Report Zephyr ROM and RAM usage in PRs

.github/workflows/compile.yml

@@ -1,6 +1,10 @@
 name: Build
 on: [push, pull_request]
 
+permissions:
+    contents: read
+    pull-requests: write
+
 concurrency:
     group: ${{ github.workflow }}-${{ github.ref }}
     cancel-in-progress: true  # Cancel in-flight jobs for the same branch or PR
@@ -129,7 +133,24 @@ jobs:
               sudo apt install --no-install-recommends git cmake ninja-build gperf ccache dfu-util device-tree-compiler wget python3-dev python3-venv python3-tk xz-utils file make gcc gcc-multilib g++-multilib libsdl2-dev libmagic1
               sudo apt install xxd
 
+          - name: Cache Zephyr
+            id: cache-zephyr
+            uses: actions/cache@v5
+            with:
+              path: zephyrproject
+              key: ${{ runner.os }}-zephyr
+
+          - name: Remove WARDuino from cache if present
+            if: steps.cache-zephyr.outputs.cache-hit == 'true'
+            working-directory: ${{ github.workspace }}/zephyrproject
+            run: |
+              rm -rf WARDuino
+
+              source .venv/bin/activate
+              west zephyr-export
+
           - name: Install Zephyr
+            if: steps.cache-zephyr.outputs.cache-hit != 'true'
             working-directory: ${{ github.workspace }}
             run: |
               python3 -m venv zephyrproject/.venv
@@ -145,8 +166,19 @@ jobs:
 
               west packages pip --install
 
-              cd zephyr
-              west sdk install
+          - name: Cache Zephyr SDK
+            id: cache-zephyr-sdk
+            uses: actions/cache@v5
+            with:
+              path: zephyr-sdk
+              key: ${{ runner.os }}-zephyr-sdk
+
+          - name: Install Zephyr SDK
+            if: steps.cache-zephyr-sdk.outputs.cache-hit != 'true'
+            working-directory: ${{ github.workspace }}/zephyrproject
+            run: |
+              source .venv/bin/activate
+              west sdk install --install-dir ${{ github.workspace }}/zephyr-sdk
 
           - name: Checkout repository
             uses: actions/checkout@v6
@@ -160,8 +192,33 @@ jobs:
               cp tests/compilation/esp32/upload.wasm platforms/Zephyr/upload.wasm
 
           - name: Build ESP32 target
+            env:
+              Zephyr-sdk_DIR: ${{ github.workspace }}/zephyr-sdk/cmake
             working-directory: ${{ github.workspace }}/zephyrproject/WARDuino
             run: |
               source ../.venv/bin/activate
               cd platforms/Zephyr
               west build -b esp32_devkitc_wroom/esp32/procpu
+
+          - name: Create ROM + RAM report
+            id: zephyr-size
+            working-directory: ${{ github.workspace }}/zephyrproject/WARDuino
+            run: |
+              source ../.venv/bin/activate
+              cd platforms/Zephyr
+
+              echo "## Zephyr build size report" > build-size.md
+              echo "### ROM" >> build-size.md
+              echo '```text' >> build-size.md
+              echo $(west build -t rom_report | tail -n1 | tr -d " " | numfmt --to=iec --format="%.2f") >> build-size.md
+              echo '```' >> build-size.md
+
+          - uses: jwalton/gh-find-current-pr@v1
+            id: finder
+
+          - name: Comment Zephyr size report
+            uses: marocchino/sticky-pull-request-comment@v3
+            with:
+              header: build-size
+              number: ${{ steps.finder.outputs.pr }}
+              path: zephyrproject/WARDuino/platforms/Zephyr/build-size.md