Read /workspace/maths/notes/supergrok-2026-08-17/house.md and follow it.

Your folder: /workspace/maths/problems/chowla-cosine Your problem: P15, Chowla's cosine problem.

Read PROBLEM.md, notes/lists/2026-08-16-proposed-50.md P15, notes/picks/2026-08-16-judge-codex.md P15, refs/walkthrough-style.md.

Goal: a certified explicit constant c that is new, or an auxiliary trigonometric polynomial whose bound is independently checkable and strictly beats the best published universal (or n>=n0) constant you can cite.

An SDP float with no exact certificate is not a dent. Do not claim the full square-root conjecture unless you prove it.

Start by fetching Green 100 #81 and the current best explicit c. Work until you have a verified dent or a documented residue with replayable compute. Write ATTACK.md as you go. Finish with WALKTHROUGH.md and RESEARCH.md.