feat: FDv2 types, refined validators, and DataManager interface by kinyoklion · Pull Request #1207 · launchdarkly/js-core

kinyoklion · 2026-03-19T22:11:48Z

This is the first of several PRs to integrate the changes from the testing FDv2 branch.

Summary

Add InitializerEntry/SynchronizerEntry type aliases for type-safe mode definitions
Refine protocolHandler validation to use isNullish for version/target fields (allows 0)
Add connectionModes config option to LDClientDataSystemOptions
Split validator arrays so synchronizers reject cache entries
Extend DataManager interface with optional setForcedStreaming, setAutomaticStreamingState, setFlushCallback methods
Export MODE_TABLE and createDataSourceStatusManager from sdk-client index

Note

Medium Risk
Medium risk due to public API surface changes (new connectionModes option, new exported types/exports, and DataManager interface extensions) plus adjusted FDv2 protocol validation that could affect event processing in edge cases (e.g., version 0).

Overview
Adds a connectionModes override to LDClientDataSystemOptions, plus new InitializerEntry/SynchronizerEntry types so mode definitions can type/validate initializers vs synchronizers differently (notably disallowing cache in synchronizers), with accompanying validator updates and tests.

Refines FDv2 protocolHandler validation to treat 0 as valid for target/version/state via isNullish, and adds warning logs when ignoring malformed or out-of-sequence events.

Extends the DataManager interface with optional streaming/lifecycle hooks (setForcedStreaming, setAutomaticStreamingState, setFlushCallback) and updates public exports (including MODE_TABLE and createDataSourceStatusManager), plus a doc fix for flag-eval kind naming.

^{Written by Cursor Bugbot for commit e315ed6. This will update automatically on new commits. Configure here.}

…xtensions Add InitializerEntry/SynchronizerEntry types for type-safe mode definitions, refine protocolHandler validation to use isNullish for version/target fields, add connectionModes config option, split validator arrays for initializers vs synchronizers, and extend DataManager with optional streaming/flush methods.

github-actions · 2026-03-19T22:13:13Z

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25661 bytes
Compressed size limit: 26000
Uncompressed size: 126143 bytes

github-actions · 2026-03-19T22:13:36Z

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 172915 bytes
Compressed size limit: 200000
Uncompressed size: 804043 bytes

github-actions · 2026-03-19T22:13:37Z

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 24994 bytes
Compressed size limit: 25000
Uncompressed size: 86916 bytes

github-actions · 2026-03-19T22:13:43Z

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 23240 bytes
Compressed size limit: 24000
Uncompressed size: 121325 bytes

kinyoklion · 2026-03-19T22:14:09Z

   * Closes the data manager. Any active connections are closed.
   */
  close(): void;
+


Adding these makes is to browser/RN can use the same data manager and also a consistent reference to the data manager type without instance checks.

It may change a little when we expose setConnectionMode.

joker23

LGTM - only nits

joker23 · 2026-03-19T23:34:58Z

      );

+      if (conditions.promise) {
+        logger?.warn('Fallback condition active for current synchronizer.');


nit: not sure why this is a warning, isn't it normal for fdv2 to have fallback conditions?

Yeah, this should be a debug.

