The ai.Coach interface gains a grounding parameter carrying standing
context about the user (the knowledge port). buildPrompt injects an
"About the user" block only when grounding is non-empty, so an empty
grounding produces a byte-for-byte unchanged prompt. Drift judge and
nudge are untouched.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>