diff --git a/ee/lib/remote_development/workspace_updates_processor.rb b/ee/lib/remote_development/workspace_updates_processor.rb
index bd3019bd92e465539458a931a5ff2c3c581116d4..4036ecd793b86ca1ebe22435b97c09736d3839a4 100644
--- a/ee/lib/remote_development/workspace_updates_processor.rb
+++ b/ee/lib/remote_development/workspace_updates_processor.rb
@@ -67,7 +67,7 @@ def process(workspace_agent_infos:, update_type:)
           persisted_actual_state_is_terminated: workspace.actual_state == States::TERMINATED, # help agentk manage state
           desired_state_is_terminated: workspace.desired_state == States::TERMINATED,
           config_to_apply: config_to_apply(workspace: workspace, update_type: update_type)
-        }.compact # remove nil entries
+        }
 
         workspace_rails_info
       end
diff --git a/ee/spec/features/remote_development/workspaces_spec.rb b/ee/spec/features/remote_development/workspaces_spec.rb
index 187f1f72b066a9785161b1033a7b8ca8ddcf0081..48615c2ce41be2047fb1eca8fc2a5b3bf5fa548a 100644
--- a/ee/spec/features/remote_development/workspaces_spec.rb
+++ b/ee/spec/features/remote_development/workspaces_spec.rb
@@ -65,7 +65,7 @@
 
         workspaces = RemoteDevelopment::Workspace.all.to_a
         expect(workspaces.length).to eq(1)
-        workspace = workspaces.first
+        workspace = workspaces[0]
         id = workspace.id
         name = workspace.name
         namespace = workspace.namespace
@@ -90,6 +90,8 @@
         force_page_refresh
         # There's better ways to make this locator, this is just a quick hack to get it working on the placeholder UI
         page.find('[data-test-column-name="displayed-state"]', text: RemoteDevelopment::States::RUNNING)
+
+        # TODO: Add state transition to TERMINATED
       end
 
       def simulate_first_poll(id:, name:, namespace:)
@@ -108,7 +110,7 @@ def simulate_first_poll(id:, name:, namespace:)
         expect(info.fetch(:namespace)).to eq(namespace)
         expect(info.fetch(:desired_state_is_terminated)).to eq(false)
         expect(info.fetch(:persisted_actual_state_is_terminated)).to eq(false)
-        expect(info.has_key?(:persisted_deployment_resource_version)).to eq(false)
+        expect(info.fetch(:persisted_deployment_resource_version)).to be_nil
 
         expected_config_to_apply = create_config_to_apply(
           workspace_id: id,
@@ -152,7 +154,7 @@ def simulate_second_poll(name:, namespace:)
         expect(info.fetch(:persisted_deployment_resource_version)).to eq(resource_version.to_s)
         expect(info.fetch(:desired_state_is_terminated)).to eq(false)
         expect(info.fetch(:persisted_actual_state_is_terminated)).to eq(false)
-        expect(info.has_key?(:config_to_apply)).to eq(false)
+        expect(info.fetch(:config_to_apply)).to be_nil
       end
 