## Summary Converts: `{polling: {initializers: ['cache', 'polling'], synchronizers: ['streaming']}}` into real factories. - Add `SourceFactoryProvider` interface and `createDefaultSourceFactoryProvider` implementation - Converts declarative `InitializerEntry`/`SynchronizerEntry` config into concrete factories and synchronizer slots - Supports per-entry endpoint overrides (custom polling/streaming URIs) and interval overrides - Handles `cache`, `polling`, and `streaming` entry types Stacked on #1207. Independent of #1208 (FlagManager.applyChanges).  --- > [!NOTE] > **Medium Risk** > Introduces a new factory layer that determines how polling/streaming/cache sources are instantiated (including endpoint/interval overrides), which can affect connection behavior if integrated incorrectly. Changes are well-covered by unit tests and are otherwise additive. > > **Overview** > Adds a new `SourceFactoryProvider` abstraction (with `createDefaultSourceFactoryProvider`) that converts declarative `InitializerEntry`/`SynchronizerEntry` configs into concrete FDv2 initializer factories and synchronizer slots, supporting `cache`, `polling`, and `streaming` entries. > > Implements per-entry overrides for endpoints and timing (poll interval and streaming reconnect delay), including ensuring the streaming ping handler always uses the latest selector and any endpoint-overridden polling requestor. > > Exports the new provider/types from `sdk-client` public entrypoint and updates CI package-size thresholds for `js-sdk-common` and `js-client-sdk-common` to accommodate the added code/tests. > > Written by [Cursor Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit de39213. This will update automatically on new commits. Configure [here](https://cursor.com/dashboard?tab=bugbot).   --- <a href="https://app.devin.ai/review/launchdarkly/js-core/pull/1209" target="_blank"> <picture> <source media="(prefers-color-scheme: dark)" srcset="https://static.devin.ai/assets/gh-open-in-devin-review-dark.svg?v=1"> <img src="https://static.devin.ai/assets/gh-open-in-devin-review-light.svg?v=1" alt="Open with Devin"> </picture> </a>

…1208) Review 1207 first. ## Summary - Add `applyChanges(context, updates, type)` method to `FlagManager` interface and `FlagPersistence` - `'full'`: replaces all flags (like init) - `'partial'`: upserts individual flags - `'none'`: persists cache (updating freshness) without changing flags Stacked on #1207.  --- > [!NOTE] > **Medium Risk** > Touches core flag update/caching behavior by adding a new update path that bypasses version and active-context checks, which could affect consistency if misused. Changes are contained and covered by new unit tests, plus a CI-only workflow tweak. > > **Overview** > Adds a new `FlagManager.applyChanges(context, updates, type)` API (and plumbing through `FlagPersistence`, `FlagUpdater`, and `FlagStore`) to support FDv2 update semantics: **`full` replace**, **`partial` merge/upsert without version/active-context guards**, and **`none` no-op flag changes while still persisting cache/freshness**. > > Updates change-event emission to match the new modes (`init` for full diffs, `patch` for partial key lists) and adds unit tests covering replacement vs merge behavior, freshness persistence on `none`, version-check bypass, and change callbacks. > > Separately relaxes the browser CI package-size gate by raising the limit from `25000` to `34000`. > > Written by [Cursor Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit b5e5dc3. This will update automatically on new commits. Configure [here](https://cursor.com/dashboard?tab=bugbot).   --- <a href="https://app.devin.ai/review/launchdarkly/js-core/pull/1208" target="_blank"> <picture> <source media="(prefers-color-scheme: dark)" srcset="https://static.devin.ai/assets/gh-open-in-devin-review-dark.svg?v=1"> <img src="https://static.devin.ai/assets/gh-open-in-devin-review-light.svg?v=1" alt="Open with Devin"> </picture> </a>

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kinyoklion commented Mar 19, 2026

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kinyoklion marked this pull request as ready for review March 19, 2026 22:18

kinyoklion requested a review from a team as a code owner March 19, 2026 22:18

This was referenced Mar 19, 2026

feat: FlagManager.applyChanges for FDv2 full/partial/none semantics #1208

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feat: SourceFactoryProvider for declarative data source creation #1209

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joker23 approved these changes Mar 19, 2026

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tanderson-ld approved these changes Mar 20, 2026

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Update FDv2DataSource.ts

e315ed6

kinyoklion merged commit d7ccfc1 into main Mar 20, 2026
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kinyoklion deleted the rlamb/fdv2-types-and-validators branch March 20, 2026 15:56

github-actions Bot mentioned this pull request Mar 20, 2026

chore: release main #1204

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feat: FDv2 types, refined validators, and DataManager interface#1207

feat: FDv2 types, refined validators, and DataManager interface#1207
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