feat(flags): ConfigurationWire parse + precomputed decode [PR1] (FFL-2686, FFL-2687)#1330
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feat(flags): ConfigurationWire parse + precomputed decode [PR1] (FFL-2686, FFL-2687)#1330btthomas wants to merge 3 commits into
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🎉 All green!🧪 All tests passed 🔗 Commit SHA: 2d20825 | Docs | Datadog PR Page | Give us feedback! |
…86, FFL-2687)
Internal, pure-JS building blocks for offline init (kept un-exported until the
exports step):
- configurationFromString / configurationToString for the ConfigurationWire v1
envelope, with a ParsedFlagsConfiguration type (distinct from the enable()
FlagsConfiguration). Lenient parse: returns {} on malformed input or an
unsupported version; accepts a known set of versions.
- decodePrecomputedFlags: maps a precomputed CDN response to the existing
FlagCacheEntry map. Injects key from the flag map key; value = typed
variationValue (integer/float -> JS number, variationType string preserved);
derives the string variationValue (JSON for objects, lowercase booleans) for
Android exposure round-trip; validates variationType and omits unknowns; throws
UnsupportedConfigurationError on obfuscated payloads.
Unit tests cover parse/round-trip, unsupported version/invalid JSON, and decode
across all variation types incl. obfuscation and mismatch handling.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
…y object values Review follow-ups on PR1: - H1: accumulate decoded flags in a Map and materialize with Object.fromEntries, so a flag keyed "__proto__" is stored as data instead of hitting the Object.prototype setter (which silently dropped it and reassigned the proto). - H2: reject array values for object-typed flags (object flags are a JSON object at the root). Arrays are omitted plus logged, like other type mismatches. Adds regression tests for both. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
…ta (review M/L) Remaining PR1 review follow-ups: - M1: integer flags require a whole number; number/float require a finite value (reject NaN/Infinity) so native parsers round-trip. - M2: document that serialId is intentionally not propagated (no FlagCacheEntry slot; native snapshot omits it too). - L3: comment that only flags (and obfuscated) are load-bearing; the rest of the response attributes are optional/ignored on purpose. - L1/L5: broaden round-trip fixture (number + nested object flags) and add tests for fractional integer, non-finite number, and a structurally broken response. L2 (distinguishing parse-failure from valid-but-empty) is intentionally left to PR2 (FFL-2688). L4 (configurationToString vs the reference's bug) is correct as-is. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Pull request overview
This PR introduces an internal (non-exported) flags/configuration module that enables offline feature-flag initialization by parsing a portable ConfigurationWire string and decoding precomputed CDN assignments into the SDK’s existing FlagCacheEntry shape.
Changes:
- Added
configurationFromString/configurationToStringfor lenient parsing/serialization ofConfigurationWirev1. - Added
decodePrecomputedFlags(+UnsupportedConfigurationError) to map precomputed CDN assignments toRecord<string, FlagCacheEntry>, including variation-type validation and prototype-safe key handling. - Added types and unit tests for wire round-trip, unsupported/malformed inputs, variation-type decoding, and obfuscation rejection.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/core/src/flags/configuration/wire.ts | Lenient parse/serialize helpers for ConfigurationWire v1 and embedded precomputed response JSON. |
| packages/core/src/flags/configuration/types.ts | Defines wire envelope types, supported versions/variation types, and parsed configuration shapes. |
| packages/core/src/flags/configuration/precomputed.ts | Decoder from precomputed CDN response to FlagCacheEntry map, with validation and predictable failures. |
| packages/core/src/flags/configuration/index.ts | Internal module boundary + re-exports for configuration parsing/decoding primitives. |
| packages/core/src/flags/configuration/tests/wire.test.ts | Unit tests for wire parsing behavior and serialization round-trip. |
| packages/core/src/flags/configuration/tests/precomputed.test.ts | Unit tests for decoding across variation types, obfuscation rejection, and prototype-safe keys. |
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| const toFlagCacheEntry = ( | ||
| key: string, | ||
| flag: PrecomputedFlag | ||
| ): FlagCacheEntry | null => { | ||
| const { variationType, variationValue } = flag; | ||
|
|
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| // `serialId` is intentionally not propagated: `FlagCacheEntry` has no slot for it | ||
| // and the native CDN-fetched snapshot omits it too, so dropping it keeps | ||
| // offline/online parity. | ||
| return { | ||
| key, | ||
| value: variationValue, | ||
| allocationKey: flag.allocationKey, | ||
| variationKey: flag.variationKey, | ||
| variationType, | ||
| variationValue: stringifyValue(variationValue), | ||
| reason: flag.reason, | ||
| doLog: flag.doLog, | ||
| extraLogging: flag.extraLogging ?? {} | ||
| }; |
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Offline feature flags — related PRs
FlagsClient.setConfiguration): feat(flags): FlagsClient.setConfiguration + context matching [PR2] (FFL-2688) #1331Summary
Adds the pure-JS building blocks for offline feature-flag initialization in the React Native SDK (FFL-2686, FFL-2687): parsing a portable
ConfigurationWirestring and decoding its precomputed assignments into the SDK's internal flag-cache shape. These let a customer load a configuration they fetched themselves and evaluate flags without a network request.New internal module
packages/core/src/flags/configuration/(not yet exported):wire.ts—configurationFromString(wire): ParsedFlagsConfigurationandconfigurationToString(config). Parses theConfigurationWirev1 envelope and is lenient: it returns an empty configuration on malformed input or an unsupported version rather than throwing.ParsedFlagsConfigurationis a distinct type (not theenable()FlagsConfiguration) and reserves aserver/rules branch for the future.precomputed.ts—decodePrecomputedFlags(response)→Record<string, FlagCacheEntry>(the shape the SDK already caches and evaluates against). The typedvariationValuebecomes the flagvalueplus a stringified form used by native Android exposure tracking;integer/floatdecode to a JSnumberwhile preserving the originalvariationType; unknown variation types are omitted; obfuscated payloads fail predictably.types.ts/index.ts— types and the internal module barrier.Tests
Unit tests cover wire parse + round-trip, unsupported version / invalid JSON, decode across every variation type, prototype-safe key handling, and obfuscation rejection. Lint and
tscare clean.