fix: attach Ready listener independent of current client status in `attachHandlersAndResolve` (closes #1331) #1332

yugisu-flux · 2026-01-20T14:35:15Z

Motivation

This PR fixes #1331

Changes

Update attachHandlersAndResolve to always attach the ProviderEvents.READY listener to the client independently of the initial state.
Add a test for the scenario listed in the associated issue.

gemini-code-assist · 2026-01-20T14:35:34Z

Summary of Changes

Hello @yugisu-flux, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the robustness of feature flag evaluation within the React SDK by modifying the useFeatureFlag hook. The change ensures that the Ready event listener for the OpenFeature client is consistently attached, thereby guaranteeing that flag evaluations are correctly updated when a provider becomes available, even in complex scenarios involving asynchronous provider setup or concurrent context changes. This resolves a potential race condition and improves the reliability of flag resolution in dynamic application environments.

Highlights

Unconditional Ready Listener Attachment: The ProviderEvents.Ready handler is now always registered within the useFeatureFlag hook, regardless of the current provider status. This ensures that flag evaluations are updated upon provider initialization, even if the provider is already in a READY state (e.g., from a NoOp provider).
Dependency Array Refinement: The status variable has been removed from the useEffect dependency array in use-feature-flag.ts, as its conditional usage for attaching the Ready handler is no longer present.
Race Condition Test Case: A new test case has been added to evaluation.spec.tsx to specifically address and prevent a race condition where setContext is called before setProvider, ensuring that flag values are correctly updated once the provider initializes asynchronously.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

gemini-code-assist

Code Review

This pull request correctly addresses a race condition by ensuring the Ready event listener is always attached in attachHandlersAndResolve, regardless of the client's initial status. This prevents components from failing to update when a new provider is set. The removal of status from the useEffect dependency array is a logical consequence of this change. The new test case effectively validates this fix by simulating the specific race condition. I have one minor suggestion to improve the clarity of the new test.

gemini-code-assist · 2026-01-20T14:36:47Z

packages/react/test/evaluation.spec.tsx

+        resolveBooleanEvaluation() {
+          return { value: false };
+        }
+        resolveNumberEvaluation() {
+          return { value: 42 };
+        }
+        resolveObjectEvaluation<T>(_: string, __: T) {
+          return { value: {} as T };
+        }


For improved clarity and conciseness, you could remove the unused resolve... methods from this test-specific CustomProvider. Since the test only evaluates a string flag, only resolveStringEvaluation is necessary. This would make the provider's purpose more focused and the test easier to understand.

While these changes could indeed improve readability, they will break the Provider interface requirement in the OpenFeature.setProvider call later on. These methods are kept as slim as possible so they don't really mess with the test's readability.

…HandlersAndResolve` Signed-off-by: Dmytrii Puzyr <dmytrii.puzyr@datadoghq.com>

lukas-reining

This looks good to me and I do not see real negative consequences.
Thanks for bringing up the issue and fixing it @yugisu-flux!
Let's wait for @toddbaert before merging.

lukas-reining · 2026-01-22T22:47:03Z

packages/react/src/evaluation/use-feature-flag.ts

-    }
+    // Always register the Ready handler to catch provider initialization
+    // even if current status is already READY (e.g., from a NoOp provider)
+    client.addHandler(ProviderEvents.Ready, updateEvaluationDetailsCallback, { signal: controller.signal });


I think this is okay as updateEvaluationDetailsCallback checks the flag details for equality.
So even if the provider renders as ready and the handler triggers, only one render should be done.
Or am I overlooking anything @toddbaert?

yugisu-flux requested review from a team as code owners January 20, 2026 14:35

yugisu-flux changed the title ~~Attach Ready listener independent of current client status in attachHandlersAndResolve~~ fix: attach Ready listener independent of current client status in attachHandlersAndResolve (closes #1331) Jan 20, 2026

gemini-code-assist bot reviewed Jan 20, 2026

View reviewed changes

Attach Ready listener independent of current client status in `attach…

a61af23

…HandlersAndResolve` Signed-off-by: Dmytrii Puzyr <dmytrii.puzyr@datadoghq.com>

yugisu-flux force-pushed the fix/use-flag-not-tracking-provider-change branch from 67bf273 to a61af23 Compare January 20, 2026 15:03

lukas-reining approved these changes Jan 22, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

fix: attach Ready listener independent of current client status in `attachHandlersAndResolve` (closes #1331) #1332

fix: attach Ready listener independent of current client status in `attachHandlersAndResolve` (closes #1331) #1332

Uh oh!

yugisu-flux commented Jan 20, 2026 •

edited

Loading

Uh oh!

gemini-code-assist bot commented Jan 20, 2026

Uh oh!

gemini-code-assist bot left a comment

Uh oh!

gemini-code-assist bot Jan 20, 2026

Uh oh!

yugisu-flux Jan 20, 2026

Uh oh!

lukas-reining left a comment

Uh oh!

lukas-reining Jan 22, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

fix: attach Ready listener independent of current client status in attachHandlersAndResolve (closes #1331) #1332

Are you sure you want to change the base?

fix: attach Ready listener independent of current client status in attachHandlersAndResolve (closes #1331) #1332

Uh oh!

Conversation

yugisu-flux commented Jan 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Motivation

Changes

Uh oh!

gemini-code-assist bot commented Jan 20, 2026

Summary of Changes

Highlights

Footnotes

Uh oh!

gemini-code-assist bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist bot Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

yugisu-flux Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

lukas-reining left a comment

Choose a reason for hiding this comment

Uh oh!

lukas-reining Jan 22, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

fix: attach Ready listener independent of current client status in `attachHandlersAndResolve` (closes #1331) #1332

fix: attach Ready listener independent of current client status in `attachHandlersAndResolve` (closes #1331) #1332

yugisu-flux commented Jan 20, 2026 •

edited

Loading