,9 +40,14 @@
   ENV['SQS_RESULT_WAIT_TIME_SECONDS'] = '10'
   ENV['SQS_RESULT_IDLE_TIMEOUT'] = '0'
   ENV['AWS_REGION'] = 'us-east-1'
+  ENV['AWS_S3_BUCKET'] = 'fake-etd-bucket'
   ENV['DSPACE_DOCTORAL_HANDLE'] = '1721.1/999999'
   ENV['DSPACE_GRADUATE_HANDLE'] = '1721.1/888888'
   ENV['DSPACE_UNDERGRADUATE_HANDLE'] = '1721.1/777777'
+  ENV['APT_CHALLENGE_SECRET'] = 'fake-challenge-secret'
+  ENV['APT_S3_BUCKET'] = 's3://fake-apt-bucket'
+  ENV['APT_LAMBDA_URL'] = 'https://fake-lambda.example.com/'
+  ENV['APT_COMPRESS_ZIP'] = 'true'
 
   # While tests run files are not watched, reloading is not necessary.
   config.enable_reloading = false
diff --git a/db/migrate/20250624182142_create_archivematica_payloads.rb b/db/migrate/20250624182142_create_archivematica_payloads.rb
new file mode 100644
index 00000000..12ee7d29
--- /dev/null
+++ b/db/migrate/20250624182142_create_archivematica_payloads.rb
@@ -0,0 +1,13 @@
+class CreateArchivematicaPayloads < ActiveRecord::Migration[7.1]
+  def change
+    create_table :archivematica_payloads do |t|
+      t.integer :preservation_status, null: false, default: 0
+      t.text :payload_json
+      t.datetime :preserved_at
+
+      t.references :thesis, null: false, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 1d1610c4..08e8f3a7 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2025_02_21_202836) do
+ActiveRecord::Schema[7.1].define(version: 2025_06_24_182142) do
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -65,6 +65,16 @@
     t.index ["degree_period_id"], name: "index_archivematica_accessions_on_degree_period_id", unique: true
   end
 
+  create_table "archivematica_payloads", force: :cascade do |t|
+    t.integer "preservation_status", default: 0, null: false
+    t.text "payload_json"
+    t.datetime "preserved_at"
+    t.integer "thesis_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["thesis_id"], name: "index_archivematica_payloads_on_thesis_id"
+  end
+
   create_table "authors", force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "thesis_id", null: false
@@ -290,6 +300,7 @@
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
   add_foreign_key "archivematica_accessions", "degree_periods"
+  add_foreign_key "archivematica_payloads", "theses"
   add_foreign_key "authors", "theses"
   add_foreign_key "authors", "users"
   add_foreign_key "degrees", "degree_types"
diff --git a/test/jobs/preservation_submission_job_test.rb b/test/jobs/preservation_submission_job_test.rb
index 55108272..66aee414 100644
--- a/test/jobs/preservation_submission_job_test.rb
+++ b/test/jobs/preservation_submission_job_test.rb
@@ -1,4 +1,5 @@
 require 'test_helper'
+require 'webmock/minitest'
 
