Function getDeferredToolsDeltaAttachment

src/utils/attachments.ts:1455–1475

(
  tools: Tools,
  model: string,
  messages: Message[] | undefined,
  scanContext?: DeferredToolsDeltaScanContext,
)

// Exported for compact.ts — the gate must be identical at both call sites.
export function getDeferredToolsDeltaAttachment(
  tools: Tools,
  model: string,
  messages: Message[] | undefined,
  scanContext?: DeferredToolsDeltaScanContext,
): Attachment[] {
  if (!isDeferredToolsDeltaEnabled()) return []
  // These three checks mirror the sync parts of isToolSearchEnabled —
  // the attachment text says "available via ToolSearch", so ToolSearch
  // has to actually be in the request. The async auto-threshold check
  // is not replicated (would double-fire tengu_tool_search_mode_decision);
  // in tst-auto below-threshold the attachment can fire while ToolSearch
  // is filtered out, but that's a narrow case and the tools announced
  // are directly callable anyway.
  if (!isToolSearchEnabledOptimistic()) return []
  if (!modelSupportsToolReference(model)) return []
  if (!isToolSearchToolAvailable(tools)) return []
  const delta = getDeferredToolsDelta(tools, messages ?? [], scanContext)
  if (!delta) return []
  return [{ type: 'deferred_tools_delta', ...delta }]
}

/**
 * Diff the current filtered agent pool against what's already been announced