Add sendAndWait API for all SDKs

[SteveSandersonMS]

Summary

Adds a new sendAndWait() method to all SDK languages that waits for the agent turn to complete. This accompanies the CLI change which makes send() return immediately instead of blocking.

Changes

New API: sendAndWait()

All SDKs now have a method that sends a message and waits for session.idle:

Language	Method	Return Type	Default Timeout
Node.js	sendAndWait(options, timeout?)	Promise<AssistantMessageEvent>	60s
.NET	SendAndWaitAsync(options, timeout?, ct?)	Task<AssistantMessageEvent?>	60s
Go	SendAndWait(options, timeout)	(*SessionEvent, error)	60s
Python	send_and_wait(options, timeout?)	SessionEvent	60s

All implementations:

• Return the last assistant.message event received before session.idle
• Handle session.error events by throwing/returning an error
• Support configurable timeout (default 60 seconds)

Updated E2E Tests

All e2e tests updated to use sendAndWait() instead of send() + getFinalAssistantMessage().

Backward Compatibility

• Old SDK + New CLI: Works (old send() still works, just returns faster)
• New SDK + Old CLI: Works (old CLI blocks anyway)

Related

• Issue: Question: Is there a way to configure the request timeout? (Currently hitting 30s limit) #17
• Depends on: React to CLI update and Anthropic response format changes #27

[Copilot]

Pull request overview

This PR adds a new sendAndWait() method to all SDK languages (Node.js, Python, Go, and .NET) that sends a message and blocks until the agent turn completes. This accompanies a CLI change where send() now returns immediately instead of blocking.

Changes:

• Implements sendAndWait() API across all four SDK languages with consistent 60-second default timeout behavior
• Updates all e2e tests to use sendAndWait() instead of send() + helper functions
• Adds forward compatibility for unknown event types in Python and .NET

Reviewed changes

Copilot reviewed 23 out of 25 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
nodejs/src/session.ts	Implements sendAndWait() method with timeout and error handling
nodejs/src/index.ts	Exports new AssistantMessageEvent type
nodejs/test/e2e/*.test.ts	Updates tests to use sendAndWait() and adds new blocking behavior tests
nodejs/examples/basic-example.ts	Updates example to use sendAndWait()
nodejs/README.md	Documents new sendAndWait() API
python/copilot/session.py	Implements send_and_wait() method
python/copilot/generated/session_events.py	Adds forward compatibility for unknown event types
python/e2e/*.py	Updates tests to use send_and_wait()
go/session.go	Implements SendAndWait() method
go/e2e/*.go	Updates tests to use SendAndWait()
dotnet/src/Session.cs	Implements SendAndWaitAsync() method
dotnet/src/Generated/SessionEvents.cs	Adds forward compatibility for unknown event types
dotnet/src/Client.cs	Adds null check for unknown events
dotnet/test/*.cs	Updates tests to use SendAndWaitAsync() and adds new blocking behavior tests
test/snapshots/session/*.yaml	New test snapshots for blocking behavior tests

Comments suppressed due to low confidence (1)

nodejs/test/e2e/session.test.ts:1

• The code accesses assistantMessages[assistantMessages.length - 1] without checking if the array is empty. If no assistant messages exist, this will throw an error. Add a check to ensure the array has at least one element before accessing it.

import { describe, expect, it, onTestFinished } from "vitest";

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