# Plan

1. Schema: optional `observed_at` (ISO date-time) on `request` events, and
   `started_at` (ISO date-time) and `elapsed_ms` (non-negative number) on
   `request-finished` and `request-failed` events.
2. Collector: stamp `observed_at` when a request is observed and copy the
   browser's `timing().startTime` and `responseEnd` into `started_at` and
   `elapsed_ms` when it reports them, admitting the strings with the other
   metadata.
3. Records: index each transaction's single finished or failed start and
   duration and give each attributable record `startedDateTime` and `time`;
   add a limitation when any record is timed.
4. Comparison: drop both fields from network evidence before fingerprinting and
   commit the rule in the built-in list and the comparison limitation.
5. Docs: the scenario contract's network evidence and the environment docs'
   browser scenario section.
6. Tests: the collector stamps both fields, records take them, the state learns
   the HAR's clock and verdicts from a timed scenario and none from an untimed
   or partly untimed one, a request that never ended or ended twice falls back
   to its observation, comparisons ignore the times (also against an untimed
   capture), and the real-Chrome network lane checks every request is observed
   and every finished request carries the browser's start and duration.