[luantaraschi]

Problem

relativeDateParseForFeatureFlagMatching subtracts months with setUTCMonth, which rolls an impossible date forward. A 1m filter evaluated on March 31 resolves to March 3 instead of February 28, and 1y on February 29 resolves to March 1. posthog-node and the Convex component use this parser for local evaluation, so is_date_before and is_date_after can answer differently from the flags service on those days.

Changes

Months and years now subtract one unit at a time and clamp the day after every step, as the local evaluator spec requires, so a two-month lookback from March 31 gives January 28. The SDK still works in UTC where the spec asks for the team's timezone, and I left that alone.

Eight of the twelve new table cases fail on main, and so does a new test that goes through matchFeatureFlagProperty with is_date_after. I also compared the two helpers against a naive month-by-month loop for every day from 2019 through 2028, with lookbacks from 0 to 129 plus 4000 and 9999, and got no differences in 964,392 comparisons.

I ran this in node:24-slim: vitest in packages/core (2368 passed, 2 skipped) and packages/node (1516 passed), the flag specs in packages/convex (83 passed), oxfmt --check on the changed files, and oxlint on packages/core/src. turbo run build --filter=posthog-node also passes.

Release info Sub-libraries affected

Libraries affected

• All of them
• posthog-js (web)
• posthog-js-lite (web lite)
• posthog-node
• posthog-react-native
• @posthog/react-native-plugin
• @posthog/react
• @posthog/ai
• @posthog/convex
• @posthog/next
• @posthog/nextjs-config
• @posthog/nuxt
• @posthog/openfeature-node-provider
• @posthog/openfeature-web-provider
• @posthog/rollup-plugin
• @posthog/webpack-plugin
• @posthog/types
• @posthog/browser-common

Checklist

• All commits are signed (see Commit signing)
• Tests for new code
• Accounted for the impact of any changes across different platforms
• Accounted for backwards compatibility of any changes (no breaking changes!)
• Took care not to unnecessarily increase the bundle size

If releasing new changes

• Added a changeset file (written by hand, I didn't run pnpm changeset)

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Luan Taraschi directed this and Claude Code (Claude Opus 5.5) wrote it and ran the checks. It came out of the same spec comparison as PostHog/posthog-python#1212, which fixes the single-jump version of this bug in the Python SDK.

[marandaneto]

The code looks good; no qualifying findings. Verdict: correct.

[github-actions]

SDK performance: posthog-node

1 change worth reviewing: 1 observed regression.

Flags require at least a 5% change in the median and all six pairs agreeing on direction. This is a noise filter, not proof of a performance change or a CI gate.

Test	Measurement	Before PR	With PR	Change
Evaluate all 1,000 flags	Time per operation	16.67 ms/op	17.69 ms/op	6.1% more time

