Document the Search subagent semantic search setting

[ntrogh]

Product change

• Source: Allow semantic search toggle for search subagent vscode#333869
• Merged: 2026-09-02T22:01:41Z

The advanced experimental setting github.copilot.chat.searchSubagent.subagentSemanticSearchEnabled controls whether the Search subagent can use semantic search. It defaults to true and does not disable semantic search elsewhere.

Why the docs need an update

docs/agents/reference/ai-settings.md does not list the setting or explain its narrow scope.

Suggested documentation

• docs/agents/reference/ai-settings.md: Add the setting to the relevant subagent settings section. Identify it as advanced and experimental, document its default, and clarify that it only affects the Search subagent.

Details to verify

• Setting: github.copilot.chat.searchSubagent.subagentSemanticSearchEnabled.
• Default: true.
• Tags: advanced and experimental.
• Scope: Search subagent semantic search only.

Acceptance criteria

• The AI settings reference includes the exact setting identifier and default.
• The experimental status and Search subagent-only scope are explicit.