[marandaneto]

💡 Motivation and Context

Local feature flag regex evaluation can return a different Boolean than the flags service and skip remote fallback. For example, PCRE matches ^foo$ against "foo\n", but the service does not. PCRE also rejects (?<=a+)b even though the service accepts it. Unicode word classes differ too: ^\w$ does not match U+200C locally, but does on the service.

This adapts the agreed shared-syntax/local-evaluation approach from posthog-js#5354 and its cross-SDK discussion to PHP's PCRE engine. It does not assume that the JS PR is merged or released.

Changes

• Keep Unicode mode and use strict default end anchors with /uD.
• Defer unsupported or non-equivalent groups, escapes, classes and repetitions through the existing inconclusive exception and remote fallback.
• For actual \w or \W escapes, keep ASCII, Unicode letters and decimal digits local. Conservatively defer other input categories, including join controls, marks, non-decimal numerals and symbols. Escaped literal word markers and Unicode patterns without these shorthands are unaffected.
• Keep invalid patterns within the admitted subset false for both operators. Preserve empty-pattern matching and existing stringification. Execution errors remain inconclusive, including during the empty-input preflight, rather than becoming matches through not_regex or cohort negation.
• Cover direct, cohort and negated-leaf fallback, plus unresolved local-only results. Include a patch change intent.

This deliberately reduces local coverage for advanced syntax and uncertain word-class inputs, even where native matching sometimes agrees. It adds no engine, dependency or public option and makes no universal regex, Unicode or resource-budget equivalence claim.

💚 How did you test it?

• Added tests before the fixes and recorded failing assertions for the original mismatch, preflight execution failure and Unicode word-class revision.
• After integrating current main, focused PHPUnit passed: 701 tests and 1,794 assertions. Full PHPUnit passed: 2,131 tests and 8,923 assertions.
• Compared the actual SDK matcher against frozen actual-service results: 10,112 comparisons, zero wrong definitive results. These finite corpora overlap and do not represent exhaustive coverage.
• Verified public fallback and local-only behavior with the existing mocked HTTP fixture, without mocking the regex engine or calling live services.
• composer api:check and strict Composer validation passed. Scoped PHPCS has zero errors; existing warnings and suite deprecations remain.

Local validation used PHP 8.5.10 / PCRE 10.48. A prior unchanged loopback timeout test flaked under concurrent activity, then passed targeted and sequential full retries without changes. The fresh post-main full run also passed. No coverage driver or additional PHP-version matrix was available locally. The literal whole-directory lint command previously exhausted memory while scanning installed vendor files, so repository source/tests were linted directly. CI results are not yet claimed.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm change to generate a change intent file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

@marandaneto directed the compatibility fix and publication. Pi agents used local file and shell tools, PHP/Composer/PHPUnit, Git, GitHub CLI and the isolated autoreview helper. No public agent-session link is available. Human review is required.

The implementation keeps proven shared behavior local and uses existing fallback for uncertain PCRE/service differences. Test-audit and behavior-neutral deslop checks were completed. Final isolated autoreview passed on the committed branch against origin/main, with no actionable findings. No dependency replacement or public API expansion was used.

[github-actions]

