Add capi.disableWebSocketResponses session option

[dereklegenzoff]

Why

WebSocket transport is now the default for the CAPI (Copilot API) Responses API whenever a model advertises the ws:/responses endpoint. That breaks for users behind proxies or in network environments where WebSockets fail, so they need a way to opt out and fall back to the HTTP Responses transport.

This is the SDK-side follow-up to runtime PR github/copilot-agent-runtime#10551 ("CLI: Graduate WebSocket Responses flag, add SDK opt-out"), explicitly requested in review by @SteveSandersonMS, who noted that session create/resume calls are hand-written and not driven by any runtime-side Zod schema, so the SDK needs to supply this option itself.

What

Adds the nested session option capi: { disableWebSocketResponses?: boolean } to session create and resume across all six SDK languages. When true, the session uses the HTTP Responses transport instead of WebSockets. It is equivalent to setting the COPILOT_CLI_DISABLE_WEBSOCKET_RESPONSES environment variable.

The option is scoped under a capi namespace (not a top-level option) by design: a single session can host multiple providers (CAPI + BYOK), so transport choice is conceptually provider-level.

Wire shape: session.create / session.resume params gain capi: { disableWebSocketResponses: true }, omitted entirely when unset.

Approach

The field is a hand-written pass-through that mirrors the existing provider (BYOK) nested option exactly, wired into both the create and resume RPC params. Session create/resume options are hand-written in every language (not codegen-driven), so this ships independently of the runtime release.

Per-language summary (each mirrors the existing provider option):

• Node.js (reference): CapiSessionOptions interface + SessionConfigBase.capi, wired in create + resume, re-exported, with a test.
• Python: CapiSessionOptions TypedDict + camelCase wire helper, capi kwarg on create/resume, exported.
• Go: CapiSessionOptions struct + Capi on configs and wire requests, set in create + resume builders.
• Java: new CapiSessionOptions (fluent setters + Jackson) + field on both configs/requests, wired in SessionRequestBuilder for create + resume.
• .NET: CapiSessionOptions class + Capi on SessionConfigBase, copy-constructor, positional in both request records, registered in the serializer context.
• Rust: CapiSessionOptions (#[non_exhaustive] + builders) + capi on configs and wire types, converted in into_wire.

Compatibility

The CLI treats this field as a harmless no-op until a runtime that includes github/copilot-agent-runtime#10551 is installed, so the SDK change is safe to land ahead of the runtime release.

Deferred follow-ups (by design)

1. No @github/copilot dependency bump / codegen re-run yet. The current schema does not contain a generated CapiSessionOptions; once #10551 is published, an optional bump + codegen re-run can produce a generated type. The hand-written pass-through is sufficient in the meantime.
2. No session.options.update (live update) wiring. This PR covers session create and resume only.

Testing

Ran the per-language unit suites for each change (Node.js, Python, Go, Java, Rust passing locally; .NET reviewed against existing serialization/clone test patterns). e2e suites that require the replay-proxy harness were out of scope for local verification.

Refs github/copilot-agent-runtime#10551

[Copilot]

Pull request overview

This PR adds a provider-scoped session option capi.disableWebSocketResponses to the session create and resume request shapes across all SDK languages, allowing users to opt out of the default WebSocket-based CAPI Responses transport and fall back to HTTP (useful in proxy-restricted environments).

Changes:

• Introduces CapiSessionOptions (language-idiomatic) and threads it through session create/resume configs and wire payloads.
• Ensures the option is omitted from the wire payload when unset (via optional fields / non-null serialization).
• Adds/extends unit tests to verify forwarding + serialization behavior.

