[renanmpimentel]

Why this test matters

A v7 implementation could discard the highest of its 48 timestamp bits yet pass tests using smaller times. This deterministic clock case checks the whole timestamp field and catches truncation above 2^40 ms.

Supertest audit method

I used the Supertest test-audit skill to probe whether the existing suite would catch a plausible violation of this contract. The regression was applied only in an isolated worktree. The regression proof records three executed states: the existing tests pass with that regression, the new assertion fails against the same regression, and the new test passes with the original production code restored. The published diff adds tests only.

Change and verification

Adds a deterministic public API test that checks all 48 timestamp bits in a UUID v7. It fixes the clock at 2 << 40 Unix milliseconds and verifies the six timestamp bytes, then restores the shared clock and monotonic state.

Regression proof: setting the highest timestamp byte to zero leaves the existing go test ./... suite passing, but fails this assertion (000000000000 instead of 020000000000). With production code restored, go test ./..., go test -race ./..., go vet ./..., gofmt, and git diff --check pass.

This PR changes tests only.

Repository guidance

CONTRIBUTING.md asks for tests and a signed CLA. Tests, race tests, vet, and formatting passed locally; the GitHub CLA check currently fails, so contribution acceptance is pending that external requirement.

[google-cla]

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