 class PreservationSubmissionJobTest < ActiveJob::TestCase
 
@@ -16,7 +17,55 @@ def setup_thesis
     thesis
   end
 
-  test 'sends report emails' do
+  def setup_thesis_two
+    thesis = theses(:published_with_sip)
+    thesis.files = []
+    thesis.save
+    file = Rails.root.join('test', 'fixtures', 'files', 'registrar_data_small_sample.csv')
+    thesis.files.attach(io: File.open(file), filename: 'registrar_data_small_sample.csv')
+    thesis
+  end
+
+  def stub_apt_lambda_success
+    stub_request(:post, ENV['APT_LAMBDA_URL'])
+      .to_return(
+        status: 200,
+        body: {
+          success: true,
+          bag: {
+            entries: {
+              "manifest-md5.txt" => { md5: "fakehash" }
+            }
+          },
+          output_zip_s3_uri: "s3://my-bucket/apt-testing/test-one-medium.zip"
+        }.to_json,
+        headers: { 'Content-Type' => 'application/json' }
+      )
+  end
+
+  def stub_apt_lambda_failure
+    stub_request(:post, ENV['APT_LAMBDA_URL'])
+      .to_return(
+        status: 500,
+        headers: { 'Content-Type' => 'application/json' }
+      )
+  end
+
+  def stub_apt_lambda_200_failure
+    stub_request(:post, ENV['APT_LAMBDA_URL'])
+      .to_return(
+        status: 200,
+        body: {
+          success: false,
+          error: "An error occurred (404) when calling the HeadObject operation: Not Found",
+          bag: { entries: {}},
+        }.to_json,
+        headers: { 'Content-Type' => 'application/json' }
+      )
+  end
+
+  test 'sends report emails on success' do
+    stub_apt_lambda_success
     ClimateControl.modify DISABLE_ALL_EMAIL: 'false' do
       assert_difference('ActionMailer::Base.deliveries.size', 1) do
         PreservationSubmissionJob.perform_now([setup_thesis])
@@ -24,60 +73,118 @@ def setup_thesis
     end
   end
 
-  test 'creates a SIP' do
+  test 'sends report emails on failure' do
+    stub_apt_lambda_success
+    ClimateControl.modify DISABLE_ALL_EMAIL: 'false' do
+      assert_difference('ActionMailer::Base.deliveries.size', 1) do
+        PreservationSubmissionJob.perform_now([setup_thesis])
+      end
+    end
+  end
+
+  test 'sends report email if post succeeds but APT fails' do
+    stub_apt_lambda_200_failure
+    ClimateControl.modify DISABLE_ALL_EMAIL: 'false' do
+      assert_difference('ActionMailer::Base.deliveries.size', 1) do
+        PreservationSubmissionJob.perform_now([setup_thesis])
+      end
+    end
+  end
+
+  test 'creates an Archivematica payload' do
+    stub_apt_lambda_success
     thesis = setup_thesis
-    assert_equal 0, thesis.submission_information_packages.count
+    assert_equal 0, thesis.archivematica_payloads.count
 
     PreservationSubmissionJob.perform_now([thesis])
-    assert_equal 1, thesis.submission_information_packages.count
+    assert_equal 1, thesis.archivematica_payloads.count
   end
 
-  test 'creates multiple SIPs' do
+  test 'creates multiple Archivematica payloads' do
+    stub_apt_lambda_success
     thesis_one = setup_thesis
     thesis_two = theses(:engineer)
-    assert_equal 0, thesis_one.submission_information_packages.count
-    assert_equal 0, thesis_two.submission_information_packages.count
+    assert_equal 0, thesis_one.archivematica_payloads.count
+    assert_equal 0, thesis_two.archivematica_payloads.count
 
     theses = [thesis_one, thesis_two]
     PreservationSubmissionJob.perform_now(theses)
-    assert_equal 1, thesis_one.submission_information_packages.count
-    assert_equal 1, thesis_two.submission_information_packages.count
+    assert_equal 1, thesis_one.archivematica_payloads.count
+    assert_equal 1, thesis_two.archivematica_payloads.count
 
     PreservationSubmissionJob.perform_now(theses)
-    assert_equal 2, thesis_one.submission_information_packages.count
-    assert_equal 2, thesis_two.submission_information_packages.count
+    assert_equal 2, thesis_one.archivematica_payloads.count
+    assert_equal 2, thesis_two.archivematica_payloads.count
   end
 
   test 'updates preservation_status to "preserved" after successfully processing a thesis' do
+    stub_apt_lambda_success
     thesis = setup_thesis
     PreservationSubmissionJob.perform_now([thesis])
-    assert_equal 'preserved', thesis.submission_information_packages.last.preservation_status
+    assert_equal 'preserved', thesis.archivematica_payloads.last.preservation_status
   end
 
   test 'updates preserved_at to the current time after successfully processing a thesis' do
+    stub_apt_lambda_success
     time = DateTime.new.getutc
     Timecop.freeze(time) do
       thesis = setup_thesis
       PreservationSubmissionJob.perform_now([thesis])
-      assert_equal time, thesis.submission_information_packages.last.preserved_at
+      assert_equal time, thesis.archivematica_payloads.last.preserved_at
     end
   end
 
   test 'throws exceptions when a thesis is unbaggable' do
+    stub_apt_lambda_failure
     assert_raises StandardError do
       PreservationSubmissionJob.perform_now([theses[:one]])
     end
 
