name: PR Check — Rust

# Rust half of the former check.yml (split in #232).
#
# Runs on PRs that change Rust, plus once a week on main to refresh the shared
# cache (see the note on the triggers). The runner has capacity 1 — jobs queue
# instead of running in parallel, so every minute spent here is a minute the
# next PR waits.
#
# No `branches:` filter on purpose. `branches: [main]` never matched a PR
# stacked on top of another feature branch, which is what /autopilot produces:
# 4 of the 5 PRs in the feature-gating milestone ran no CI at all.

on:
  pull_request:
    paths:
      - 'src-tauri/**'
      - '.forgejo/workflows/check-rust.yml'
      # Whole directory, not just audit.toml: a later .cargo/config.toml
      # (rustflags, linker, target dir) would change the Rust build, and an
      # exact-path entry would let it skip Rust CI unnoticed.
      - '.cargo/**'
  # The weekly run is what feeds the cache to pull requests (#234). The runner
  # (forgejo-runner v12.7.0) isolates what a pull_request run writes to that
  # PR's ref: later pushes to the same PR read it back, other PRs never see it.
  # A PR run falls back to the shared, non-isolated entries only when nothing
  # matches in its own scope. Scheduled and dispatched runs write to the shared
  # scope, which makes them this workflow's only writers of it (a merged PR's
  # `closed` event would be another, but this workflow does not subscribe to
  # it).
  #
  # The runner deletes an entry unused for 7 days or created more than 30 days
  # ago, and keeps only the newest entry per key, whatever its scope; the next
  # Monday run saves a fresh one. Cold runs that do not mean #234 is back (a
  # timeout would):
  # - a new stable Rust (the toolchain floats on `stable`) or a change to this
  #   job's `env:`: the key hashes rustc and the CARGO*, RUST*, CC*, CFLAGS*,
  #   CXX* and CMAKE* variables. Cold until the next Monday;
  # - a PR run that saves under the shared entry's key evicts it for every PR
  #   until the next Monday. It saves when its own scope holds an older entry
  #   for another Cargo.lock, served before the shared one: a PR that bumped a
  #   dependency, then went back to main's lockfile. Two open PRs on the same
  #   lockfile, different from main's, evict each other the same way;
  # - PR runs once an entry that only got exact hits, hence never re-saved,
  #   reaches 30 days;
  # - after a week without any cache request, the Monday restore can fail with
  #   a 404: the lookup does not refresh the entry, and the cleanup it triggers
  #   may delete it (forgejo/runner#1741). The run then saves a fresh entry.
  # workflow_dispatch re-seeds by hand.
  schedule:
    # Mondays 06:30 UTC, after audit.yml (06:00 UTC).
    - cron: '30 6 * * 1'
  workflow_dispatch:

# Cancel obsolete runs (e.g. on force-push) so only the latest commit runs.
# Distinct from the frontend group: a shared group would make the two
# workflows cancel each other on a PR that touches both.
concurrency:
  group: ci-rust-${{ github.ref }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  rust:
    runs-on: ubuntu
    container: ubuntu:22.04
    env:
      PATH: /root/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
      CARGO_TERM_COLOR: always
      # rust-cache keeps the dependencies and drops this crate's own artifacts
      # before saving, so incremental data would never be reused — pure
      # overhead — and test debug info would only make the cached target/
      # bigger.
      CARGO_INCREMENTAL: 0
      CARGO_PROFILE_TEST_DEBUG: 0
    steps:
      - name: Install system dependencies, Node.js and Rust
        run: |
          apt-get update
          # zstd: the cache archives are compressed with it when present,
          # faster and smaller than the gzip fallback.
          apt-get install -y --no-install-recommends \
            curl wget git ca-certificates build-essential pkg-config \
            libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev libssl-dev \
            libdbus-1-dev zstd
          # Node.js runs the JavaScript actions: actions/checkout (node20) and
          # Swatinem/rust-cache (node24 since v2.9). The runner starts them
          # with whatever `node` the container has, so install the newest
          # runtime they declare. taiki-e/install-action is a composite action.
          curl -fsSL https://deb.nodesource.com/setup_24.x | bash -
          apt-get install -y nodejs
          # Rust toolchain
          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --profile minimal
          node --version
          rustc --version
          cargo --version

