Add capi.enableWebSocketResponses and provider.transport session options

[dereklegenzoff]

Why

Two related WebSocket transport controls for the SDK's hand-written session options, both follow-ups to runtime PRs that were already merged/under review and explicitly called out as needing a corresponding SDK change:

1. capi.enableWebSocketResponses — 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 networks where WebSockets fail, so they need a way to opt out and fall back to the HTTP Responses transport. SDK-side follow-up to github/copilot-agent-runtime#10551 (requested in review by @SteveSandersonMS).
2. provider.transport — BYOK OpenAI-compatible providers need the opposite knob: an opt-in to deliver Responses API requests over a persistent WebSocket connection instead of HTTP (better for long-running, tool-call-heavy sessions that benefit from incremental previous_response_id continuations). SDK-side follow-up to github/copilot-agent-runtime#9557.

These are two distinct, complementary toggles: capi.enableWebSocketResponses: false opts out of WS for GitHub's Copilot API; provider.transport: "websockets" opts in to WS for your own BYOK endpoint. They are independent and coexist.

What

1. capi.enableWebSocketResponses

New nested session option capi: { enableWebSocketResponses?: boolean } on session create and resume. WebSocket transport is enabled by default when the model advertises ws:/responses; set this to false to force the HTTP Responses transport instead. Setting it to false is equivalent to setting the COPILOT_CLI_DISABLE_WEBSOCKET_RESPONSES environment variable (the env var name is unchanged). 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: { enableWebSocketResponses: false }, omitted entirely when unset.

2. provider.transport

New field transport?: "http" | "websockets" (default "http") on the BYOK ProviderConfig. When "websockets", Responses API requests for that OpenAI-compatible provider are delivered over a persistent WebSocket connection. Flows through the already-wired provider option on session create and resume.

Wire shape: provider.transport serializes as a plain camelCase string, omitted when unset.

Approach

Both options are hand-written pass-throughs. Session create/resume options — and the ProviderConfig type — are hand-written in every language (not codegen-driven), so these ship independently of the runtime releases:

• capi is a new nested type mirroring the existing provider (BYOK) nested option exactly, wired into both the create and resume RPC params in every language.
• transport is a single new field on ProviderConfig mirroring the existing wireApi field; it needs no new wiring because the whole provider object is already serialized end-to-end.

Per-language summary:

• Node.js (reference): CapiSessionOptions interface + SessionConfigBase.capi wired in create/resume + re-export; transport on ProviderConfig. Tests added.
• Python: CapiSessionOptions TypedDict + camelCase wire helper + capi kwarg + export; transport on ProviderConfig TypedDict + wire mapping. Tests added.
• Go: CapiSessionOptions struct + Capi on configs/wire requests/builders; Transport on ProviderConfig. Tests added.
• Java: new CapiSessionOptions (fluent + Jackson) wired in SessionRequestBuilder for create/resume; transport field + getter/fluent-setter on ProviderConfig. Tests added.
• .NET: CapiSessionOptions class + Capi on SessionConfigBase (copy-ctor, both request records, serializer context); Transport on ProviderConfig. Tests added.
• Rust: CapiSessionOptions (#[non_exhaustive] + builders) + capi on configs/wire; transport field + with_transport builder on ProviderConfig. Tests added.

Compatibility

Both fields are harmless no-ops on a CLI runtime that predates the corresponding runtime PR, so the SDK changes are safe to land ahead of (or independently of) the runtime releases.

Deferred follow-up (by design)

• No @github/copilot dependency bump / codegen re-run. The current schema does not contain a generated CapiSessionOptions, and the generated ProviderConfig is not the consumer-facing type (the SDK exports a hand-written one). Once the runtime PRs publish, an optional bump + codegen re-run can produce generated types; the hand-written pass-throughs are sufficient in the meantime.
• No session.options.update (live update) wiring. This PR covers session create and resume only.

Testing

Built and ran the per-language unit suites for every change — Node.js, Python, Go, Java, Rust, and .NET all pass locally (formatting/lint/clippy/spotless clean where applicable). e2e suites that require the replay-proxy harness were out of scope for local verification.

Refs github/copilot-agent-runtime#10551, github/copilot-agent-runtime#9557

[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 ✅

Both new features (capi.enableWebSocketResponses and provider.transport) are implemented consistently across all six SDK implementations. No cross-language consistency issues found.

Feature 1: CapiSessionOptions with enableWebSocketResponses

SDK	Type	Field	On create	On resume	Wire key
Node.js	CapiSessionOptions interface	enableWebSocketResponses?: boolean	✅ capi? on SessionConfigBase	✅ (inherited)	enableWebSocketResponses
Python	CapiSessionOptions TypedDict	enable_web_socket_responses: bool	✅ capi kwarg	✅ capi kwarg	enableWebSocketResponses
Go	CapiSessionOptions struct	EnableWebSocketResponses *bool	✅ Capi *CapiSessionOptions	✅ Capi field	enableWebSocketResponses
.NET	CapiSessionOptions class	EnableWebSocketResponses bool?	✅ Capi on SessionConfigBase	✅ (inherited)	enableWebSocketResponses
Java	CapiSessionOptions class	getEnableWebSocketResponses() / setEnableWebSocketResponses()	✅ setCapi() on SessionConfig	✅ setCapi() on ResumeSessionConfig	enableWebSocketResponses
Rust	CapiSessionOptions struct	enable_web_socket_responses: Option<bool>	✅ with_capi() on SessionConfig	✅ with_capi() on ResumeSessionConfig	enableWebSocketResponses

Feature 2: provider.transport

SDK	Field	Type
Node.js	transport?	"http" | "websockets"
Python	transport	Literal["http", "websockets"] (optional in TypedDict)
Go	Transport	string (omitempty)
.NET	Transport	string?
Java	transport	String (getter/setter)
Rust	transport	Option<String> + with_transport() builder

All SDKs serialize correctly to the same camelCase wire format (capi.enableWebSocketResponses, transport), use appropriate language idioms for optional/nullable types, include the CapiSessionOptions type in public exports where applicable (Node.js index.ts, Python __init__.py), and include unit tests covering both features.

Generated by SDK Consistency Review Agent for issue #1711 · sonnet46 1.3M · ◷