+    stub_apt_lambda_success
     assert_nothing_raised do
       PreservationSubmissionJob.perform_now([setup_thesis])
     end
   end
 
-  test 'does not create a SIP if the job enters an error state' do
-    thesis = theses(:one)
-    assert_empty thesis.submission_information_packages
+  test 'does not create payloads if job fails' do
+    stub_apt_lambda_failure
+    bad_thesis = theses(:one)
+    good_thesis = setup_thesis
+    another_good_thesis = setup_thesis_two
+    assert_empty bad_thesis.archivematica_payloads
+    assert_empty good_thesis.archivematica_payloads
+    assert_empty another_good_thesis.archivematica_payloads
 
-    PreservationSubmissionJob.perform_now([thesis])
-    assert_empty thesis.submission_information_packages
+    PreservationSubmissionJob.perform_now([good_thesis, bad_thesis, another_good_thesis])
+
+    # first thesis should succeed and have a payload
+    assert_equal 1, good_thesis.archivematica_payloads.count
+
+    # second thesis should fail and not have a payload
+    assert_empty bad_thesis.archivematica_payloads
+
+    # third thesis should succeed and have a payload, despite prior failure
+    assert_equal 1, another_good_thesis.archivematica_payloads.count
+  end
+
+  test 'does not create payloads if post succeeds but APT fails' do
+    stub_apt_lambda_200_failure
+    bad_thesis = theses(:one)
+    good_thesis = setup_thesis
+    another_good_thesis = setup_thesis_two
+    assert_empty bad_thesis.archivematica_payloads
+    assert_empty good_thesis.archivematica_payloads
+    assert_empty another_good_thesis.archivematica_payloads
+
+    PreservationSubmissionJob.perform_now([good_thesis, bad_thesis, another_good_thesis])
+
+    # first thesis should succeed and have a payload
+    assert_equal 1, good_thesis.archivematica_payloads.count
+
+    # second thesis should fail and not have a payload
+    assert_empty bad_thesis.archivematica_payloads
+
+    # third thesis should succeed and have a payload, despite prior failure
+    assert_equal 1, another_good_thesis.archivematica_payloads.count
   end
 end
diff --git a/test/models/archivematica_payload_test.rb b/test/models/archivematica_payload_test.rb
new file mode 100644
index 00000000..6de45836
--- /dev/null
+++ b/test/models/archivematica_payload_test.rb
@@ -0,0 +1,63 @@
+# == Schema Information
+#
+# Table name: archivematica_payloads
+#
+#  id                  :integer          not null, primary key
+#  preservation_status :integer          default("unpreserved"), not null
+#  payload_json        :text
+#  preserved_at        :datetime
+#  thesis_id           :integer          not null
+#  created_at          :datetime         not null
+#  updated_at          :datetime         not null
+#
+require 'test_helper'
+
+class ArchivematicaPayloadTest < ActiveSupport::TestCase
+  def setup
+    @thesis = theses(:published)
+    @payload = @thesis.archivematica_payloads.create!
+  end
+
+  test 'new payload has default preservation_status of unpreserved' do
+    assert_equal 'unpreserved', @payload.preservation_status
+  end
+
+  test 'payload_json exists and contains valid JSON' do
+    assert @payload.payload_json.present?
+
+    json = @payload.payload_json
+    assert json.is_a?(String) # Payload JSON should be a string
+
+    parsed = JSON.parse(json)
+    assert parsed.is_a?(Hash) # Parsed JSON should be a valid hash
+  end
+
+  test 'payload_json contains expected structure' do
+    parsed = JSON.parse(@payload.payload_json)
+    assert_equal parsed['action'], 'create-bagit-zip'
+    assert parsed['challenge_secret']
