docs: document user-agent template behavior with platform headers

fern/products/sdks/generators/csharp/configuration.mdx

@@ -96,7 +96,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="include-platform-headers" type="boolean" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/1.2.0 (linux; x86_64) dotnet/8.0.4`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omit-fern-headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/1.2.0 (linux; x86_64) dotnet/8.0.4`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omit-fern-headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="package-id" type="string" required={false} toc={true}>
@@ -122,3 +122,14 @@ When enabled, places core SDK classes (like base client classes and utilities) i
 <ParamField path="use-discriminated-unions" type="boolean" required={false} toc={true}>
 When enabled, generates discriminated union types for API responses that can contain multiple different object types. This provides type-safe handling of polymorphic responses.
 </ParamField>
+
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-dotnet-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-dotnet-sdk/0.1.0`. With [`include-platform-headers`](#include-platform-headers) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-dotnet-sdk/0.1.0 (linux; x86_64) dotnet/8.0.4`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-dotnet`, is used as-is and no version segment is added.
+</ParamField>

fern/products/sdks/generators/go/configuration.mdx

@@ -55,7 +55,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="includePlatformHeaders" type="boolean" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Go/1.22.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Go/1.22.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="enableWireTests" type="boolean" default="true" required={false} toc={true}>
@@ -172,4 +172,15 @@ Controls the union type generation strategy. Use 'v0' for the legacy union imple
 
 <ParamField path="useReaderForBytesRequest" type="boolean" default="true" required={false} toc={true}>
 When enabled, uses `io.Reader` interface for handling byte request bodies instead of byte slices. This is more memory-efficient for large payloads and follows Go best practices for streaming data.
+</ParamField>
+
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. Unlike the other Go options, this key is hyphenated. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-go-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-go-sdk/0.1.0`. With [`includePlatformHeaders`](#includeplatformheaders) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-go-sdk/0.1.0 (linux; x86_64) Go/1.22.0`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-go`, is used as-is and no version segment is added.
 </ParamField>

