Fix CI dependency caching: per-platform cache keys and fallbacks [androidbuild] [iosbuild]

.github/workflows/reusable/cached-install/action.yml

@@ -4,18 +4,43 @@ description: "install dependencies, build and cache result, or restore from cach
 runs:
   using: "composite"
   steps:
-    - name: cache homedir
+    # The cache keys must distinguish the TARGET platform, not just the
+    # runner: the macOS host build, the iOS build and the Android build
+    # all run on the same macos runner image, and GitHub's cache is
+    # write-once per key — with a shared key the first job to save owns
+    # the cache forever and the other platforms' saves fail ("Cache save
+    # failed."), so their dependencies were rebuilt from source on every
+    # run (~30 min Android, ~35 min iOS). ARCHFLAGS is the workflow-level
+    # platform selector (empty = host, --ios, --android). The vcpkg
+    # submodule commit is part of the key because the tool version
+    # changes what it builds; the restore-keys prefix fallback reuses the
+    # newest previous cache on any key miss — vcpkg's own per-package ABI
+    # hashing makes stale archive entries harmless (they are ignored) and
+    # `vcpkg install` reconciles a stale installed tree.
+    - name: compute cache keys
+      id: keys
+      run: |
+        echo "platform=${ARCHFLAGS:-host}" >> "$GITHUB_OUTPUT"
+        echo "vcpkg_sha=$(git rev-parse HEAD:vcpkg)" >> "$GITHUB_OUTPUT"
+      shell: bash
+    - name: cache vcpkg binary archives
       id: cache-homedir
       uses: actions/cache/restore@v4
       with:
-        key: ${{ runner.arch }}-${{ runner.os }}-cache-homedir2-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        key: ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-archives-${{ steps.keys.outputs.vcpkg_sha }}-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        restore-keys: |
+          ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-archives-${{ steps.keys.outputs.vcpkg_sha }}-
+          ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-archives-
         path: |
           ~/.cache/vcpkg/archives
     - name: cache vcpkg installed
       id: cache-vcpkg-installed
       uses: actions/cache/restore@v4
       with:
-        key: ${{ runner.arch }}-${{ runner.os }}-cache-vcpkg-installed2-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        key: ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-installed-${{ steps.keys.outputs.vcpkg_sha }}-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        restore-keys: |
+          ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-installed-${{ steps.keys.outputs.vcpkg_sha }}-
+          ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-installed-
         path: |
           ./build/vcpkg_installed
     - name: install-prerequisities
@@ -45,30 +70,22 @@ runs:
           exit "$EXITCODE"
         fi
       shell: bash
-    - name: cache homedir save
+    # Save even on failure (if: always()) so a partially built dependency
+    # set is reused by the retry. Saving is skipped when the exact key was
+    # already restored (nothing new to store).
+    - name: cache vcpkg binary archives save
       id: cache-homedir-save
-      if: always()
+      if: always() && steps.cache-homedir.outputs.cache-hit != 'true'
       uses: actions/cache/save@v4
       with:
-        key: ${{ runner.arch }}-${{ runner.os }}-cache-homedir2-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        key: ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-archives-${{ steps.keys.outputs.vcpkg_sha }}-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
         path: |
           ~/.cache/vcpkg/archives
     - name: cache vcpkg installed save
       id: cache-vcpkg-installed-save
-      if: always()
+      if: always() && steps.cache-vcpkg-installed.outputs.cache-hit != 'true'
       uses: actions/cache/save@v4
       with:
-        key: ${{ runner.arch }}-${{ runner.os }}-cache-vcpkg-installed2-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
+        key: ${{ runner.arch }}-${{ runner.os }}-${{ steps.keys.outputs.platform }}-installed-${{ steps.keys.outputs.vcpkg_sha }}-${{ hashFiles('./vcpkg.json', './overlaytriplets/**', './overlayports/**') }}
         path: |
           ./build/vcpkg_installed
-    #- name: Commit compiled binaries
-    #  run: |
-    #    git config --global user.name 'github-actions[bot]'
-    #    git config --global user.email 'github-actions[bot]@users.noreply.github.com'
-    #    git add packages/streamr-libstreamrproxyclient/dist
-    #    git add packages/streamr-libstreamrproxyclient/wrappers/go
-    #    git commit -m "Automatically compiled binaries"
-    #    git pull --rebase --no-edit
-    #    git push --no-verify
-    #  shell: bash
-

packages/streamr-proto-rpc/CMakeLists.txt

@@ -96,7 +96,11 @@ file(WRITE "${CMAKE_BINARY_DIR}/streamr-proto-rpc-config.cmake"
 # and the plugin runs on the developer machine anyway. (Previously this
 # sat inside the modules block below and was skipped on Android only as
 # a side effect of the modules gate being OFF there.)
-if(NOT CMAKE_CROSSCOMPILING)
+# NOTE the explicit IOS check: iOS package builds keep the host
+# CMAKE_SYSTEM_NAME (they use the Homebrew compiler and only swap the
+# SDK/sysroot — see homebrewClang.cmake), so CMAKE_CROSSCOMPILING is
+# FALSE there; IOS is set by toolchains/ios.toolchain.cmake.
+if(NOT IOS AND NOT CMAKE_CROSSCOMPILING)
     add_executable(protobuf-streamr-plugin src/PluginCodeGeneratorMain.cpp include/streamr-proto-rpc/PluginCodeGenerator.hpp)
 
     target_include_directories(