Fix terminal Stop Dictation clearing text with the built-in engine

[Copilot]

Description

With the built-in on-device engine, the terminal dictation transcript is only staged (shown as ghost text) until accepted. Accepting via Stop Dictation in Terminal is asynchronous — stop(true) sets _builtinFinalizing and awaits the engine's final transcript in _finalizeBuiltinThenStop().

TerminalVoiceSession also tears down on onDidChangeActiveInstance / onDidDisposeInstance via stop() (send = false). When such a teardown races in during the finalize await (e.g. the active instance changing as the command palette closes while running the Stop command), it cancels the engine mid-transcribe and wipes the staged input. The finalize's guard then returns early, so the text is never committed and the ghost text just disappears — the reported "text gets cleared".

Changes

• terminalVoice.ts — In stop(), ignore a concurrent teardown-only (send = false) call while a built-in finalize is in flight, letting the finalize complete and commit the transcript:

  if (this._builtinFinalizing && !send) {
      return;
  }

• terminalVoice.test.ts — Added a TerminalVoiceSession regression test that fires an active-instance change during the accept await and asserts the dictated text is still sent (fails without the fix).

• Fixes microsoft/vscode-internalbacklog#8708

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@anthonykim1

Matched files:

• src/vs/workbench/contrib/terminalContrib/voice/browser/terminalVoice.ts
• src/vs/workbench/contrib/terminalContrib/voice/test/browser/terminalVoice.test.ts

[Copilot]

Pull request overview

Fixes a race where terminal dictation teardown can interrupt built-in speech finalization.

Changes:

• Defers teardown while built-in transcription is finalizing.
• Adds a regression test for active-instance changes during finalization.

Show a summary per file

File	Description
terminalVoice.ts	Guards built-in finalization from concurrent teardown.
terminalVoice.test.ts	Tests the finalization race.

Review details

Suppressed comments (1)

src/vs/workbench/contrib/terminalContrib/voice/test/browser/terminalVoice.test.ts:118

• This multi-line inline comment exceeds the project's one-line limit for comments inside a function body and largely repeats the test name. Keep only a brief note about the ordering constraint.

	// Stopping the built-in engine fetches its final transcript asynchronously.
	// A teardown-only stop() racing in during that await (e.g. the active
	// terminal instance changing as the command palette closes when the Stop
	// Dictation command runs) must not cancel the engine and drop the text.

• Files reviewed: 2/2 changed files
• Comments generated: 3
• Review effort level: Balanced