warm-rust-cache.yml

# Warm the shared Rust cache on every push to develop.
#
# CI runs only on pull_request, and GitHub scopes a cache saved during a PR
# run to that PR's own merge ref. Nothing used to save a Rust cache on
# develop itself, so the first CI run of every new PR started cold: measured
# ~30-37 min for the Rust job versus ~15-21 min warm. PR runs may restore
# caches created on their base branch, so populating develop's cache under
# the same `ci-macos` shared key that ci.yml restores makes fresh PRs start
# warm.
#
# This job only compiles — clippy plus `cargo test --no-run`, the same
# artifact set the ci.yml Rust job needs. It never executes tests and denies
# no warnings: develop was already gated by CI before merge, so this is a
# cache producer, not a quality gate, and a red herring here must not block
# cache publication (`cache-on-failure` below).
#
# Mirrors the toolchain setup in ci.yml (Rust stable, swatinem/rust-cache,
# same workspace mapping and shared key). If ci.yml's Rust steps change,
# change this file to match.

name: "Warm Rust cache"

on:
  push:
    branches:
      - develop

# Serialize warm runs, but never cancel one that is already building.
#
# This used to be `cancel-in-progress: true`, on the theory that macOS runner
# slots should not be spent on stale SHAs. Measured over 20 consecutive
# develop pushes, 11 runs were cancelled -- and every one of them died inside
# `cargo test (build only)`, the longest step and the only one that produces
# the test-profile artifacts this workflow exists to publish. `cache-on-failure`
# then saved the truncated result under the exact key ci.yml restores, so PR
# runs got a cache holding clippy's check artifacts and nothing else, and paid
# 17m37s recompiling all 43 workspace crates in `cargo test --workspace`.
#
# With cancellation off, GitHub runs the current warm to completion and keeps
# only the newest push queued behind it, so a busy merge day costs at most one
# extra queued run instead of a day of unusable caches.
concurrency:
  group: warm-rust-cache-develop
  cancel-in-progress: false

jobs:
  # ── Change scope ────────────────────────────────────────────────────────────
  # Frontend-only merges cannot invalidate any Rust artifact, so skip the
  # macOS runner entirely. Reuses ci.yml's detection script to avoid drift.
  changes:
    name: Detect warm scope
    runs-on: ubuntu-latest
    outputs:
      rust_required: ${{ steps.scope.outputs.rust_required }}

    steps:
      - name: Checkout
        uses: actions/checkout@v6
        with:
          fetch-depth: 0

      - name: Detect Rust-relevant changes
        id: scope
        env:
          BEFORE_SHA: ${{ github.event.before }}
          HEAD_SHA: ${{ github.sha }}
        run: |
          # Branch creation and force pushes leave no usable `before` SHA.
          # Warm rather than guess, matching the detect script's fail-closed
          # stance on an empty diff.
          if ! git cat-file -e "${BEFORE_SHA}" 2>/dev/null; then
            echo "rust_required=true" >> "${GITHUB_OUTPUT}"
            echo "Rust required: true (no usable before SHA)"
            exit 0
          fi
          rust_required="$(
            git diff --name-only -z "${BEFORE_SHA}" "${HEAD_SHA}" |
              node scripts/ci/detect-rust-changes.cjs
          )"
          echo "rust_required=${rust_required}" >> "${GITHUB_OUTPUT}"
          echo "Rust required: ${rust_required}"

  # ── Warm ────────────────────────────────────────────────────────────────────
  warm:
    name: Rust (warm cache)
    needs: changes
    if: needs.changes.outputs.rust_required == 'true'
    runs-on: macos-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v6

      - name: Install Rust stable
        uses: dtolnay/rust-toolchain@stable

      # Same workspace mapping and shared key as ci.yml so PR runs restoring
      # from the base branch get an exact-key hit. `cache-on-failure` keeps a
      # partially built dependency cache even if a compile step breaks — a
      # partial warm still beats a cold start for the next run.
      - name: Rust cache
        uses: swatinem/rust-cache@v2
        with:
          workspaces: "./src-tauri -> target"
          shared-key: "ci-macos"
          cache-on-failure: true

      - name: Stage org2-pm sidecar
        run: node scripts/tauri/prepare-sidecars.cjs --profile debug

      # Populates the check-mode dependency artifacts ci.yml's clippy step
      # restores. No `-D warnings`: this job must publish a cache, not gate.
      - name: cargo clippy (all targets)
        working-directory: src-tauri
        run: cargo clippy --workspace --all-targets

      # Populates the codegen and link artifacts for every test target
      # without spending runner time executing ~6800 already-gated tests.
      - name: cargo test (build only)
        working-directory: src-tauri
        run: cargo test --workspace --no-run