From f5ce2b962e13e2d938b21185bcbc12c61e999a67 Mon Sep 17 00:00:00 2001
From: Ron Cohen <ron@reflag.com>
Date: Thu, 24 Sep 2026 21:05:45 +0200
Subject: [PATCH] fix(browser-sdk): avoid false initialization diagnostics

---
 .changeset/quiet-flags-initialize.md    |  5 +++++
 packages/browser-sdk/src/client.ts      |  6 +----
 packages/browser-sdk/src/flag/flags.ts  |  7 ++++++
 packages/browser-sdk/test/usage.test.ts | 29 +++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/quiet-flags-initialize.md

diff --git a/.changeset/quiet-flags-initialize.md b/.changeset/quiet-flags-initialize.md
new file mode 100644
index 000000000..5520b56ec
--- /dev/null
+++ b/.changeset/quiet-flags-initialize.md
@@ -0,0 +1,5 @@
+---
+"@reflag/browser-sdk": patch
+---
+
+Avoid reporting `CLIENT_NOT_INITIALIZED` when a flag is evaluated from the initial flag state while client initialization is completing.
diff --git a/packages/browser-sdk/src/client.ts b/packages/browser-sdk/src/client.ts
index d4f0f80fe..4f63bbbef 100644
--- a/packages/browser-sdk/src/client.ts
+++ b/packages/browser-sdk/src/client.ts
@@ -501,7 +501,6 @@ function shouldShowToolbar(opts: InitOptions) {
  */
 export class ReflagClient {
   private state: State = "idle";
-  private initializationFinished = false;
   private contextUpdateLoading = false;
   private readonly publishableKey: string;
   private context: ReflagContext;
@@ -740,7 +739,6 @@ export class ReflagClient {
         "ms" +
         (this.config.offline ? " (offline mode)" : ""),
     );
-    this.initializationFinished = true;
     this.setState("initialized");
   }
 
@@ -1422,9 +1420,7 @@ export class ReflagClient {
   getFlag(flagKey: string): Flag {
     const f = this.getFlags()[flagKey];
     const evaluatedBeforeInitialization =
-      !this.initializationFinished &&
-      !this.config.offline &&
-      !this.config.bootstrapped;
+      !this.flagsClient.hasFlagState() && !this.config.offline;
 
     // eslint-disable-next-line @typescript-eslint/no-this-alias
     const self = this;
diff --git a/packages/browser-sdk/src/flag/flags.ts b/packages/browser-sdk/src/flag/flags.ts
index 8ac9b0448..aed3e47c9 100644
--- a/packages/browser-sdk/src/flag/flags.ts
+++ b/packages/browser-sdk/src/flag/flags.ts
@@ -298,6 +298,7 @@ export class FlagsClient {
   private initialized = false;
   private bootstrapped = false;
   private initializationComplete = false;
+  private flagStateAvailable = false;
 
   private rateLimiter: RateLimiter;
   private readonly logger: Logger;
@@ -425,6 +426,10 @@ export class FlagsClient {
     return this.fetchedFlags;
   }
 
+  hasFlagState(): boolean {
+    return this.flagStateAvailable;
+  }
+
   requestOptInFlags() {
     this.optInFlagsRequested = true;
 
@@ -545,6 +550,8 @@ export class FlagsClient {
     triggerEvent = true,
     flagStateVersion?: number,
   ) {
+    // Mark the state available before notifying consumers from updateFlags().
+    this.flagStateAvailable = true;
     // Create a new fetched flags object making sure to clone the flags
     this.fetchedFlags = { ...fetchedFlags };
     this.fetchedFlagStateVersion = flagStateVersion;
diff --git a/packages/browser-sdk/test/usage.test.ts b/packages/browser-sdk/test/usage.test.ts
index 44e001f70..60e8a3752 100644
--- a/packages/browser-sdk/test/usage.test.ts
+++ b/packages/browser-sdk/test/usage.test.ts
@@ -485,6 +485,35 @@ describe(`sends "check" events `, () => {
       );
     });
 
+    it("does not add initialization diagnostics once flag state is available", async () => {
+      const sendCheckEventSpy = vi.spyOn(
+        FlagsClient.prototype,
+        "sendCheckEvent",
+      );
+      const client = new ReflagClient({ publishableKey: KEY });
+      const evaluatedDuringInitialization = vi.fn();
+
+      client.on("flagsUpdated", () => {
+        expect(client.getState()).toBe("initializing");
+        expect(client.getFlag("flagA").isEnabled).toBe(true);
+        evaluatedDuringInitialization();
+      });
+
+      await client.initialize();
+
+      expect(evaluatedDuringInitialization).toHaveBeenCalledOnce();
+      expect(sendCheckEventSpy).toHaveBeenCalledWith(
+        expect.objectContaining({
+          action: "check-is-enabled",
+          key: "flagA",
+          value: true,
+          version: 1,
+          evaluationErrors: flagsResult.flagA.evaluationErrors,
+        }),
+        expect.any(Function),
+      );
+    });
+
     it("does not add initialization diagnostics to bootstrapped evaluations", () => {
       const sendCheckEventSpy = vi.spyOn(
         FlagsClient.prototype,