Under Node 24 on Windows, running node --test with --test-concurrency=4
causes 4 concurrent gsd-tools subprocesses to each spawn a synckit
worker_threads worker for the SDK bridge. The 4 workers simultaneously
contend on SharedArrayBuffer + Atomics.wait under Windows Defender
scanning and NTFS latency, triggering OS-level resource exhaustion that
kills worker processes with empty stderr before any output is flushed.
The symptom: intermittent exit 1 with 0 test failures, varying affected
test files per run, all sharing the pattern of invoking gsd-tools as a
subprocess. Empty stderr distinguishes OS crash from gsd-tools app error
(the error() path writes to stderr before exiting).
Fix: platform-aware concurrency default — 2 on win32, 4 on Linux/macOS.
The existing TEST_CONCURRENCY env-var override is preserved. Also adds
a [stderr: (empty) exit:N] diagnostic note in helpers.cjs runGsdTools
catch block so future empty-stderr crashes are visible in CI logs.
Fixesgsd-build/get-shit-done#3869
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
3169d5cda6