Revert "Refactor enableThinking/reasoningEffort into IModelCapabilityOptions"

[bhavyaus]

Reverts #308294

[Copilot]

Pull request overview

Reverts the earlier refactor that moved enableThinking/reasoningEffort into IMakeChatRequestOptions.modelCapabilities, restoring the flattened request options shape and moving Anthropic capability helpers back to the Anthropic-specific module.

Changes:

• Remove IModelCapabilityOptions and reintroduce top-level enableThinking / reasoningEffort on IMakeChatRequestOptions, updating call sites and tests accordingly.
• Move tool-search/context-editing capability logic back into platform/networking/common/anthropic.ts and remove corresponding endpoint metadata fields/types.
• Update tool-calling loops/endpoints to forward the new flattened options when issuing chat requests.

Show a summary per file

File	Description
extensions/copilot/src/platform/networking/common/networking.ts	Restores flattened enableThinking/reasoningEffort options and removes modelCapabilities typing.
extensions/copilot/src/platform/networking/common/anthropic.ts	Reintroduces Anthropic-specific capability helpers/constants (tool search + context editing) and updates enablement checks.
extensions/copilot/src/platform/endpoint/test/node/messagesApi.spec.ts	Updates tests to use flattened request options.
extensions/copilot/src/platform/endpoint/node/responsesApi.ts	Switches to options.reasoningEffort when building Responses API requests.
extensions/copilot/src/platform/endpoint/node/messagesApi.ts	Uses flattened thinking/effort fields and changes tool-search/context-editing gating logic.
extensions/copilot/src/platform/endpoint/node/chatEndpoint.ts	Removes tool-search/context-editing endpoint properties and updates Anthropic beta header construction.
extensions/copilot/src/platform/endpoint/common/endpointProvider.ts	Removes tool_search / context_editing from capabilities typing.
extensions/copilot/src/platform/endpoint/common/chatModelCapabilities.ts	Removes tool-search/context-editing helpers/constants that were moved out.
extensions/copilot/src/extension/tools/node/toolSearchTool.ts	Imports supported-model list from Anthropic module.
extensions/copilot/src/extension/prompt/node/searchSubagentToolCallingLoop.ts	Forwards flattened thinking/effort options into subagent requests.
extensions/copilot/src/extension/prompt/node/executionSubagentToolCallingLoop.ts	Forwards flattened thinking/effort options into subagent requests.
extensions/copilot/src/extension/prompt/node/defaultIntentRequestHandler.ts	Updates default tool-calling loop to use flattened thinking options.
extensions/copilot/src/extension/intents/node/toolCallingLoop.ts	Threads reasoningEffort as a first-class fetch option instead of nested modelCapabilities.
extensions/copilot/src/extension/externalAgents/node/oaiLanguageModelServer.ts	Updates request construction to use flattened enableThinking.
extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts	Passes reasoningEffort directly on request options.
extensions/copilot/src/extension/chatSessions/claude/node/claudeLanguageModelServer.ts	Updates request construction to use flattened enableThinking.

Copilot's findings

Comments suppressed due to low confidence (1)

extensions/copilot/src/extension/prompt/node/defaultIntentRequestHandler.ts:702

• fetch() forwards enableThinking but drops opts.reasoningEffort. Since ToolCallingLoop now computes/passes reasoningEffort via ToolCallingLoopFetchOptions, this override should forward it to makeChatRequest2 as well; otherwise the user-selected/configured reasoning effort never reaches the endpoint for default intent requests.

		const location = this.options.overrideRequestLocation ?? this.options.location;
		const isThinkingLocation = location === ChatLocation.Agent || location === ChatLocation.MessagesProxy;
		return this.options.invocation.endpoint.makeChatRequest2({
			...opts,
			enableThinking: isThinkingLocation && opts.enableThinking,
			debugName,
			conversationId: this.options.conversation.sessionId,
			turnId: opts.turnId,
			finishedCb: (text, index, delta) => {

• Files reviewed: 16/16 changed files
• Comments generated: 1