diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a4639b9..1ac931a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,6 +21,12 @@ on:
           detected from project/build.properties.
         type: string
         default: ''
+      clean_task:
+        description: >-
+          sbt task that cleans the working directory. Defaults to `cleanFull` on sbt 2 and 
+          `clean` on sbt 1, detected from project/build.properties.
+        type: string
+        default: ''
       coverage:
         description: 'Collect test coverage and upload it to Coveralls'
         type: boolean
@@ -34,7 +40,7 @@ on:
         type: boolean
         default: true
       doc_check:
-        description: 'Check that scaladoc builds'
+        description: 'Check that Scaladoc builds'
         type: boolean
         default: true
       sonar:
@@ -95,7 +101,7 @@ jobs:
           disk-cache: ${{ !inputs.coverage }}
 
       - name: resolve test task
-        id: tasks
+        id: test-task
         env:
           TEST_TASK: ${{ inputs.test_task }}
         run: |
@@ -108,15 +114,29 @@ jobs:
             echo "test=test" >> "$GITHUB_OUTPUT"
           fi
 
+      - name: resolve clean task
+        id: clean-task
+        env:
+          CLEAN_TASK: ${{ inputs.clean_task }}
+        run: |
+          if [[ -n "$CLEAN_TASK" ]]; then
+            echo "clean=$CLEAN_TASK" >> "$GITHUB_OUTPUT"
+          elif grep -qE '^sbt\.version\s*=\s*2\.' project/build.properties; then
+            # in sbt 2 the `clean` doesn't remove all generated classes
+            echo "clean=cleanFull" >> "$GITHUB_OUTPUT"
+          else
+            echo "clean=clean" >> "$GITHUB_OUTPUT"
+          fi
+
       # The coverage build runs before any other compile: scoverage's instrumentation is not part of
       # sbt's compile cache key, so a plain compile done first would be reused here and the coverage
       # report would come out empty.
       - name: build ${{ matrix.scala }}
         run: |
           if [[ "${{ inputs.coverage }}" == "true" ]]; then
-            sbt "++${{ matrix.scala }}; clean; coverage; ${{ steps.tasks.outputs.test }}; coverageAggregate"
+            sbt "++${{ matrix.scala }}; ${{ steps.clean-task.outputs.clean }}; coverage; ${{ steps.test-task.outputs.test }}; coverageAggregate"
           else
-            sbt "++${{ matrix.scala }}; clean; ${{ steps.tasks.outputs.test }}"
+            sbt "++${{ matrix.scala }}; ${{ steps.clean-task.outputs.clean }}; ${{ steps.test-task.outputs.test }}"
           fi
 
       - name: locate coverage report
diff --git a/README.md b/README.md
index 992b9c2..abbf295 100644
--- a/README.md
+++ b/README.md
@@ -2,8 +2,8 @@
 
 ## Scala CI workflow
 
-Runs tests, coverage, binary compatibility, formatting and scaladoc on every push and pull request.
-Replaces the hand-written `ci.yml` that each project used to carry.
+Runs tests, coverage, binary compatibility, formatting and Scaladoc on every push and pull request.
+Replaces the handwritten `ci.yml` that each project used to carry.
 
 ### Setup
 
@@ -42,19 +42,19 @@ alternatives and drops the security rating to C:
 
 ### Inputs
 
-| input | default | notes |
-|---|---|---|
-| `scala_versions` | `'["2.13.18", "3.3.8"]'` | JSON array; becomes the build matrix |
-| `java_version` | `'17'` | |
-| `java_distribution` | `'temurin'` | |
-| `test_task` | auto | `testFull` on sbt 2, `test` on sbt 1, read from `project/build.properties` |
-| `coverage` | `true` | collect coverage and upload to Coveralls |
-| `version_policy_check` | `true` | requires [sbt-version-policy](https://github.com/scalacenter/sbt-version-policy/) |
-| `scalafmt_check` | `true` | |
-| `doc_check` | `true` | runs `Compile/doc` |
-| `sonar` | `false` | run a SonarQube Cloud scan, see below |
-| `sonar_project_key` | `<owner>_<repo>` | |
-| `sonar_args` | `''` | extra `-D` arguments for the scanner |
+| input                  | default                  | notes                                                                             |
+|------------------------|--------------------------|-----------------------------------------------------------------------------------|
+| `scala_versions`       | `'["2.13.18", "3.3.8"]'` | JSON array; becomes the build matrix                                              |
+| `java_version`         | `'17'`                   |                                                                                   |
+| `java_distribution`    | `'temurin'`              |                                                                                   |
+| `test_task`            | auto                     | `testFull` on sbt 2, `test` on sbt 1, read from `project/build.properties`        |
+| `coverage`             | `true`                   | collect coverage and upload to Coveralls                                          |
+| `version_policy_check` | `true`                   | requires [sbt-version-policy](https://github.com/scalacenter/sbt-version-policy/) |
+| `scalafmt_check`       | `true`                   |                                                                                   |
+| `doc_check`            | `true`                   | runs `Compile/doc`                                                                |
+| `sonar`                | `false`                  | run a SonarQube Cloud scan, see below                                             |
+| `sonar_project_key`    | `<owner>_<repo>`         |                                                                                   |
+| `sonar_args`           | `''`                     | extra `-D` arguments for the scanner                                              |
 
 Example for a project without `sbt-version-policy` and on a different Scala set:
 
@@ -78,10 +78,10 @@ Two sbt 2 behaviours make a naive coverage setup report nothing while still pass
   on any run whose build files did not change. This workflow sets `disk-cache: false` whenever
   coverage is enabled.
 
-The workflow also fails if the produced cobertura report has no valid lines, so a silently empty
+The workflow also fails if the produced Cobertura report has no valid lines, so a silently empty
 report is an error rather than a green build.
 
-Binary compatibility, formatting and scaladoc run as **explicit sbt tasks**, not via a project-local
+Binary compatibility, formatting and Scaladoc run as **explicit sbt tasks**, not via a project-local
 `check` alias. An alias can be stubbed out (`addCommandAlias("check", "show version")`), which makes
 the gate silently guarantee nothing.