[fi3ework]

Summary

rstack-ecosystem-ci runs only test:unit and lint for this repo today. Its root override — local builds of @rstest/core / @rslint/core injected into the consumer checkout — cannot reach the E2E fixtures: every fixture is its own pnpm workspace root and installs published packages from npm. This PR adds the harness support the eco-ci suites need to run the E2E slices against an unreleased toolchain.

 packages/vscode/e2e/
 ├── run.mjs                    # re-exec under `xvfb-run -a` on Linux, only for slices that launch VS Code
+├── vscodeTestCache.ts         # VSCODE_TEST_CACHE_PATH shared by every @vscode/test-electron entry
 ├── setupFixtures.mjs          # RSTACK_E2E_TOOLCHAIN_OVERRIDES: pack once, copy into each fixture
 ├── runTest.ts
 ├── rstest/runTest.ts
 └── lint/runTest.ts

• RSTACK_E2E_TOOLCHAIN_OVERRIDES="name=<absolute package dir>,…" packs each package once into the first fixture's .toolchain/, copies the tarball into every fixture that consumes it, and writes a fixture-relative file: override into that fixture's pnpm-workspace.yaml. The relative spec is required: the dependency-recovery suites copy a fixture to tmpdir and reinstall with --frozen-lockfile. A later run with a different override set replaces the block an earlier run wrote.
• Setup fails loudly when an overridden package still resolves from the registry (a local build and a published release can share a version number, which proves nothing) and when no fixture in the run used any override.
• Rslint needs two entries, @rslint/core and the host @rslint/native-<tuple>: core resolves its binary through require.resolve('@rslint/native-<tuple>/bin'), so overriding the core alone leaves the published binary in place.
• VSCODE_TEST_CACHE_PATH moves the VS Code download out of .vscode-test/. rstack-ecosystem-ci runs git clean -fdxq in the checkout before each suite, which would wipe it.
• The Linux xvfb re-exec is gated on a selected slice that launches VS Code, so a plain-Node slice (smoke) starts no X server. This repo's own CI stays Windows + macOS; the Linux path runs only in rstack-ecosystem-ci.

Evidence

Before: eco-ci ran test:unit + lint only, so the E2E fixtures installed the published toolchain and never saw the unreleased build.

After (local, macOS, marker-patched tarballs that print a unique line when loaded):

• pnpm lint → pass (204 files); pnpm test:unit → 384 passed.
• VSCODE_CLI=1 node e2e/run.mjs rstest with the marker @rstest/core → exit 0; all 4 fixtures reported resolved through .toolchain (no registry version in pnpm-lock.yaml); 23 [PROBE-RSTEST-CORE] 0.12.5-probe.1 loaded lines from the test worker.
• VSCODE_CLI=1 node e2e/run.mjs smoke lint with marker @rslint/core + @rslint/native-darwin-arm64 → exit 0; 12 fixture resolutions (6 fixtures × 2 packages); all 21 lint suites ran; [PROBE-RSLINT-CORE] 0.10.0-probe.1 loaded.
• VSCODE_TEST_CACHE_PATH=<scratch dir> downloaded VS Code (339.67 MB) into that directory and the filtered lint suite passed; .vscode-test/ was not touched.

Merge Danger

Door: two-way

Reverting restores the previous harness behavior; the extension itself does not change at runtime.

Blast Radius: ecosystem-ci

This repo's CI is unchanged (Windows + macOS). The Linux/xvfb path is only exercised by rstack-ecosystem-ci, whose suite change follows separately.

Supersedes the closed #66; related to #40. The companion rstack-ecosystem-ci change will follow separately.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-05T03:11:39.806932Z	6f15987	PR opened

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