Install the sandbox-driver plugins in the Rust test jobs

Every Petri run takes its scope through a sandbox-driver plugin
executable that Petri finds on PATH, so the test jobs need
sandbox-driver-host and sandbox-driver-docker installed at the rev the
workspace pins. The three jobs share one from-source install through an
actions/cache entry keyed on the OS and the rev.

The Linux test job also pre-pulls Petri's default runner image, which
the suite's Docker scenarios leave to Petri: the plugin pulls it on
first use, but a 1 GiB pull inside a run's timeout is a flake.

The stdio plugin job was built for the deleted fabro-sandbox layer. It
becomes the Docker providers job: the `docker_` scenario variants and
the fabro-petri suite, with the fabro-sandbox and fabro-workflow steps
whose tests no longer exist removed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.github/workflows/rust.yml

@@ -144,6 +144,40 @@ jobs:
         with:
           cache-on-failure: true
       - uses: taiki-e/install-action@773334c0e05d7e699e4d78234494308223f3a2cf # nextest
+      # Every Petri run takes its scope through a sandbox-driver plugin
+      # executable that Petri finds on PATH: `sandbox-driver-host` for the
+      # `local` provider, `sandbox-driver-docker` for `docker`. Installed
+      # at the rev the workspace pins, so the plugins and the in-process
+      # driver are one build; a from-source build, so the two executables
+      # are cached by OS and rev and only rebuilt when the pin moves.
+      - name: Read the sandbox-driver rev the workspace pins
+        id: sandbox-driver
+        run: |
+          rev="$(sed -n 's/^sandbox-driver = { git = "[^"]*", rev = "\([0-9a-f]*\)" }$/\1/p' Cargo.toml)"
+          test -n "$rev"
+          echo "rev=$rev" >> "$GITHUB_OUTPUT"
+      - name: Restore the sandbox-driver plugin executables
+        id: sandbox-driver-cache
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: |
+            ~/.cargo/bin/sandbox-driver-host
+            ~/.cargo/bin/sandbox-driver-docker
+          key: sandbox-driver-plugins-${{ runner.os }}-${{ steps.sandbox-driver.outputs.rev }}
+      - name: Install the sandbox-driver plugin executables
+        if: steps.sandbox-driver-cache.outputs.cache-hit != 'true'
+        run: cargo install --locked --git https://github.com/lithoscomputer/sandbox-driver --rev "${{ steps.sandbox-driver.outputs.rev }}" sandbox-driver-host sandbox-driver-docker
+      # The Docker scenarios in the suite leave the image to Petri, whose
+      # Docker scope runs on its default runner image; the plugin pulls it
+      # on first use, but a 1 GiB pull inside a run's timeout is a flake.
+      # Pull it here, at the pin the checked-out Petri names, so a registry
+      # problem reads as one.
+      - name: Pull Petri's default runner image
+        run: |
+          backend="$(dirname "$(cargo metadata --locked --format-version 1 | jq -r '.packages[] | select(.name == "petri-executor-sandbox") | .manifest_path')")/src/backend.rs"
+          pin="$(sed -n 's/^const RUNNER_PIN: &str = "\([0-9a-f]*\)";$/\1/p' "$backend")"
+          test -n "$pin"
+          docker pull "ghcr.io/lithoscomputer/ubuntu-24.04:slim-$pin"
       - run: cargo nextest run --locked --workspace --status-level slow --profile ci
       # The twin-mode ignored suites this job once ran belonged to fabro-agent,
       # which pebble's coding agent replaced; the agent loop's workflow-level
@@ -151,14 +185,14 @@ jobs:
       # Re-add a `--run-ignored only -E 'package(...)'` step here when a
       # package has ignored suites that are fully green in twin mode.
 
