diff --git a/.rubocop_gradual.lock b/.rubocop_gradual.lock
index 1ff2a0f8..6bf6e50c 100644
--- a/.rubocop_gradual.lock
+++ b/.rubocop_gradual.lock
@@ -21,11 +21,11 @@
   "lib/oauth2/response.rb:2054901929": [
     [53, 5, 204, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 996912427]
   ],
-  "spec/oauth2/access_token_spec.rb:373808463": [
+  "spec/oauth2/access_token_spec.rb:3464059918": [
     [3, 1, 34, "RSpec/SpecFilePathFormat: Spec path should end with `o_auth2/access_token*_spec.rb`.", 1972107547],
-    [809, 13, 25, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 770233088],
-    [879, 9, 101, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3022740639],
-    [883, 9, 79, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 2507338967]
+    [824, 13, 25, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 770233088],
+    [894, 9, 101, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3022740639],
+    [898, 9, 79, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 2507338967]
   ],
   "spec/oauth2/authenticator_spec.rb:853320290": [
     [3, 1, 36, "RSpec/SpecFilePathFormat: Spec path should end with `o_auth2/authenticator*_spec.rb`.", 819808017],
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 47c1a7e8..a52a91f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ Please file a bug if you notice a violation of semantic versioning.
 
 ## [Unreleased]
 ### Added
+- [gh!671][gh!671] - Complete documentation example for Instagram by @pboling
 - .env.local.example for contributor happiness
 - note lack of builds for JRuby 9.2, 9.3 & Truffleruby 22.3, 23.0
   - [actions/runner - issues/2347][GHA-continue-on-error-ui]
@@ -25,7 +26,7 @@ Please file a bug if you notice a violation of semantic versioning.
 - [gh!670][gh!670] - AccessToken: verb-dependent token transmission mode by @mrj
   - e.g., Instagram GET=:query, POST/DELETE=:header
 ### Changed
-- [gh!669][gh!669] - Upgrade to kettle-dev v1.1.9
+- [gh!669][gh!669] - Upgrade to kettle-dev v1.1.9 by @pboling
 ### Deprecated
 ### Removed
 ### Fixed
@@ -35,6 +36,7 @@ Please file a bug if you notice a violation of semantic versioning.
 
 [gh!669]: https://github.com/ruby-oauth/oauth2/pull/669
 [gh!670]: https://github.com/ruby-oauth/oauth2/pull/670
+[gh!671]: https://github.com/ruby-oauth/oauth2/pull/671
 [GHA-continue-on-error-ui]: https://github.com/actions/runner/issues/2347
 [GHA-allow-failure]: https://github.com/orgs/community/discussions/15452
 
diff --git a/README.md b/README.md
index b9b30a76..d69fc2f5 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@
 
 ⭐️ including OAuth 2.1 draft spec & OpenID Connect (OIDC)
 
-[![Version][👽versioni]][👽version] [![GitHub tag (latest SemVer)][⛳️tag-img]][⛳️tag] [![License: MIT][📄license-img]][📄license-ref] [![Downloads Rank][👽dl-ranki]][👽dl-rank] [![Open Source Helpers][👽oss-helpi]][👽oss-help] [![CodeCov Test Coverage][🔑codecovi]][🔑codecov] [![Coveralls Test Coverage][🔑coveralls-img]][🔑coveralls] [![QLTY Test Coverage][🔑qlty-covi]][🔑qlty-cov] [![QLTY Maintainability][🔑qlty-mnti]][🔑qlty-mnt] [![CI Heads][🚎3-hd-wfi]][🚎3-hd-wf] [![CI Runtime Dependencies @ HEAD][🚎12-crh-wfi]][🚎12-crh-wf] [![CI Current][🚎11-c-wfi]][🚎11-c-wf] [![CI Truffle Ruby][🚎9-t-wfi]][🚎9-t-wf] [![CI JRuby][🚎10-j-wfi]][🚎10-j-wf] [![Deps Locked][🚎13-🔒️-wfi]][🚎13-🔒️-wf] [![Deps Unlocked][🚎14-🔓️-wfi]][🚎14-🔓️-wf] [![CI Supported][🚎6-s-wfi]][🚎6-s-wf] [![CI Legacy][🚎4-lg-wfi]][🚎4-lg-wf] [![CI Unsupported][🚎7-us-wfi]][🚎7-us-wf] [![CI Ancient][🚎1-an-wfi]][🚎1-an-wf] [![CI Test Coverage][🚎2-cov-wfi]][🚎2-cov-wf] [![CI Style][🚎5-st-wfi]][🚎5-st-wf] [![CodeQL][🖐codeQL-img]][🖐codeQL]
+[![Version][👽versioni]][👽version] [![GitHub tag (latest SemVer)][⛳️tag-img]][⛳️tag] [![License: MIT][📄license-img]][📄license-ref] [![Downloads Rank][👽dl-ranki]][👽dl-rank] [![Open Source Helpers][👽oss-helpi]][👽oss-help] [![Coveralls Test Coverage][🔑coveralls-img]][🔑coveralls] [![QLTY Test Coverage][🔑qlty-covi]][🔑qlty-cov] [![QLTY Maintainability][🔑qlty-mnti]][🔑qlty-mnt] [![CI Heads][🚎3-hd-wfi]][🚎3-hd-wf] [![CI Runtime Dependencies @ HEAD][🚎12-crh-wfi]][🚎12-crh-wf] [![CI Current][🚎11-c-wfi]][🚎11-c-wf] [![CI Truffle Ruby][🚎9-t-wfi]][🚎9-t-wf] [![CI JRuby][🚎10-j-wfi]][🚎10-j-wf] [![Deps Locked][🚎13-🔒️-wfi]][🚎13-🔒️-wf] [![Deps Unlocked][🚎14-🔓️-wfi]][🚎14-🔓️-wf] [![CI Supported][🚎6-s-wfi]][🚎6-s-wf] [![CI Legacy][🚎4-lg-wfi]][🚎4-lg-wf] [![CI Unsupported][🚎7-us-wfi]][🚎7-us-wf] [![CI Ancient][🚎1-an-wfi]][🚎1-an-wf] [![CI Test Coverage][🚎2-cov-wfi]][🚎2-cov-wf] [![CI Style][🚎5-st-wfi]][🚎5-st-wf] [![CodeQL][🖐codeQL-img]][🖐codeQL]
 
 If ☝️ `ci_badges.map(&:color).detect { it != "green"}`  [let me know][🖼️galtzo-discord], as I may have missed the [discord notification][🖼️galtzo-discord].
 
diff --git a/spec/oauth2/access_token_spec.rb b/spec/oauth2/access_token_spec.rb
index c23b7e35..2234b2cd 100644
--- a/spec/oauth2/access_token_spec.rb
+++ b/spec/oauth2/access_token_spec.rb
@@ -429,6 +429,21 @@ def assert_initialized_token(target)
             expect(subject.__send__(verb, "/token/#{mode.call(verb)}").body).to include(token)
           end
         end
+
+        context "when invalid" do
+          subject(:invalid_target) { target.__send__(http_verb, "/token/#{mode.call(http_verb)}") }
+
+          let(:http_verb) { :get }
+          let(:mode) do
+            lambda do |_verb|
+              "foobar"
+            end
+          end
+
+          it "correctly handles an invalid mode by raising an error" do
+            block_is_expected.to raise_error("invalid :mode option of foobar")
+          end
+        end
       end
 
       context "with client.options[:raise_errors] = false" do