Encourage browser tab reuse in open tools

[kycutler]

Closes #306971

[Copilot]

Pull request overview

This PR addresses tab-spam from browser tools by encouraging reuse of an already-open integrated browser page (by host) instead of always opening a new one.

Changes:

• Adds a forceNew?: boolean parameter to the open-browser tool schema to allow explicitly opening a new page.
• Implements “reuse existing page by host” behavior for both agentic (OpenBrowserTool) and non-agentic (OpenBrowserToolNonAgentic) open flows.
• Centralizes the reuse detection + “already open” tool result formatting in browserToolHelpers.ts.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/vs/workbench/contrib/browserView/electron-browser/tools/openBrowserTool.ts	Adds forceNew param and reuses an existing tracked page with the same host when possible.
src/vs/workbench/contrib/browserView/electron-browser/tools/openBrowserToolNonAgentic.ts	Applies the same reuse behavior for the non-agentic open tool.
src/vs/workbench/contrib/browserView/electron-browser/tools/browserToolHelpers.ts	Introduces shared helper to find an existing page by host and return an “already open” result.

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/browserView/electron-browser/tools/openBrowserToolNonAgentic.ts:58

• This tool now prefers reusing an existing page by default (unless forceNew is set), but OpenBrowserToolNonAgenticData.modelDescription still tells the model to "Open a new browser page…" and omits the reuse/forceNew guidance that exists in OpenBrowserToolData. Updating the non-agentic tool's model description to reflect the new default behavior will better align with the PR goal (discouraging tab spam) and reduce unnecessary calls that immediately return "already open".

		if (!params.forceNew) {
			const existing = await findExistingPageByHost(this.editorService, undefined, params.url);
			if (existing) {
				return alreadyOpenResult(existing);
			}

[vs-code-engineering]

📬 CODENOTIFY

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

@jruales

Matched files:

• src/vs/workbench/contrib/browserView/electron-browser/tools/browserToolHelpers.ts
• src/vs/workbench/contrib/browserView/electron-browser/tools/openBrowserTool.ts
• src/vs/workbench/contrib/browserView/electron-browser/tools/openBrowserToolNonAgentic.ts