Improve caching.

.github/workflows/canary.yml

@@ -382,15 +382,23 @@ jobs:
           nuget sources Disable -Name "Microsoft Visual Studio Offline Packages"
           nuget sources Add -Source https://api.nuget.org/v3/index.json & exit 0
 
+      # The caches are restored/saved explicitly (not via the combined
+      # actions/cache) because the combined action only saves in a post
+      # step gated on job success: any later build or packing failure
+      # would discard hours of library builds. The explicit saves below
+      # run right after the libraries are pruned, before the fragile
+      # steps.
       - name: ThirdParty cache.
-        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        id: cache-third-party
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: ${{ env.TBUILD }}\ThirdParty
           key: ${{ runner.OS }}-${{ runner.arch }}-third-party-${{ env.CACHE_KEY }}
           restore-keys: ${{ runner.OS }}-${{ runner.arch }}-third-party-
 
       - name: Libraries cache.
-        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        id: cache-libs
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: |
             ${{ env.LibrariesPath }}\*
@@ -402,7 +410,8 @@ jobs:
           restore-keys: ${{ runner.OS }}-x64-libs-v2rel-
 
       - name: Qt cache.
-        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        id: cache-qt
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: |
             ${{ env.LibrariesPath }}\[qQ]t[_-]*
@@ -434,6 +443,34 @@ jobs:
         shell: bash
         run: find $LibrariesPath '(' '(' ! '(' -name '*.lib' -o -name '*.a' -o -name '*.exe' -o -name '*.h' -o -name '*.hpp' -o -name '*.inc' -o -name '*.cmake' -o -name '*.pc' -o -path '*/include/*' -o -path '*/objects-*' -o -path '*/cache_keys/*' -o -path '*/patches/*' -o -path '*/nv-codec-headers/*' ')' -type f ')' -o -empty ')' -delete
 
+      - name: Save ThirdParty cache.
+        if: steps.cache-third-party.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: ${{ env.TBUILD }}\ThirdParty
+          key: ${{ steps.cache-third-party.outputs.cache-primary-key }}
+
+      - name: Save Libraries cache.
+        if: steps.cache-libs.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: |
+            ${{ env.LibrariesPath }}\*
+            !${{ env.LibrariesPath }}\cache_keys
+            !${{ env.LibrariesPath }}\[qQ]t[_-]*
+            ${{ env.LibrariesPath }}\cache_keys\*
+            !${{ env.LibrariesPath }}\cache_keys\[qQ]t[_-]*
+          key: ${{ steps.cache-libs.outputs.cache-primary-key }}
+
+      - name: Save Qt cache.
+        if: steps.cache-qt.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: |
+            ${{ env.LibrariesPath }}\[qQ]t[_-]*
+            ${{ env.LibrariesPath }}\cache_keys\[qQ]t[_-]*
+          key: ${{ steps.cache-qt.outputs.cache-primary-key }}
+
       - name: Telegram Desktop build.
         run: |
           cd %TBUILD%\%REPO_NAME%\Telegram
@@ -622,8 +659,13 @@ jobs:
 
           sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
 
+      # Restore/save is explicit (not the combined actions/cache): the
+      # combined action saves in a post step gated on job success, so
+      # every failed signing or packing attempt was discarding the full
+      # library build. The save below runs right after the prune step.
       - name: Libraries cache.
-        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        id: cache-libs
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: |
             Libraries
@@ -650,6 +692,15 @@ jobs:
       - name: Free up some disk space.
         run: find Libraries '(' '(' ! '(' -name '*.a' -o -name '*.h' -o -name '*.hpp' -o -name '*.inc' -o -name '*.cmake' -o -path '*/include/*' -o -path '*/objects-*' -o -path '*/cache_keys/*' -o -path '*/patches/*' -o -perm +111 ')' -type f ')' -o -empty ')' -delete
 
+      - name: Save Libraries cache.
+        if: steps.cache-libs.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: |
+            Libraries
+            ThirdParty
+          key: ${{ steps.cache-libs.outputs.cache-primary-key }}
+
       - name: Telegram Desktop build.
         run: |
           cd $REPO_NAME/Telegram
@@ -886,14 +937,21 @@ jobs:
         uses: jlumbroso/free-disk-space@54081f138730dfa15788a46383842cd2f914a1be
         with:
           tool-cache: true
+          # The default large-packages cleanup apt-removes azure-cli,
+          # which the azure/login step below needs for update signing.
+          large-packages: false
 
       - name: Set up Docker Buildx.
         id: setup-buildx
         uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4
 
+      # Restore/save is explicit (not the combined actions/cache): the
+      # combined action saves in a post step gated on job success, so
+      # every failed build or packing attempt was discarding the whole
+      # docker layer cache. The save runs right after "Move cache.".
       - name: Libraries cache.
         id: cache-libs
-        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
         with:
           path: |
             ${{ runner.temp }}/.buildx-cache
@@ -923,6 +981,20 @@ jobs:
           rm -rf ${{ runner.temp }}/.buildx-cache
           mv ${{ runner.temp }}/.buildx-cache{-new,}
 
+      # The saved .mount-cache is the restored one, not the state after
+      # this run's docker build (cache-dance only extracts in its post
+      # step, which is also success-gated): slightly stale ccache/dnf
+      # mounts only cost time when the Dockerfile hash changes, while
+      # the fresh layer cache above carries the actual library builds.
+      - name: Save Libraries cache.
+        if: steps.cache-libs.outputs.cache-hit != 'true'
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6
+        with:
+          path: |
+            ${{ runner.temp }}/.buildx-cache
+            ${{ runner.temp }}/.mount-cache
+          key: ${{ steps.cache-libs.outputs.cache-primary-key }}
+
       - name: Generate a stub DesktopPrivate.
         run: |
           mkdir -p ../DesktopPrivate