diff --git a/Gemfile b/Gemfile
index a6860ed..fe3388f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ gem "multi_json"
 
 gem "minitest-line"
 
-gem "trailblazer", path: "../trailblazer"
+gem "trailblazer"
 # gem "trailblazer-operation", path: "../operation"
 
-gem "dry-validation"
+gem "dry-validation", "~> 0.11"
diff --git a/Gemfile.lock b/Gemfile.lock
index 874053f..6cf8b47 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,11 +1,3 @@
-PATH
-  remote: ../trailblazer
-  specs:
-    trailblazer (2.1.0.rc1)
-      trailblazer-macro (>= 2.1.0.rc1, < 2.2.0)
-      trailblazer-macro-contract (= 2.1.0.rc1)
-      trailblazer-operation
-
 PATH
   remote: .
   specs:
@@ -15,53 +7,52 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    concurrent-ruby (1.0.2)
+    concurrent-ruby (1.1.5)
     declarative (0.0.10)
     declarative-builder (0.1.0)
       declarative-option (< 0.2.0)
     declarative-option (0.1.0)
-    disposable (0.4.4)
+    disposable (0.4.7)
       declarative (>= 0.0.9, < 1.0.0)
       declarative-builder (< 0.2.0)
       declarative-option (< 0.2.0)
       representable (>= 2.4.0, <= 3.1.0)
       uber (< 0.2.0)
-    dry-configurable (0.3.0)
+    dry-configurable (0.9.0)
       concurrent-ruby (~> 1.0)
-    dry-container (0.5.0)
+      dry-core (~> 0.4, >= 0.4.7)
+    dry-container (0.7.2)
       concurrent-ruby (~> 1.0)
       dry-configurable (~> 0.1, >= 0.1.3)
-    dry-core (0.2.0)
+    dry-core (0.4.9)
+      concurrent-ruby (~> 1.0)
+    dry-equalizer (0.3.0)
+    dry-inflector (0.2.0)
+    dry-logic (0.6.1)
       concurrent-ruby (~> 1.0)
-    dry-equalizer (0.2.0)
-    dry-logic (0.4.0)
-      dry-container (~> 0.2, >= 0.2.6)
-      dry-core (~> 0.1)
+      dry-core (~> 0.2)
       dry-equalizer (~> 0.2)
-    dry-matcher (0.5.0)
-    dry-types (0.9.0)
+    dry-matcher (0.8.3)
+      dry-core (>= 0.4.8)
+    dry-types (0.14.1)
       concurrent-ruby (~> 1.0)
-      dry-configurable (~> 0.1)
       dry-container (~> 0.3)
-      dry-core (~> 0.1)
+      dry-core (~> 0.4, >= 0.4.4)
       dry-equalizer (~> 0.2)
-      dry-logic (~> 0.4, >= 0.4.0)
-      inflecto (~> 0.0.0, >= 0.0.2)
-    dry-validation (0.10.3)
+      dry-inflector (~> 0.1, >= 0.1.2)
+      dry-logic (~> 0.5, >= 0.5)
+    dry-validation (0.13.3)
       concurrent-ruby (~> 1.0)
       dry-configurable (~> 0.1, >= 0.1.3)
-      dry-container (~> 0.2, >= 0.2.8)
-      dry-core (~> 0.1)
+      dry-core (~> 0.2, >= 0.2.1)
       dry-equalizer (~> 0.2)
-      dry-logic (~> 0.4, >= 0.4.0)
-      dry-types (~> 0.9, >= 0.9.0)
-    hirb (0.7.3)
-    inflecto (0.0.2)
-    minitest (5.9.1)
-    minitest-line (0.6.3)
+      dry-logic (~> 0.5, >= 0.5.0)
+      dry-types (~> 0.14.0)
+    minitest (5.14.0)
+    minitest-line (0.6.5)
       minitest (~> 5.0)
-    multi_json (1.12.1)
-    rake (11.3.0)
+    multi_json (1.14.1)
+    rake (13.0.1)
     reform (2.2.4)
       disposable (>= 0.4.1)
       representable (>= 2.4.0, < 3.1.0)
@@ -69,16 +60,27 @@ GEM
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
       uber (< 0.2.0)
-    trailblazer-activity (0.7.1)
-      hirb
-      trailblazer-context
-    trailblazer-context (0.1.2)
-    trailblazer-macro (2.1.0.rc1)
-    trailblazer-macro-contract (2.1.0.rc1)
+    trailblazer (2.1.0)
+      trailblazer-macro (>= 2.1.0, < 2.2.0)
+      trailblazer-macro-contract (>= 2.1.0, < 2.2.0)
+      trailblazer-operation
+    trailblazer-activity (0.10.0)
+      trailblazer-context (>= 0.2.0, < 0.3.0)
+    trailblazer-activity-dsl-linear (0.2.6)
+      trailblazer-activity (>= 0.9.1, < 1.0.0)
+    trailblazer-context (0.2.0)
+    trailblazer-developer (0.0.10)
+      representable
+      trailblazer-activity (>= 0.10.0, < 1.0.0)
+      trailblazer-activity-dsl-linear
+    trailblazer-macro (2.1.1)
+      trailblazer-operation (>= 0.6.0)
+    trailblazer-macro-contract (2.1.0)
       reform (>= 2.2.0, < 3.0.0)
-    trailblazer-operation (0.4.1)
-      trailblazer-activity (>= 0.7.1, < 0.8.0)
-      trailblazer-context (>= 0.1.1, < 0.3.0)
+    trailblazer-operation (0.6.0)
+      trailblazer-activity (>= 0.10.0, < 1.0.0)
+      trailblazer-activity-dsl-linear (>= 0.2.1, < 1.0.0)
+      trailblazer-developer (>= 0.0.8)
     uber (0.1.0)
 