View all results

Test	Measurement	Before PR	With PR	Change	Assessment
Capture and deliver events (32-byte payload, burst) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Capture and deliver events (32-byte payload, steady) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Queue an event (32-byte payload) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Queue an event (4,096-byte payload) Shard: capture	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate all 10 flags Shard: flags-scaling	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate all 100 flags Shard: flags-scaling	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate all 1,000 flags Shard: flags-scaling	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate one boolean flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a cohort-filtered flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a flag (early match) Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a flag (late match) Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a flag (no match) Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a property-filtered flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a regex-filtered flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a rollout flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Evaluate a multivariate flag Shard: flags-single	Allocations per operation	—	—	—	unavailable; base:​ unsupported; head:​ unsupported; base:​ V8 samples do not expose total allocation count; sample count is not object count.​; head:​ V8 samples do not expose total allocation count; sample count is not object count.​
Capture and deliver events (32-byte payload, burst) Shard: capture	Allocated memory per operation (estimated)	10.2 KiB/op	9.83 KiB/op	3.7% less memory	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Time per operation	12.41 µs/op	12.13 µs/op	2.3% less time	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Idle process memory (RSS)	102.64 MiB	102.69 MiB	<0.1% more memory	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Observed peak process memory (RSS)	106.33 MiB	106.1 MiB	0.2% less memory	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Managed heap after settling	9.97 MiB	9.97 MiB	<0.1% less memory	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Process memory after settling (RSS)	106.06 MiB	105.79 MiB	0.3% less memory	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Process CPU time per operation	23.08 µs/op	22.54 µs/op	2.4% less time	Not flagged
Capture and deliver events (32-byte payload, burst) Shard: capture	Lifetime peak process memory (RSS)	106.59 MiB	106.32 MiB	0.3% less memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Allocated memory per operation (estimated)	17.12 KiB/op	17.44 KiB/op	1.9% more memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Time per operation	22.69 µs/op	22.69 µs/op	<0.1% more time	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Idle process memory (RSS)	103.23 MiB	103.26 MiB	<0.1% more memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Observed peak process memory (RSS)	113.68 MiB	114.12 MiB	0.4% more memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Managed heap after settling	9.98 MiB	9.98 MiB	<0.1% less memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Process memory after settling (RSS)	109.54 MiB	110.06 MiB	0.5% more memory	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Process CPU time per operation	33.56 µs/op	33.23 µs/op	1% less time	Not flagged
Capture and deliver events (4,096-byte payload, burst) Shard: capture	Lifetime peak process memory (RSS)	116.44 MiB	116.9 MiB	0.4% more memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Allocated memory per operation (estimated)	9.94 KiB/op	9.71 KiB/op	2.3% less memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Time per operation	13.32 µs/op	13.17 µs/op	1.1% less time	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Idle process memory (RSS)	102.53 MiB	102.51 MiB	<0.1% less memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Observed peak process memory (RSS)	106.82 MiB	106.9 MiB	<0.1% more memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Managed heap after settling	10.05 MiB	10.05 MiB	<0.1% less memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Process memory after settling (RSS)	106.9 MiB	106.68 MiB	0.2% less memory	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Process CPU time per operation	24.56 µs/op	24.2 µs/op	1.5% less time	Not flagged
