test(backend): isolate sandbox env and bound OpenCode stop in binary-backed tests

[chriswritescode-dev]

Summary

Fixes two backend test failures that also reproduce on main.

Sandbox env leaking into Vitest

test/services/sandbox/command.test.ts ("returns no provisioning args when the exec user does not resolve to numeric uid and gid") failed whenever the host shell exported SANDBOX_EXEC_USER (e.g. 1001 in the dev container), because the test assumes the default exec user. test/setup.ts now clears ambient SANDBOX_* and MSB_* variables (except the config-pinned MSB_PATH) so the suite is deterministic. This is not a product bug: at runtime the verify step only runs when provisioning args are non-empty.

Binary-backed OpenCode stop exceeding the hook timeout

After an agent turn, OpenCode takes ~25s to exit on SIGTERM. The test helper waited 10s before SIGKILL, equal to Vitest's 10s hook timeout, so the afterAll in test/routes/opencode-proxy.test.ts timed out, and it never confirmed exit after SIGKILL. The helper now escalates after 5s and waits up to 2s for the process to close. Production stop logic (opencode-single-server.ts, 10s grace then SIGKILL) already handles slow exits.

Validation

With SANDBOX_EXEC_USER=1001 exported:

• pnpm test in backend/: bun suites 46 pass; Vitest 176 files / 3667 tests pass; coverage above 80% thresholds
• pnpm typecheck and eslint on changed files: clean

Summary by CodeRabbit

• Chores
  • Updated test cleanup to use a shorter graceful shutdown period, confirm termination after forced shutdown, and remove temporary directories even when shutdown fails.
  • Isolated test runs by clearing selected environment settings while preserving the required path setting.
  • These changes affect test execution only; no end-user functionality has changed.

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Reviewing files that changed from the base of the PR and between d102cd5 and 6ee719c.

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• backend/test/helpers/opencode-binary.ts

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📝 Walkthrough

Backend test setup now removes selected environment variables. The OpenCode shutdown helper uses a shorter SIGTERM grace period and waits for process closure after sending SIGKILL.

Changes: OpenCode shutdown

Layer / File(s)	Summary
Terminate and confirm process closure backend/test/helpers/opencode-binary.ts	The helper waits up to 5 seconds after SIGTERM. If the process is still running, it sends SIGKILL and waits up to 2 seconds for closure.

Test environment cleanup

Layer / File(s)	Summary
Clear selected environment variables backend/test/setup.ts	Module initialization deletes environment variables with the SANDBOX_ or MSB_ prefix, except MSB_PATH.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Other

Merge Risk: 🔵 Low · up to d102c

A narrow test-helper failure can leave an owned temporary directory behind. This is a bounded cleanup risk, not an identified production issue.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly summarizes both main changes: sandbox environment isolation and bounded OpenCode shutdown in backend tests.
Description check		The description provides a detailed summary, explains the test failures, documents the implementation changes, and reports validation results. It omits the template's Type of Change and Checklist sect…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @backend/test/helpers/opencode-binary.ts:
- Line 211: Update terminate() and stop() so removeOwnedDirectories() runs in a
finally path even when waiting for the child’s close event rejects after
SIGKILL, while preserving the termination error. Add a test child that emits an
error on SIGKILL and assert stop() still removes the owned directory.

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ℹ️ Review info

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• Configuration used: Repository UI
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Reviewing files that changed from the base of the PR and between a7b961f and d102cd5.

📒 Files selected for processing: 2

• backend/test/helpers/opencode-binary.ts
• backend/test/setup.ts

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[chriswritescode-dev]

Fixes Applied Successfully

Fixed 1 file based on 1 CodeRabbit feedback item(s).

Files modified:

• backend/test/helpers/opencode-binary.ts

Commit: 6ee719cf1

The latest autofix changes are on the fix/backend-test-isolation branch.