fix disposable leak + fix empty thinking container

[justschen]

fix #302066

[Copilot]

Pull request overview

Fixes a disposable leak in the chat tool-invocation rendering flow (notably when tool parts are created lazily inside a thinking container) and removes/disposes thinking containers that become empty after a tool is moved out (e.g. for confirmation), addressing #302066.

Changes:

• Extend the lazy tool-part factory return shape to include a disposable so lazy-created tool parts can be lifecycle-managed.
• Add ChatThinkingContentPart.isEffectivelyEmpty() to detect thinking containers with no meaningful content.
• When a tool is moved out of thinking during confirmation transition, remove/dispose the thinking container if it becomes empty.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/vs/workbench/contrib/chat/browser/widget/chatListRenderer.ts	Updates lazy tool-part factory return type and adds logic to remove/dispose empty thinking containers during confirmation transitions.
src/vs/workbench/contrib/chat/browser/widget/chatContentParts/chatThinkingContentPart.ts	Adds isEffectivelyEmpty() helper to determine when a thinking container has no displayable content.

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/browser/widget/chatListRenderer.ts:2055

• In the branch where the tool part wasn’t previously created, this code path creates a new ChatToolInvocationPart via createToolPart() and appends its domNode, but does not register the returned disposable anywhere. Since the renderer is currently holding a no-op placeholder part at this content index, this tool part may never be disposed, reintroducing the leaked-disposable issue. Suggestion: either (a) avoid creating/appending the tool part here and let the normal render/diff cycle create + track it, or (b) capture disposable and add it to an appropriate disposable store (and ensure future renders don’t create a duplicate part).

				templateData.value.appendChild(domNode);
			}

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