      - name: Checkout
        uses: https://github.com/actions/checkout@v4

      # Caches ~/.cargo (registry, git, bin) and src-tauri/target, keyed on the
      # rustc version, the job's CARGO*/RUST* environment, the dependencies
      # declared in the Cargo manifests and lockfile (not the app's own
      # version), and this job. Saved only when the job succeeds and the key
      # was not an exact hit. Served by
      # the runner's cache proxy on port 28100, which ufw opens to the Docker
      # job networks only; until 2026-10-03 every restore and save timed out
      # there (#234, la-compagnie-maximus docs/forgejo-ops.md). What a PR run
      # saves stays private to that PR: see the note on the triggers.
      - name: Rust cache
        uses: https://github.com/Swatinem/rust-cache@v2
        with:
          workspaces: "src-tauri -> target"

      - name: cargo check
        run: cargo check --manifest-path src-tauri/Cargo.toml --all-targets

      # Anti-rot guard for the suppressions in .cargo/audit.toml (#310). Each
      # entry there is justified by its crate being absent from every shipped
      # target's graph — a property of today's resolved graph, not a permanent
      # one. rsa is currently reachable from nothing: its only parent in the
      # lockfile is sqlx-mysql, which this SQLite project never compiles. If a
      # dependency change ever pulls it into a shipped target, the suppression
      # would silently hide a live advisory and the daily audit would stay
      # green: the inverse of the permanent red #310 exists to kill.
      #
      # Such a change would itself touch src-tauri, which is exactly what
      # triggers this workflow. Runs after cargo check so the registry index is
      # already warm, and --locked so cargo tree cannot rewrite the lockfile the
      # audit was taken against.
      #
      # CRATES must mirror the crates named in .cargo/audit.toml. Adding an
      # entry there without adding its crate here leaves it unguarded.
      #
      # Every check echoes its result, including the passing ones. A guard that
      # is silent on success cannot be told apart in the log from a guard that
      # never ran — which is the same silent-skip failure mode this step exists
      # to catch, one level up.
      - name: Verify suppressed advisories are still unreachable
        run: |
          set -u
          CRATES="rsa"
          TARGETS="x86_64-unknown-linux-gnu x86_64-pc-windows-msvc"
          rc=0
          checks=0
          for crate in $CRATES; do
            for target in $TARGETS; do
              # An absent crate exits 0 with empty stdout ("nothing to print"
              # goes to stderr). A non-zero exit means cargo tree itself failed
              # — treat that as a failure rather than as proof of absence.
              out=$(cargo tree --manifest-path src-tauri/Cargo.toml --locked \
                      -i "$crate" --target "$target" 2>/dev/null) || {
                echo "cargo tree failed for $crate / $target — cannot verify the suppression"
                rc=1
                continue
              }
              if [ -n "$out" ]; then
                echo "FAIL: $crate is now compiled for $target — its .cargo/audit.toml suppression is no longer justified (see #310)."
                rc=1
              else
                echo "ok: $crate absent from $target"
              fi
              checks=$((checks + 1))
            done
          done
          # Canary: a crate known to be present. If this stops being found, the
          # loop above is broken and its silence means nothing.
          canary=$(cargo tree --manifest-path src-tauri/Cargo.toml --locked \
                     -i tar --target x86_64-unknown-linux-gnu 2>/dev/null) || true
          if [ -z "$canary" ]; then
            echo "FAIL: canary 'tar' was not found although it is a known dependency. The guard is not proving anything."
            rc=1
          else
            echo "ok: canary 'tar' found for x86_64-unknown-linux-gnu"
          fi
          echo "Suppression guard: $checks checks, exit $rc"
          exit $rc

      - name: cargo test
        run: cargo test --manifest-path src-tauri/Cargo.toml --all-targets

      # Prebuilt binary. `cargo install --locked cargo-audit` recompiled the
      # tool from source on every single run (~4m40s). No continue-on-error:
      # a tooling failure should fail the job rather than be swallowed.
      - name: Install cargo-audit
        uses: https://github.com/taiki-e/install-action@v2
        with:
          tool: cargo-audit

      # Advisories are informational — they can land on unrelated crates and
      # would otherwise stall unrelated work — so the step is non-blocking.
      # It no longer hides real failures behind `|| true` though. Daily
      # RustSec coverage outside Rust PRs lives in audit.yml.
      - name: cargo audit
        continue-on-error: true
        run: cargo audit --file src-tauri/Cargo.lock