posthog-php-fork_curl Compliance Report

Date: 2026-10-22T18:36:50.104513+00:00
Duration: 112398ms

⚠️ Some Tests Failed

36/47 tests passed, 11 failed

---

Capture Tests

⚠️ 19/30 tests passed, 11 failed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	34ms
Format Validation.Event Has Uuid	✅	529ms
Format Validation.Event Has Lib Properties	✅	531ms
Format Validation.Distinct Id Is String	✅	529ms
Format Validation.Token Is Present	✅	530ms
Format Validation.Custom Properties Preserved	✅	530ms
Format Validation.Event Has Timestamp	✅	531ms
Format Validation.Non Utc Event Timestamp Is Converted To Utc	✅	530ms
Retry Behavior.Retries On 503	❌	5533ms
Retry Behavior.Does Not Retry On 400	✅	2534ms
Retry Behavior.Does Not Retry On 401	✅	2532ms
Retry Behavior.Respects Retry After Header	❌	5535ms
Retry Behavior.Implements Backoff	❌	15537ms
Retry Behavior.Retries On 500	❌	5044ms
Retry Behavior.Retries On 502	❌	5536ms
Retry Behavior.Retries On 504	❌	5535ms
Retry Behavior.Max Retries Respected	❌	15545ms
Deduplication.Generates Unique Uuids	✅	539ms
Deduplication.Preserves Uuid On Retry	❌	5532ms
Deduplication.Preserves Uuid And Timestamp On Retry	❌	10543ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	❌	5540ms
Deduplication.No Duplicate Events In Batch	✅	537ms
Deduplication.Different Events Have Different Uuids	✅	532ms
Compression.Sends Gzip When Enabled	✅	533ms
Batch Format.Uses Proper Batch Structure	✅	531ms
Batch Format.Flush With No Events Sends Nothing	✅	519ms
Batch Format.Multiple Events Batched Together	✅	520ms
Error Handling.Does Not Retry On 403	✅	2532ms
Error Handling.Does Not Retry On 413	✅	2533ms
Error Handling.Retries On 408	❌	5536ms

Failures

retry_behavior.retries_on_503

Expected at least 3 requests, got 1

retry_behavior.respects_retry_after_header

Expected at least 2 requests, got 1

retry_behavior.implements_backoff

Expected at least 3 requests, got 1

retry_behavior.retries_on_500

Expected at least 2 requests, got 1

retry_behavior.retries_on_502

Expected at least 2 requests, got 1

retry_behavior.retries_on_504

Expected at least 2 requests, got 1

retry_behavior.max_retries_respected

Expected 4 requests, got 1

deduplication.preserves_uuid_on_retry

Need at least 2 requests to check retry

deduplication.preserves_uuid_and_timestamp_on_retry

Expected at least 3 requests, got 1

deduplication.preserves_uuid_and_timestamp_on_batch_retry

Expected at least 2 requests, got 1

error_handling.retries_on_408

Expected at least 2 requests, got 1

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	524ms
Request Payload.Flags Request Uses V2 Query Param	✅	522ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	522ms
Request Payload.Flags Request Omits Authorization Header	✅	521ms
Request Payload.Token In Flags Body Matches Init	✅	521ms
Request Payload.Groups Round Trip	✅	522ms
Request Payload.Groups Default To Empty Object	✅	522ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	522ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	521ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	521ms
Request Lifecycle.No Flags Request On Init Alone	✅	517ms
Request Lifecycle.No Flags Request On Normal Capture	✅	516ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	525ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	523ms
Retry Behavior.Retries Flags On 502	✅	625ms
Retry Behavior.Retries Flags On 504	✅	626ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	537ms

[github-actions]

posthog-php-socket Compliance Report

Date: 2026-10-22T18:37:10.061617+00:00
Duration: 114783ms

⚠️ Some Tests Failed

45/47 tests passed, 2 failed

---

Capture Tests

⚠️ 28/30 tests passed, 2 failed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	27ms
Format Validation.Event Has Uuid	✅	522ms
Format Validation.Event Has Lib Properties	✅	521ms
Format Validation.Distinct Id Is String	✅	523ms
Format Validation.Token Is Present	✅	522ms
Format Validation.Custom Properties Preserved	✅	522ms
Format Validation.Event Has Timestamp	✅	522ms
Format Validation.Non Utc Event Timestamp Is Converted To Utc	✅	522ms
Retry Behavior.Retries On 503	✅	5829ms
Retry Behavior.Does Not Retry On 400	✅	2524ms
Retry Behavior.Does Not Retry On 401	✅	2527ms
Retry Behavior.Respects Retry After Header	❌	5630ms
Retry Behavior.Implements Backoff	✅	16240ms
Retry Behavior.Retries On 500	✅	5134ms
Retry Behavior.Retries On 502	✅	5630ms
Retry Behavior.Retries On 504	✅	5630ms
Retry Behavior.Max Retries Respected	✅	16244ms
Deduplication.Generates Unique Uuids	✅	530ms
Deduplication.Preserves Uuid On Retry	✅	5629ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10837ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5634ms
Deduplication.No Duplicate Events In Batch	✅	529ms
Deduplication.Different Events Have Different Uuids	✅	523ms
Compression.Sends Gzip When Enabled	✅	522ms
Batch Format.Uses Proper Batch Structure	✅	522ms
Batch Format.Flush With No Events Sends Nothing	✅	518ms
Batch Format.Multiple Events Batched Together	✅	512ms
Error Handling.Does Not Retry On 403	✅	2524ms
Error Handling.Does Not Retry On 413	✅	2523ms
Error Handling.Retries On 408	❌	5531ms

