perf(test): raise memory-profile file concurrency to eight

[tnunamak]

Summary

Memory-default test runs use eight file workers by default. PostgreSQL test runs retain two because their backup/restore oracle shares PDPP_TEST_POSTGRES_RESTORE_URL. A positive PDPP_TEST_CONCURRENCY still overrides either profile.

This PR also fixes the test-accounting transcript terminal-event ordering defect: malformed accounting output now resolves to the final nonzero status before the transcript is closed.

Changed

• Updated the test runner concurrency default so memory-default uses 8 workers unless PDPP_TEST_CONCURRENCY is set.
• Preserved the PostgreSQL profile default at 2 workers because the restore oracle shares PDPP_TEST_POSTGRES_RESTORE_URL.
• Fixed accounting transcript close order so malformed accounting output records the final nonzero status before terminal transcript closure.
• Added receipt-pair artifacts, verifier coverage, and guidance contract tests.

Evidence

reference-implementation/docs/receipts/gate-concurrency-memory-cap-2.receipt.json and ...cap-8.receipt.json, with their checked-in transcripts, record two clean-source memory-default runs on Node 22.23.1. Both select 1,033 files and record 6,961 assertions: 6,335 passed, 396 failed, and 230 skipped. They retain the same 396 failure identities, meaning the same failing test names are observed under both caps, and exit code 1. Cap 2 took 352.198 seconds; cap 8 took 141.066 seconds.

The receipt-pair test verifies each transcript digest and binding, then compares selection, structured outcome counts, failure identities, source digest, and timing fields. The checked-in receipt generator refuses a dirty source tree and uses the memory-default profile plus the documented cap.

This PR does not make the full test suite green and does not claim PostgreSQL concurrency equivalence.

Reviewer Findings Addressed

• P1 — missing reviewable receipt pair: Added the generated cap-2/cap-8 receipt-and-transcript pair, their verifier, and a pair-comparison test. The artifacts bind the measured clean source head eb6a890d57658c14aef706bdbe4f756b14238d21; the later artifact-only commit carries those generated files.
• P2 — contradictory concurrency guidance: Replaced the old universal cap-2 guidance with the runner’s profile-specific policy and added a contract test that reads both the source and the checked-in guidance.

Validation

• node --test --import tsx for the receipt unit, receipt-pair, concurrency-cap, authority exit-order, and authority concurrency tests: 14 passing.
• Biome check over the changed scripts: passing.
• Mutation checks: changing the PostgreSQL default from 2 to 8 makes the cap contract fail; changing a checked-in receipt cap makes the pair verifier fail.

Assisted-by: AI

[tnunamak]

Rebase onto current main was blocked before the first signed commit: GPG opened interactive pinentry; cancellation caused signing to fail. The batch stopped under the requested GPG rule. This rebase was aborted. Head: fe27010 → fe27010 (unchanged). No new CI ran; existing checks show 7 success, 4 failure, 1 skipped. Needs work: unlock GPG and retry the rebase/CI verification.

Assisted-by: AI

[tnunamak]

Locally rebased onto main bac5526 with no conflicts: fe27010 → 5a2a77513f377b36c9bb6a1fca4faac99649cefc. Original patches are unchanged (range-diff and stable patch-ID comparison).

PARKED: unattended GPG signing failed with “No pinentry”. Rewritten commits have Tim’s identity and DCO but remain unsigned locally under the owner’s fallback policy; nothing was pushed. The remote head and its old hosted CI results are unchanged; no fresh hosted checks ran.

Fresh cap-2/cap-8 comparison failed: both completed 1,036 files and 10,249 assertions; cap 2 had 9,880 pass / 0 fail / 369 skip, cap 8 had 9,878 pass / 2 fail / 369 skip. The two manual-upload tests pass alone, but their cap-8 failures remain unresolved. Needs work; outcome equivalence is not established.

Assisted-by: AI