 PLATFORMS
@@ -86,13 +88,13 @@ PLATFORMS
 
 DEPENDENCIES
   bundler
-  dry-validation
+  dry-validation (~> 0.11)
   minitest
   minitest-line
   multi_json
   rake
-  trailblazer!
+  trailblazer
   trailblazer-endpoint!
 
 BUNDLED WITH
-   1.16.2
+   1.17.2
diff --git a/lib/trailblazer/endpoint.rb b/lib/trailblazer/endpoint.rb
index 8879e38..4489e2b 100644
--- a/lib/trailblazer/endpoint.rb
+++ b/lib/trailblazer/endpoint.rb
@@ -1,35 +1,28 @@
 require "dry/matcher"
+require "trailblazer/endpoint/rails"
 
 module Trailblazer
   class Endpoint
-    # this is totally WIP as we need to find best practices.
-    # also, i want this to be easily extendable.
     Matcher = Dry::Matcher.new(
-      present: Dry::Matcher::Case.new( # DISCUSS: the "present" flag needs some discussion.
-        match:   ->(result) { result.success? && result["present"] },
-        resolve: ->(result) { result }),
-      success: Dry::Matcher::Case.new(
-        match:   ->(result) { result.success? },
-        resolve: ->(result) { result }),
-      created: Dry::Matcher::Case.new(
-        match:   ->(result) { result.success? && result["model.action"] == :new }, # the "model.action" doesn't mean you need Model.
-        resolve: ->(result) { result }),
-      not_found: Dry::Matcher::Case.new(
-        match:   ->(result) { result.failure? && result["result.model"] && result["result.model"].failure? },
-        resolve: ->(result) { result }),
-      # TODO: we could add unauthorized here.
-      unauthenticated: Dry::Matcher::Case.new(
-        match:   ->(result) { result.failure? && result["result.policy.default"].failure? }, # FIXME: we might need a &. here ;)
-        resolve: ->(result) { result }),
-      invalid: Dry::Matcher::Case.new(
-        match:   ->(result) { result.failure? && result["result.contract.default"] && result["result.contract.default"].failure? },
-        resolve: ->(result) { result })
+      not_found: Dry::Matcher::Case.new { |result| result_error_matching?(result, :not_found) ? result : Dry::Matcher::Undefined },
+      unauthenticated: Dry::Matcher::Case.new { |result| result_error_matching?(result, :unauthenticated) ? result : Dry::Matcher::Undefined },
+      unauthorized: Dry::Matcher::Case.new { |result| result_error_matching?(result, :unauthorized) ? result : Dry::Matcher::Undefined },
+      invalid_params: Dry::Matcher::Case.new { |result| result_error_matching?(result, :invalid_params) ? result : Dry::Matcher::Undefined },
     )
 
-    # `call`s the operation.
-    def self.call(operation_class, handlers, *args, &block)
-      result = operation_class.(*args)
-      new.(result, handlers, &block)
+    class << self
+      # `call`s the operation.
+      def call(operation_class, handlers, *args, &block)
+        result = operation_class.(*args)
+        new.(result, handlers, &block)
+      end
+
+      private
+
+      def result_error_matching?(result, state)
+        end_state = result.event.to_h[:semantic]
+        result.failure? && end_state == state
+      end
     end
 
     def call(result, handlers=nil, &block)
diff --git a/lib/trailblazer/endpoint/rails.rb b/lib/trailblazer/endpoint/rails.rb
index dac01ab..8d7e102 100644
--- a/lib/trailblazer/endpoint/rails.rb
+++ b/lib/trailblazer/endpoint/rails.rb
@@ -1,5 +1,3 @@
-require "trailblazer/endpoint"
-
 module Trailblazer::Endpoint::Handlers
   # Generic matcher handlers for a Rails API backend.
   #
@@ -15,13 +13,34 @@ def initialize(controller, options)
 
