ci(repo): set up rust toolchain directly instead of via mise

.github/workflows/build-release.yml

@@ -132,7 +132,23 @@ jobs:
         with:
           ref: refs/tags/${{ needs.resolve.outputs.tag }}
           fetch-depth: 0
-      - uses: jdx/mise-action@v4
+      # Set up the Rust toolchain directly instead of via mise: the self-hosted
+      # `build` runner (used for x86_64-linux) doesn't ship rustup, so mise's
+      # `rust = "stable"` silently no-ops and `cargo` goes missing. Install rustup
+      # when absent, pin stable, and add the cross target this matrix leg builds.
+      - name: Set up Rust toolchain
+        shell: bash
+        run: |
+          set -euo pipefail
+          if ! command -v rustup >/dev/null 2>&1; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
+              | sh -s -- -y --profile minimal --default-toolchain stable
+            echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+            export PATH="$HOME/.cargo/bin:$PATH"
+          fi
+          rustup toolchain install stable --profile minimal
+          rustup default stable
+          rustup target add "${{ matrix.target }}"
       - name: Build & upload binaries
         uses: taiki-e/upload-rust-binary-action@v1
         with:

.github/workflows/ci.yml

@@ -60,9 +60,27 @@ jobs:
     needs: [check-runners]
     runs-on: ${{ fromJson(needs.check-runners.outputs.runner) }}
     if: github.event.pull_request.draft == false
+    env:
+      RUST_BACKTRACE: "1"
     steps:
       - uses: actions/checkout@v4
-      - uses: jdx/mise-action@v4
+      # Set up the Rust toolchain directly instead of via mise. The self-hosted
+      # `build` runners don't ship rustup, so mise's `rust = "stable"` silently
+      # no-ops there and `cargo` ends up missing (`cargo: command not found`).
+      # Install rustup when absent, then pin stable with the components fmt/clippy need.
+      - name: Set up Rust toolchain
+        shell: bash
+        run: |
+          set -euo pipefail
+          if ! command -v rustup >/dev/null 2>&1; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
+              | sh -s -- -y --profile minimal --default-toolchain stable
+            echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+            export PATH="$HOME/.cargo/bin:$PATH"
+          fi
+          rustup toolchain install stable --profile minimal
+          rustup default stable
+          rustup component add rustfmt clippy
       - uses: Swatinem/rust-cache@v2
       - name: fmt
         run: cargo fmt --all -- --check