ci: save Rust caches only from pushes to main

.github/workflows/clippy.yml

@@ -28,4 +28,7 @@ jobs:
         with:
           components: clippy
       - uses: Swatinem/rust-cache@v2
+        with:
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - run: cargo clippy --all-targets -- -D warnings

.github/workflows/integration-cassandra.yml

@@ -65,6 +65,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Configure Cassandra authentication
         run: |
           docker exec ${{ job.services.cassandra.id }} sed -i \
@@ -121,6 +123,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Configure Cassandra authentication
         run: |
           docker exec ${{ job.services.cassandra.id }} sed -i \
@@ -172,6 +176,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Configure Cassandra authentication
         run: |
           docker exec ${{ job.services.cassandra.id }} sed -i \
@@ -208,6 +214,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Check production Cassandra feature graph
         run: cargo check --release --no-default-features --features cassandra
 

.github/workflows/integration-mongodb.yml

@@ -41,6 +41,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - uses: actions/setup-python@v5
         with:
           python-version: "3.11"
@@ -64,6 +66,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Start replica set
         # Same bootstrap developers run locally; --mongo-only skips the
         # server and prints the URI. No pipe: a bootstrap failure must fail
@@ -109,6 +113,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - uses: actions/setup-python@v5
         with:
           python-version: "3.11"
@@ -128,6 +134,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
       - name: Check production MongoDB feature graph
         run: cargo check --release --no-default-features --features mongodb
 

.github/workflows/integration.yml

@@ -54,6 +54,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release
         run: cargo build --release
@@ -116,6 +118,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release (SQLite backend)
         run: cargo build --release -p extenddb --no-default-features --features sqlite
@@ -178,6 +182,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release (dev mode, in-memory SQLite)
         run: cargo build --release -p extenddb --no-default-features --features sqlite-memory,dev-mode
@@ -240,6 +246,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release
         run: cargo build --release
@@ -354,6 +362,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release
         run: cargo build --release
@@ -415,6 +425,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Build release (SQLite backend)
         run: cargo build --release -p extenddb --no-default-features --features sqlite

.github/workflows/test.yml

@@ -34,6 +34,9 @@ jobs:
         with:
           toolchain: ${{ matrix.toolchain }}
       - uses: Swatinem/rust-cache@v2
+        with:
+          # Only pushes to main save, so other runs restore main's cache.
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       # Local S3 endpoint for the backup-store conformance suite. moto is a
       # pip package, so it needs no container image; MinIO no longer