diff --git a/.github/workflows/validation.yml b/.github/workflows/validation.yml
new file mode 100644
index 00000000000..226080f2f01
--- /dev/null
+++ b/.github/workflows/validation.yml
@@ -0,0 +1,194 @@
+name: Validation
+
+on:
+  pull_request:
+    branches: ['main', '25.*']
+  merge_group:
+  workflow_dispatch:
+    inputs:
+      components:
+        description: 'Space-separated component names (e.g. "grid combo-box"), empty for all'
+        required: false
+        default: ''
+
+permissions:
+  contents: read
+  checks: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.event.merge_group.head_ref || github.ref }}
+  cancel-in-progress: true
+
+env:
+  FORK_COUNT: 5
+
+jobs:
+  validation:
+    name: Build and Test
+    runs-on: ubuntu-latest
+    timeout-minutes: 120
+    services:
+      selenium:
+        image: selenium/standalone-chrome:latest
+        options: --shm-size=2g
+        ports:
+          - 4444:4444
+    steps:
+      - name: Set Maven args
+        run: |
+          args="-ntp -B"
+          [ "${{ runner.debug }}" != "1" ] && args="$args -q"
+          echo "MAVEN_ARGS=$args" >> "$GITHUB_ENV"
+
+      - uses: actions/checkout@v6
+        with:
+          ref: ${{ github.event.pull_request.head.sha || github.event.merge_group.head_sha || github.sha }}
+          fetch-depth: ${{ github.event_name == 'merge_group' && 50 || 1 }}
+
+      - name: Setup JDK 21
+        uses: actions/setup-java@v5
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+          cache: 'maven'
+
+      - name: Setup Node 20
+        uses: actions/setup-node@v6
+        with:
+          node-version: '20'
+
+      - name: Install TestBench license
+        if: env.TB_LICENSE != ''
+        env:
+          TB_LICENSE: ${{ secrets.TB_LICENSE }}
+        run: |
+          mkdir -p ~/.vaadin
+          user="${TB_LICENSE%%/*}"
+          key="${TB_LICENSE#*/}"
+          echo "{\"username\":\"${user}\",\"proKey\":\"${key}\"}" > ~/.vaadin/proKey
+
+      - name: Show environment info
+        run: |
+          java -version
+          mvn -version
+          node --version
+          npm --version
+
+      - name: Compile all sources
+        run: mvn clean test-compile -DskipFrontend $MAVEN_ARGS
+
+      - name: Unit tests and install
+        run: |
+          mvn install -Drelease -T $FORK_COUNT $MAVEN_ARGS || {
+            echo "::warning::First attempt failed (Maven multi-thread race). Retrying..."
+            sleep 15
+            mvn install -Drelease -T $FORK_COUNT $MAVEN_ARGS
+          }
+
+      - name: Check for skip-ci
+        id: skip-ci
+        if: github.event_name == 'pull_request' || github.event_name == 'merge_group'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          PR_TITLE: ${{ github.event.pull_request.title }}
+        run: |
+          if [ "${{ github.event_name }}" = "merge_group" ]; then
+            echo "skip=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          if echo "$PR_TITLE" | grep -q '\[skip ci\]'; then
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          pr_number="${{ github.event.pull_request.number }}"
+          commits=$(gh api "repos/${{ github.repository }}/pulls/$pr_number/commits" --jq '.[].commit.message')
+          if echo "$commits" | grep -q '\[skip ci\]'; then
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          echo "skip=false" >> "$GITHUB_OUTPUT"
+
+      - name: Detect modified components
+        id: components
+        if: steps.skip-ci.outputs.skip != 'true'
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          elements="${{ github.event.inputs.components || '' }}"
+          changed_files=""
+          if [ -z "$elements" ] && [ "${{ github.event_name }}" = "pull_request" ]; then
+            pr_number="${{ github.event.pull_request.number }}"
+            changed_files=$(gh api "repos/${{ github.repository }}/pulls/$pr_number/files" --jq '.[].filename')
+          elif [ -z "$elements" ] && [ "${{ github.event_name }}" = "merge_group" ]; then
+            changed_files=$(git diff --name-only "${{ github.event.merge_group.base_sha }}" "${{ github.event.merge_group.head_sha }}")
+          fi
+          if [ -n "$changed_files" ]; then
+            modified=$(echo "$changed_files" \
+              | grep 'vaadin.*flow-parent' \
+              | sed 's,^vaadin-\(.*\)-flow-parent.*,\1,' \
+              | sort -u)
+            nmods=$(echo "$modified" | wc -w | tr -d ' ')
+            all_files=$(echo "$changed_files" | sort -u | tr -d '[:space:]')
+            component_files=$(echo "$changed_files" | grep 'vaadin.*flow-parent' | sort -u | tr -d '[:space:]')
+            if [ "$nmods" -lt 5 ] && [ ${#all_files} -eq ${#component_files} ]; then
+              elements=$(echo $modified | tr '\n' ' ')
+              echo "Running partial build for: $elements"
+            fi
+          fi
+          echo "elements=$elements" >> "$GITHUB_OUTPUT"
+
+      - name: npm install
+        if: steps.skip-ci.outputs.skip != 'true'
+        run: npm install --ignore-scripts --silent --quiet --no-progress
+
+      - name: Merge ITs
+        if: steps.skip-ci.outputs.skip != 'true'
+        run: node scripts/mergeITs.js ${{ steps.components.outputs.elements }}
+
+      - name: Pre-compile merged ITs
+        if: steps.skip-ci.outputs.skip != 'true'
+        run: cd integration-tests && mvn compile test-compile $MAVEN_ARGS -DskipUnitTests
+
+      - name: WTR tests
+        if: steps.skip-ci.outputs.skip != 'true'
+        run: node scripts/wtr.js ${{ steps.components.outputs.elements }}
+
+      - name: Run integration tests
+        if: steps.skip-ci.outputs.skip != 'true'
+        env:
+          TBLICENSE: ${{ secrets.TB_LICENSE }}
+        run: |
+          args="$MAVEN_ARGS"
+          [ -n "$TBLICENSE" ] && args="$args -Dvaadin.testbench.developer.license=$TBLICENSE"
+          args="$args -Dtest.use.hub=true -Dcom.vaadin.testbench.Parameters.hubHostname=localhost -Dcom.vaadin.testbench.Parameters.hubPort=4444"
+          args="$args -Dfailsafe.rerunFailingTestsCount=2 -Dmaven.test.redirectTestOutputToFile=true"
+          mode="-Dfailsafe.forkCount=$FORK_COUNT -Dcom.vaadin.testbench.Parameters.testsInParallel=1"
+
+          mvn verify -Dvaadin.pnpm.enable -Drun-it -Drelease -Dvaadin.productionMode \
+            -Dvaadin.force.production.build=true \
+            $mode $args -pl integration-tests -DskipUnitTests
+
+      - name: Publish unit test results
+        if: always()
+        ## Make sonar happy for external actions
+        uses: dorny/test-reporter@a43b3a5f7366b97d083190328d2c652e1a8b6aa2
+        with:
+          name: Unit Tests
+          path: '**/target/surefire-reports/TEST-*.xml'
+          reporter: java-junit
+
+      - name: Publish integration test results
+        if: always()
+        uses: dorny/test-reporter@a43b3a5f7366b97d083190328d2c652e1a8b6aa2
+        with:
+          name: Integration Tests
+          path: 'integration-tests/target/failsafe-reports/TEST-*.xml'
+          reporter: java-junit
+
+      - name: Upload error screenshots
+        if: failure()
+        uses: actions/upload-artifact@v5
+        with:
+          name: error-screenshots
+          path: 'integration-tests/error-screenshots/'
+          retention-days: 5
diff --git a/scripts/build.sh b/scripts/build.sh
index 5a364ea8983..f5a7a5b2b9e 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -157,6 +157,10 @@ cmd="node scripts/mergeITs.js "`echo $elements`
 tcLog "Merge IT modules - $cmd"
 $cmd || tcStatus 1 "Merging ITs failed"
 
