Compatibility

Spec version 0.1.0. Source: SDK master plus live registry checks on 2026-09-11. v1 scope is ADR-0010: control-point reads and target registration only.

Language surfaces share the same nine methods and registerTarget. Casing and entry-point names differ. Do not assume a camelCase method exists in Python or Rust.

Packages and publish state

Surface	Package	Published (2026-09-09)
Node / Bun / Deno	`@fireweaveai/server-sdk`	npm 2.3.0. `@fireweaveai/sdk` is frozen at 2.1.0 — not the install target.
Python	`fireweave`	PyPI 2.3.0. No `[openfeature]` or `[posthog]` extra.
Go	`github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2`	v2.3.0. `/v2` suffix required.
Java	`ai.fireweave:fireweave-sdk`	Maven Central 2.3.0. `fireweave-openfeature`, `fireweave-adapter-posthog`, and `fireweave-testing` remain at 0.1.0.
Browser	`@fireweaveai/web-sdk`	npm 2.3.0
Rust	`fireweave`	crates.io 2.3.0
Swift	in-tree `sdks/swift`	Not installable. `Package.swift` is not at the repo root.

Runtime floors (manifests)

CI also runs extra cells (latest / stable / canary). Those float. Support floors are the manifest numbers.

SDK	Manifest floor	Also exercised in CI (not a guarantee)
Node	Node `>=20.20` (`engines`)	Node 20 + 24
Bun (same package)	Bun `1.2` (runtime docs)	Bun 1.2 + latest
Deno (same package)	Deno `2.0` (runtime docs)	`v2.x` + canary
Python	Python `>=3.10`	3.10 + 3.14
Go	`go 1.25.13` (`go.mod`)	`1.25.x` + stable
Java	Java 11+	JDK 11 + 25
Web	Browser. No Node/Deno target.	Bun + happy-dom only
Rust	rust-version 1.75	crate CI

Evaluation types

The wire uses flagKey. Native product noun is control point.

	Native evaluate	Boolean	String	Number	Object
Node	`client.controlPoints.*`	`getBooleanValue`	`getStringValue`	IEEE-754 `number`	`getObjectValue`
Python	`client.control_points.*`	`get_boolean_value`	`get_string_value`	`get_number_value`	`get_object_value`
Go	`client.ControlPoints()`	`GetBooleanValue`	`GetStringValue`	`GetNumberValue` (`float64`)	`GetObjectValue`
Java	`client.controlPoints()`	`getBooleanValue`	`getStringValue`	`getNumberValue` (`double`)	`getObjectValue`
Web	`client.controlPoints.` (sync*)	`getBooleanValue`	`getStringValue`	IEEE-754 `number`	`getObjectValue`
Rust	`client.control_points.*`	`get_boolean_value`	`get_string_value`	`get_number_value`	`get_object_value`

Each language also ships the four *Details methods plus evaluate. That is the nine-method surface in conformance/surface/control-points.surface.json.

Numeric limitations

Language	Limitation
Node / Web	Single IEEE-754 double. Integers beyond ±(2^53−1) are not lossless.
All	Canonical JSON numbers. Cross-language integer reliability within ±(2^53−1).

Python get_integer_value is a deprecated alias of get_number_value. Go and Java no longer split integer/float on the native surface (FlagTypeNumber / FlagType.NUMBER only).

Feature matrix

Capability	Node	Python	Go	Java	Web	Rust
Entry point	`initFireweave`	`init_fireweave`	`Init`	`Fireweave.init`	`initFireweave`	`init_fireweave`
Required `mode`	yes	yes	yes	yes	yes	yes
Product namespace	`controlPoints`	`control_points`	`ControlPoints()`	`controlPoints()`	`controlPoints` (sync)	`control_points`
`registerTarget`	`client.registerTarget`	`client.register_target`	`client.RegisterTarget`	`client.registerTarget`	`registerTarget` + `identify`	`client.register_target`
Remote adapter	yes	yes	yes	yes	`FireweaveRemoteWebAdapter`	yes
Local / dev adapter	yes	yes	`infrastructure/adapters/local`	yes	yes	yes
In-memory adapter	yes	yes	yes	testing leftover	yes	yes
OpenFeature provider	absent	absent	absent	leftover 0.1.0 only	absent	absent
PostHog adapter	absent	absent	absent	leftover 0.1.0 only	absent	absent
`releases` / `exposures` / `signals` / `capabilities` / `guardrails`	absent	absent	absent	absent	absent	absent
Env-var config	no	no	no	no	no	no
Default host allowlist	Fireweave hosts + loopback	Fireweave hosts + loopback	Fireweave hosts + loopback	Fireweave + leftover PostHog hosts + loopback	Fireweave hosts + loopback	Fireweave hosts + loopback

Conformance asserts the cut namespaces via mustNotExpose in conformance/surface/control-points.surface.json.

Conformance

The suite is a 65×7 aggregate: the same 65 fixtures run against all seven language bindings (scripts/conformance-all.sh). Surface parity (the nine methods plus registerTarget) is green for node, web, python, java, go, rust, and swift. All behavioural skips, when present, are pre-declared (skipped-with-documented-limitation). Node/Web IEEE-754 integer fixtures are the documented numeric limitation.

Server vs web

	Server SDKs	Web
`controlPoints.*`	Promise / blocking	synchronous
Evaluation source	per-call (remote)	prefetched cache
Extra lifecycle	—	STALE (5s prefetch ceiling)
Config	explicit init options	explicit init options

Known gaps (do not paper over)

Swift is not distributable — in-tree only; SwiftPM cannot resolve Package.swift from the repository URL.
Java leftover artifacts — fireweave-openfeature, fireweave-adapter-posthog, and fireweave-testing stay at 0.1.0. They are not the 2.3.0 SDK.
OpenFeature is unbundled — no core SDK ships a provider. A future optional bridge is not forbidden; it is not published as part of 2.3.0.

Language pages

Node.js, Bun, Deno

@fireweaveai/server-sdk 2.3.0.

Python

fireweave 2.3.0 — control_points, no extras.

Go

ControlPoints() and RegisterTarget on /v2.

Java

controlPoints(), registerTarget(), 2.3.0 / 0.1.0 skew.

Browser

Sync reads, identify, fw_public_ keys.

Rust

crates.io fireweave 2.3.0.

Get Started

SDKs

Concepts

Production

CLI

Terraform

Testing

Troubleshooting

Migration

Reference

Packages and publish state

Runtime floors (manifests)

Evaluation types

Numeric limitations

Feature matrix

Conformance

Server vs web

Known gaps (do not paper over)

Language pages

Node.js, Bun, Deno

Python

Go

Java

Browser

Rust

​Packages and publish state

​Runtime floors (manifests)

​Evaluation types

​Numeric limitations

​Feature matrix

​Conformance

​Server vs web

​Known gaps (do not paper over)

​Language pages

Node.js, Bun, Deno

Python

Go

Java

Browser

Rust

Packages and publish state

Runtime floors (manifests)

Evaluation types

Numeric limitations

Feature matrix

Conformance

Server vs web

Known gaps (do not paper over)

Language pages