name: Warm build cache

# Release builds run on TAG refs, and GitHub Actions cache isolation only
# lets a run restore caches created on its OWN ref or the DEFAULT branch.
# No workflow ran on `main`, so every release compiled the whole workspace
# cold on all five targets (~50 min wall clock, gated by Windows). This
# workflow builds the same `release-dist` profile on `main` so tag builds
# restore a warm default-branch cache.
#
# Triggers: dependency-affecting pushes to main (each release's version-bump
# commit warms the cache for the NEXT release), a weekly refresh so the
# cache never hits GitHub's 7-day unused-eviction, and manual dispatch.
#
# The setup steps mirror release.yml's build job (toolchain, target,
# dotslash/protoc, rust-cache key) — keep them in lockstep, or the cache
# key won't match and releases go back to cold builds.

on:
  push:
    branches: ["main"]
    paths:
      - "Cargo.lock"
      - "Cargo.toml"
      - "rust-toolchain.toml"
      - ".github/workflows/warm-cache.yml"
  schedule:
    - cron: "17 5 * * 1"
  workflow_dispatch:

permissions:
  contents: read

env:
  CARGO_TERM_COLOR: always

concurrency:
  group: warm-cache
  cancel-in-progress: true

jobs:
  warm:
    name: warm (${{ matrix.target }})
    strategy:
      fail-fast: false
      matrix:
        include:
          - target: aarch64-apple-darwin
            os: macos-14
          - target: x86_64-apple-darwin
            os: macos-14
          - target: x86_64-unknown-linux-gnu
            os: ubuntu-24.04
          - target: aarch64-unknown-linux-gnu
            os: ubuntu-24.04-arm
          - target: x86_64-pc-windows-msvc
            os: windows-2022
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@v4

      - name: Install toolchain (rust-toolchain.toml)
        run: rustup show

      - name: Add build target
        run: rustup target add ${{ matrix.target }}

      - name: Install dotslash (protoc launcher)
        run: cargo install dotslash --locked

      - name: Install protoc (Windows PATH fallback)
        if: runner.os == 'Windows'
        shell: pwsh
        run: |
          $url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.3/protoc-29.3-win64.zip"
          Invoke-WebRequest -Uri $url -OutFile protoc.zip
          Expand-Archive protoc.zip -DestinationPath "$env:USERPROFILE\protoc"
          Add-Content $env:GITHUB_PATH "$env:USERPROFILE\protoc\bin"

      # Same key as release.yml so tag builds restore this cache verbatim.
      - uses: Swatinem/rust-cache@v2
        with:
          key: ${{ matrix.target }}

      - name: Build kigi (release-dist)
        run: cargo build --profile release-dist -p kigi-bin --locked --target ${{ matrix.target }}