+    assert_not_nil parsed['verbose']
+    assert parsed['input_files'].is_a?(Array)
+    assert_equal ['md5'], parsed['checksums_to_generate']
+    assert parsed['output_zip_s3_uri'].end_with?('.zip')
+    assert parsed['compress_zip'].in?([true, false])
+    # Check S3 URI format
+    parsed['input_files'].each do |file|
+      assert_match %r{^s3://#{ENV.fetch('AWS_S3_BUCKET', nil)}/}, file['uri']
+    end
+  end
+
+  test 'input_files includes thesis files and metadata_csv' do
+    parsed = JSON.parse(@payload.payload_json)
+    thesis_files = @thesis.files.count
+    assert_equal thesis_files + 1, parsed['input_files'].size
+    assert_equal @thesis.files.first.filename.to_s, parsed['input_files'].first['filepath']
+    assert_equal 'metadata/metadata.csv', parsed['input_files'].last['filepath']
+  end
+
+  test 'metadata_csv is attached and has correct filename/content type' do
+    assert @payload.metadata_csv.attached?
+    assert_equal 'metadata.csv', @payload.metadata_csv.filename.to_s
+    assert_equal 'text/csv', @payload.metadata_csv.content_type
+  end
+end
diff --git a/test/models/submission_information_package_zipper_test.rb b/test/models/submission_information_package_zipper_test.rb
deleted file mode 100644
index 2857178f..00000000
--- a/test/models/submission_information_package_zipper_test.rb
+++ /dev/null
@@ -1,50 +0,0 @@
-require 'test_helper'
-
-class SubmissionInformationPackageZipperTest < ActiveSupport::TestCase
-    
-  # because we need to actually use the file it's easier to attach it in the test rather
-  # than use our fixtures as the fixtures oddly don't account for the file actually being
-  # where ActiveStorage expects them to be. We also need this to be a record that looks like
-  # a published record so we'll use the published fixture, remove the fixtured files, and attach
-  # one again.
-  def setup_thesis
-    thesis = theses(:published)
-    thesis.files = []
-    thesis.save
-    file = Rails.root.join('test', 'fixtures', 'files', 'registrar_data_small_sample.csv')
-    thesis.files.attach(io: File.open(file), filename: 'registrar_data_small_sample.csv')
-    thesis
-  end
-
-  test 'sip has an attached zipped bag' do
-    thesis = setup_thesis
-    sip = thesis.submission_information_packages.create
-    SubmissionInformationPackageZipper.new(sip)
-
-    assert_equal("application/zip", thesis.submission_information_packages.first.bag.blob.content_type)
-  end
-
-  # Failure to properly close the handles can allow the zip creation to appear correct but actually be invalid
-  # this is a regression test to ensure we avoid that situation
-  # You can see this test fail by removing the `tmpfile.close` from the end of bagamatic.
-  test 'zip is valid' do
-    thesis = setup_thesis
-    sip = thesis.submission_information_packages.create
-    SubmissionInformationPackageZipper.new(sip)
-
-    blob = thesis.submission_information_packages.last.bag.blob
-    Zip::File.open(blob.service.send(:path_for, blob.key)) do |zipfile|
-      assert_nil(zipfile.find_entry("file_not_in_zipfile.txt"))
-      assert_equal('manifest-md5.txt', zipfile.find_entry("manifest-md5.txt").to_s)
-    end
-  end
-
-  test 'sip has the correct key' do
-    thesis = setup_thesis
-    sip = thesis.submission_information_packages.create
-    SubmissionInformationPackageZipper.new(sip)
-
-    blob = thesis.submission_information_packages.last.bag.blob
-    assert blob.key.starts_with? "etdsip/#{thesis.graduation_year}/#{thesis.graduation_month}-#{thesis.accession_number}"
-  end
-end