Yemohyle/add to ext telemetrey

[yemohyleyemohyle]

New fields in VSCodeExt telemetry event response.success:

modelCallId -- unique ID for this model call (surfaced from the fetcher)
subType -- "subagent/search" / "subagent/search" / absent
parentRequestId -- parent's requestId (enables child.parentRequestId = parent.requestId joins)
parentModelCallId -- parent's modelCallId (links to exact model call that spawned subagent)
iterationNumber -- 0-based tool-calling loop iteration

New fields in VSCode internal telemetry event model.modelCall.input/output:

parentModelCallId -- parent's modelCallId
iterationNumber -- 0-based tool-calling loop iteration

[Copilot]

Pull request overview

This PR extends Copilot extension and internal model-call telemetry to better correlate subagent requests and tool-calling iterations by propagating a modelCallId plus new parent/iteration linking fields through the request/response pipeline.

Changes:

• Adds modelCallId to successful fetch results and forwards it into response.success telemetry.
• Propagates parentModelCallId and iterationNumber through tool-calling loops and subagent tool invocations.
• Enriches internal model.modelCall.input/output telemetry with parentModelCallId and iterationNumber.

Show a summary per file

File	Description
extensions/copilot/src/platform/networking/node/chatStream.ts	Adds parentModelCallId and iterationNumber to internal model.modelCall.* telemetry events.
extensions/copilot/src/platform/networking/common/networking.ts	Extends IChatRequestTelemetryProperties with parentModelCallId and iterationNumber.
extensions/copilot/src/platform/chat/common/commonTypes.ts	Adds optional modelCallId to success fetch results.
extensions/copilot/src/extension/tools/node/searchSubagentTool.ts	Passes parentModelCallId into subagent invocation telemetry context.
extensions/copilot/src/extension/tools/node/executionSubagentTool.ts	Passes parentModelCallId into subagent invocation telemetry context.
extensions/copilot/src/extension/prompt/node/searchSubagentToolCallingLoop.ts	Threads parentModelCallId and iterationNumber into subagent requests’ telemetry properties.
extensions/copilot/src/extension/prompt/node/executionSubagentToolCallingLoop.ts	Threads parentModelCallId and iterationNumber into subagent requests’ telemetry properties.
extensions/copilot/src/extension/prompt/node/defaultIntentRequestHandler.ts	Adds iterationNumber to main request telemetry properties.
extensions/copilot/src/extension/prompt/node/chatMLFetcherTelemetry.ts	Adds new response.success telemetry fields (including modelCallId, parent linking, iteration).
extensions/copilot/src/extension/prompt/common/intents.ts	Extends prompt context to carry parentModelCallId for downstream subagent tools.
extensions/copilot/src/extension/intents/node/toolCallingLoop.ts	Tracks last headerRequestId and modelCallId from successful fetches and passes them via prompt context; threads iterationNumber through fetch options.

Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 3

[Copilot]

PR description says response.success.subType should be one of "subagent" / "system-initiated" / absent, but this code forwards baseTelemetry.properties.subType verbatim. Existing callers set more specific values like subagent/search and subagent/execution, which will now surface in response.success and may violate the intended schema. If the event needs a stable, low-cardinality enum, consider normalizing here (e.g. map any subagent/* to subagent).

[Copilot]

The new propagation/storage of lastModelCallId and the revised parent header request id selection are not covered by existing ToolCallingLoop unit tests. Adding a focused test that runs two iterations and asserts that createPromptContext() exposes parentHeaderRequestId/parentModelCallId from the previous successful fetch (including the fallback behavior) would help prevent regressions in subagent telemetry linking.