     def call
       ->(m) do
-        m.not_found       { |result| controller.head 404 }
-        m.unauthenticated { |result| controller.head 401 }
-        m.present         { |result| controller.render json: result["representer.serializer.class"].new(result['model']), status: 200 }
-        m.created         { |result| controller.head 201, location: "#{@path}/#{result["model"].id}" }#, result["representer.serializer.class"].new(result["model"]).to_json
-        m.success         { |result| controller.head 200, location: "#{@path}/#{result["model"].id}" }
-        m.invalid         { |result| controller.render json: result["representer.errors.class"].new(result['result.contract.default'].errors).to_json, status: 422 }
+        m.not_found { |res| render_json_error(res, 404) }
+        m.unauthenticated { |res| render_json_error(res, 401) }
+        m.unauthorized { |res| render_json_error(res, 403) }
+        m.invalid_params { |res| render_validation_errors(res, 422) }
       end
     end
+
+    private
+
+    def render_json_error(ctx, status)
+      err_msg = ctx['trailblazer-endpoint.error'] || default_for(status)
+      controller.render(json: err_msg, status: status)
+    end
+
+    def render_validation_errors(ctx, status)
+      err_msg = ctx['result.contract.default']&.errors&.messages || default_for(status)
+      controller.render(json: err_msg, status: status)
+    end
+
+    def default_for(status_code)
+      default_msg = {
+        401 => 'Unauthorized.',
+        403 => 'Forbidden.',
+        404 => 'Resource not found.',
+        422 => 'Unprocessable entity.'
+      }
+
+      default_msg[status_code]
+    end
   end
 end
diff --git a/test/endpoint_matcher_test.rb b/test/endpoint_matcher_test.rb
new file mode 100644
index 0000000..177b8ea
--- /dev/null
+++ b/test/endpoint_matcher_test.rb
@@ -0,0 +1,65 @@
+require 'test_helper'
+
+class EndpointMatcherTest < Minitest::Spec
+  class TestOperation < Trailblazer::Operation
+    NotFound = Class.new(Trailblazer::Activity::Signal)
+    Unauthenticated = Class.new(Trailblazer::Activity::Signal)
+    Unauthorized = Class.new(Trailblazer::Activity::Signal)
+    InvalidParams = Class.new(Trailblazer::Activity::Signal)
+
+    SignalMatchers = {
+      not_found: NotFound,
+      unauthenticated: Unauthenticated,
+      unauthorized: Unauthorized,
+      invalid_params: InvalidParams,
+    }
+
+    step ->(_, tested_state:, **) { SignalMatchers[tested_state] || true },
+      Output(NotFound, :not_found) => End(:not_found),
+      Output(Unauthenticated, :unauthenticated) => End(:unauthenticated),
+      Output(Unauthorized, :unauthorized) => End(:unauthorized),
+      Output(InvalidParams, :invalid_params) => End(:invalid_params)
+  end
+
+  let(:my_handlers) do
+    ->(m) do
+      m.not_found       { |_| @its_a_match = :not_found }
+      m.unauthenticated { |_| @its_a_match = :unauthenticated }
+      m.unauthorized    { |_| @its_a_match = :unauthorized }
+      m.invalid_params  { |_| @its_a_match = :invalid_params }
+    end
+  end
+
+  before do
+    @its_a_match = :no_match
+  end
+
+  # 404 :not_found
+  it 'matches the :not_found state' do
+    result = TestOperation.call(tested_state: :not_found)
+    Trailblazer::Endpoint.new.call(result, my_handlers)
+
+    _(@its_a_match).must_equal(:not_found)
+  end
+
+  it 'matches the :unauthenticated state' do
+    result = TestOperation.call(tested_state: :unauthenticated)
+    Trailblazer::Endpoint.new.call(result, my_handlers)
+
+    _(@its_a_match).must_equal(:unauthenticated)
+  end
+
+  it 'matches the :unauthorized state' do
+    result = TestOperation.call(tested_state: :unauthorized)
+    Trailblazer::Endpoint.new.call(result, my_handlers)
+
+    _(@its_a_match).must_equal(:unauthorized)
+  end
+
+  it 'matches the :unauthorized state' do
+    result = TestOperation.call(tested_state: :invalid_params)
+    Trailblazer::Endpoint.new.call(result, my_handlers)
+
+    _(@its_a_match).must_equal(:invalid_params)
+  end
+end
diff --git a/test/endpoint_rails_test.rb b/test/endpoint_rails_test.rb
new file mode 100644
index 0000000..64edf3a
--- /dev/null
+++ b/test/endpoint_rails_test.rb
@@ -0,0 +1,139 @@
+require 'test_helper'
+
+class EndpointHandlerTest < Minitest::Spec
+  class TestOperation < Trailblazer::Operation
+    NotFound = Class.new(Trailblazer::Activity::Signal)
