perf: optimize CI workflow for speed and concurrency

- Run docker job in parallel with build-and-test (no dependency)
- Add concurrency group to cancel superseded runs
- Remove redundant actions/cache (gradle/actions/setup-gradle handles it)
- Remove sdkman setup (JDK from setup-java, Gradle from wrapper)
- Consolidate 5 Gradle invocations into single ./gradlew clean build
  jacocoTestCoverageVerification (build task already runs lint + tests)
- Update ci-validator agent and CLAUDE.md to match

Author: claude

.claude/agents/ci-validator.md

@@ -13,22 +13,17 @@ Validate CI pipeline steps locally before pushing to prevent CI failures. Mirror
 
 ## GitHub Actions Workflow (`.github/workflows/ci.yml`)
 
-The CI pipeline runs on push/PR to `main` with these steps:
+The CI pipeline runs on push/PR to `main`. Uses `concurrency` to cancel superseded runs. Two jobs run **in parallel**:
 
 ### Job: build-and-test
 1. Checkout repository
 2. Set up JDK 21 (IBM Semeru)
-3. Setup Gradle
-4. Cache Gradle dependencies
-5. Validate Gradle wrapper
-6. Setup sdkman
-7. **Build**: `make clean build`
-8. **Lint**: `make lint`
-9. **Test**: `make test`
-10. **Coverage**: `make coverage-check`
-11. **Run**: `make run`
-
-### Job: docker (needs: build-and-test)
+3. Setup Gradle (includes caching)
+4. Validate Gradle wrapper
+5. **Build, lint, test, coverage**: `./gradlew clean build jacocoTestCoverageVerification` (single invocation)
+6. **Run**: `./gradlew :app:run --no-configuration-cache`
+
+### Job: docker (runs in parallel)
 1. Checkout repository
 2. Setup Docker Buildx
 3. **Build image**: `make docker-build`
@@ -44,15 +39,16 @@ CI Step 4/5: Coverage -> ./gradlew jacocoTestReport jacocoTestCoverageVerificati
 CI Step 5/5: Run      -> ./gradlew :app:run
 ```
 
+Note: `make ci` runs steps individually for clearer output. The GitHub workflow consolidates build+lint+test+coverage into a single Gradle invocation for speed.
+
 ## Diagnosing CI Failures
 
-1. **sdkman setup**: ensure `$HOME/.sdkman/bin/sdkman-init.sh` exists
-2. **Gradle wrapper validation**: ensure `gradle/wrapper/gradle-wrapper.jar` is genuine
-3. **Cache issues**: clean with `make clean` then rebuild
-4. **Checkstyle violations**: run `make lint` to see style issues
-5. **Test failures**: run `make test` with `--info` for details
-6. **Coverage below 60%**: run `make coverage-generate` and check the HTML report
-7. **Docker build fails**: check Dockerfile, base image availability
+1. **Gradle wrapper validation**: ensure `gradle/wrapper/gradle-wrapper.jar` is genuine
+2. **Cache issues**: clean with `make clean` then rebuild
+3. **Checkstyle violations**: run `make lint` to see style issues
+4. **Test failures**: run `make test` with `--info` for details
+5. **Coverage below 60%**: run `make coverage-generate` and check the HTML report
+6. **Docker build fails**: check Dockerfile, base image availability
 
 ## Workflow
 

.github/workflows/ci.yml

@@ -8,6 +8,10 @@ on:
   pull_request:
     branches: [ main ]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build-and-test:
 
@@ -26,36 +30,14 @@ jobs:
     - name: Setup Gradle
       uses: gradle/actions/setup-gradle@0723195856401067f7a2779048b490ace7a47d7c # v5
 
-      # Cache Gradle dependencies and build outputs to speed up future builds
-    - name: Cache Gradle and build outputs
-      uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5
-      with:
-        path: |
-          ~/.gradle/caches
-          ~/.gradle/wrapper
-          build
-        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
-        restore-keys: ${{ runner.os }}-gradle-
-
     - name: Validate Gradle wrapper
       uses: gradle/actions/wrapper-validation@0723195856401067f7a2779048b490ace7a47d7c # v5
 
-    - uses: sfesenko/setup-sdkman@c360e935fffb3cfa33eddd5748464329240cfd89 # v1
-
-    - name: Build
-      run: make clean build
-
-    - name: Lint
-      run: make lint
-
-    - name: Test
-      run: make test
-
-    - name: Verify code coverage meets minimum threshold ( > 60%)
-      run: make coverage-check
+    - name: Build, lint, test, and verify coverage
+      run: ./gradlew clean build jacocoTestCoverageVerification
 
     - name: Run
-      run: make run
+      run: ./gradlew :app:run --no-configuration-cache --warning-mode all
 
     - name: Upload test results
       if: always()
@@ -77,7 +59,6 @@ jobs:
         retention-days: 14
 
   docker:
-    needs: build-and-test
     runs-on: ubuntu-latest
 
     steps:

CLAUDE.md

@@ -83,10 +83,12 @@ Configure push target with environment variables:
 ## CI
 
 GitHub Actions (`.github/workflows/ci.yml`):
-- **build-and-test** job: builds, lints, tests, verifies coverage, and runs the app on every push/PR to `main`
-- **docker** job: builds Docker image after tests pass, conditionally pushes on main branch merge
+- **build-and-test** job: single `./gradlew clean build jacocoTestCoverageVerification` invocation (build + lint + test + coverage), then runs the app
+- **docker** job: builds Docker image **in parallel** with build-and-test, conditionally pushes on main branch merge
+- **concurrency**: superseded runs on the same branch are automatically cancelled
+- No sdkman in CI — JDK via `actions/setup-java`, Gradle via `gradle/actions/setup-gradle` (includes caching)
 
-Run CI locally before pushing: `make ci` (mirrors the build-and-test job exactly)
+Run CI locally before pushing: `make ci` (mirrors the build-and-test job)
 Run CI with Docker: `make ci-docker`
 
 ## Claude Code Agent Team