Changelog

(fix): Multipart form requests now send enum fields as plain form values (DUE_DILIGENCE) instead of JSON-encoded strings ("DUE_DILIGENCE"), matching the other SDKs. Lists of enums are sent the same way, one plain part per value.

(fix): WebhooksHelper.verifyRequest now parses name=value settings headers when webhook-signature.algorithm-header sets key-id-parameter/algorithm-parameter (e.g. Twilio’s X-Twilio-Webhooks-Signature-Settings: key=<id>,algorithm=HMAC_SHA256), so the key resolver receives the bare key ID instead of key=<id>. Requires IR 67.33.0.

(fix): Format date and date-time path parameters before encoding them into the request URL. Previously a date path parameter was sent as Go’s default time.Time string (e.g. /schedule-by-date/2023-01-15%2000:00:00%20+0000%20UTC) instead of 2023-01-15.

(fix): Generated wire tests now expect object, map, and list query parameters in the same key[field]=value form the SDK sends, instead of comparing against "[object Object]".

(fix): The generated WebhooksHelper now consumes algorithm-header from api.settings.webhook-signature: a request-level verifyRequest helper reads the configured signature header first (missing or empty fails early with “could not run: missing signature header”), then the algorithm-selection header (e.g. X-Twilio-Webhook-Signature-Settings: <key_id>;HMAC_SHA256) to pick the HMAC algorithm from the configured wire values and hand the key ID to an application-supplied secret resolver. When the header is absent the configured default algorithm and the plain secret are used, so legacy auth-token flows keep working. Following VerifySignature, the Go helper reports these early failures as (false, error) rather than logging. VerifySignatureWithAlgorithm additionally accepts the configured wire values alongside the generic algorithm names.

(fix): Unknown JSON keys that match a declared field’s wire name case-insensitively (e.g. VALUE next to a declared value) are no longer kept in ExtraProperties when decoding, so they are not re-emitted after the declared field on encode. Case-insensitive, last-wins decoders such as Go’s encoding/json would otherwise read the re-emitted key instead of the declared field. MarshalJSONWithExtraProperties now also rejects extra properties that collide case-insensitively with a declared key. Unknown keys that don’t collide (e.g. brand_new_field) are still preserved and round-tripped.

(fix): SSE unions discriminated by the event: line (x-fern-discriminator-context: protocol) now parse both variant styles: envelope variants ({event, data: Payload}) are built from the data: JSON, and payload variants (the data: JSON itself) get the event: value injected as the discriminant. The event name no longer has to be repeated inside the data: JSON.

(fix): Fix uncompilable streaming methods when errorCodes: per-endpoint is set and the endpoint declares no specific error responses. The streaming call no longer references the global ErrorCodes variable, which is not generated in per-endpoint mode.

(feat): XML (TwiML) types can now carry XML comments. Comment(text) adds <!--text--> inside the element at its position in the ordered content (interleaved with AddText segments and child elements), while CommentBefore(text) / CommentAfter(text) render a comment immediately before or after the element itself (as a sibling in its parent, or around the root element after the XML declaration). Comments in parsed documents are preserved by FromXml and round-trip through ToXml; XmlElement.AddComment and the new core.XmlComment node expose the same for untyped elements.

(fix): Enum-typed attributes and text on XML (TwiML) types are open on the wire: FromXml keeps a value the enum does not declare (e.g. a voice added after the SDK was generated) instead of returning an error, and it round-trips through ToXml. This matches how the same enums already behave in JSON.

(feat): Add opt-in userAgentOnly config. When enabled, generated clients send the User-Agent header (including the structured form from includePlatformHeaders) but omit the X-Fern-Language, X-Fern-SDK-Name, and X-Fern-SDK-Version headers. Disabled by default, so existing generated output is unchanged. omitFernHeaders still takes precedence and drops the User-Agent too.

