Add desktop GUI latency harness

Co-authored-by: Tyler Longwell <tlongwell@block.xyz>
Signed-off-by: Tyler Longwell <tlongwell@block.xyz>

.github/workflows/ci.yml

@@ -432,6 +432,55 @@ jobs:
           fi
           echo "Desktop E2E Integration shards passed"
 
+  desktop-e2e-perf:
+    name: Desktop GUI Latency Harness
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    continue-on-error: true
+    needs: [changes]
+    if: github.event_name == 'push' || needs.changes.outputs.desktop == 'true' || needs.changes.outputs.desktop-rust == 'true' || needs.changes.outputs.rust == 'true'
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
+      - uses: cashapp/activate-hermit@e49f5cb4dd64ff0b0b659d1d8df499595451155a # v1
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        run: echo "STORE_PATH=$(pnpm store path --silent)" >> "$GITHUB_OUTPUT"
+      - name: Restore pnpm store cache
+        uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: pnpm-${{ runner.os }}-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: pnpm-${{ runner.os }}-
+      - name: Install desktop dependencies
+        run: just desktop-install-ci
+      - name: Get Playwright version
+        id: pw-version
+        run: echo "version=$(cd desktop && node -e "console.log(require('@playwright/test/package.json').version)")" >> "$GITHUB_OUTPUT"
+      - name: Restore Playwright browser cache
+        id: playwright-cache
+        uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
+        with:
+          path: ${{ env.PLAYWRIGHT_BROWSERS_PATH }}
+          key: playwright-${{ runner.os }}-${{ steps.pw-version.outputs.version }}
+      - name: Install Playwright Chromium
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
+        run: cd desktop && pnpm exec playwright install chromium
+      - name: Install Playwright system dependencies
+        run: cd desktop && pnpm exec playwright install-deps chromium
+      - name: Desktop GUI latency harness
+        run: just desktop-e2e-perf
+      - name: Upload desktop latency artifacts
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
+        with:
+          name: desktop-gui-latency-artifacts
+          path: |
+            desktop/playwright-report
+            desktop/test-results
+          if-no-files-found: ignore
+
   backend-integration:
     name: Backend Integration (relay e2e)
     runs-on: ubuntu-latest