fix(flags): align presence operator semantics

[marandaneto]

💡 Motivation and Context

sdk-specs PR #49 defines is_not_set using partial property context. The PHP local evaluator returned an inconclusive exception even when the caller supplied the property key.

This change returns false for is_not_set whenever the key is present, including null and other falsey values. An omitted key remains inconclusive.

💚 How did you test it?

• php -l lib/FeatureFlag.php
• php -l test/FeatureFlagLocalEvaluationTest.php
• Direct smoke checks for present and omitted property behavior
• Autoreview completed with no actionable findings.

PHPUnit was not run locally because vendor dependencies were unavailable. CI will run the complete test suite.

📝 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)

Pi coding agent worker subagents implemented the focused matcher change and regression tests. The bundled autoreview tool reviewed the final committed diff against origin/main.

[github-actions]

posthog-php Compliance Report

Date: 2026-08-26 07:49:34 UTC
Duration: 95313ms

✅ All Tests Passed!

46/46 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	12ms
Format Validation.Event Has Uuid	✅	6ms
Format Validation.Event Has Lib Properties	✅	6ms
Format Validation.Distinct Id Is String	✅	5ms
Format Validation.Token Is Present	✅	6ms
Format Validation.Custom Properties Preserved	✅	6ms
Format Validation.Event Has Timestamp	✅	5ms
Retry Behavior.Retries On 503	✅	5316ms
Retry Behavior.Does Not Retry On 400	✅	2009ms
Retry Behavior.Does Not Retry On 401	✅	2010ms
Retry Behavior.Respects Retry After Header	✅	8014ms
Retry Behavior.Implements Backoff	✅	15729ms
Retry Behavior.Retries On 500	✅	5115ms
Retry Behavior.Retries On 502	✅	5115ms
Retry Behavior.Retries On 504	✅	5114ms
Retry Behavior.Max Retries Respected	✅	16530ms
Deduplication.Generates Unique Uuids	✅	12ms
Deduplication.Preserves Uuid On Retry	✅	5113ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10312ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5117ms
Deduplication.No Duplicate Events In Batch	✅	12ms
Deduplication.Different Events Have Different Uuids	✅	6ms
Compression.Sends Gzip When Enabled	✅	6ms
Batch Format.Uses Proper Batch Structure	✅	6ms
Batch Format.Flush With No Events Sends Nothing	✅	3ms
Batch Format.Multiple Events Batched Together	✅	10ms
Error Handling.Does Not Retry On 403	✅	2008ms
Error Handling.Does Not Retry On 413	✅	2009ms
Error Handling.Retries On 408	✅	5115ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	7ms
Request Payload.Flags Request Uses V2 Query Param	✅	4ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	5ms
Request Payload.Flags Request Omits Authorization Header	✅	4ms
Request Payload.Token In Flags Body Matches Init	✅	5ms
Request Payload.Groups Round Trip	✅	4ms
Request Payload.Groups Default To Empty Object	✅	5ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	5ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	4ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	5ms
Request Lifecycle.No Flags Request On Init Alone	✅	2ms
Request Lifecycle.No Flags Request On Normal Capture	✅	5ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	7ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	5ms
Retry Behavior.Retries Flags On 502	✅	107ms
Retry Behavior.Retries Flags On 504	✅	107ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	7ms

[greptile-apps]

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