+    Unauthenticated = Class.new(Trailblazer::Activity::Signal)
+    Unauthorized = Class.new(Trailblazer::Activity::Signal)
+    InvalidParams = Class.new(Trailblazer::Activity::Signal)
+
+    SignalMatchers = {
+      not_found: NotFound,
+      unauthenticated: Unauthenticated,
+      unauthorized: Unauthorized,
+      invalid_params: InvalidParams,
+    }
+
+    step ->(_, tested_state:, **) { SignalMatchers[tested_state] || true },
+      Output(NotFound, :not_found) => End(:not_found),
+      Output(Unauthenticated, :unauthenticated) => End(:unauthenticated),
+      Output(Unauthorized, :unauthorized) => End(:unauthorized),
+      Output(InvalidParams, :invalid_params) => End(:invalid_params)
+  end
+
+  def build_controller(test_op)
+    c = Class.new do
+      include Trailblazer::Endpoint::Controller
+
+      attr_accessor :http_response
+
+      def initialize(op)
+        @test_op = op
+        @http_response = {}
+      end
+
+      def render(options)
+        @http_response = options
+      end
+
+      def action_ending_in(state, **p)
+        endpoint(@test_op, args: [tested_state: state, params: p])
+      end
+    end
+    c.new(test_op)
+  end
+
+  let(:controller) { build_controller(TestOperation) }
+
+  describe ':not_found' do
+    it 'returns a 404 HTTP code' do
+      controller.action_ending_in(:not_found)
+
+      _(controller.http_response[:status]).must_equal(404)
+    end
+
+    it 'returns an error message' do
+      controller.action_ending_in(:not_found)
+
+      _(controller.http_response[:json]).must_equal('Resource not found.')
+    end
+  end
+
+  describe ':unauthenticated' do
+    it 'returns a 401 HTTP code' do
+      controller.action_ending_in(:unauthenticated)
+
+      _(controller.http_response[:status]).must_equal(401)
+    end
+
+    it 'returns an error message' do
+      controller.action_ending_in(:unauthenticated)
+
+      _(controller.http_response[:json]).must_equal('Unauthorized.')
+    end
+  end
+
+  describe ':unauthorized' do
+    it 'returns a 403 HTTP code' do
+      controller.action_ending_in(:unauthorized)
+
+      _(controller.http_response[:status]).must_equal(403)
+    end
+
+    it 'returns an error message' do
+      controller.action_ending_in(:unauthorized)
+
+      _(controller.http_response[:json]).must_equal('Forbidden.')
+    end
+  end
+
+  describe ':invalid_params' do
+    describe 'when used with Reform' do
+      TestModel = Struct.new(:id, :name)
+
+      class TestContract < Reform::Form
+        feature Reform::Form::Dry
+        property :name
+
+        validation do
+          required(:name).filled
+        end
+      end
+
+      class TestContractOp < Trailblazer::Operation
+        step Model(TestModel, :new)
+        step Contract::Build(constant: TestContract)
+        step Contract::Validate(), Output(:failure) => End(:invalid_params)
+      end
+    end
+
+    describe 'when used in standalone' do
+      it 'returns a 422 HTTP code' do
+        controller.action_ending_in(:invalid_params, {})
+
+        _(controller.http_response[:status]).must_equal(422)
+      end
+
+      it 'returns the contract errors messages' do
+        controller.action_ending_in(:invalid_params)
+
+        _(controller.http_response[:json]).must_equal('Unprocessable entity.')
+      end
+    end
+  end
+
+  describe 'error message overloading' do
+    class TestErrorOperation < Trailblazer::Operation
+      step ->(ctx, **) { ctx['trailblazer-endpoint.error'] = 'Very error'; false },
+        Output(:failure) => End(:not_found)
+    end
+
+    let(:controller) { build_controller(TestErrorOperation) }
+
+    it 'returns the value set in `ctx[\'trailblazer-endpoint.error\']`' do
+      controller.action_ending_in(:not_found)
+
+      _(controller.http_response[:json]).must_equal('Very error')
+    end
+  end
+end
diff --git a/test/endpoint_test.rb b/test/endpoint_test.old.rb
similarity index 100%
rename from test/endpoint_test.rb
rename to test/endpoint_test.old.rb
diff --git a/test/test_helper.rb b/test/test_helper.rb
index ada5c51..7e6c3d1 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,6 @@
 require "minitest/autorun"
 require "trailblazer"
 require "trailblazer/endpoint"
+require "dry-validation"
+require "reform/form/dry"
+require "dry/validation/compat/form"