React to CLI update and Anthropic response format changes

[SteveSandersonMS]

As of updating to latest CLI, the E2E tests failed because of response format changes.

1. Update snapshots for Anthropic extended thinking

The CLI now coalesces tool calls into single assistant messages for Anthropic extended thinking compatibility. This updates all affected snapshots to match the new format.

2. Skip writing snapshots on test failure

Prevents corrupted snapshots from being written when tests fail. Each language uses its native test framework hooks:

• Node.js: vitest \onTestFailed()\ hook
• Python: \pytest_runtest_makereport\ hook
• Go: \ .Failed()\ check in cleanup
• .NET: Checks \CI\ env var (xUnit lacks failure detection hooks)

[Copilot]

Pull request overview

This PR introduces two improvements to the E2E test infrastructure: preventing corrupted snapshots on test failure and updating snapshots to reflect CLI changes for Anthropic extended thinking compatibility.

Changes:

• Implements test failure detection in each language's test framework to skip writing snapshots when tests fail
• Updates snapshot files to reflect new CLI behavior that coalesces tool calls into single assistant messages for Anthropic extended thinking

Reviewed changes

Copilot reviewed 26 out of 27 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/harness/replayingCapiProxy.ts	Adds support for skipWritingCache parameter to prevent snapshot writes on test failure
python/e2e/testharness/proxy.py	Adds skip_writing_cache parameter to stop() method
python/e2e/testharness/context.py	Passes test_failed flag to proxy teardown to conditionally skip snapshot writes
python/e2e/conftest.py	Implements pytest hook to track test failures and skip snapshot writes
nodejs/test/e2e/harness/sdkTestContext.ts	Uses Vitest's onTestFailed hook to track failures and adds COPILOT_CLI_PATH env var support
nodejs/test/e2e/harness/CapiProxy.ts	Adds skipWritingCache parameter to stop() method
go/e2e/testharness/proxy.go	Adds StopWithOptions method with skipWritingCache parameter
go/e2e/testharness/context.go	Uses Go's t.Failed() to detect test failures and skip snapshot writes
dotnet/test/Harness/E2ETestContext.cs	Checks CI environment variable to skip snapshot writes (xUnit limitation)
dotnet/test/Harness/CapiProxy.cs	Adds skipWritingCache parameter to StopAsync method
test/snapshots/tools/invokes_built_in_tools.yaml	Updated snapshot reflecting coalesced tool calls format
test/snapshots/session/*.yaml	Updated snapshots with minor variations in assistant responses
test/snapshots/permissions/*.yaml	Updated snapshots with coalesced tool calls and response variations
test/snapshots/mcp-and-agents/*.yaml	Updated snapshots with response variations

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