Paid Measurement Loop

Reads a paid-ads change back against a control over a fixed readback window and returns Promote / Keep-testing / Rollback / Unproven. This is the paid readback loop — distinct from roi-calculator (the ROI/CPA math, which this delegates to) and performance-analyzer (cross-channel rollup); it owns the decision, the window, and the control.

Quick Start

Read back the budget increase I made on Campaign X two weeks ago — did ROAS hold vs the control?
I rotated in new creative on the prospecting set on the 10th — promote, keep testing, or roll back?
Compare ROAS on my Meta vs Google search campaigns (I have both CSV exports)

Skill Contract

Expected output: a per-change readback verdict (Promote / Keep-testing / Rollback / Unproven) with delta-vs-control on a primary metric (ROAS or CPA), the readback window used, normalization notes (attribution window + currency), and a handoff summary ready for memory/ad/paid-measurement-loop/.