Remove anthropic.thinking.budgetTokens setting and hardcode budget to 16000

[bhavyaus]

Summary

Remove the user-configurable setting github.copilot.chat.anthropic.thinking.budgetTokens and hardcode the thinking budget to 16000 (the previous default value).

Changes

• configurationService.ts — removed AnthropicThinkingBudget setting definition
• package.json — removed the configuration property
• package.nls.json — removed the localization string
• messagesApi.ts — replaced config lookup with hardcoded 16000, removed "explicitly disabled" code path
• anthropicProvider.ts — replaced config lookup with hardcoded 16000, simplified _getThinkingBudget()
• messagesApi.spec.ts — removed mockConfig.setConfig call and cleaned up unused imports/variables

[vs-code-engineering]

This PR will be automatically cherry-picked to release/1.118 when merged.

[Copilot]

Pull request overview

This PR removes the user-facing configuration for Anthropic “thinking” budget tokens and standardizes behavior by hardcoding the budget to the previous default (16000) across the Anthropic request builders.

Changes:

• Removes the github.copilot.chat.anthropic.thinking.budgetTokens setting from configuration definitions and extension contributions.
• Hardcodes the Anthropic thinking budget to 16000 in both the Messages API request builder and the BYOK Anthropic provider.
• Updates tests and localization/configuration assets to eliminate now-dead configuration wiring.

Show a summary per file

File	Description
extensions/copilot/src/platform/endpoint/test/node/messagesApi.spec.ts	Removes test configuration setup tied to the deleted setting.
extensions/copilot/src/platform/endpoint/node/messagesApi.ts	Replaces config lookup/disable path with a hardcoded thinking budget and simplified logic.
extensions/copilot/src/platform/configuration/common/configurationService.ts	Deletes the internal ConfigKey entry for the removed setting.
extensions/copilot/src/extension/byok/vscode-node/anthropicProvider.ts	Hardcodes thinking budget in BYOK Anthropic provider and simplifies _getThinkingBudget().
extensions/copilot/package.nls.json	Removes the localization string for the deleted setting.
extensions/copilot/package.json	Removes the contributed configuration property for the deleted setting.

Copilot's findings

Comments suppressed due to low confidence (1)

extensions/copilot/src/platform/endpoint/node/messagesApi.ts:148

• This introduces a hardcoded magic number (16000) inside request-body construction. Since the same budget is also hardcoded elsewhere (e.g. BYOK Anthropic provider), consider defining a shared constant (and/or a single helper) so the default can’t drift across codepaths.

		const hardcodedBudget = 16000;
		if (endpoint.supportsAdaptiveThinking) {
			thinkingConfig = { type: 'adaptive', display: 'summarized' };
		} else if (endpoint.maxThinkingBudget && endpoint.minThinkingBudget) {
			const maxTokens = options.postOptions.max_tokens ?? 1024;
			const minBudget = endpoint.minThinkingBudget ?? 1024;
			const normalizedBudget = hardcodedBudget < minBudget ? minBudget : hardcodedBudget;
			const maxBudget = endpoint.maxThinkingBudget ?? 32000;
			const thinkingBudget = Math.min(maxBudget, maxTokens - 1, normalizedBudget);

• Files reviewed: 6/6 changed files
• Comments generated: 2