Price QQ16 scratch access and stream bank-major sweeps

[petalas]

Summary

PR #2709 leaves the physical seek cost of QQ16 output-slice scratch access open. This source-bound package prices its two scalar sweeps and supplies one paid streaming variant.

unchanged per-site word, bank-major: 8564*N^2 + 306*N - 2 steps
unchanged per-site word, site-major: 9300*N - 432 steps
24 extra unit ADDs, bank-major streaming: 11866*N - 2840 steps

Eight scratch subtractions use an existing dirty Z0 output and restore it exactly. The variant needs no additional payload array in the declared word-address model. It raises the complete added local scalar allowance from 17,280 to 17,472 and requires exclusive W-bank ownership across each whole window. Native events remain unchanged.

The package includes a proof for every positive integer N, a pinned compressed source word, exact receipts, a standalone checker and registered replay. Credit ywz65/PR #2709 and #2540, commdata2338/PR #2651, and the retained QQ16 lineage. Direct source head is d7749c49e967b214537c0bd832e435e177e21d4f; exact pins and provenance are in SOURCES.json and TASK.json.

Evidence

• Before: PR Reuse QQ16 output slices under an explicit scratch-access contract #2709's access contract leaves seeks and staging unpriced.
  After: exact coefficients derived from the literal word, checked against address traces at N=1..32,64, with rational dirty-state and restoration controls at N=2,3,5.
• CPython 3.12.15 registered normal/optimized replay and four artifact tests pass. Direct Python 3.14 checks and Ruff E/F/B/UP/SIM pass. Git-free read-only export, source/typed-receipt corruption and equivalent recompression are covered.

python3.12 -I -B scripts/research_package.py --package research/qq16-scratch-travel

Priority revision 5, task joint-query-controller; initial main c3c94c2ea, checked main 78ceed413, relevant guidance/inputs unchanged. Claim and handoff. Complete overlap snapshots and limitations are recorded in TASK.json.

Merge Danger

Door: two-way.

Blast Radius: isolated.

One new research package and its opt-in replay. No selected-frontier change. These are fixed-protocol address tariffs, not global schedule minima or a runtime/kappa improvement. Whole-window ownership/retention, bit arithmetic, instruction control, surrounding native placement and a complete caller remain open. No selected cold replay, native-kernel admission or Lean proof is claimed. New work is Apache-2.0.