1.0.0-alpha7: collector contract substrate The most architecturally significant release in the 1.x line. Reframes cwv from "real-user CWV with cache visibility" to a correlation substrate where cache state is one of many backend signal axes. The contract defines four collector shapes (synchronous, async-decoration, probe, panel-contribution) frozen at beta1 and lived with for the entire 1.x line. What ships in alpha7: - Four interfaces and default base classes for the collector shapes. - Single-tag service discovery (cwv_collector with interface introspection). - New beacon payload envelope: forwards the entire serverTiming array, condensed navigation timing, viewport object. Backward compatibility for the alpha6 envelope rides out cached HTML; drops at beta1. - Request ID mechanism: kernel.response stamps Server-Timing: cwv-rid;desc=<id> on every page response. Beacon JS forwards it. AsyncContextStore reconciles page-request observations with the later-arriving beacon. - Four migrated/new collectors exercising every shape: UserStateCollector and DrupalCacheCollector (synchronous), KernelTimingDecorator (async-decoration), EdgeCacheProbeCollector (probe), five panel contributors (cache comparison, distribution, per-route, daily counts, recent measurements). - cwv_probes table for synthetic observations. Cache-vendor- agnostic header parsing covers LSCache, Cloudflare, Varnish, Fastly, AWS CloudFront, X-Drupal-Cache, X-Drupal-Dynamic-Cache. No new end-user features land in alpha7; this is the substrate phase. Backend cache instrumentation, render-tree, database, and external-services collectors all build on this contract in the 1.1+ minor releases. See docs/collector-contract.md for the full design and ROADMAP.md for the multi-year trajectory.