Records why codegraph read savings (-75%) under-convert to wall-clock (-16%): the bottleneck is round-trips + the synthesis turn, not reads. Ablation (arms A-I) shows explore is 68% of payload but load-bearing, trace is path-scoped but under-adopted, instruction/description steering cannot match an append-prompt's salience (and regresses), and the shippable win is making the trace output sufficient (arm I). Adds harness: seq-matrix, run-arms/arms-*, parse-arms.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Colby McHenry