Under the hood
Context-usage estimates for embedding hosts no longer count the subagent system-prompt append.
The options built for the get_context_usage control-protocol subtype no longer include appendSubagentSystemPrompt alongside appendSystemPrompt and systemPromptSnapshot. Context-usage and token estimates reported to embedding hosts no longer account for the subagent system-prompt append when sizing context. The appendSubagentSystemPrompt setting itself is unaffected and still used elsewhere, including when building actual prompts; this is a scoped change to the usage-estimation path only.