diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..4ea9215
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,41 @@
+name: CI
+
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: OTP ${{ matrix.otp }}
+    runs-on: ubuntu-latest
+    container:
+      image: erlang:${{ matrix.otp }}
+    strategy:
+      fail-fast: false
+      matrix:
+        # 26 is what chef-server currently pins; 27 and 28 are covered so
+        # regressions surface before that pin moves.
+        otp: ['26', '27', '28']
+    steps:
+      - uses: actions/checkout@v4
+      - name: Compile
+        run: rebar3 compile
+      - name: EUnit
+        run: rebar3 eunit
+
+  dialyzer:
+    name: Dialyzer (informational)
+    runs-on: ubuntu-latest
+    container:
+      image: erlang:26
+    # Not a gate yet: 3 outstanding warnings on a clean checkout, all of them
+    # unresolved external functions rather than defects in this code. Drop
+    # continue-on-error once they are addressed.
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v4
+      - run: rebar3 dialyzer
diff --git a/rebar.lock b/rebar.lock
index bee6d70..e5c1794 100644
--- a/rebar.lock
+++ b/rebar.lock
@@ -7,7 +7,7 @@
   0},
  {<<"erlcloud">>,
   {git,"https://github.com/chef/erlcloud",
-       {branch,"lbaker/presigned-headers"}},
+       {ref,"27724cc615bb71595e88665ffd3ea083bf51ecb3"}},
   0},
  {<<"jsx">>,{pkg,<<"jsx">>,<<"2.11.0">>},1},
  {<<"lhttpc">>,
diff --git a/rebar3.crashdump b/rebar3.crashdump
new file mode 100644
index 0000000..f8ed29c
--- /dev/null
+++ b/rebar3.crashdump
@@ -0,0 +1,57 @@
+Error: {case_clause,
+           {{badmatch,
+                {'EXIT',
+                    {badarg,
+                        [{erlang,binary_to_atom,
+                             [<<101,114,108,99,108,111,117,100,80,115,116,97,
+                                114,116,176,97,112,112,108,105,99,97,116,105,
+                                111,110,64,108,111,97,100,192,97,112,112,108,
+                                105,99,97,116,105,111,110,115,112,103,101,116,
+                                95,107,101,121,32,111,107,176,109,111,100,117,
+                                108,101,95,105,110,102,111,96,101,114,108,97,
+                                110,103,240,103,101,116,95,109,111,100,117,108,
+                                101,95,105,110,102,111,8,19,45,115,116,97,114,
+                                116,47,48,45,108,99,36,94,48,47,49,45,48,45,
+                                208,98,97,100,95,103,101,110,101,114,97,116,
+                                111,114,80,101,114>>,
+                              utf8],
+                             [{error_info,#{module => erl_erts_errors}}]},
+                         {beam_lib,extract_atom,2,
+                             [{file,"beam_lib.erl"},{line,862}]},
+                         {beam_lib,get_atom_data,8,
+                             [{file,"beam_lib.erl"},{line,639}]},
+                         {beam_lib,scan_beam1,2,
+                             [{file,"beam_lib.erl"},{line,600}]},
+                         {beam_lib,scan_beam,4,
+                             [{file,"beam_lib.erl"},{line,585}]},
+                         {beam_lib,read_all_chunks,1,
+                             [{file,"beam_lib.erl"},{line,541}]},
+                         {dialyzer_cplt,compute_md5_from_file,1,
+                             [{file,"dialyzer_cplt.erl"},{line,365}]},
+                         {dialyzer_cplt,compute_new_md5_1,3,
+                             [{file,"dialyzer_cplt.erl"},{line,340}]}]}}},
+            [{beam_lib,read_all_chunks,1,[{file,"beam_lib.erl"},{line,541}]},
+             {dialyzer_cplt,compute_md5_from_file,1,
+                 [{file,"dialyzer_cplt.erl"},{line,365}]},
+             {dialyzer_cplt,compute_new_md5_1,3,
+                 [{file,"dialyzer_cplt.erl"},{line,340}]},
+             {dialyzer_cplt,check_plt1,3,
+                 [{file,"dialyzer_cplt.erl"},{line,310}]},
+             {dialyzer_cplt,'-subproc/1-fun-0-',1,
+                 [{file,"dialyzer_cplt.erl"},{line,419}]}]}}
+[{dialyzer_cl,check_plt,3,[{file,"dialyzer_cl.erl"},{line,281}]},
+ {dialyzer_cl,plt_common,3,[{file,"dialyzer_cl.erl"},{line,208}]},
+ {dialyzer,run_report_modules_changed_and_analyzed,1,
+           [{file,"dialyzer.erl"},{line,225}]},
+ {dialyzer,run_report_modules_analyzed,1,[{file,"dialyzer.erl"},{line,210}]},
+ {dialyzer,run,1,[{file,"dialyzer.erl"},{line,195}]},
+ {rebar_prv_dialyzer,run_dialyzer,3,
+                     [{file,"/usr/src/rebar3-src/apps/rebar/src/rebar_prv_dialyzer.erl"},
+                      {line,631}]},
+ {rebar_prv_dialyzer,check_plt,5,
+                     [{file,"/usr/src/rebar3-src/apps/rebar/src/rebar_prv_dialyzer.erl"},
+                      {line,420}]},
+ {rebar_prv_dialyzer,build_proj_plt,5,
+                     [{file,"/usr/src/rebar3-src/apps/rebar/src/rebar_prv_dialyzer.erl"},
+                      {line,460}]}]
+