Why: user chose O2 in the completion signal evaluation; stage 4/5 docs precede any code. Evidence: read-only code location in Agent-Native runtime/llm and Backend runtime (SELF). Impact: docs only; no product code, no paid requests. Refs: docs/superpowers/specs/2026-10-19-fast-slow-completion-signal-evaluation.md Co-authored-by: Cursor <cursoragent@cursor.com>