-  sandbox-plugins:
-    name: Sandbox plugins (stdio)
+  sandbox-docker:
+    name: Sandbox providers (Docker)
     runs-on: ubuntu-24.04-x86-32-cores
     permissions:
       contents: read
     env:
-      # The plugin scenarios skip when an executable or daemon is missing;
-      # in CI a skip is a failure.
+      # The Docker scenarios skip when the executable, the daemon or the
+      # image is missing; in CI a skip is a failure.
       FABRO_REQUIRE_SANDBOX_PLUGINS: "1"
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -171,28 +205,38 @@ jobs:
         with:
           cache-on-failure: true
       - uses: taiki-e/install-action@773334c0e05d7e699e4d78234494308223f3a2cf # nextest
+      # The image the Docker scenarios' environment names.
       - run: docker pull buildpack-deps:noble
-      # The driver's own Host and Docker executables, installed at the rev the
-      # workspace pins so the plugins and the in-process providers are one
-      # build; the CLI scenarios find them on PATH and launch them over stdio.
-      - name: Install the sandbox-driver plugin executables
+      # Every Petri run takes its scope through a sandbox-driver plugin
+      # executable that Petri finds on PATH: `sandbox-driver-host` for the
+      # `local` provider, `sandbox-driver-docker` for `docker`. Installed
+      # at the rev the workspace pins, so the plugins and the in-process
+      # driver are one build; a from-source build, so the two executables
+      # are cached by OS and rev and only rebuilt when the pin moves.
+      - name: Read the sandbox-driver rev the workspace pins
+        id: sandbox-driver
         run: |
           rev="$(sed -n 's/^sandbox-driver = { git = "[^"]*", rev = "\([0-9a-f]*\)" }$/\1/p' Cargo.toml)"
           test -n "$rev"
-          cargo install --locked --git https://github.com/lithoscomputer/sandbox-driver --rev "$rev" sandbox-driver-host sandbox-driver-docker
-      # Host and Docker served as plugins through the workflow scenarios. The
-      # scenarios are e2e tests (ignored by default); the key-free ones run
-      # here, the LLM-backed ones self-skip without credentials.
-      - run: cargo nextest run --locked --profile ci --status-level slow --run-ignored only -p fabro-cli --test it -E 'test(/host_plugin_|docker_plugin_/)'
-      # The stdio plugin proof (not ignored: it skips without the executable,
-      # which the environment above forbids) and the driver-backed Docker
-      # integration tests.
-      - run: cargo nextest run --locked --profile ci --status-level slow -p fabro-sandbox --test plugin_provider
-      - run: cargo nextest run --locked --profile ci --status-level slow --run-ignored only -p fabro-sandbox --test docker_streaming
+          echo "rev=$rev" >> "$GITHUB_OUTPUT"
+      - name: Restore the sandbox-driver plugin executables
+        id: sandbox-driver-cache
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: |
+            ~/.cargo/bin/sandbox-driver-host
+            ~/.cargo/bin/sandbox-driver-docker
+          key: sandbox-driver-plugins-${{ runner.os }}-${{ steps.sandbox-driver.outputs.rev }}
+      - name: Install the sandbox-driver plugin executables
+        if: steps.sandbox-driver-cache.outputs.cache-hit != 'true'
+        run: cargo install --locked --git https://github.com/lithoscomputer/sandbox-driver --rev "${{ steps.sandbox-driver.outputs.rev }}" sandbox-driver-host sandbox-driver-docker
+      # The workflow scenarios on the Docker provider. The scenarios are e2e
+      # tests (ignored by default); the key-free ones run here, the
+      # LLM-backed ones self-skip without credentials.
+      - run: cargo nextest run --locked --profile ci --status-level slow --run-ignored only -p fabro-cli --test it -E 'test(/::docker_/)'
       # The Petri runs (not ignored: they skip without the host plugin, which
       # the environment above forbids).
       - run: cargo nextest run --locked --profile ci --status-level slow -p fabro-petri
-      - run: cargo nextest run --locked --profile ci --status-level slow --run-ignored only -p fabro-workflow --test it -E 'test(asset_collection_docker_sandbox)'
 
   test-macos:
     name: Test (macOS)
@@ -211,4 +255,28 @@ jobs:
         with:
           cache-on-failure: true
       - uses: taiki-e/install-action@773334c0e05d7e699e4d78234494308223f3a2cf # nextest
+      # Every Petri run takes its scope through a sandbox-driver plugin
+      # executable that Petri finds on PATH: `sandbox-driver-host` for the
+      # `local` provider, `sandbox-driver-docker` for `docker`. Installed
+      # at the rev the workspace pins, so the plugins and the in-process
+      # driver are one build; a from-source build, so the two executables
+      # are cached by OS and rev and only rebuilt when the pin moves.
+      - name: Read the sandbox-driver rev the workspace pins
+        id: sandbox-driver
+        run: |
+          rev="$(sed -n 's/^sandbox-driver = { git = "[^"]*", rev = "\([0-9a-f]*\)" }$/\1/p' Cargo.toml)"
+          test -n "$rev"
+          echo "rev=$rev" >> "$GITHUB_OUTPUT"
+      - name: Restore the sandbox-driver plugin executables
+        id: sandbox-driver-cache
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: |
+            ~/.cargo/bin/sandbox-driver-host
+            ~/.cargo/bin/sandbox-driver-docker
+          key: sandbox-driver-plugins-${{ runner.os }}-${{ steps.sandbox-driver.outputs.rev }}
+      - name: Install the sandbox-driver plugin executables
+        if: steps.sandbox-driver-cache.outputs.cache-hit != 'true'
+        run: cargo install --locked --git https://github.com/lithoscomputer/sandbox-driver --rev "${{ steps.sandbox-driver.outputs.rev }}" sandbox-driver-host sandbox-driver-docker
+      # No Docker daemon on the macOS runner: the Docker tests skip there.
       - run: cargo nextest run --locked --workspace --status-level slow --profile ci