Show a summary per file

File	Description
rust/src/wire.rs	Adds optional capi field to Rust create/resume wire payload structs.
rust/src/types.rs	Introduces CapiSessionOptions, adds capi to SessionConfig/ResumeSessionConfig, and adds serialization tests.
python/test_client.py	Adds unit test ensuring capi options are forwarded on create/resume.
python/copilot/client.py	Adds CapiSessionOptions TypedDict, wire conversion helper, and capi kwarg wiring for create/resume.
python/copilot/init.py	Re-exports CapiSessionOptions from the package surface.
nodejs/test/client.test.ts	Adds test verifying capi forwarding on session.create and session.resume.
nodejs/src/types.ts	Adds CapiSessionOptions and capi?: to shared session config base types.
nodejs/src/index.ts	Re-exports CapiSessionOptions in public entrypoint.
nodejs/src/client.ts	Forwards config.capi into session.create / session.resume request params.
java/src/test/java/com/github/copilot/JsonIncludeNonNullTest.java	Adds JSON non-null include annotation coverage for CapiSessionOptions.
java/src/test/java/com/github/copilot/CapiSessionOptionsTest.java	New test suite covering Java option defaults, fluent setters, and request inclusion/omission.
java/src/main/java/com/github/copilot/SessionRequestBuilder.java	Wires config.getCapi() into create/resume request builders.
java/src/main/java/com/github/copilot/rpc/SessionConfig.java	Adds capi field + getter/setter + clone propagation.
java/src/main/java/com/github/copilot/rpc/ResumeSessionConfig.java	Adds capi field + getter/setter + clone propagation.
java/src/main/java/com/github/copilot/rpc/CreateSessionRequest.java	Adds capi JSON property + accessor methods on the wire request type.
java/src/main/java/com/github/copilot/rpc/ResumeSessionRequest.java	Adds capi JSON property + accessor methods on the wire request type.
java/src/main/java/com/github/copilot/rpc/CapiSessionOptions.java	New Java RPC type with Jackson annotations and fluent setter for disableWebSocketResponses.
go/types.go	Adds CapiSessionOptions, threads it through session configs and create/resume request structs.
go/client.go	Forwards config.Capi into create/resume RPC request builders.
go/client_test.go	Adds tests ensuring capi.disableWebSocketResponses is serialized/forwarded and omitted when unset.
dotnet/test/Unit/SerializationTests.cs	Adds serialization coverage for CapiSessionOptions and create/resume request inclusion/omission.
dotnet/test/Unit/CloneTests.cs	Extends clone coverage to ensure Capi is copied consistently.
dotnet/src/Types.cs	Introduces CapiSessionOptions, adds it to SessionConfigBase, and registers it for source-gen serialization.
dotnet/src/Client.cs	Threads config.Capi through internal create/resume request records and serializer context.

Copilot's findings

• Files reviewed: 24/24 changed files
• Comments generated: 0

[github-actions]

Cross-SDK Consistency Review ✅

This PR adds capi.disableWebSocketResponses to all six SDK implementations. Cross-language consistency looks excellent.

Consistency checklist

Concern	Result
Feature added to all 6 SDKs	✅ Node.js, Python, Go, .NET, Java, Rust
Both create and resume wired	✅ All SDKs
Wire field name ("disableWebSocketResponses")	✅ Uniform across all SDKs
capi field omitted when unset	✅ All SDKs (omitempty / NON_NULL / null guards)
Language-idiomatic naming	✅ See table below
Type exported/public in each SDK	✅ All SDKs
capi positioned after provider in configs	✅ Consistent ordering across all SDKs

Naming conventions (idiomatic per language)

SDK	Config field	Type field	Wire
Node.js	capi?: CapiSessionOptions	disableWebSocketResponses?: boolean	disableWebSocketResponses
Python	capi: CapiSessionOptions | None	disable_web_socket_responses: bool (TypedDict)	converted → disableWebSocketResponses
Go	Capi *CapiSessionOptions	DisableWebSocketResponses *bool	"capi,omitempty"
.NET	Capi CapiSessionOptions?	DisableWebSocketResponses bool?	[JsonPropertyName]
Java	setCapi(CapiSessionOptions)	setDisableWebSocketResponses(Boolean)	@JsonProperty("disableWebSocketResponses")
Rust	capi: Option<CapiSessionOptions>	disable_web_socket_responses: Option<bool>	#[serde(rename_all = "camelCase")]

All naming follows each language's established conventions and mirrors the existing provider / ProviderConfig pattern exactly — Python's TypedDict for CapiSessionOptions is consistent with ProviderConfig already being a TypedDict in that SDK.

No cross-SDK consistency issues found.

Generated by SDK Consistency Review Agent for issue #1711 · sonnet46 1.5M · ◷