Capture and deliver events (32-byte payload, steady) Shard: capture	Lifetime peak process memory (RSS)	106.84 MiB	106.9 MiB	<0.1% more memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Allocated memory per operation (estimated)	18.24 KiB/op	17.35 KiB/op	4.9% less memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Time per operation	20.07 µs/op	19.39 µs/op	3.4% less time	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Idle process memory (RSS)	102.74 MiB	102.92 MiB	0.2% more memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Observed peak process memory (RSS)	109.62 MiB	109.38 MiB	0.2% less memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Managed heap after settling	10.06 MiB	10.06 MiB	<0.1% less memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Process memory after settling (RSS)	108.43 MiB	108.12 MiB	0.3% less memory	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Process CPU time per operation	31.04 µs/op	30.79 µs/op	0.8% less time	Not flagged
Capture and deliver events (4,096-byte payload, steady) Shard: capture	Lifetime peak process memory (RSS)	109.65 MiB	109.38 MiB	0.2% less memory	Not flagged
Queue an event (32-byte payload) Shard: capture	Allocated memory per operation (estimated)	8.52 KiB/op	8.65 KiB/op	1.6% more memory	Not flagged
Queue an event (32-byte payload) Shard: capture	Time per operation	9.33 µs/op	8.95 µs/op	4.1% less time	Not flagged
Queue an event (32-byte payload) Shard: capture	Process CPU time per operation	18.73 µs/op	18.11 µs/op	3.3% less time	Not flagged
Queue an event (4,096-byte payload) Shard: capture	Allocated memory per operation (estimated)	8.53 KiB/op	8.39 KiB/op	1.7% less memory	Not flagged
Queue an event (4,096-byte payload) Shard: capture	Time per operation	8.49 µs/op	8.69 µs/op	2.5% more time	Not flagged
Queue an event (4,096-byte payload) Shard: capture	Process CPU time per operation	16.97 µs/op	17.02 µs/op	0.3% more time	Not flagged
Evaluate all 10 flags Shard: flags-scaling	Allocated memory per operation (estimated)	132.73 KiB/op	133.65 KiB/op	0.7% more memory	Not flagged
Evaluate all 10 flags Shard: flags-scaling	Time per operation	183.18 µs/op	181.28 µs/op	1% less time	Not flagged
Evaluate all 10 flags Shard: flags-scaling	Process CPU time per operation	306.39 µs/op	306.74 µs/op	0.1% more time	Not flagged
Evaluate all 100 flags Shard: flags-scaling	Allocated memory per operation (estimated)	1.23 MiB/op	1.22 MiB/op	0.7% less memory	Not flagged
Evaluate all 100 flags Shard: flags-scaling	Time per operation	1.59 ms/op	1.59 ms/op	0.3% more time	Not flagged
Evaluate all 100 flags Shard: flags-scaling	Process CPU time per operation	2.63 ms/op	2.64 ms/op	0.4% more time	Not flagged
Evaluate all 1,000 flags Shard: flags-scaling	Allocated memory per operation (estimated)	12.13 MiB/op	12.11 MiB/op	0.2% less memory	Not flagged
Evaluate all 1,000 flags Shard: flags-scaling	Time per operation	16.67 ms/op	17.69 ms/op	6.1% more time	Worth reviewing: observed regression
Evaluate all 1,000 flags Shard: flags-scaling	Process CPU time per operation	26.08 ms/op	27.12 ms/op	4% more time	Not flagged
Evaluate 1,000 flags under concurrent load Shard: flags-memory	Idle process memory (RSS)	285.94 MiB	286.31 MiB	0.1% more memory	Not flagged
Evaluate 1,000 flags under concurrent load Shard: flags-memory	Observed peak process memory (RSS)	295.49 MiB	296.28 MiB	0.3% more memory	Not flagged
Evaluate 1,000 flags under concurrent load Shard: flags-memory	Managed heap after settling	9.62 MiB	9.62 MiB	<0.1% less memory	Not flagged
Evaluate 1,000 flags under concurrent load Shard: flags-memory	Process memory after settling (RSS)	295.41 MiB	296.21 MiB	0.3% more memory	Not flagged
Evaluate 1,000 flags under concurrent load Shard: flags-memory	Lifetime peak process memory (RSS)	295.66 MiB	296.28 MiB	0.2% more memory	Not flagged
Refresh 1,000 flag definitions Shard: flags-memory	Idle process memory (RSS)	222.33 MiB	224.92 MiB	1.2% more memory	Not flagged
Refresh 1,000 flag definitions Shard: flags-memory	Observed peak process memory (RSS)	239.33 MiB	239.4 MiB	<0.1% more memory	Not flagged
Refresh 1,000 flag definitions Shard: flags-memory	Managed heap after settling	11.63 MiB	11.63 MiB	<0.1% less memory	Not flagged
Refresh 1,000 flag definitions Shard: flags-memory	Process memory after settling (RSS)	234.79 MiB	234.72 MiB	<0.1% less memory	Not flagged
