Add server-side PostHog feature-flag evaluation to the API and wire three
high-leverage uses. The flags live in PostHog (project 127747), dormant and
fail-open, so this commit is a no-op until POSTHOG_PERSONAL_API_KEY is set and
a switch is flipped.
Phase 1 - upstream kill switches:
PostHogService gains local flag evaluation (onlyEvaluateLocally +
sendFeatureFlagEvents:false -> zero decode latency, no VIN leak) and
isSourceLive(). Guards at each source's decode entry (parts-catalogs, emex,
pl24 whole-source + per-brand via LEGACY_ARCH_SOURCE_TAG) let a flailing
upstream be disabled from the PostHog UI in ~5s instead of a
code-fix -> dev -> prod redeploy. Fail-open: any unresolved flag keeps the
source live, so a PostHog outage can never black out decoding.
Phase 2 - guarded rollout primitive:
isEnabled()/variant() with VIN bucketing, ready to ramp a new decode/parser
path 0->100% behind a decode-*-v2 flag (recipe in feature-flags-strategy.md).
Phase 4 - remote-config ops tuning:
prefetch-worker reads cfg-backfill-tuning to retune backfill
batchSize/maxBacklog/businessHoursOnly live; malformed/missing -> the
compiled-in constants.
POSTHOG_PERSONAL_API_KEY wired into the api + worker compose blocks (empty ->
flags inert, no added latency). Tests updated for the new constructor params.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Semih Yesilyurt
ed45021d71