Add Playwright CI tests for mix-fetch internal-dev harness

Per-PR smoke test (ci-sdk-wasm.yml): loads WASM runtimes and inits
MixFetch on Chromium, Firefox, and WebKit.

Nightly stress test (nightly-mix-fetch-stress.yml): connects to mainnet
via random gateway, runs 10 mixed-size fetches, asserts >= 80% pass.

.github/workflows/ci-sdk-wasm.yml

@@ -54,6 +54,30 @@ jobs:
       - name: "Build"
         run: make sdk-wasm-build
 
+      - name: "Build mix-fetch WASM (debug)"
+        run: |
+          make -C wasm/mix-fetch/go-mix-conn build-debug-dev
+          make -C wasm/mix-fetch build-rust-debug
+
+      - name: "Build mix-fetch internal-dev harness"
+        working-directory: wasm/mix-fetch/internal-dev
+        run: npm install && npm run build
+
+      - name: "Install Playwright browsers"
+        working-directory: wasm/mix-fetch/tests
+        run: npm install && npx playwright install --with-deps # --with-deps assumes Ubuntu/Debian, see note in wasm/mix-fetch/tests/README.md
+
+      - name: "Smoke-test mix-fetch internal-dev (headless)"
+        working-directory: wasm/mix-fetch/tests
+        run: npm run test:smoke
+
+      - name: Upload Playwright traces on failure
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: mix-fetch-playwright-traces
+          path: wasm/mix-fetch/tests/test-results/
+
       - name: "Test"
         run: make sdk-wasm-test
 

.github/workflows/nightly-mix-fetch-stress.yml

@@ -0,0 +1,61 @@
+name: nightly-mix-fetch-stress
+
+on:
+  schedule:
+    - cron: '0 3 * * *'
+  workflow_dispatch:
+
+jobs:
+  stress:
+    runs-on: arc-linux-latest
+    env:
+      CARGO_TERM_COLOR: always
+      RUSTUP_PERMIT_COPY_RENAME: 1
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ vars.REQUIRED_RUSTC_VERSION }}
+          target: wasm32-unknown-unknown
+          override: true
+
+      - name: Set up Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: "1.24.6"
+
+      - name: Install wasm-pack
+        run: curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh
+
+      - name: Install wasm-bindgen-cli
+        run: cargo install wasm-bindgen-cli
+
+      - name: "Build mix-fetch WASM (debug)"
+        run: |
+          make -C wasm/mix-fetch/go-mix-conn build-debug-dev
+          make -C wasm/mix-fetch build-rust-debug
+
+      - name: "Build internal-dev harness"
+        working-directory: wasm/mix-fetch/internal-dev
+        run: npm install && npm run build
+
+      - name: "Install Playwright browsers"
+        working-directory: wasm/mix-fetch/tests
+        run: npm install && npx playwright install --with-deps
+
+      - name: "Stress-test mix-fetch through mainnet"
+        working-directory: wasm/mix-fetch/tests
+        run: npm run test:stress
+
+      - name: Upload Playwright traces on failure
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: mix-fetch-stress-traces
+          path: wasm/mix-fetch/tests/test-results/