       def force_page_refresh
diff --git a/ee/spec/lib/remote_development/workspace_updates_processor_reconciliation_scenarios_spec.rb b/ee/spec/lib/remote_development/workspace_updates_processor_reconciliation_scenarios_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..f0681a46d17d813e547eb79486d28ba4f99f1325
--- /dev/null
+++ b/ee/spec/lib/remote_development/workspace_updates_processor_reconciliation_scenarios_spec.rb
@@ -0,0 +1,135 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+# TODO: This spec is dense and cryptic. Make it better.
+RSpec.describe ::RemoteDevelopment::WorkspaceUpdatesProcessor, 'Reconciliation Scenarios', feature_category: :remote_development do
+  include_context 'with remote development shared fixtures'
+
+  # See following documentation for details on all scenarios:
+  #
+  # https://gitlab.com/gitlab-org/remote-development/gitlab-remote-development-docs/-/blob/main/doc/workspace-updates.md
+  #
+  # Columns:
+  #
+  # initial_db_state: Initial state of workspace in DB. nil for new workspace, 2-tuple of [desired_state, actual_state]
+  #   for existing workspace.
+  #
+  # user_desired_state_update: Optional first request event. nil if there is no user action, symbol for state if there
+  #   is a user action.
+  #
+  # agent_actual_state_updates: Array of actual state updates from agent. nil if agent reports no info for workspace,
+  #   otherwise an array of [previous_actual_state, current_actual_state, workspace_exists]
+  #   to be used as args when calling #create_workspace_agent_info to generate the workspace agent info fixture.
+  #
+  # response_expectations: Array corresponding to entries in agent_actual_state_updates, representing
+  #   expected rails_info hash response to agent for the workspace. Array is a 2-tuple of booleans for
+  #   [config_to_apply_present?, persisted_deployment_resource_version_present?].
+  #
+  # db_expectations: Array corresponding to entries in
+  #  (initial_db_state + user_desired_state_update + agent_actual_state_updates).
+  #  Array entry is nil, or 2-tuple of symbols for [desired_state, actual_state].
+
+  # rubocop:disable Layout/LineLength
+  where(:initial_db_state, :user_desired_state_update, :agent_actual_state_updates, :response_expectations, :db_expectations) do
+    [
+      #
+      # actual:Creating* / desired: Running -> actual: Running / desired: Running
+      [nil, :running, [nil, [:creating, :starting, false], [:starting, :running, true]], [[true, false], [false, true], [false, true]], [[:running, :creating], [:running, :creating], [:running, :starting], [:running, :running]]],
+      #
+      # actual:Running / desired: Running -> actual: Stopped / desired: Stopped
+      [[:running, :running], :stopped, [nil, [:running, :stopping, true], [:stopping, :stopped, false]], [[true, true], [false, true], [false, true]], [[:running, :running], [:stopped, :running], [:stopped, :running], [:stopped, :stopping], [:stopped, :stopped]]]
+    ]
+  end
+  # rubocop:enable Layout/LineLength
+
+  with_them do
+    it 'behaves as expected' do
+      workspace = nil
+      db_expectation_index = 0
+      initial_resource_version = 1
+
+      # Handle initial db state, if necessary
+      # noinspection RubyResolve
+      if initial_db_state
+        workspace = create(
+          :workspace,
+          desired_state: initial_db_state[0].to_s.capitalize,
+          actual_state: initial_db_state[1].to_s.capitalize,
+          deployment_resource_version: initial_resource_version
+        )
+
+        # assert on the workspace state in the db after initial creation
+        expect(workspace.slice(:desired_state, :actual_state).values)
+          .to eq(db_expectations[db_expectation_index].map(&:to_s).map(&:capitalize))
+        db_expectation_index += 1
+      end
+
+      # handle user desired state update, if necessary
+      # noinspection RubyResolve
+      if user_desired_state_update
+        if workspace
+          # noinspection RubyResolve
+          workspace.update!(desired_state: user_desired_state_update.capitalize)
+        else
+          workspace = create(:workspace, :unprovisioned)
+        end
+
+        # assert on the workspace state in the db after user desired state update
+        expect(workspace.slice(:desired_state, :actual_state).values)
+          .to eq(db_expectations[db_expectation_index].map(&:to_s).map(&:capitalize))
+        db_expectation_index += 1
+      end
+
+      raise 'Must have workspace by now, either from initial_db_state or user_desired_state_update' unless workspace
+
+      # Handle agent updates
+      # noinspection RubyResolve
+      agent_actual_state_updates.each_with_index do |actual_state_update_fixture_args, response_expectations_index|
+        update_type = RemoteDevelopment::WorkspaceUpdatesParamsParser::UPDATE_TYPE_PARTIAL
+        deployment_resource_version_from_agent ||= initial_resource_version
+
+        workspace_agent_infos =
+          if actual_state_update_fixture_args
+            previous_actual_state = actual_state_update_fixture_args[0].to_s.capitalize
+            current_actual_state = actual_state_update_fixture_args[1].to_s.capitalize
+            workspace_exists = actual_state_update_fixture_args[2]
+            [
+              create_workspace_agent_info(
+                workspace_name: workspace.name,
+                workspace_namespace: workspace.namespace,
+                agent_id: workspace.agent.id,
+                owning_inventory: "#{workspace.name}-workspace-inventory",
+                resource_version: deployment_resource_version_from_agent += 1,
+                current_actual_state: current_actual_state,
+                previous_actual_state: previous_actual_state,
+                workspace_exists: workspace_exists
+              )
+            ]
+          else
+            []
+          end
+
+        result = described_class.new.process(workspace_agent_infos: workspace_agent_infos, update_type: update_type)
+        workspace_rails_infos = result[0].fetch(:workspace_rails_infos)
+
+        # assert on the rails_info response to the agent
+        expect(workspace_rails_infos.size).to eq(1)
+        response_expectation = response_expectations[response_expectations_index]
+        # assert on the config_to_apply presence
+        expected_config_to_apply_present = response_expectation[0]
+        expect(workspace_rails_infos[0].fetch(:config_to_apply).present?).to eq(expected_config_to_apply_present)
+        # assert on the persisted_deployment_resource_version presence/value
+        expected_persisted_deployment_resource_version =
+          response_expectation[1] ? deployment_resource_version_from_agent.to_s : nil
+        persisted_deployment_resource_version = workspace_rails_infos[0].fetch(:persisted_deployment_resource_version)
+        expect(persisted_deployment_resource_version).to eq(expected_persisted_deployment_resource_version)
+
+        # assert on the workspace state in the db after processing the agent update
+        expect(workspace.reload.slice(:desired_state, :actual_state).values)
+          .to eq(db_expectations[db_expectation_index].map(&:to_s).map(&:capitalize))
+        db_expectation_index += 1
+      end
+    end
+  end
+end
diff --git a/ee/spec/lib/remote_development/workspace_updates_processor_spec.rb b/ee/spec/lib/remote_development/workspace_updates_processor_spec.rb
index d7b8f4ec6e023cf79217302a506131ef33695aa1..45ad4145d882ee0a6403ba2017c5aa5bd26f10d9 100644
--- a/ee/spec/lib/remote_development/workspace_updates_processor_spec.rb
+++ b/ee/spec/lib/remote_development/workspace_updates_processor_spec.rb
@@ -69,7 +69,8 @@
             name: provisioned_workspace.name,
             namespace: provisioned_workspace.namespace,
             persisted_deployment_resource_version: expected_deployment_resource_version,
-            persisted_actual_state_is_terminated: expected_value_for_persisted_actual_state_is_terminated
+            persisted_actual_state_is_terminated: expected_value_for_persisted_actual_state_is_terminated,
+            config_to_apply: nil
           }
         end
 
@@ -378,7 +379,8 @@
             name: unprovisioned_workspace.name,
             namespace: unprovisioned_workspace.namespace,
             config_to_apply: expected_config_to_apply,
-            persisted_actual_state_is_terminated: false
+            persisted_actual_state_is_terminated: false,
+            persisted_deployment_resource_version: nil
           }
         end