refactor(gateway): explicit boolean comparison in webhook timestamp check

[marcusrbrown]

Aligns checkTimestamp in the gateway HMAC module with the project's strict-boolean convention — Number.isFinite(parsedMs) === false instead of !Number.isFinite(parsedMs). No behavior change; the two forms are equivalent. refactor scope so it doesn't trigger a release on its own.

[fro-bot]

Verdict: PASS

This is a one-line, behavior-preserving refactor: !Number.isFinite(parsedMs) → Number.isFinite(parsedMs) === false in checkTimestamp (packages/gateway/src/http/hmac.ts:76).

I verified:

• Behavioral equivalence. Number.isFinite always returns a real boolean, and parsedMs is typed number (from Date.parse). === false and ! are identical here with no coercion subtlety. The NaN / unparseable branch returns the same {ok: false, reason: 'timestamp_expired'}.
• Convention claim holds. The strict-boolean style is pervasive in this package (90+ === true/=== false matches), including the structurally identical Number.isFinite(httpPort) === false at config.ts:327. The change genuinely aligns with house style rather than introducing a one-off.
• Test coverage exists. hmac.test.ts already exercises the touched branch — unparseable timestamp describe block (garbage string and empty string both assert timestamp_expired), plus the in-window / boundary / expired cases. No new behavior to test.
• Commit scope. refactor scope correctly avoids triggering a release, matching the PR description's intent.

Blocking issues

None

Non-blocking concerns

None — the explicit form is marginally more verbose but is the established package convention, so it's the right call here.

Missing tests

None — no behavior changed; the affected branch is already covered.

Risk assessment (LOW): No behavior change to a pure, well-tested function. No public API surface change (signature and return shape identical). Blast radius is a single conditional inside one function; regression likelihood is effectively nil and there is no new security exposure on the auth path.

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Run Summary

Field	Value
Event	pull_request
Repository	fro-bot/agent
Run ID	26676988757
Cache	hit
Session	ses_1886847a7ffepR5mGe63aA68fE