+## Pre-compile merged ITs to avoid incremental compilation issues
+tcLog "Pre-compiling merged ITs"
+(cd integration-tests && mvn compile test-compile $args -DskipUnitTests) || tcStatus 1 "Merged ITs compilation failed"
+
 ## Compute variable to run tests
 [ -n "$TBLICENSE" ] && args="$args -Dvaadin.testbench.developer.license=$TBLICENSE"
 [ -n "$TBHUB" ] && args="$args -Dtest.use.hub=true -Dcom.vaadin.testbench.Parameters.hubHostname=$TBHUB"
@@ -197,7 +201,7 @@ then
 else
   mode="-Dfailsafe.forkCount=$FORK_COUNT -Dcom.vaadin.testbench.Parameters.testsInParallel=$TESTS_IN_PARALLEL"
   ### Run IT's in merged module
-  cmd="mvn $verify -Drun-it -Drelease -Dvaadin.productionMode -Dfailsafe.rerunFailingTestsCount=2 $mode $args -pl integration-tests -DskipUnitTests"
+  cmd="mvn $verify -Drun-it -Drelease -Dvaadin.productionMode -Dvaadin.force.production.build=true -Dfailsafe.rerunFailingTestsCount=2 $mode $args -pl integration-tests -DskipUnitTests"
   tcLog "Running merged ITs - mvn $verify -B -Drun-it -Drelease -pl integration-tests ..."
   echo $cmd
   $cmd
diff --git a/scripts/mergeITs.js b/scripts/mergeITs.js
index c641a8077e1..f2f70fa626d 100755
--- a/scripts/mergeITs.js
+++ b/scripts/mergeITs.js
@@ -252,6 +252,20 @@ async function copySources() {
       }
     });
 