Failures

retry_behavior.respects_retry_after_header

Retry delay too short: 101ms < 2500ms

error_handling.retries_on_408

Expected at least 2 requests, got 1

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	523ms
Request Payload.Flags Request Uses V2 Query Param	✅	521ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	522ms
Request Payload.Flags Request Omits Authorization Header	✅	521ms
Request Payload.Token In Flags Body Matches Init	✅	521ms
Request Payload.Groups Round Trip	✅	521ms
Request Payload.Groups Default To Empty Object	✅	521ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	523ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	521ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	522ms
Request Lifecycle.No Flags Request On Init Alone	✅	518ms
Request Lifecycle.No Flags Request On Normal Capture	✅	508ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	526ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	524ms
Retry Behavior.Retries Flags On 502	✅	624ms
Retry Behavior.Retries Flags On 504	✅	624ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	524ms

[github-actions]

posthog-php-lib_curl Compliance Report

Date: 2026-10-22T18:37:13.224379+00:00
Duration: 116402ms

⚠️ Some Tests Failed

46/47 tests passed, 1 failed

---

Capture Tests

⚠️ 29/30 tests passed, 1 failed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	24ms
Format Validation.Event Has Uuid	✅	520ms
Format Validation.Event Has Lib Properties	✅	521ms
Format Validation.Distinct Id Is String	✅	521ms
Format Validation.Token Is Present	✅	521ms
Format Validation.Custom Properties Preserved	✅	521ms
Format Validation.Event Has Timestamp	✅	521ms
Format Validation.Non Utc Event Timestamp Is Converted To Utc	✅	521ms
Retry Behavior.Retries On 503	✅	5830ms
Retry Behavior.Does Not Retry On 400	✅	2523ms
Retry Behavior.Does Not Retry On 401	✅	2523ms
Retry Behavior.Respects Retry After Header	❌	6330ms
Retry Behavior.Implements Backoff	✅	16243ms
Retry Behavior.Retries On 500	✅	5630ms
Retry Behavior.Retries On 502	✅	5629ms
Retry Behavior.Retries On 504	✅	5629ms
Retry Behavior.Max Retries Respected	✅	17043ms
Deduplication.Generates Unique Uuids	✅	227ms
Deduplication.Preserves Uuid On Retry	✅	5629ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10835ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5632ms
Deduplication.No Duplicate Events In Batch	✅	525ms
Deduplication.Different Events Have Different Uuids	✅	522ms
Compression.Sends Gzip When Enabled	✅	521ms
Batch Format.Uses Proper Batch Structure	✅	521ms
Batch Format.Flush With No Events Sends Nothing	✅	517ms
Batch Format.Multiple Events Batched Together	✅	511ms
Error Handling.Does Not Retry On 403	✅	2523ms
Error Handling.Does Not Retry On 413	✅	2523ms
Error Handling.Retries On 408	✅	5628ms

Failures

retry_behavior.respects_retry_after_header

Retry delay too short: 803ms < 2500ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	520ms
Request Payload.Flags Request Uses V2 Query Param	✅	519ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	520ms
Request Payload.Flags Request Omits Authorization Header	✅	519ms
Request Payload.Token In Flags Body Matches Init	✅	519ms
Request Payload.Groups Round Trip	✅	519ms
Request Payload.Groups Default To Empty Object	✅	520ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	519ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	519ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	520ms
Request Lifecycle.No Flags Request On Init Alone	✅	515ms
Request Lifecycle.No Flags Request On Normal Capture	✅	507ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	522ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	521ms
Retry Behavior.Retries Flags On 502	✅	622ms
Retry Behavior.Retries Flags On 504	✅	621ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	521ms

[posthog]

PostHog Review · Standard · reviewed aee01e2: no findings.

This Standard review started from the posthog-review label. Comment @posthog review --deep for a Deep review, or @posthog help to see all commands.