[kinyoklion]

Summary

Before the client is initialized, and while the data store is not initialized either, allFlagsState evaluates whatever flags the store holds into an invalid state. A store can hold LaunchDarkly flags without being initialized, for example a persistent store with data but without the marker that a complete data set was written. With an override source configured, the state was marked valid whenever the merged read through the overlay returned any flag, so a source whose layer is empty turned that invalid state into a valid one. Configuring a source that supplies nothing must change nothing (OVERRIDE Requirement 1.2.2).

Whether the override layer holds flags now decides the validity, instead of whether the merged read returned any. The read itself still goes through the overlay, so the state holds the store's flags with the override layer's entries taking precedence. Overrides only add to the flags the state would report without them, and never remove one: a layer with flags gives a valid state of the store's flags plus the overrides, and a layer without flags gives exactly the state that a client without an override source gives. The once-per-client warning now says that the state holds flags from the override layer and the data store.

This was found while reviewing the same code in the .NET port (launchdarkly/dotnet-core#364). In the other server-side SDKs this branch returned an empty state before overrides, so a state of the override flags alone adds to it there; in this SDK the store's flags were already in the state, so they stay.

Tests

Two tests in LDClientImpl.overrides.test.ts use a persistent store that holds LaunchDarkly flags but reports that it is not initialized. One checks that a client with an empty override source reports the same invalid state as a client without a source. The other checks that a client with overrides reports the store's flags with the overrides added and taking precedence for a shared key. Reading the layer alone fails the second; deciding validity from the merged read fails the first. The sdk-server suite passes (1561 passed, 7 skipped), and lint and formatting are clean.

_{Opened from termag}

SDK-3419

---

Note

Overview
When allFlagsState runs before the client and persistent store are initialized, the SDK still reads flags through the store overlay, but LDFlagsState.valid no longer follows “any merged flag came back.” Validity now depends only on whether the override layer has feature flags, so an empty override source cannot turn an otherwise invalid partial-store snapshot into a valid one (OVERRIDE 1.2.2).

If the override layer has flags, the state is valid and includes store flags plus overrides (overrides win on key clashes); the once-per-client warning text now says flags come from both the override layer and the data store. If the layer is empty, behavior matches a client with no override source: invalid state with whatever the store returned, plus the existing “data store not available” path when appropriate.

Tests add an uninitialized store that still holds LD flags and assert the empty-source vs merged-override cases; existing override tests were updated for the new log message.

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[kinyoklion]

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@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 32220 bytes
Compressed size limit: 32500
Uncompressed size: 152548 bytes

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@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 34474 bytes
Compressed size limit: 35000
Uncompressed size: 122974 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 26066 bytes
Compressed size limit: 44000
Uncompressed size: 168326 bytes

[kinyoklion]

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