fix: Disable client when project token is missing

[marandaneto]

Summary

• Normalize ProjectToken and legacy ProjectApiKey by trimming and treating empty/whitespace as missing
• Add a PostHogOptions.Disabled user-configurable flag (default false) and compute the effective disabled state in PostHogClient
• No-op client calls when disabled instead of sending an empty api_key or throwing later
• Log a warning when public client methods are called while the SDK is disabled
• No-op public methods that require personal_api_key when it is not configured, including local-only feature flag evaluation and remote config payloads
• Add focused coverage for missing/empty/whitespace ProjectToken and legacy ProjectApiKey, disabled-call logging, and personal_api_key-protected methods

Tests

• dotnet test tests/UnitTests/UnitTests.csproj --framework net8.0 --filter "FullyQualifiedName~TheDisabledClient|FullyQualifiedName~ThePersonalApiKeyProtectedMethods|FullyQualifiedName~LogsWarningWhenPersonalApiKey|FullyQualifiedName~LogsErrorWhenProjectTokenIsMissing|FullyQualifiedName~LogsWarningWhenProjectApiKeyIsUsed"
• dotnet test tests/UnitTests/UnitTests.csproj --framework net8.0 (fails in existing CaptureException tests: CaptureExceptionWithInvalidFilePathInStackFrame, CaptureExceptionCauseIOFailureEmptyContext)

Note: requested context files context.md and plan.md were not present in this checkout.

[github-actions]

posthog-dotnet Compliance Report

Date: 2026-05-06 09:19:40 UTC
Duration: 431ms

⚠️ Some Tests Failed

2/16 tests passed, 14 failed

---

Feature_Flags Tests

⚠️ 2/16 tests passed, 14 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	❌	33ms
Request Payload.Flags Request Uses V2 Query Param	❌	16ms
Request Payload.Flags Request Hits Flags Path Not Decide	❌	4ms
Request Payload.Flags Request Omits Authorization Header	❌	3ms
Request Payload.Token In Flags Body Matches Init	❌	4ms
Request Payload.Groups Round Trip	❌	4ms
Request Payload.Groups Default To Empty Object	❌	3ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	❌	4ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	❌	4ms
Request Payload.Disable Geoip Omitted Defaults To False	❌	3ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	❌	4ms
Request Lifecycle.No Flags Request On Init Alone	✅	2ms
Request Lifecycle.No Flags Request On Normal Capture	✅	163ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	❌	5ms
Request Lifecycle.Mock Response Value Is Returned To Caller	❌	4ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	❌	3ms

Failures

request_payload.request_with_person_properties_device_id

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.flags_request_uses_v2_query_param

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.flags_request_hits_flags_path_not_decide

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.flags_request_omits_authorization_header

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.token_in_flags_body_matches_init

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.groups_round_trip

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.groups_default_to_empty_object

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.person_properties_distinct_id_auto_populated_when_caller_omits_it

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.disable_geoip_false_propagates_as_geoip_disable_false

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.disable_geoip_omitted_defaults_to_false

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_payload.flag_keys_to_evaluate_contains_only_requested_key

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_lifecycle.two_flag_calls_produce_two_remote_requests

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

request_lifecycle.mock_response_value_is_returned_to_caller

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

side_effect_events.get_feature_flag_captures_feature_flag_called_event

404, message='Not Found', url='http://sdk-adapter:8080/get_feature_flag'

[marandaneto]

@PostHog/team-client-libraries and @haacked i think this is what SDKs should do
can you double check so i can port this fix across SDKs? (i have a bunch of draft PRs already but some of them didnt address all stuff i found during this one)

[greptile-apps]

Comments Outside Diff (1)

1. src/PostHog/PostHogClient.cs, line 757-761 (link)

   Double warning log in LoadFeatureFlagsAsync

   Same issue as GetRemoteConfigPayloadAsync: IsPersonalApiKeyMissing already logs the generic "personal_api_key is not configured" warning before control reaches LogWarningPersonalApiKeyRequired inside the if-body. The old call is now redundant and should be removed.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: src/PostHog/PostHogClient.cs
   Line: 757-761
   
   Comment:
   **Double warning log in `LoadFeatureFlagsAsync`**
   
   Same issue as `GetRemoteConfigPayloadAsync`: `IsPersonalApiKeyMissing` already logs the generic "personal_api_key is not configured" warning before control reaches `LogWarningPersonalApiKeyRequired` inside the `if`-body. The old call is now redundant and should be removed.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
src/PostHog/PostHogClient.cs:553-556
**Double warning log emitted when `PersonalApiKey` is missing**

`IsPersonalApiKeyMissing` already emits `LogWarningPersonalApiKeyMissing` ("PostHog personal_api_key is not configured; {MethodName} is a no-op.") before this `if`-body executes. The call to `LogWarningPersonalApiKeyRequiredForRemoteConfigPayload` on line 555 then fires a second, redundant warning for the same condition. The same pattern exists in `LoadFeatureFlagsAsync` (line 759, `LogWarningPersonalApiKeyRequired`). The old method-specific log calls should be removed now that the unified `IsPersonalApiKeyMissing` helper handles the logging, otherwise every missing-key event produces two warnings.

```suggestion
        if (IsPersonalApiKeyMissing(nameof(GetRemoteConfigPayloadAsync)))
        {
            return null;
        }
```

### Issue 2 of 2
src/PostHog/PostHogClient.cs:757-761
**Double warning log in `LoadFeatureFlagsAsync`**

Same issue as `GetRemoteConfigPayloadAsync`: `IsPersonalApiKeyMissing` already logs the generic "personal_api_key is not configured" warning before control reaches `LogWarningPersonalApiKeyRequired` inside the `if`-body. The old call is now redundant and should be removed.

```suggestion
        if (IsPersonalApiKeyMissing(nameof(LoadFeatureFlagsAsync)))
        {
            return;
        }
```

_{Reviews (1): Last reviewed commit: "Disable client when project token is mis..." | Re-trigger Greptile}

[haacked]

A few suggestions in-line.

[haacked]

suggestion: This method is async Task<…> but the disabled path returns synchronously, so the C# compiler still allocates the async state machine and walks ExecutionContext. GroupIdentifyAsync (line 182) shows the pattern: Task return, no async, Task.FromResult(...) on the fast path, delegate to a private async core for the real work.

Same applies to AliasAsync (148), IdentifyAsync (163), CaptureException (277), IsFeatureEnabledAsync (369), GetFeatureFlagAsync (395), GetRemoteConfigPayloadAsync (545), LoadFeatureFlagsAsync (748), GetLocalEvaluatorAsync (798).

Pairs with the cached-result singletons above to make the disabled path truly zero-allocation.

[marandaneto]

Partially addressed — cached the no-op return values. I kept the async method structure intact to keep this fix focused and avoid a large control-flow refactor.

[marandaneto]

A few suggestions in-line.

Thanks and done.
can you double check?

[haacked]

Some nits, but nothing major.