add gateway backend communication harness (#949)

.github/workflows/check.yml

@@ -40,6 +40,18 @@ jobs:
       - name: Run tests
         run: pnpm run test
 
+      - name: Run harness checks
+        run: pnpm run harness:ci
+
+      - name: Upload harness artifacts
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: harness-artifacts
+          path: artifacts/harness
+          if-no-files-found: warn
+          retention-days: 7
+
   build:
     runs-on: windows-latest
     env:

.github/workflows/harness.yml

@@ -0,0 +1,49 @@
+name: Harness
+
+on:
+  workflow_dispatch:
+  pull_request:
+    branches:
+      - main
+    paths:
+      - 'harness/**'
+      - 'tests/unit/harness-specs.test.ts'
+      - 'package.json'
+      - 'pnpm-lock.yaml'
+      - 'pnpm-workspace.yaml'
+      - '.github/workflows/harness.yml'
+
+jobs:
+  harness:
+    runs-on: ubuntu-latest
+    env:
+      ELECTRON_SKIP_BINARY_DOWNLOAD: '1'
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+          cache: 'pnpm'
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Run harness CI checks
+        run: pnpm run harness:ci
+
+      - name: Upload harness artifacts
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: harness-artifacts
+          path: artifacts/harness
+          if-no-files-found: warn
+          retention-days: 7