Refresh 1,000 flag definitions Shard: flags-memory	Lifetime peak process memory (RSS)	240.77 MiB	241.07 MiB	0.1% more memory	Not flagged
Evaluate one boolean flag Shard: flags-single	Allocated memory per operation (estimated)	17.28 KiB/op	17.28 KiB/op	<0.1% less memory	Not flagged
Evaluate one boolean flag Shard: flags-single	Time per operation	41.31 µs/op	40.79 µs/op	1.3% less time	Not flagged
Evaluate one boolean flag Shard: flags-single	Process CPU time per operation	45 µs/op	43.9 µs/op	2.4% less time	Not flagged
Evaluate a cohort-filtered flag Shard: flags-single	Allocated memory per operation (estimated)	14.12 KiB/op	13.95 KiB/op	1.2% less memory	Not flagged
Evaluate a cohort-filtered flag Shard: flags-single	Time per operation	22.31 µs/op	21.77 µs/op	2.4% less time	Not flagged
Evaluate a cohort-filtered flag Shard: flags-single	Process CPU time per operation	26.92 µs/op	26.46 µs/op	1.7% less time	Not flagged
Evaluate a flag (early match) Shard: flags-single	Allocated memory per operation (estimated)	17.67 KiB/op	17.65 KiB/op	0.1% less memory	Not flagged
Evaluate a flag (early match) Shard: flags-single	Time per operation	22.62 µs/op	23.25 µs/op	2.8% more time	Not flagged
Evaluate a flag (early match) Shard: flags-single	Process CPU time per operation	26.91 µs/op	27.19 µs/op	1.1% more time	Not flagged
Evaluate a flag (late match) Shard: flags-single	Allocated memory per operation (estimated)	22.49 KiB/op	22.45 KiB/op	0.2% less memory	Not flagged
Evaluate a flag (late match) Shard: flags-single	Time per operation	23.26 µs/op	23.42 µs/op	0.7% more time	Not flagged
Evaluate a flag (late match) Shard: flags-single	Process CPU time per operation	27.12 µs/op	27.54 µs/op	1.6% more time	Not flagged
Evaluate a flag (no match) Shard: flags-single	Allocated memory per operation (estimated)	17.01 KiB/op	16.92 KiB/op	0.5% less memory	Not flagged
Evaluate a flag (no match) Shard: flags-single	Time per operation	3.05 µs/op	3.09 µs/op	1.2% more time	Not flagged
Evaluate a flag (no match) Shard: flags-single	Process CPU time per operation	6.1 µs/op	6.14 µs/op	0.6% more time	Not flagged
Evaluate a property-filtered flag Shard: flags-single	Allocated memory per operation (estimated)	12.75 KiB/op	12.89 KiB/op	1.1% more memory	Not flagged
Evaluate a property-filtered flag Shard: flags-single	Time per operation	21.87 µs/op	21.9 µs/op	0.1% more time	Not flagged
Evaluate a property-filtered flag Shard: flags-single	Process CPU time per operation	25.79 µs/op	25.77 µs/op	<0.1% less time	Not flagged
Evaluate a regex-filtered flag Shard: flags-single	Allocated memory per operation (estimated)	18.1 KiB/op	18.25 KiB/op	0.8% more memory	Not flagged
Evaluate a regex-filtered flag Shard: flags-single	Time per operation	42.19 µs/op	41.75 µs/op	1% less time	Not flagged
Evaluate a regex-filtered flag Shard: flags-single	Process CPU time per operation	46.13 µs/op	45.73 µs/op	0.9% less time	Not flagged
Evaluate a rollout flag Shard: flags-single	Allocated memory per operation (estimated)	14.39 KiB/op	14.16 KiB/op	1.6% less memory	Not flagged
Evaluate a rollout flag Shard: flags-single	Time per operation	31.37 µs/op	31.6 µs/op	0.8% more time	Not flagged
Evaluate a rollout flag Shard: flags-single	Process CPU time per operation	34.75 µs/op	35.04 µs/op	0.8% more time	Not flagged
Evaluate a multivariate flag Shard: flags-single	Allocated memory per operation (estimated)	17.38 KiB/op	17.41 KiB/op	0.2% more memory	Not flagged
Evaluate a multivariate flag Shard: flags-single	Time per operation	41.16 µs/op	41.33 µs/op	0.4% more time	Not flagged
Evaluate a multivariate flag Shard: flags-single	Process CPU time per operation	44.96 µs/op	45.6 µs/op	1.4% more time	Not flagged

Values are medians of paired measurements. Not flagged does not mean unchanged. Unavailable means a measurement could not be provided, not zero. Estimated allocation measurements retain their instrumentation uncertainty. RSS measures the whole process, not just SDK allocations; observed peaks are sampled checkpoints. Paired ranges in the diagnostics describe variability, not confidence intervals.

Each shard uses its own runner; compare Before PR against With PR within a row, not across shards.

Compared eb11f00d30c734d2de3a5f71aa7d814343588a9f → 37a1cd611f1087d43e41b0caf708e9afb88db1a3.

Full report and diagnostics

102 metric rows; 102 rows shown in all results. Omitted or shortened data remain in comparison.json, including per-runner environments, resource limits, measurement methods, samples and checkpoints.