agentHost: support for client-provided tools

[connor4312]

Does a half-way cleanup of state related to the active client and supports client-provided tools -- initially the runTests tool, task tools, and problems tools.

[Copilot]

Pull request overview

Adds support for “client-provided tools” in agent host sessions (initially runTests/task/problems tools) by flowing tool definitions from the renderer to the agent-host process, routing tool execution back to the owning client, and keeping session refresh logic in sync with active client changes.

Changes:

• Introduces a new chat.agentHost.clientTools setting and wires renderer-side tool allowlisting + publishing into session/activeClientChanged and session/activeClientToolsChanged.
• Implements client-tool execution: Copilot agent registers SDK tools that defer to the client, and the renderer executes tool calls and dispatches session/toolCallComplete.
• Updates protocol/event plumbing to carry toolClientId, and extends agent interfaces + tests accordingly.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostClientTools.test.ts	Adds unit/integration-style tests for client tool conversion and registration logic.
src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostChatContribution.test.ts	Updates test stubs to accommodate the new tools service + config setting.
src/vs/workbench/contrib/chat/common/constants.ts	Adds ChatConfiguration.AgentHostClientTools.
src/vs/workbench/contrib/chat/browser/chat.contribution.ts	Registers chat.agentHost.clientTools configuration with defaults.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostSessionHandler.ts	Publishes allowlisted client tools, executes owned client tool calls, and converts tool results to protocol.
src/vs/platform/agentHost/test/node/mockAgent.ts	Adds required IAgent methods for client tools in mock agents.
src/vs/platform/agentHost/test/node/copilotAgentSession.test.ts	Updates construction to new CopilotAgentSession options object.
src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts	Adds client tool SDK tool registration + deferred completion handling via session/toolCallComplete.
src/vs/platform/agentHost/node/copilot/copilotAgent.ts	Tracks per-session active client snapshot (plugins + tools), refreshes sessions when snapshot changes, and forwards tool completion.
src/vs/platform/agentHost/node/agentSideEffects.ts	Forwards client tool definitions to agents and forwards tool completion callbacks.
src/vs/platform/agentHost/node/agentEventMapper.ts	Maps toolClientId onto protocol tool call start actions.
src/vs/platform/agentHost/common/state/protocol/state.ts	Minor doc cleanup around tool definition types.
src/vs/platform/agentHost/common/state/protocol/actions.ts	Updates docs/annotations for client-dispatchable tool streaming content.
src/vs/platform/agentHost/common/state/protocol/action-origin.generated.ts	Marks session/toolCallContentChanged as client-dispatchable and updates unions.
src/vs/platform/agentHost/common/state/protocol/.ahp-version	Bumps protocol sync version.
src/vs/platform/agentHost/common/agentService.ts	Extends IAgent with setClientTools and onClientToolCallComplete.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostClientTools.test.ts:481

• This test doesn’t exercise the production filtering logic (it re-implements allowlist filtering inline instead of observing what AgentHostSessionHandler publishes/dispatches). Consider driving the handler with a mock tools service + config and asserting the resulting dispatched activeClientChanged/activeClientToolsChanged tool definitions.

		test('excludes tools not in the allowlist', () => {
			createHandlerWithMocks(disposables, [testRunTestsTool, testRunTaskTool, testUnlistedTool], {
				clientTools: ['runTests'],
			});

			// Validate the filtering logic: only 'runTests' should match the allowlist.
			const filteredTools = [testRunTestsTool, testRunTaskTool, testUnlistedTool]
				.filter(t => t.toolReferenceName !== undefined && ['runTests'].includes(t.toolReferenceName));
			assert.strictEqual(filteredTools.length, 1);
			assert.strictEqual(filteredTools[0].toolReferenceName, 'runTests');
		});

• Files reviewed: 16/16 changed files
• Comments generated: 5

[github-actions]

Screenshot Changes

Base: cf7f246a Current: 848b9a0a

Changed (9)

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