+  // clean stale Flow-generated files from previous runs
+  ['package.json', 'package-lock.json', 'pnpm-lock.yaml', 'tsconfig.json', 'types.d.ts', 'vite.generated.ts', '.npmrc', '.pnpmfile.cjs']
+    .forEach(f => {
+      const file = `${itFolder}/${f}`;
+      if (fs.existsSync(file)) {
+        console.log(`removing ${file}`);
+        fs.rmSync(file);
+      }
+    });
+
+  // Create empty package.json so that build-frontend does not
+  // perform aggressive cleanup that deletes flow-build-info.json
+  fs.writeFileSync(`${itFolder}/package.json`, '{}');
+
   modules.forEach(parent => {
     const id = parent.replace('-parent', '');
     console.log(`Copying ${parent}/${id}-integration-tests`);
diff --git a/scripts/run.js b/scripts/run.js
index c3a427d1c34..534595dda68 100755
--- a/scripts/run.js
+++ b/scripts/run.js
@@ -98,9 +98,9 @@ function generateHistoryItems() {
 // === Maven Execution ===
 
 function runMvn(module, modeKey, args, message, onOutput) {
-  const command = `mvn ${args.join(' ')}`;
+  const command = `mvn -B -ntp ${args.join(' ')}`;
   args = [...args, '-Dstyle.color=always'];
-  console.log(`\n${message}\n`);
+  console.log(`\n${message}\n${command}\n`);
 
   const mvn = spawn('mvn', args, { stdio: ['inherit', 'pipe', 'pipe'] });
 
diff --git a/scripts/wtr.js b/scripts/wtr.js
index 122558cbb55..20e894d1f07 100755
--- a/scripts/wtr.js
+++ b/scripts/wtr.js
@@ -47,7 +47,7 @@ function runTests() {
       }
 
       // Install the IT module dependencies
-      execSync(`mvn -DskipTests flow:prepare-frontend flow:build-frontend`, {
+      execSync(`mvn -DskipTests -Dvaadin.force.production.build=true flow:prepare-frontend flow:build-frontend`, {
         cwd: itFolder,
         stdio: 'inherit'
       });