fern/products/sdks/generators/java/configuration.mdx

@@ -110,7 +110,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="includePlatformHeaders" type="boolean" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `com.fern.sdk/0.0.1 (linux; x86_64) Java/17.0.13`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omit-fern-headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `com.fern.sdk/0.0.1 (linux; x86_64) Java/17.0.13`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omit-fern-headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="package-layout" type="'nested' | 'flat'" default="nested" required={false} toc={true}>
@@ -159,6 +159,8 @@ groups:
 ```
 
 With this configuration, an organization named `plantstore` with an API named `plants` generates an SDK that sends `User-Agent: plantstore-plants/0.1.0 (java)`.
+
+With [`includePlatformHeaders`](#includeplatformheaders) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: a template of `plantstore-plants/{version}` sends `User-Agent: plantstore-plants/0.1.0 (linux; x86_64) Java/17.0.13`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-java`, is used as-is and no version segment is added.
 </ParamField>
 
 <ParamField path="wrapped-aliases" type="boolean" default="false" required={false} toc={true}>

fern/products/sdks/generators/php/configuration.mdx

@@ -58,7 +58,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="includePlatformHeaders" type="boolean" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) PHP/8.2.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) PHP/8.2.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="packageName" type="string" required={false} toc={true}>
@@ -72,3 +72,14 @@ Specifies the directory path where the generated SDK source files should be plac
 <ParamField path="propertyAccess" type="'public' | 'private'" required={false} toc={true}>
 Controls the access level of generated class properties. When set to 'public', properties are public and getter/setter methods are omitted. When set to 'private', properties are private and getter/setter methods are generated for encapsulation.
 </ParamField>
+
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. Unlike the other PHP options, this key is hyphenated. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-php-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-php-sdk/0.1.0`. With [`includePlatformHeaders`](#includeplatformheaders) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-php-sdk/0.1.0 (linux; x86_64) PHP/8.2.0`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-php`, is used as-is and no version segment is added.
+</ParamField>

fern/products/sdks/generators/python/configuration.mdx

@@ -181,7 +181,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="include_platform_headers" type="bool" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `fern_examples/0.0.1 (linux; x86_64) Python/3.11.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omit_fern_headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `fern_examples/0.0.1 (linux; x86_64) Python/3.11.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omit_fern_headers` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="pyproject_python_version" type="string" default="^3.10" required={false} toc={true}>
@@ -219,6 +219,17 @@ When enabled, skips code formatting (like black) on the generated Python code.
   Sets the client timeout in seconds, or `infinity` to disable timeouts.
 </ParamField>
 
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. Unlike the other Python options, this key is hyphenated. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-python-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-python-sdk/0.1.0`. With [`include_platform_headers`](#include_platform_headers) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-python-sdk/0.1.0 (linux; x86_64) Python/3.11.0`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-python`, is used as-is and no version segment is added.
+</ParamField>
+
 <ParamField path="use_api_name_in_package" type="bool" default="false" required={false} toc={true}>
 When enabled, includes the API name as part of the package structure and naming.
 </ParamField>

fern/products/sdks/generators/ruby/configuration.mdx

@@ -101,7 +101,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="includePlatformHeaders" type="boolean" default="false" required={false} toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Ruby/3.2.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Ruby/3.2.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="requirePaths" type="array of strings" required={false} toc={true}>
@@ -118,3 +118,14 @@ config:
 
 This will load `lib/<gem>/custom_integration.rb` and `lib/<gem>/sentry_integration.rb` when the gem is required.
 </ParamField>
+
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. Unlike the other Ruby options, this key is hyphenated. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-ruby-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-ruby-sdk/0.1.0`. With [`includePlatformHeaders`](#includeplatformheaders) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-ruby-sdk/0.1.0 (linux; x86_64) Ruby/3.2.0`. A resolved value whose trailing segment isn't a version, such as `plantstore/sdk-ruby`, is used as-is and no version segment is added.
+</ParamField>

fern/products/sdks/generators/typescript/configuration.mdx

@@ -406,7 +406,7 @@ When enabled, the generated SDK omits the `X-Fern-Language`, `X-Fern-SDK-Name`,
 </ParamField>
 
 <ParamField path="includePlatformHeaders" type="boolean" default="false" toc={true}>
-When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Node/20.11.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
+When enabled, the generated SDK sends a single structured `User-Agent` header of the form `{sdkName}/{version} ({os}; {arch}) {runtime}/{runtimeVersion}` (for example, `my-sdk/0.0.1 (linux; x86_64) Node/20.11.0`), carrying SDK, operating system, architecture, and runtime information in place of the default `User-Agent` and discrete platform headers. A configured [`user-agent`](#user-agent) template supplies the leading product token. If `omitFernHeaders` is enabled, no `User-Agent` or platform headers are sent and this option has no effect.
 </ParamField>
 
 <ParamField path="outputSourceFiles" type="boolean" default="true" toc={true}>
@@ -526,6 +526,17 @@ The default is `web`.
   When `treatUnknownAsAny` is enabled, [unknown types from Fern are generated into TypeScript using `any` instead of the `unknown` type](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-0.html#new-unknown-top-type).
 </ParamField>
 
+<ParamField path="user-agent" type="string" default="{packageName}/{version}" required={false} toc={true}>
+Sets a custom `User-Agent` header template for requests sent by the generated SDK. Unlike the other TypeScript options, this key is hyphenated. The template is resolved at generation time and supports the `{packageName}`, `{version}`, `{language}`, `{generatorVersion}`, `{organization}`, and `{apiName}` placeholders.
+
+```yaml title="generators.yml"
+config:
+  user-agent: "plantstore-node-sdk/{version}"
+```
+
+This configuration sends `User-Agent: plantstore-node-sdk/0.1.0`. With [`includePlatformHeaders`](#includeplatformheaders) enabled, the resolved template becomes the product token of the structured header, followed by the platform and runtime segments: `User-Agent: plantstore-node-sdk/0.1.0 (linux; x86_64) Node/20.11.0`. A resolved value whose trailing segment isn't a version, such as `@plantstore/sdk`, is used as-is and no version segment is added.
+</ParamField>
+
 <ParamField path="useBigInt" type="boolean" default="false" toc={true}>
 When `useBigInt` is set to `true`, a customized JSON serializer & deserializer is used that will preserve the precision of `bigint`'s, as opposed to the native `JSON.stringify` and `JSON.parse` function which converts `bigint`'s to number's losing precision.
 

fern/products/sdks/reference/generators-yml-reference.mdx

@@ -663,6 +663,8 @@ groups:
           noSerdeLayer: false
 ```
 
+Most keys are specific to one generator, but `user-agent` is resolved by the CLI, so it behaves identically in every generator's `config`: it sets a [`User-Agent` header template](/learn/sdks/generators/typescript/configuration#user-agent) interpolated at generation time, defaulting to `{packageName}/{version}`. The TypeScript, Python, Go, Java, .NET, PHP, and Ruby generators send the resolved value; the Rust and Swift generators ignore it.
+
 <CardGroup cols={3}>
 <Card title="TypeScript" icon={<img src="../images/icons/ts-light.svg" alt="TypeScript" className="h-6 w-6" noZoom />} href="/sdks/generators/typescript/configuration">
 </Card>