fix: reclaim non-writable /tmp/gh-aw/sandbox before AWF writeConfigs() to prevent EACCES

[Copilot]

Rootless containers on GitHub-hosted runners can leave /tmp/gh-aw/sandbox owned by root. AWF's writeConfigs() then dies with EACCES: mkdir /tmp/gh-aw/sandbox/firewall/logs before the agent is ever invoked — and the chmod -R a+rX fallback inside AWF fails for the same reason, making the error unrecoverable. This manifests as a per-runner ownership race: identical runs succeed or fail depending on whether a prior rootless job ran on the same runner.

Changes

• create_gh_aw_tmp_dir.sh — added a pre-flight check before mkdir: if /tmp/gh-aw/sandbox exists but is not writable by the current user, remove it with sudo rm -rf (falling back to plain rm -rf) so the subsequent mkdir -p creates a fresh, uid-owned tree before AWF starts

  if [ -d "${sandbox_dir}" ] && ! [ -w "${sandbox_dir}" ]; then
    echo "[WARN] ... reclaiming before AWF starts..."
    sudo rm -rf "${sandbox_dir}" 2>/dev/null || rm -rf "${sandbox_dir}" 2>/dev/null || ...
  fi

  Uses [ -w ] rather than UID comparison — portable across Linux/macOS and directly tests the condition that causes EACCES.

• create_gh_aw_tmp_dir_test.sh — new test covering: syntax validity, normal creation, user-owned sandbox preservation (no removal), and simulated non-writable sandbox reclaim (fake sudo records arguments and mimics root privilege).

[Copilot]

Pull request overview

This PR hardens gh-aw’s runner setup by proactively reclaiming a stale, non-writable /tmp/gh-aw/sandbox (often left root-owned by prior rootless container jobs) so AWF writeConfigs() doesn’t fail early with EACCES during sandbox config/log directory creation.

Changes:

• Add preflight detection and reclamation of /tmp/gh-aw/sandbox when it exists but is not writable, using sudo rm -rf with a fallback to rm -rf.
• Add a shell test script validating normal creation, preservation of user-owned sandboxes, and simulated reclaim behavior.
• Add a changeset documenting the patch release.

Show a summary per file

File	Description
actions/setup/sh/create_gh_aw_tmp_dir.sh	Adds sandbox reclamation logic prior to creating gh-aw temp directories.
actions/setup/sh/create_gh_aw_tmp_dir_test.sh	Adds a dedicated test script to validate the new sandbox reclaim behavior.
.changeset/patch-reclaim-sandbox-rootless-eacces.md	Documents the patch release rationale and behavior change.

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• Files reviewed: 3/3 changed files
• Comments generated: 3
• Review effort level: Low

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