fix: remove pre-installed Rust stable toolchain to stabilize CI cache keys

.github/workflows/e2e.yml

@@ -63,6 +63,12 @@ jobs:
       - name: Setup environment variables
         run: |
           echo "RUSTFLAGS=--remap-path-prefix=${GITHUB_WORKSPACE}=/builds/dfinity" >> $GITHUB_ENV
+      # Remove pre-installed stable toolchain so it doesn't pollute the
+      # rust-cache environment hash.  macOS (and sometimes Linux) runner
+      # images ship with varying stable versions, making the hash
+      # non-deterministic and causing constant cache misses.
+      - name: Remove pre-installed Rust stable toolchain
+        run: rustup toolchain remove stable 2>/dev/null || true
       # This step also handles Rust-specific caching
       - name: Install Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1

.github/workflows/lint.yml

@@ -47,7 +47,12 @@ jobs:
 
     steps:
       - uses: actions/checkout@v6
-
+      # Remove pre-installed stable toolchain so it doesn't pollute the
+      # rust-cache environment hash.  macOS (and sometimes Linux) runner
+      # images ship with varying stable versions, making the hash
+      # non-deterministic and causing constant cache misses.
+      - name: Remove pre-installed Rust stable toolchain
+        run: rustup toolchain remove stable 2>/dev/null || true
       # This step also handles Rust-specific caching
       - name: Install Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1

.github/workflows/release.yml

@@ -66,6 +66,13 @@ jobs:
           echo "TARBALL_2_FILENAME=dfx-${{ matrix.target }}.tar.gz" >> $GITHUB_ENV
           echo "SHA256_2_FILENAME=dfx-${{ matrix.target }}.tar.gz.sha256" >> $GITHUB_ENV
 
+      # Remove pre-installed stable toolchain so it doesn't pollute the
+      # rust-cache environment hash.  macOS (and sometimes Linux) runner
+      # images ship with varying stable versions, making the hash
+      # non-deterministic and causing constant cache misses.
+      - name: Remove pre-installed Rust stable toolchain
+        run: rustup toolchain remove stable 2>/dev/null || true
+
       # This step also handles Rust-specific caching
       - name: Install Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1

.github/workflows/unit.yml

@@ -48,6 +48,12 @@ jobs:
         os: [ ubuntu-24.04, ubuntu-24.04-arm, macos-15 ]
     steps:
       - uses: actions/checkout@v6
+      # Remove pre-installed stable toolchain so it doesn't pollute the
+      # rust-cache environment hash.  macOS (and sometimes Linux) runner
+      # images ship with varying stable versions, making the hash
+      # non-deterministic and causing constant cache misses.
+      - name: Remove pre-installed Rust stable toolchain
+        run: rustup toolchain remove stable 2>/dev/null || true
       # This step also handles Rust-specific caching
       - name: Install Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1

src/canisters/frontend/icx-asset/src/main.rs

@@ -136,7 +136,7 @@ fn style() -> Styles {
 async fn main() -> anyhow::Result<()> {
     let opts: Opts = Opts::parse();
 
-    let logger = support::new_logger(opts.log_level.into());
+    let (logger, _async_guard) = support::new_logger(opts.log_level.into());
 
     let agent = Agent::builder()
         .with_url(&opts.replica)

src/canisters/frontend/icx-asset/src/support.rs

@@ -42,10 +42,13 @@ impl<D: slog_term::Decorator> slog::Drain for TermLogFormat<D> {
     }
 }
 
-pub(crate) fn new_logger(level: Level) -> Logger {
+pub(crate) fn new_logger(level: Level) -> (Logger, slog_async::AsyncGuard) {
     let decorator = slog_term::TermDecorator::new().build();
     let drain = TermLogFormat::new(decorator).fuse();
     let drain = slog::LevelFilter::new(drain, level).fuse();
-    let drain = slog_async::Async::new(drain).build().fuse();
-    Logger::root(drain, slog::o!())
+    let (drain, guard) = slog_async::Async::new(drain)
+        .overflow_strategy(slog_async::OverflowStrategy::Block)
+        .build_with_guard();
+    let drain = drain.fuse();
+    (Logger::root(drain, slog::o!()), guard)
 }