fix: exclude synthetic user messages from chat history processing

[DonJayamanne]

Co-authored-by: Copilot copilot@github.com

Fixes #310897

[github-actions]

Screenshot Changes

Base: 1f9cd94d Current: 6175605a

Changed (2)

chat/aiCustomizations/aiCustomizationManagementEditor/McpBrowseMode/Light

Before	After

editor/inlineCompletions/other/JumpToHint/Dark

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[Copilot]

Pull request overview

Adjusts Copilot CLI chat-history reconstruction to ignore “synthetic” user.message events (e.g. skill invocations) so the VS Code chat UI doesn’t mis-render or attribute turns incorrectly (fixes #310897).

Changes:

• Prevent sdkRequestId from being overwritten by subsequent user.message events during a single request.
• Filter out synthetic user.message events when rebuilding chat turns, including when determining the “last user message”.
• Introduce isSyntheticUserMessage(...) helper for the filtering logic.

Show a summary per file

File	Description
extensions/copilot/src/extension/chatSessions/copilotcli/node/copilotcliSession.ts	Keeps the first captured SDK request ID for metadata mapping, avoiding later overwrites.
extensions/copilot/src/extension/chatSessions/copilotcli/common/copilotCLITools.ts	Skips synthetic user messages during history building and adds helper used for filtering.

Copilot's findings

Comments suppressed due to low confidence (1)

extensions/copilot/src/extension/chatSessions/copilotcli/common/copilotCLITools.ts:1745

• isSyntheticUserMessage currently returns true when event.data.source is missing or equals 'user', which will classify normal user messages (including ones emitted by this extension that don't set source) as synthetic. This will cause user turns to be skipped in buildChatHistoryFromEvents and likely break history rendering/tests. Invert the predicate so only explicitly non-user sources (e.g. skill/system) are treated as synthetic, and treat missing/empty source as a regular user message.

export function isSyntheticUserMessage(event: Extract<SessionEvent, { type: 'user.message' }>): boolean {
	return event.type === 'user.message' && (!event.data.source || (event.data.source ?? '').toLowerCase() === 'user');
}

• Files reviewed: 2/2 changed files
• Comments generated: 1

[DonJayamanne]

@copilot fix the test failures in copilotCLITools.spec.ts, copilotCliSessionService.spec.ts