backend-matrix.yml

# SPDX-License-Identifier: MPL-2.0
# Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
#
# backend-matrix.yml — Per-prover smoke matrix for vcl-ut → echidna wire.
#
# One matrix job per ProverKind variant. Authoritative list comes from
# echidna's .machine_readable/provers.a2ml (source-of-truth: the
# ProverKind enum in echidna/src/rust/provers/mod.rs). The prep job
# parses provers.a2ml and emits a matrix JSON ephemerally as a GHA
# output — no committed JSON artefact (memory rule: tools emit A2ML,
# not JSON).
#
# Current scope of per-job work:
#   - Runs the vcltotal-echidna-client wiremock integration suite
#     with the target prover slug injected as ECHIDNA_PROVER env.
#   - When echidna's REST surface expands to all 105 backends (today
#     it exposes 17), each job can diverge per slug to exercise a
#     live echidna container. That upgrade is tracked as Package 4
#     step 7; the matrix shape here is ready for it.
#
# Resource budget: max-parallel=3 per the user's standing constraint
# on parallel subagents / bash invocations applied to CI.

name: Backend Matrix

on:
  pull_request:
    branches: ['**']
  push:
    branches: [main, master]
  workflow_dispatch: {}

permissions:
  contents: read

jobs:
  prep:
    name: Derive matrix from echidna provers.a2ml
    runs-on: ubuntu-latest
    timeout-minutes: 15
    outputs:
      provers: ${{ steps.parse.outputs.provers }}
      count:   ${{ steps.parse.outputs.count }}
    steps:
      - name: Checkout vcl-ut
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

      - name: Checkout echidna (authoritative ProverKind source)
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          repository: hyperpolymath/echidna
          path: echidna
          fetch-depth: 1

      - name: Parse provers.a2ml → matrix JSON (ephemeral GHA output only)
        id: parse
        run: |
          set -euo pipefail
          a2ml=echidna/.machine_readable/provers.a2ml
          test -f "$a2ml"
          # Extract `slug = "..."` values from each [prover.X] section.
          # Keep only the slug; nothing else is needed by the matrix yet.
          slugs=$(grep -E '^slug = ' "$a2ml" | sed -E 's/slug = "(.+)"/\1/')
          count=$(echo "$slugs" | wc -l | tr -d ' ')
          # Convert to JSON array for GitHub Actions matrix consumption.
          # (GHA matrix strategies require JSON; this is runtime
          # marshalling, not a persisted artefact.)
          json=$(printf '%s\n' "$slugs" | jq -R . | jq -sc .)
          echo "provers=$json" >> "$GITHUB_OUTPUT"
          echo "count=$count"  >> "$GITHUB_OUTPUT"
          echo "Derived matrix: $count provers"

  smoke:
    name: Smoke (${{ matrix.prover }})
    needs: prep
    runs-on: ubuntu-latest
    timeout-minutes: 15
    strategy:
      fail-fast: false
      max-parallel: 3
      matrix:
        prover: ${{ fromJson(needs.prep.outputs.provers) }}
    env:
      ECHIDNA_PROVER: ${{ matrix.prover }}
    steps:
      - name: Checkout vcl-ut
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

      - name: Install Rust toolchain
        uses: dtolnay/rust-toolchain@4be9e76fd7c4901c61fb841f559994984270fce7 # stable

      - name: Cache cargo registry and build
        uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2
        with:
          shared-key: backend-matrix

      # The vcl-ut workspace has a path-dependency
      # `echidna-core = { path = "../../../echidna/crates/echidna-core" }`
      # (src/interface/Cargo.toml), so the whole workspace fails to load
      # unless echidna is present as a sibling of the checkout. Provide it.
      - name: Provide echidna sibling (echidna-core path-dependency)
        run: git clone --depth 1 https://github.com/hyperpolymath/echidna ../echidna

      - name: Client wiremock suite (ECHIDNA_PROVER=${{ matrix.prover }})
        # `vcltotal-echidna-client` is intentionally NOT a member of the root
        # workspace (v0.2.0 workspace cleanup: its transitive echidna-core
        # path-dep breaks standalone CI), so `-p` cannot select it. It is its
        # own standalone workspace root; run it by manifest path now that the
        # echidna sibling has been cloned above.
        # NOTE: echidna-client is a standalone workspace with NO committed
        # Cargo.lock — its transitive `echidna-core` path-dep only exists once
        # the sibling is cloned (step above), so a lockfile cannot be committed
        # and `--locked` can never be satisfied: it fails before the tests even
        # build ("cannot create the lock file ... because --locked was passed").
        # Resolve fresh against the just-cloned sibling instead (omit --locked).
        run: cargo test --manifest-path src/interface/echidna-client/Cargo.toml --tests