(feat): The generated WebhooksHelper HMAC verifier now accepts a per-call algorithm override via a VerifySignatureWithAlgorithm(...) method (VerifySignature keeps the configured default), one of sha1, sha256, sha384 or sha512. When omitted, the algorithm configured in webhook-signature is used, so existing callers are unchanged. This lets one endpoint verify both legacy HMAC-SHA1 (auth-token) and HMAC-SHA256 (shared-key) signed webhooks. The verifier also logs a warning distinguishing an early failure (missing signature header) from a failed verification (signature mismatch); it still returns false and never throws.

(feat): XML (TwiML) types keep text segments, typed child elements and raw core.XmlElement children in a single ordered Content slice, so ToXml() emits them in the order they were added (response.Say(a).AddChild(custom).Say(b) yields <Say>a</Say><Custom /><Say>b</Say>) and FromXml() preserves document order, including the position of unknown elements and repeated wrapper elements. Adds AddText(string) to XML types and core.XmlElement for mixed content such as <Say>Hi <break strength="weak" /> world</Say>. Typed child properties and ExtraChildren remain available and are reconciled into Content on serialization.

(feat): Support SDK variables (variables in api.yml / x-fern-sdk-variables in OpenAPI). Path parameters bound to a variable via x-fern-sdk-variable are removed from endpoint signatures and request wrappers and are configured once on the client with the generated option.With<Variable>(...) helper (also accepted per request). Variables that declare an env fall back to that environment variable, and a string variable that is still unset fails with a clear error before the request is sent.

(fix): XML-encoded (TwiML) types now return their XML representation from String() instead of JSON, and ToXml() prepends the <?xml version="1.0" encoding="UTF-8"?> declaration. Use ToXmlElement().ToXml() to serialize without the declaration.

(fix): option.WithBodyProperties now overrides generated request fields that share the same wire-format key instead of returning a cannot add extra property error, so you can force or replace any JSON or form URL encoded request body property. The generated README documents the option in a new “Additional Body Properties” section, including that it isn’t applied to multipart file upload or raw byte requests.

(fix): The generated README’s client snippets use the configured client constructor (clientName, exportedClientName, clientConstructorName) instead of always writing client.NewClient, and the Environments section of a multi-URL SDK passes the environment through option.WithEnvironment instead of option.WithBaseURL, which takes a string and does not compile against an environment struct.

(feat): Add the opt-in legacyNullableAliasPointers custom config option. When enabled, optional or nullable fields that reference an alias which already renders as a Go pointer (e.g. type DiscoveryURL = *string) keep the outer pointer (*DiscoveryURL), matching SDKs generated before v1.46.1. Field types, setters, and code snippets all use the legacy shape. The option is off by default, so existing output is unchanged.

(fix): Restore pointer types for optional fields that reference a nullable list, map, or unknown alias (for example a type: [object, "null"] schema with additionalProperties, or a type: [array, "null"] schema). Since 1.46.1 these fields were generated as bare values (Metadata MetadataAlias) instead of pointers (Metadata *MetadataAlias), which was a breaking change for existing SDKs. The double-pointer guard now only applies to aliases that actually render as Go pointers (nullable primitives, enums, objects, and unions). Dynamic snippets now render &Alias{...} literals for these fields (including aliases of such aliases), take the address of unknown alias values, and no longer emit && for aliases that already render as pointers.

(fix): Return a completed HTTP response instead of discarding it when the request context is canceled after the response has been fully received but before it is decoded. Caller.Call previously re-checked ctx.Err() at that point and returned context.Canceled / context.DeadlineExceeded with a nil response, which dropped valid responses that had already been buffered (for example by a logging http.RoundTripper that ends its scope before returning). Calls canceled before the request is sent, and calls whose response body cannot be read to completion once the context ends, continue to fail with the context’s error, and a canceled context still never triggers a retry.

(chore): Bump bundled @fern-api/generator-cli to 0.10.3. When the hosted auto-version analysis of the full SDK diff fails, generator-cli now retries chunk-by-chunk instead of silently applying a PATCH bump; any remaining unavailable or incomplete analysis adds a “Version bump not verified” notice to the SDK PR body and disables automerge.