Preserve Responses API output item order

[dileepyavan]

Summary

• preserve the original Responses API ordering of assistant message, reasoning, and compaction items when replaying stateless history
• propagate message and reasoning output_index metadata through tool-call rounds
• render commentary before reasoning when that is the order returned by the API
• add regression coverage for stream metadata, request serialization, and prompt rendering

fixes #318813

[Copilot]

Pull request overview

Preserves Responses API output ordering when replaying stateless tool-call history.

Changes:

• Propagates message and reasoning output indices.
• Serializes assistant, reasoning, and compaction content in rendered order.
• Adds stream, serialization, and prompt-rendering regression tests.

Show a summary per file

File	Description
extensions/copilot/src/platform/thinking/common/thinking.ts	Adds reasoning output-index metadata.
extensions/copilot/src/platform/networking/common/fetch.ts	Exposes message output indices in response deltas.
extensions/copilot/src/platform/endpoint/node/test/responsesApi.spec.ts	Tests serialization and streamed indices.
extensions/copilot/src/platform/endpoint/node/responsesApi.ts	Preserves content order and emits indices.
extensions/copilot/src/extension/prompts/node/panel/toolCalling.tsx	Reorders replayed response and reasoning content.
extensions/copilot/src/extension/prompts/node/panel/test/toolCalling.spec.ts	Tests commentary-before-reasoning rendering.
extensions/copilot/src/extension/prompt/common/toolCallRound.ts	Stores output-index metadata.
extensions/copilot/src/extension/prompt/common/intents.ts	Extends the tool-round contract.
extensions/copilot/src/extension/intents/node/toolCallingLoop.ts	Accumulates and propagates message indices.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 2
• Review effort level: Medium

[vs-code-engineering]

❌ Failed to queue vscode build for 6ac8a16200a8f0a2d1948271f072b1350861af5b due to an Azure DevOps permission issue — eval-assessment did not start.

The federated identity vscode-bot-managed-identity is missing Queue builds permission on pipeline ⭐️ VS Code (id 111) in project Monaco.

Fix: in Azure DevOps, open the pipeline → ⋮ → Security, and grant vscode-bot-managed-identity the Queue builds permission, then re-apply the ~requires-eval-assessment label.

• Workflow run: https://github.com/microsoft/vscode-engineering/actions/runs/29623788697

az pipelines run output

WARNING: Auto-detect was enabled but no Azure DevOps remote was found in the current git repository. Ensure your git remote points to an Azure DevOps URL (e.g., https://dev.azure.com/MyOrganization/...).
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