feat: add evaluateFlags() API for single-call flag evaluation#131
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feat: add evaluateFlags() API for single-call flag evaluation#131
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Phase 1 of the Server SDK Feature Flag Evaluations RFC. Mirrors the Node (posthog-js#3476) and Python (posthog-python#539) implementations. * `Client::evaluateFlags()` returns a `FeatureFlagEvaluations` snapshot. Reads on the snapshot do not trigger additional `/flags` requests; access via `isEnabled` / `getFlag` fires a deduped `$feature_flag_called` event the first time each key is touched. `getFlagPayload` is silent. * `capture()` accepts a `flags` snapshot to attach `$feature/<key>` and `$active_feature_flags` properties without a fresh `/flags` round trip. * The single-flag dedup is extracted to `Client::captureFlagCalledIfNeeded()`, shared by the legacy path and the snapshot. * `flag_keys_to_evaluate` and `geoip_disable` are forwarded on the `/flags` request body when callers pass `flagKeys` or `disableGeoip`. * New `feature_flags_log_warnings` option silences filter warnings emitted from `only()` / `onlyAccessed()`. Also fixes a pre-existing bug in `SizeLimitedHash::contains/add` that caused the per-distinct_id `$feature_flag_called` dedup to never match after the first event. The new snapshot path requires real dedup, and existing tests only ever made a single call so the bug was invisible until now. Generated-By: PostHog Code Task-Id: 1f29305a-ee56-456e-a341-8faa4eb8716d
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The file pairs `require_once 'test/error_log_mock.php'` with class declarations, matching the pattern in FeatureFlagLocalEvaluationTest. The existing tests do the same thing; suppressing the rule per-file is consistent with that precedent. Generated-By: PostHog Code Task-Id: 1f29305a-ee56-456e-a341-8faa4eb8716d
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Summary
Adds
evaluateFlags(), a single-call flag evaluation API that returns aFeatureFlagEvaluationssnapshot for one distinct id:/flagsrequest per call; reads on the snapshot make zero further requests.isEnabled($key)/getFlag($key)fire a deduped$feature_flag_calledevent with full metadata (id, version, reason, request_id) on first access.getFlagPayload($key)is silent.only([...])/onlyAccessed()return filtered clones for scoping which flags attach to a captured event.capture(['flags' => $snapshot, …])attaches$feature/<key>and$active_feature_flagswithout a fresh/flagsround trip.getFeatureFlag/getFeatureFlagResult/getAllFlags/send_feature_flagspaths keep working.RFC · reference SDK PRs: posthog-python#539, posthog-js#3476.
Design decisions
FeatureFlagEvaluationsHostinterface (captureFlagCalledIfNeeded,logWarning) instead of a fullClient, so unit tests can use a fake without spinning up the SDK.recordAccessrather than at every call site, soisEnabled/getFlagstill return sane values without leaking events with empty actors.$feature_flag_request_id(it's per-/flags-response) but emitlocally_evaluated=trueand reason"Evaluated locally"to match the existing single-flag local path.flags=oncapture()takes precedence oversend_feature_flags, letting callers adopt the new path without ripping the old one out.SizeLimitedHash::contains/addwere comparing values to keys and pushing onto the outer map, so the per-distinct_id$feature_flag_calleddedup never matched after the first event. The new snapshot path requires real dedup, so it's fixed here.Phase 2 follow-ups (deliberately out of scope)
getFeatureFlag,isFeatureEnabled,getFeatureFlagResult,getAllFlags, and thesend_feature_flagscapture option.flag_definitions_loaded_atthrough the snapshot — posthog-php doesn't track that timestamp on the local poller today.Created with PostHog Code